WorldWideScience

Sample records for hybrid zones introgression

  1. Climate, demography, and zoogeography predict introgression thresholds in salmonid hybrid zones in Rocky Mountain streams

    Science.gov (United States)

    Michael K. Young; Daniel J. Isaak; Kevin S. McKelvey; Taylor M. Wilcox; Daniel M. Bingham; Kristine L. Pilgrim; Kellie J. Carim; Matthew R. Campbell; Matthew P. Corsi; Dona L. Horan; David E. Nagel; Michael K. Schwartz

    2016-01-01

    Among the many threats posed by invasions of nonnative species is introgressive hybridization, which can lead to the genomic extinction of native taxa. This phenomenon is regarded as common and perhaps inevitable among native cutthroat trout and introduced rainbow trout in western North America, despite that these taxa naturally co-occur in some locations. We conducted...

  2. Introgressive hybridization as a promoter of genome reshuffling in natural homoploid fish hybrids (Cyprinidae, Leuciscinae)

    Czech Academy of Sciences Publication Activity Database

    Pereira, C. S.; Aboim, M. A.; Ráb, Petr; Collares-Pereira, M. J.

    2014-01-01

    Roč. 112, č. 3 (2014), s. 343-350 ISSN 0018-067X Institutional support: RVO:67985904 Keywords : comparative genome hybridization * hybrid zones * introgression Subject RIV: EG - Zoology Impact factor: 3.805, year: 2014

  3. Distortion of symmetrical introgression in a hybrid zone: evidence for locus-specific selection and uni-directional range expansion

    NARCIS (Netherlands)

    Johannesen, J.; Johannesen, B.; Baran, I.; Rizvan-Tunc, M.; Kiefer, A.; Veith, M.K.H.

    2006-01-01

    The fate of species integrity upon natural hybridization depends on the interaction between selection and dispersal. The relative significance of these processes may be studied in the initial phase of contact before selection and gene flow reach equilibrium. Here we study a hybrid zone of two

  4. Characterizing the physical and genetic structure of the lodgepole pine × jack pine hybrid zone: mosaic structure and differential introgression.

    Science.gov (United States)

    Cullingham, Catherine I; James, Patrick M A; Cooke, Janice E K; Coltman, David W

    2012-12-01

    Understanding the physical and genetic structure of hybrid zones can illuminate factors affecting their formation and stability. In north-central Alberta, lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia) and jack pine (Pinus banksiana Lamb) form a complex and poorly defined hybrid zone. Better knowledge of this zone is relevant, given the recent host expansion of mountain pine beetle into jack pine. We characterized the zone by genotyping 1998 lodgepole, jack pine, and hybrids from British Columbia, Alberta, Saskatchewan, Ontario, and Minnesota at 11 microsatellites. Using Bayesian algorithms, we calculated genetic ancestry and used this to model the relationship between species occurrence and environment. In addition, we analyzed the ancestry of hybrids to calculate the genetic contribution of lodgepole and jack pine. Finally, we measured the amount of gene flow between the pure species. We found the distribution of the pine classes is explained by environmental variables, and these distributions differ from classic distribution maps. Hybrid ancestry was biased toward lodgepole pine; however, gene flow between the two species was equal. The results of this study suggest that the hybrid zone is complex and influenced by environmental constraints. As a result of this analysis, range limits should be redefined.

  5. Introgressive hybridization: brown bears as vectors for polar bear alleles.

    Science.gov (United States)

    Hailer, Frank

    2015-03-01

    The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. © 2015 John Wiley & Sons Ltd.

  6. Repeated unidirectional introgression towards Populus balsamifera in contact zones of exotic and native poplars

    NARCIS (Netherlands)

    Thompson, S.L.; Lamothe, M.; Meirmans, P.G.; Périnet, P.; Isabel, N.

    2010-01-01

    As the evolutionary significance of hybridization is largely dictated by its extent beyond the first generation, we broadly surveyed patterns of introgression across a sympatric zone of two native poplars (Populus balsamifera, Populus deltoides) in Quebec, Canada within which European exotic Populus

  7. Extensive hybridization and introgression between Melastoma candidum and M. sanguineum.

    Directory of Open Access Journals (Sweden)

    Ting Liu

    Full Text Available Natural hybridization can lead to various evolutionary outcomes in plants, including hybrid speciation and interspecific gene transfer. It can also cause taxonomic problems, especially in plant genera containing multiple species. In this study, the hybrid status of Melastoma affine, the most widespread taxon in this genus, and introgression between its putative parental species, M. candidum and M. sanguineum, were assessed on two sites, Hainan and Guangdong, using 13 SSR markers and sequences of a chloroplast intergenic spacer. Bayesian-based STRUCTURE analysis detected two most likely distinct clusters for the three taxa, and 76.0% and 73.9% of the morphologically identified individuals of M. candidum and M. sanguineum were correctly assigned, respectively. 74.5% of the M. affine individuals had a membership coefficient to either parental species between 0.1 and 0.9, suggesting admixture between M. candidum and M. sanguineum. Furthermore, NewHybrids analysis suggested that most individuals of M. affine were F2 hybrids or backcross hybrids to M. candidum, and that there was extensive introgression between M. candidum and M. sanguineum. These SSR data thus provides convincing evidence for hybrid origin of M. affine and extensive introgression between M. candidum and M. sanguineum. Chloroplast DNA results were consistent with this conclusion. Much higher hybrid frequency on the more disturbed Guangdong site suggests that human disturbance might offer suitable habitats for the survival of hybrids, a hypothesis that is in need of further testing.

  8. Discordant introgression in a rapidly expanding hybrid swarm

    Science.gov (United States)

    Ward, Jessica L.; Blum, Mike J.; Walters, David M.; Porter, Brady A.; Burkhead, Noel; Freeman, Byron

    2012-01-01

    The erosion of species boundaries can involve rapid evolutionary change. Consequently, many aspects of the process remain poorly understood, including the formation, expansion, and evolution of hybrid swarms. Biological invasions involving hybridization present exceptional opportunities to study the erosion of species boundaries because timelines of interactions and outcomes are frequently well known. Here, we examined clinal variation across codominant and maternally inherited genetic markers as well as phenotypic traits to characterize the expansion and evolution of a hybrid swarm between native Cyprinella venusta and invasive Cyprinella lutrensis minnows. Discordant introgression of phenotype, microsatellite multilocus genotype, and mtDNA haplotype indicates that the observable expansion of the C. venusta x C. lutrensis hybrid swarm is a false invasion front. Both parental and hybrid individuals closely resembling C. lutrensis are numerically dominant in the expansion wake, indicating that the non-native parental phenotype may be selectively favored. These findings show that cryptic introgression can extend beyond the phenotypic boundaries of hybrid swarms and that hybrid swarms likely expand more rapidly than can be documented from phenotypic variation alone. Similarly, dominance of a single parental phenotype following an introduction event may lead to instances of species erosion being mistaken for species displacement without hybridization.

  9. Mitochondrial introgression suggests extensive ancestral hybridization events among Saccharomyces species.

    Science.gov (United States)

    Peris, David; Arias, Armando; Orlić, Sandi; Belloch, Carmela; Pérez-Través, Laura; Querol, Amparo; Barrio, Eladio

    2017-03-01

    Horizontal gene transfer (HGT) in eukaryotic plastids and mitochondrial genomes is common, and plays an important role in organism evolution. In yeasts, recent mitochondrial HGT has been suggested between S. cerevisiae and S. paradoxus. However, few strains have been explored given the lack of accurate mitochondrial genome annotations. Mitochondrial genome sequences are important to understand how frequent these introgressions occur, and their role in cytonuclear incompatibilities and fitness. Indeed, most of the Bateson-Dobzhansky-Muller genetic incompatibilities described in yeasts are driven by cytonuclear incompatibilities. We herein explored the mitochondrial inheritance of several worldwide distributed wild Saccharomyces species and their hybrids isolated from different sources and geographic origins. We demonstrated the existence of several recombination points in mitochondrial region COX2-ORF1, likely mediated by either the activity of the protein encoded by the ORF1 (F-SceIII) gene, a free-standing homing endonuclease, or mostly facilitated by A+T tandem repeats and regions of integration of GC clusters. These introgressions were shown to occur among strains of the same species and among strains of different species, which suggests a complex model of Saccharomyces evolution that involves several ancestral hybridization events in wild environments. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Obtaining of interspecific hybrids for pea introgressive breeding

    Directory of Open Access Journals (Sweden)

    Sergey Vasilevich Bobkov

    2015-09-01

    Full Text Available Background. Overcoming of reproductive isolation, identification and transfer of agronomic value genes from wild relatives into cultivated pea genomes is an important task for pea introgressive breeding. Materials and methods. Reciprocal hybridization of cultivated pea with wide set of P. fulvum accessions was conducted. Identification of hybrids was carried out with use of biochemical and morphological markers. Identification of unique protein was conducted with use of electrophoretic spectra of mature seeds. Results. Pea interspecific hybrids were obtained in two reciprocal directions of crosses. Cross efficiency in Р. sativum × P. fulvum and P. fulvum × Р. sativum combinations was 36 % and 7 %, respectively. All tested seeds in crosses Р. sativum × P. fulvum were hybrids. Crosses in direction P. fulvum × Р. sativum led to formation of puny seeds restricted in embryo growth. Protein markers of one seed derived in cross P. fulvum × Р. sativum proved its hybrid nature. Morphological markers demonstrated that plant derived from another cross was also a hybrid. Culture of immature embryos was developed for recovering plants in interspecific crosses. Morphogenic calli and regenerated plants were obtained in culture of immature embryos P. fulvum (И592589 × Р. sativum (Aest. Identification of unique protein 7 of P. fulvum was conducted. Inheritance of that protein was proved as monogenic dominant. Conclusion. Efficiency of hybridization in combination P. fulvum × Р. sativum was significantly less in compare to reciprocal one. All products of that cross combination were tested as hybrids. Unique protein 7 of P. fulvum was revealed as a result of mature seed electrophoretic spectra analysis. Inheritance of that protein was determined as monogenic dominant.

  11. Fitness of crop-wild hybrid sunflower under competitive conditions: implications for crop-to-wild introgression.

    Science.gov (United States)

    Mercer, Kristin L; Emry, D Jason; Snow, Allison A; Kost, Matthew A; Pace, Brian A; Alexander, Helen M

    2014-01-01

    Understanding the likelihood and extent of introgression of novel alleles in hybrid zones requires comparison of lifetime fitness of parents and hybrid progeny. However, fitness differences among cross types can vary depending on biotic conditions, thereby influencing introgression patterns. Based on past work, we predicted that increased competition would enhance introgression between cultivated and wild sunflower (Helianthus annuus) by reducing fitness advantages of wild plants. To test this prediction, we established a factorial field experiment in Kansas, USA where we monitored the fitness of four cross types (Wild, F1, F2, and BCw hybrids) under different levels of interspecific and intraspecific competition. Intraspecific manipulations consisted both of density of competitors and of frequency of crop-wild hybrids. We recorded emergence of overwintered seeds, survival to reproduction, and numbers of seeds produced per reproductive plant. We also calculated two compound fitness measures: seeds produced per emerged seedling and seeds produced per planted seed. Cross type and intraspecific competition affected emergence and survival to reproduction, respectively. Further, cross type interacted with competitive treatments to influence all other fitness traits. More intense competition treatments, especially related to density of intraspecific competitors, repeatedly reduced the fitness advantage of wild plants when considering seeds produced per reproductive plant and per emerged seedling, and F2 plants often became indistinguishable from the wilds. Wild fitness remained superior when seedling emergence was also considered as part of fitness, but the fitness of F2 hybrids relative to wild plants more than quadrupled with the addition of interspecific competitors and high densities of intraspecific competitors. Meanwhile, contrary to prediction, lower hybrid frequency reduced wild fitness advantage. These results emphasize the importance of taking a full life cycle

  12. Fitness of crop-wild hybrid sunflower under competitive conditions: implications for crop-to-wild introgression.

    Directory of Open Access Journals (Sweden)

    Kristin L Mercer

    Full Text Available Understanding the likelihood and extent of introgression of novel alleles in hybrid zones requires comparison of lifetime fitness of parents and hybrid progeny. However, fitness differences among cross types can vary depending on biotic conditions, thereby influencing introgression patterns. Based on past work, we predicted that increased competition would enhance introgression between cultivated and wild sunflower (Helianthus annuus by reducing fitness advantages of wild plants. To test this prediction, we established a factorial field experiment in Kansas, USA where we monitored the fitness of four cross types (Wild, F1, F2, and BCw hybrids under different levels of interspecific and intraspecific competition. Intraspecific manipulations consisted both of density of competitors and of frequency of crop-wild hybrids. We recorded emergence of overwintered seeds, survival to reproduction, and numbers of seeds produced per reproductive plant. We also calculated two compound fitness measures: seeds produced per emerged seedling and seeds produced per planted seed. Cross type and intraspecific competition affected emergence and survival to reproduction, respectively. Further, cross type interacted with competitive treatments to influence all other fitness traits. More intense competition treatments, especially related to density of intraspecific competitors, repeatedly reduced the fitness advantage of wild plants when considering seeds produced per reproductive plant and per emerged seedling, and F2 plants often became indistinguishable from the wilds. Wild fitness remained superior when seedling emergence was also considered as part of fitness, but the fitness of F2 hybrids relative to wild plants more than quadrupled with the addition of interspecific competitors and high densities of intraspecific competitors. Meanwhile, contrary to prediction, lower hybrid frequency reduced wild fitness advantage. These results emphasize the importance of taking

  13. Fitness of Crop-Wild Hybrid Sunflower under Competitive Conditions: Implications for Crop-to-Wild Introgression

    Science.gov (United States)

    Mercer, Kristin L.; Emry, D. Jason; Snow, Allison A.; Kost, Matthew A.; Pace, Brian A.; Alexander, Helen M.

    2014-01-01

    Understanding the likelihood and extent of introgression of novel alleles in hybrid zones requires comparison of lifetime fitness of parents and hybrid progeny. However, fitness differences among cross types can vary depending on biotic conditions, thereby influencing introgression patterns. Based on past work, we predicted that increased competition would enhance introgression between cultivated and wild sunflower (Helianthus annuus) by reducing fitness advantages of wild plants. To test this prediction, we established a factorial field experiment in Kansas, USA where we monitored the fitness of four cross types (Wild, F1, F2, and BCw hybrids) under different levels of interspecific and intraspecific competition. Intraspecific manipulations consisted both of density of competitors and of frequency of crop-wild hybrids. We recorded emergence of overwintered seeds, survival to reproduction, and numbers of seeds produced per reproductive plant. We also calculated two compound fitness measures: seeds produced per emerged seedling and seeds produced per planted seed. Cross type and intraspecific competition affected emergence and survival to reproduction, respectively. Further, cross type interacted with competitive treatments to influence all other fitness traits. More intense competition treatments, especially related to density of intraspecific competitors, repeatedly reduced the fitness advantage of wild plants when considering seeds produced per reproductive plant and per emerged seedling, and F2 plants often became indistinguishable from the wilds. Wild fitness remained superior when seedling emergence was also considered as part of fitness, but the fitness of F2 hybrids relative to wild plants more than quadrupled with the addition of interspecific competitors and high densities of intraspecific competitors. Meanwhile, contrary to prediction, lower hybrid frequency reduced wild fitness advantage. These results emphasize the importance of taking a full life cycle

  14. Asymmetric hybridization and introgression between pink salmon and chinook salmon in the Laurentian Great Lakes

    Science.gov (United States)

    Rosenfield, Jonathan A.; Todd, Thomas; Greil, Roger

    2000-01-01

    Among Pacific salmon collected in the St. Marys River, five natural hybrids of pink salmon Oncorhynchus gorbuscha and chinook salmon Oncorhynchus tshawytscha and one suspected backcross have been detected using morphologic, meristic, and color evidence. One allozyme (LDH, l-lactate dehydrogenase from muscle) and one nuclear DNA locus (growth hormone) for which species-specific fixed differences exist were analyzed to detect additional hybrids and to determine if introgression had occurred. Restriction fragment length polymorphism of mitochondrial DNA (mtDNA) was used to identify the maternal parent of each hybrid. Evidence of introgression was found among the five previously identified hybrids. All hybrid specimens had chinook salmon mtDNA, indicating that hybridization between chinook salmon and pink salmon in the St. Marys River is asymmetric and perhaps unidirectional. Ecological, physiological, and sexual selection forces may contribute to this asymmetric hybridization. Introgression between these highly differentiated species has implications for management, systematics, and conservation of Pacific salmon.

  15. An Arabidopsis introgression zone studied at high spatio-temporal resolution: interglacial and multiple genetic contact exemplified using whole nuclear and plastid genomes.

    Science.gov (United States)

    Hohmann, Nora; Koch, Marcus A

    2017-10-23

    Gene flow between species, across ploidal levels, and even between evolutionary lineages is a common phenomenon in the genus Arabidopsis. However, apart from two genetically fully stabilized allotetraploid species that have been investigated in detail, the extent and temporal dynamics of hybridization are not well understood. An introgression zone, with tetraploid A. arenosa introgressing into A. lyrata subsp. petraea in the Eastern Austrian Forealps and subsequent expansion towards pannonical lowlands, was described previously based on morphological observations as well as molecular data using microsatellite and plastid DNA markers. Here we investigate the spatio-temporal context of this suture zone, making use of the potential of next-generation sequencing and whole-genome data. By utilizing a combination of nuclear and plastid genomic data, the extent, direction and temporal dynamics of gene flow are elucidated in detail and Late Pleistocene evolutionary processes are resolved. Analysis of nuclear genomic data significantly recognizes the clinal structure of the introgression zone, but also reveals that hybridization and introgression is more common and substantial than previously thought. Also tetraploid A. lyrata and A. arenosa subsp. borbasii from outside the previously defined suture zone show genomic signals of past introgression. A. lyrata is shown to serve usually as the maternal parent in these hybridizations, but one exception is identified from plastome-based phylogenetic reconstruction. Using plastid phylogenomics with secondary time calibration, the origin of A. lyrata and A. arenosa lineages is pre-dating the last three glaciation complexes (approx. 550,000 years ago). Hybridization and introgression followed during the last two glacial-interglacial periods (since approx. 300,000 years ago) with later secondary contact at the northern and southern border of the introgression zone during the Holocene. Footprints of adaptive introgression in the

  16. Interspecies introgressive hybridization in spiny frogs Quasipaa (Family Dicroglossidae) revealed by analyses on multiple mitochondrial and nuclear genes.

    Science.gov (United States)

    Zhang, Qi-Peng; Hu, Wen-Fang; Zhou, Ting-Ting; Kong, Shen-Shen; Liu, Zhi-Fang; Zheng, Rong-Quan

    2018-01-01

    Introgression may lead to discordant patterns of variation among loci and traits. For example, previous phylogeographic studies on the genus Quasipaa detected signs of genetic introgression from genetically and morphologically divergent Quasipaa shini or Quasipaa spinosa . In this study, we used mitochondrial and nuclear DNA sequence data to verify the widespread introgressive hybridization in the closely related species of the genus Quasipaa , evaluate the level of genetic diversity, and reveal the formation mechanism of introgressive hybridization. In Longsheng, Guangxi Province, signs of asymmetrical nuclear introgression were detected between Quasipaa boulengeri and Q. shini . Unidirectional mitochondrial introgression was revealed from Q. spinosa to Q. shini . By contrast, bidirectional mitochondrial gene introgression was detected between Q. spinosa and Q. shini in Lushan, Jiangxi Province. Our study also detected ancient hybridizations between a female Q. spinosa and a male Q. jiulongensis in Zhejiang Province. Analyses on mitochondrial and nuclear genes verified three candidate cryptic species in Q. spinosa , and a cryptic species may also exist in Q. boulengeri . However, no evidence of introgressive hybridization was found between Q. spinosa and Q. boulengeri . Quasipaa exilispinosa from all the sampling localities appeared to be deeply divergent from other communities. Our results suggest widespread introgressive hybridization in closely related species of Quasipaa and provide a fundamental basis for illumination of the forming mechanism of introgressive hybridization, classification of species, and biodiversity assessment in Quasipaa .

  17. Widespread hybridization and bidirectional introgression in sympatric species of coral reef fish

    KAUST Repository

    Harrison, Hugo B.

    2017-10-28

    Coral reefs are highly diverse ecosystems, where numerous closely related species often coexist. How new species arise and are maintained in these high geneflow environments have been long-standing conundrums. Hybridization and patterns of introgression between sympatric species provide a unique insight into the mechanisms of speciation and the maintenance of species boundaries. In this study, we investigate the extent of hybridization between two closely related species of coral reef fish: the common coral trout (Plectropomus leopardus) and the bar-cheek coral trout (Plectropomus maculatus). Using a complementary set of 25 microsatellite loci, we distinguish pure genotype classes from first- and later-generation hybrids, identifying 124 interspecific hybrids from a collection of 2,991 coral trout sampled in inshore and mid-shelf reefs of the southern Great Barrier Reef. Hybrids were ubiquitous among reefs, fertile and spanned multiple generations suggesting both ecological and evolutionary processes are acting to maintain species barriers. We elaborate on these finding to investigate the extent of genomic introgression and admixture from 2,271 SNP loci recovered from a ddRAD library of pure and hybrid individuals. An analysis of genomic clines on recovered loci indicates that 261 SNP loci deviate from a model of neutral introgression, of which 132 indicate a pattern of introgression consistent with selection favouring both hybrid and parental genotypes. Our findings indicate genome-wide, bidirectional introgression between two sympatric species of coral reef fishes and provide further support to a growing body of evidence for the role of hybridization in the evolution of coral reef fishes.

  18. Genomic markers reveal introgressive hybridization in the Indo-West Pacific mangroves: a case study.

    Directory of Open Access Journals (Sweden)

    Mei Sun

    2011-05-01

    Full Text Available Biodiversity of mangrove ecosystems is difficult to assess, at least partly due to lack of genetic verification of morphology-based documentation of species. Natural hybridization, on the one hand, plays an important role in evolution as a source of novel gene combinations and a mechanism of speciation. However, on the other hand, recurrent introgression allows gene flow between species and could reverse the process of genetic differentiation among populations required for speciation. To understand the dynamic evolutionary consequences of hybridization, this study examines genomic structure of hybrids and parental species at the population level. In the Indo-West Pacific, Bruguiera is one of the dominant mangrove genera and species ranges overlap extensively with one another. Morphological intermediates between sympatric Bruguiera gymnorrhiza and Bruguiera sexangula have been reported as a variety of B. sexangula or a new hybrid species, B. × rhynchopetala. However, the direction of hybridization and extent of introgression are unclear. A large number of species-specific inter-simple sequence repeat (ISSR markers were found in B. gymnorrhiza and B. sexangula, and the additive ISSR profiling of B. × rhynchopetala ascertained its hybrid status and identified its parental origin. The varying degree of scatterness among hybrid individuals in Principal Coordinate Analysis and results from NewHybrids analysis indicate that B. × rhynchopetala comprises different generations of introgressants in addition to F(1s. High genetic relatedness between B. × rhynchopetala and B. gymnorrhiza based on nuclear and chloroplast sequences suggests preferential hybrid backcrosses to B. gymnorrhiza. We conclude that B. × rhynchopetala has not evolved into an incipient hybrid species, and its persistence can be explained by recurrent hybridization and introgression. Genomic data provide insights into the hybridization dynamics of mangrove plants. Such information

  19. A Phylogenetic Synthesis for Oceanic Dolphins: Total Evidence, Cytonuclear Discordance, and Possible Introgressive Hybridization

    OpenAIRE

    Haisten, David

    2016-01-01

    Introgressive hybridization is increasingly being detected in vertebrate taxa but was thought to be rare in mammals. Recent evidence suggests that this view might not correct and cetaceans may be pre-disposed for the capacity to hybridize. Numerous instances of cetacean (dolphins, whales, and porpoises) hybridization have been reported both in captivity and in the wild, many of which occurred in oceanic dolphins: family Delphinidae. The rapid radiation of Delphinidae commenced during the Mio...

  20. Natural hybridization and introgression between Ligularia cymbulifera and L. tongolensis (Asteraceae, Senecioneae) in four different locations.

    Science.gov (United States)

    Yu, Jiaojun; Kuroda, Chiaki; Gong, Xun

    2014-01-01

    Natural hybridization has been considered to represent an important factor influencing the high diversity of the genus Ligularia Cass. in the Hengduan Mountains, China. Natural hybridization has been confirmed to occur frequently in Ligularia. To date, however, it has been demonstrated only within a single population. In this paper, we present evidence of natural hybridization in Ligularia from four different locations. The internal transcribed spacer (ITS) region of the nuclear ribosomal DNA and three chloroplast intergenic spacers (trnK-rps16, trnL-rpl32 and trnQ-5'rps16) of 149 accessions of putative hybrids and their putative parents (L. cymbulifera and L. tongolensis) were analyzed for evidence of hybridization. The ITS data clearly distinguished two putative parental species and sympatric L. vellerea and supported the hypothesis that those morphological intermediates were products of natural hybridization between L. cymbulifera and L. tongolensis. Moreover, several identified morphological parents were actual introgressed products. Because of hybridization and introgression, chloroplast DNA sequences generated a poorly resolved network. The present results indicate that varying degrees of hybridization and introgression occur differently depending on the habitat context. We conclude that gene flow caused by natural hybridization in Ligularia indeed plays an important role in the species diversity.

  1. Genetic conflict outweighs heterogametic incompatibility in the mouse hybrid zone?

    Directory of Open Access Journals (Sweden)

    Dufková Petra

    2008-10-01

    Full Text Available Abstract Background The Mus musculus musculus/M. m. domesticus contact zone in Europe is characterised by sharp frequency discontinuities for sex chromosome markers at the centre of wider clines in allozyme frequencies. Results We identify a triangular area (approximately 330 km2 where the musculus Y chromosome introgresses across this front for up to 22 km into domesticus territory. Introgression of the Y chromosome is accompanied by a perturbation of the census sex ratio: the sex ratio is significantly female biased in musculus localities and domesticus localities lacking Y chromosome introgression. In contrast, where the musculus Y is detected in domesticus localities, the sex ratio is close to parity, and significantly different from both classes of female biased localities. The geographic position of an abrupt cline in an X chromosome marker, and autosomal clines centred on the same position, seem unaffected by the musculus Y introgression. Conclusion We conclude that sex ratio distortion is playing a role in the geographic separation of speciation genes in this section of the mouse hybrid zone. We suggest that clines for genes involved in sex-ratio distortion have escaped from the centre of the mouse hybrid zone, causing a decay in the barrier to gene flow between the two house mouse taxa.

  2. Mitochondrial Recombination and Introgression during Speciation by Hybridization.

    Science.gov (United States)

    Leducq, Jean-Baptiste; Henault, Mathieu; Charron, Guillaume; Nielly-Thibault, Lou; Terrat, Yves; Fiumera, Heather L; Shapiro, B Jesse; Landry, Christian R

    2017-08-01

    Genome recombination is a major source of genotypic diversity and contributes to adaptation and speciation following interspecies hybridization. The contribution of recombination in these processes has been thought to be largely limited to the nuclear genome because organelles are mostly uniparentally inherited in animals and plants, which prevents recombination. Unicellular eukaryotes such as budding yeasts do, however, transmit mitochondria biparentally, suggesting that during hybridization, both parents could provide alleles that contribute to mitochondrial functions such as respiration and metabolism in hybrid populations or hybrid species. We examined the dynamics of mitochondrial genome transmission and evolution during speciation by hybridization in the natural budding yeast Saccharomyces paradoxus. Using population-scale mitochondrial genome sequencing in two endemic North American incipient species SpB and SpC and their hybrid species SpC*, we found that both parental species contributed to the hybrid mitochondrial genome through recombination. We support our findings by showing that mitochondrial recombination between parental types is frequent in experimental crosses that recreate the early step of this speciation event. In these artificial hybrids, we observed that mitochondrial genome recombination enhances phenotypic variation among diploid hybrids, suggesting that it could play a role in the phenotypic differentiation of hybrid species. Like the nuclear genome, the mitochondrial genome can, therefore, also play a role in hybrid speciation. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Hybrids and horizontal transfer: introgression allows adaptive allele discovery

    Czech Academy of Sciences Publication Activity Database

    Schmickl, Roswitha; Marburger, S.; Bray, S.; Yant, L.

    2017-01-01

    Roč. 68, č. 20 (2017), s. 5453-5470 ISSN 0022-0957 R&D Projects: GA ČR(CZ) GJ16-15134Y Institutional support: RVO:67985939 Keywords : evolution * hybridization * population genetics Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 5.830, year: 2016

  4. Marked hybridization and introgression in Ophrys sect. Pseudophrys in the western Iberian Peninsula.

    Science.gov (United States)

    Cotrim, Helena; Monteiro, Filipa; Sousa, Eva; Pinto, Manuel J; Fay, Michael F

    2016-04-01

    Orchids in the genus Ophrys represent extraordinary cases of tight coevolution between plants and their pollinators, and as a result, they present opportunities for studying hybridization, or a lack thereof, during speciation. However, few studies assess the real effect of hybridization in diversification. The three most representative species of section Pseudophrys in the western Iberian Peninsula-O. dyris, O. fusca, and O. lutea-were chosen to study evolutionary relationships and examine speciation. Using eight specific nuclear microsatellite loci, 357 individuals from 28 locations were studied; 142 of these samples were also studied with four plastid microsatellite loci. Data were analyzed using Bayesian cluster analysis, a median-joint network, and multivariate analysis. Many O. dyris and O. fusca specimens had three or four alleles and were therefore treated as tetraploid. Ophrys dyris is poorly genetically separated from O. fusca, and pure populations are rare. Ophrys fusca and O. lutea are distinct, but hybrids/introgressed individuals were detected in most of the populations and supported by plastid haplotypes. Ophrys fusca is subdivided into three well-delimited genetic lineages with a strict geographic correspondence confirmed by plastid haplotypes. Because postzygotic barriers are weak, leakage in this highly specialized orchid-pollinator system contributes to hybridization and introgression. These leakages may have occurred during periods of past climate change, promoting homogenization and the potential for generations of new biodiversity via production of novel genotypes/phenotypes interacting with pollinators. © 2016 Botanical Society of America.

  5. Reticulate evolution: frequent introgressive hybridization among chinese hares (genus lepus revealed by analyses of multiple mitochondrial and nuclear DNA loci

    Directory of Open Access Journals (Sweden)

    Wu Shi-Fang

    2011-07-01

    Full Text Available Abstract Background Interspecific hybridization may lead to the introgression of genes and genomes across species barriers and contribute to a reticulate evolutionary pattern and thus taxonomic uncertainties. Since several previous studies have demonstrated that introgressive hybridization has occurred among some species within Lepus, therefore it is possible that introgressive hybridization events also occur among Chinese Lepus species and contribute to the current taxonomic confusion. Results Data from four mtDNA genes, from 116 individuals, and one nuclear gene, from 119 individuals, provides the first evidence of frequent introgression events via historical and recent interspecific hybridizations among six Chinese Lepus species. Remarkably, the mtDNA of L. mandshuricus was completely replaced by mtDNA from L. timidus and L. sinensis. Analysis of the nuclear DNA sequence revealed a high proportion of heterozygous genotypes containing alleles from two divergent clades and that several haplotypes were shared among species, suggesting repeated and recent introgression. Furthermore, results from the present analyses suggest that Chinese hares belong to eight species. Conclusion This study provides a framework for understanding the patterns of speciation and the taxonomy of this clade. The existence of morphological intermediates and atypical mitochondrial gene genealogies resulting from frequent hybridization events likely contribute to the current taxonomic confusion of Chinese hares. The present study also demonstrated that nuclear gene sequence could offer a powerful complementary data set with mtDNA in tracing a complete evolutionary history of recently diverged species.

  6. Maize x Teosinte Hybrid Cobs Do Not Prevent Crop Gene Introgression.

    Science.gov (United States)

    Chavez, Nancy B; Flores, Jose J; Martin, Joseph; Ellstrand, Norman C; Guadagnuolo, Roberto; Heredia, Sylvia; Welles, Shana R

    2012-06-01

    Maize x Teosinte Hybrid Cobs Do Not Prevent Crop Gene Introgression. Whether introgression from crops to wild relatives can occur is an important component of transgene risk assessment. In the case of maize, which co-occurs with its wild relative teosinte in Mexico, the possibility of introgression has been controversial. Maize is cross-compatible with teosinte, and spontaneous hybridization is known to occur. Some scientists have hypothesized that the maize x teosinte cob infructescence will prevent progeny dispersal, thus preventing introgression. Motivated by a prior study where we found maize x teosinte hybrid fruits naturally dispersed under field conditions, we tested whether hybrid cobs hold their fruits as tightly as maize cobs. We found the force required to detach hybrid fruits was substantially and significantly less than that for maize. Consequently, we expect that introgression of transgenes from maize into teosinte in Mexico should occur largely unimpeded by the hybrid cob.La mazorca o elote híbrido de maíz x teocintle no impide la introgresión de genes transgénicos provenientes del cultivo. La introgresión entre el maíz cultivado y el maíz silvestre, o teocintle, es un componente importante en la evaluación ambiental relacionada con los riesgos de la introducción de genes transgénicos. La posibilidad de introgresión entre el maíz domesticado y el teocintle ha sido un tema controversial, en particular en México, donde maíz y teocintle coexisten. El maíz es compatible con el teocintle y la hibridización espontánea ocurre entre ellos. Algunos científicos han planteado como hipótesis que al cruzar el maíz con teocintle, la estructura interna de la infrutescencia que sujeta los frutos conocida como la mazorca de maíz o el elote, impide la dispersión de la progenie evitando que la introgresión ocurra. Los resultados de un estudio previo evidencian la dispersión de los frutos híbridos del maíz x teocintle en condiciones naturales

  7. Evidence of Natural Hybridization and Introgression between Vasconcellea Species (Caricaceae) from Southern Ecuador Revealed by Chloroplast, Mitochondrial and Nuclear DNA Markers

    Science.gov (United States)

    VAN DROOGENBROECK, B.; KYNDT, T.; ROMEIJN-PEETERS, E.; VAN THUYNE, W.; GOETGHEBEUR, P.; ROMERO-MOTOCHI, J. P.; GHEYSEN, G.

    2006-01-01

    • Background and Aims Vasconcellea × heilbornii is believed to be of natural hybrid origin between V. cundinamarcensis and V. stipulata, and is often difficult to discriminate from V. stipulata on morphological grounds. The aim of this paper is to examine individuals of these three taxa and of individuals from the closely related species V. parviflora and V. weberbaueri, which all inhabit a hybrid zone in southern Ecuador. • Methods Molecular data from mitochondrial, chloroplast and nuclear DNA from 61 individuals were analysed. • Key Results Molecular analysis confirmed occasional contemporary hybridization between V. stipulata, V. cundinamarcensis and V. × heilbornii and suggested the possible involvement of V. weberbaueri in the origin of V. × heilbornii. In addition, the molecular data indicated unidirectional introgression of the V. cundinamarcensis nuclear genome into that of V. stipulata. Several of the individuals examined with morphology similar to that of V. stipulata had genetic traces of hybridization with V. cundinamarcensis, which only seems to act as pollen donor in interspecific hybridization events. Molecular analyses also strongly suggested that most of the V. × heilbornii individuals are not F1 hybrids but instead are progeny of repeated backcrosses with V. stipulata. • Conclusions The results of the present study point to the need for re-evaluation of natural populations of V. stipulata and V. × heilbornii. In general, this analysis demonstrates the complex patterns of genetic and morphological diversity found in natural plant hybrid zones. PMID:16500954

  8. Recent introgressive hybridization revealed by exclusive mtDNA transfer from Oreochromis leucostictus (Trewavas, 1933) to Oreochromis niloticus (Linnaeus, 1758) in Lake Baringo, Kenya

    OpenAIRE

    Nyingi, Dorothy W.; Agnèse, Jean-François

    2007-01-01

    Nuclear DNA and mtDNA polymorphisms were surveyed in various species of East African Oreochromis. In Lake Baringo, where only Oreochromis niloticus baringoensis is present, alien mtDNA haplotypes were observed, apparently the result of introgressive hybridization with Oreochromis leucostictus. This introgression is not accompanied by any substantial or recorded transfer of nuclear genes into O. n. baringoensis.

  9. Genomic change, retrotransposon mobilization and extensive cytosine methylation alteration in Brassica napus introgressions from two intertribal hybridizations.

    Directory of Open Access Journals (Sweden)

    Xueli Zhang

    Full Text Available Hybridization and introgression represent important means for the transfer and/or de novo origination of traits and play an important role in facilitating speciation and plant breeding. Two sets of introgression lines in Brassica napus L. were previously established by its intertribal hybridizations with two wild species and long-term selection. In this study, the methods of amplified fragment length polymorphisms (AFLP, sequence-specific amplification polymorphism (SSAP and methylation-sensitive amplified polymorphism (MSAP were used to determine their genomic change, retrotransposon mobilization and cytosine methylation alteration in these lines. The genomic change revealed by the loss or gain of AFLP bands occurred for ∼10% of the total bands amplified in the two sets of introgressions, while no bands specific for wild species were detected. The new and absent SSAP bands appeared for 9 out of 11 retrotransposons analyzed, with low frequency of new bands and their total percentage of about 5% in both sets. MSAP analysis indicated that methylation changes were common in these lines (33.4-39.8% and the hypermethylation was more frequent than hypomethylation. Our results suggested that certain extents of genetic and epigenetic alterations were induced by hybridization and alien DNA introgression. The cryptic mechanism of these changes and potential application of these lines in breeding were also discussed.

  10. Genomic change, retrotransposon mobilization and extensive cytosine methylation alteration in Brassica napus introgressions from two intertribal hybridizations.

    Science.gov (United States)

    Zhang, Xueli; Ge, Xianhong; Shao, Yujiao; Sun, Genlou; Li, Zaiyun

    2013-01-01

    Hybridization and introgression represent important means for the transfer and/or de novo origination of traits and play an important role in facilitating speciation and plant breeding. Two sets of introgression lines in Brassica napus L. were previously established by its intertribal hybridizations with two wild species and long-term selection. In this study, the methods of amplified fragment length polymorphisms (AFLP), sequence-specific amplification polymorphism (SSAP) and methylation-sensitive amplified polymorphism (MSAP) were used to determine their genomic change, retrotransposon mobilization and cytosine methylation alteration in these lines. The genomic change revealed by the loss or gain of AFLP bands occurred for ∼10% of the total bands amplified in the two sets of introgressions, while no bands specific for wild species were detected. The new and absent SSAP bands appeared for 9 out of 11 retrotransposons analyzed, with low frequency of new bands and their total percentage of about 5% in both sets. MSAP analysis indicated that methylation changes were common in these lines (33.4-39.8%) and the hypermethylation was more frequent than hypomethylation. Our results suggested that certain extents of genetic and epigenetic alterations were induced by hybridization and alien DNA introgression. The cryptic mechanism of these changes and potential application of these lines in breeding were also discussed.

  11. Non-introgressive genome chimerisation by malsegregation in autodiploidised allotetraploids during meiosis of Saccharomyces kudriavzevii x Saccharomyces uvarum hybrids.

    Science.gov (United States)

    Karanyicz, Edina; Antunovics, Zsuzsa; Kallai, Z; Sipiczki, M

    2017-06-01

    Saccharomyces strains with chimerical genomes consisting of mosaics of the genomes of different species ("natural hybrids") occur quite frequently among industrial and wine strains. The most widely endorsed hypothesis is that the mosaics are introgressions acquired via hybridisation and repeated backcrosses of the hybrids with one of the parental species. However, the interspecies hybrids are sterile, unable to mate with their parents. Here, we show by analysing synthetic Saccharomyces kudriavzevii x Saccharomyces uvarum hybrids that mosaic (chimeric) genomes can arise without introgressive backcrosses. These species are biologically separated by a double sterility barrier (sterility of allodiploids and F1 sterility of allotetraploids). F1 sterility is due to the diploidisation of the tetraploid meiosis resulting in MAT a /MAT α heterozygosity which suppresses mating in the spores. This barrier can occasionally be broken down by malsegregation of autosyndetically paired chromosomes carrying the MAT loci (loss of MAT heterozygosity). Subsequent malsegregation of additional autosyndetically paired chromosomes and occasional allosyndetic interactions chimerise the hybrid genome. Chromosomes are preferentially lost from the S. kudriavzevii subgenome. The uniparental transmission of the mitochondrial DNA to the hybrids indicates that nucleo-mitochondrial interactions might affect the direction of the genomic changes. We propose the name GARMe (Genome AutoReduction in Meiosis) for this process of genome reduction and chimerisation which involves no introgressive backcrossings. It opens a way to transfer genetic information between species and thus to get one step ahead after hybridisation in the production of yeast strains with beneficial combinations of properties of different species.

  12. Differential pollinator effectiveness and importance in a milkweed (Asclepias, Apocynaceae) hybrid zone.

    Science.gov (United States)

    Stoepler, Teresa M; Edge, Andrea; Steel, Anna; O'Quinn, Robin L; Fishbein, Mark

    2012-03-01

    Exceptions to the ideal of complete reproductive isolation between species are commonly encountered in diverse plant, animal, and fungal groups, but often the causative ecological processes are poorly understood. In flowering plants, the outcome of hybridization depends in part on the effectiveness of pollinators in interspecific pollen transport. In the Asclepias exaltata and A. syriaca (Apocynaceae) hybrid zone in Shenandoah National Park, Virginia, extensive introgression has been documented. The objectives of this study were to (1) determine the extent of pollinator overlap among A. exaltata, A. syriaca, and their hybrids and (2) identify the insect taxa responsible for hybridization and introgression. We observed focal plants of parental species and hybrids to measure visitation rate, visit duration, and per-visit pollinia removal and deposition, and we calculated pollinator effectiveness and importance. Visitation rates varied significantly between the 2 yr of the study. Overall, Apis mellifera, Bombus sp., and Epargyreus clarus were the most important pollinators. However, Bombus sp. was the only visitor that was observed to both remove and insert pollinia for both parent species as well as hybrids. We conclude that Bombus may be a key agent of hybridization and introgression in these sympatric milkweed populations, and hybrids are neither preferred nor selected against by pollinators. Thus, we have identified a potential mechanism for how hybrids act as bridges to gene flow between A. exaltata and A. syriaca. These results provide insights into the breakdown of prezygotic isolating mechanisms.

  13. Evidence for hybridization and introgression within a species-rich oak (Quercus spp. community

    Directory of Open Access Journals (Sweden)

    Finkeldey Reiner

    2007-11-01

    Full Text Available Abstract Background Analysis of interspecific gene flow is crucial for the understanding of speciation processes and maintenance of species integrity. Oaks (genus Quercus, Fagaceae are among the model species for the study of hybridization. Natural co-occurrence of four closely related oak species is a very rare case in the temperate forests of Europe. We used both morphological characters and genetic markers to characterize hybridization in a natural community situated in west-central Romania and which consists of Quercus robur, Q. petraea, Q. pubescens, and Q. frainetto, respectively. Results On the basis of pubescence and leaf morphological characters ~94% of the sampled individuals were assigned to pure species. Only 16 (~6% individual trees exhibited intermediate morphologies or a combination of characters of different species. Four chloroplast DNA haplotypes were identified in the study area. The distribution of haplotypes within the white oak complex showed substantial differences among species. However, the most common haplotypes were present in all four species. Furthermore, based on a set of 7 isozyme and 6 microsatellite markers and using a Bayesian admixture analysis without any a priori information on morphology we found that four genetic clusters best fit the data. There was a very good correspondence of each species with one of the inferred genetic clusters. The estimated introgression level varied markedly between pairs of species ranging from 1.7% between Q. robur and Q. frainetto to 16.2% between Q. pubescens and Q. frainetto. Only nine individuals (3.4% appeared to be first-generation hybrids. Conclusion Our data indicate that natural hybridization has occurred at relatively low rates. The different levels of gene flow among species might be explained by differences in flowering time and spatial position within the stand. In addition, a partial congruence between phenotypically and genetically intermediate individuals was

  14. Natural hybridization and asymmetric introgression at the distribution margin of two Buddleja species with a large overlap.

    Science.gov (United States)

    Liao, Rong-Li; Ma, Yong-Peng; Gong, Wei-Chang; Chen, Gao; Sun, Wei-Bang; Zhou, Ren-Chao; Marczewski, Tobias

    2015-06-18

    Natural hybridization in plants is universal and plays an important role in evolution. Based on morphology it has been presumed that hybridization occurred in the genus Buddleja, though genetic studies confirming this assumption have not been conducted to date. The two species B. crispa and B. officinalis overlap in their distributions over a wide range in South-West China, and we aimed to provide genetic evidence for ongoing hybridization in this study. We investigated the occurrence of hybrids between the two species at the southern-most edge of the distribution of B. crispa using five nuclear loci and pollination experiments. The genetic data suggest substantial differentiation between the two species as species-specific alleles are separated by at least 7-28 mutations. The natural hybrids found were nearly all F1s (21 of 23), but backcrosses were detected, and some individuals, morphologically indistinguishable from the parental species, showed introgression. Pollen viability test shows that the percentage of viable pollen grains was 50 ± 4% for B. crispa, and 81 ± 2% for B. officinalis. This difference is highly significant (t = 7.382, p < 0.0001). Hand cross-pollination experiments showed that B. crispa is not successful as pollen-parent, but B. officinalis is able to pollinate B. crispa to produce viable hybrid seed. Inter-specific seed-set is low (8 seeds per fruit, as opposed to about 65 for intra-specific pollinations), suggesting post-zygotic reproductive barriers. In addition, one of the reference populations also suggests a history of introgression at other localities. The occurrence of morphologically intermediate individuals between B. crispa and B. officinalis at Xishan Mountain is unequivocally linked to hybridization and almost all examined individuals of the putative hybrids were likely F1s. Despite pollination experiments indicating higher chances for introgression into B. officinalis (hybrids only produced viable seed when

  15. Characterizing haploinsufficiency of SHELL gene to improve fruit form prediction in introgressive hybrids of oil palm.

    Science.gov (United States)

    Teh, Chee-Keng; Muaz, Siti Dalila; Tangaya, Praveena; Fong, Po-Yee; Ong, Ai-Ling; Mayes, Sean; Chew, Fook-Tim; Kulaveerasingam, Harikrishna; Appleton, David

    2017-06-08

    The fundamental trait in selective breeding of oil palm (Eleais guineensis Jacq.) is the shell thickness surrounding the kernel. The monogenic shell thickness is inversely correlated to mesocarp thickness, where the crude palm oil accumulates. Commercial thin-shelled tenera derived from thick-shelled dura × shell-less pisifera generally contain 30% higher oil per bunch. Two mutations, sh MPOB (M1) and sh AVROS (M2) in the SHELL gene - a type II MADS-box transcription factor mainly present in AVROS and Nigerian origins, were reported to be responsible for different fruit forms. In this study, we have tested 1,339 samples maintained in Sime Darby Plantation using both mutations. Five genotype-phenotype discrepancies and eight controls were then re-tested with all five reported mutations (sh AVROS , sh MPOB , sh MPOB2 , sh MPOB3 and sh MPOB4 ) within the same gene. The integration of genotypic data, pedigree records and shell formation model further explained the haploinsufficiency effect on the SHELL gene with different number of functional copies. Some rare mutations were also identified, suggesting a need to further confirm the existence of cis-compound mutations in the gene. With this, the prediction accuracy of fruit forms can be further improved, especially in introgressive hybrids of oil palm. Understanding causative variant segregation is extremely important, even for monogenic traits such as shell thickness in oil palm.

  16. Mitochondrial introgression via ancient hybridization, and systematics of the Australian endemic pygopodid gecko genus Delma.

    Science.gov (United States)

    Brennan, Ian G; Bauer, Aaron M; Jackman, Todd R

    2016-01-01

    Of the more than 1500 species of geckos found across six continents, few remain as unfamiliar as the pygopodids - Family Pygopodidae (Gray, 1845). These gekkotans are limited to Australia (44 species) and New Guinea (2 species), but have diverged extensively into the most ecologically diverse limbless radiation save Serpentes. Current phylogenetic understanding of the family has relied almost exclusively on two works, which have produced and synthesized an immense amount of morphological, geographical, and molecular data. However, current interspecific relationships within the largest genus Delma Gray 1831 are based chiefly upon data from two mitochondrial loci (16s, ND2). Here, we reevaluate the interspecific relationships within the genus Delma using two mitochondrial and four nuclear loci (RAG1, MXRA5, MOS, DYNLL1), and identify points of strong conflict between nuclear and mitochondrial genomic data. We address mito-nuclear discordance, and remedy this conflict by recognizing several points of mitochondrial introgression as the result of ancient hybridization events. Owing to the legacy value and intraspecific informativeness, we suggest the continued use of ND2 as a phylogenetic marker. Results identify strong support for species groups, but relationships among these clades, and the placement of several enigmatic taxa remain uncertain. We suggest a more careful review of Delma australis and the 'northwest Australia' clade. Accurately assessing and addressing species richness and relationships within this endemic Australian Gekkotan genus is relevant for understanding patterns of squamate speciation across the region. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. New insight into hybridization and unidirectional introgression between Ammodytes japonicus and Ammodytes heian (Trachiniformes, Ammodytidae).

    Science.gov (United States)

    Kim, Jin-Koo; Bae, Seung Eun; Lee, Soo Jeong; Yoon, Moon Geun

    2017-01-01

    Based on northern (NOL) and southern (SOL) mitochondrial lineages, recently, it proposed the new species Ammodytes heian and revived the species name Ammodytes japonicus to describe sand lances from the northwestern Pacific Ocean. This study used molecular methods to investigate genetic relationships between the two sand lance species in Korea and Japan. In total, 154 specimens were collected from four locations in Korea (Baengnyeongdo in the Yellow Sea, Tongyeong in the Korean Strait, and Jumunjin and Gijang in the East Sea), and 50 specimens were collected from a single location in Japan (Wakkanai in the Okhotsk Sea). Mitochondrial DNA analysis demonstrated that the individuals from Baengnyeongdo and Tongyeong all belonged to the SOL, whereas those from Gijang, Jumunjin, and Wakkanai included individuals from both the NOL and SOL (over 75% NOL). Population structure analyses were performed on the same individuals using seven microsatellite DNA markers. The population structure analysis based on 201 specimens identified two clusters (named as northern group and southern group), with the admixture proportion (q) of heian. However, the admixture proportion in the Jumunjin and Gijang sand lances was 0.71-0.75 for the southern group, indicating that hybridization and unidirectional introgression from SOL to NOL occurs in southwestern margin of the East Sea. Our findings illustrate the speciation process based on different patterns of gene flow between Korean and Japanese sand lance, which is strongly influenced by both the paleo-climatic change and the contemporary local oceanic current pattern.

  18. The responses of crop - wild Brassica hybrids to simulated herbivory and interspecific competition: implications for transgene introgression.

    Science.gov (United States)

    Sutherland, Jamie P; Justinova, Lenka; Poppy, Guy M

    2006-01-01

    Brassica rapa grows as a wild and weedy species throughout the world and is the most likely recipient of transgenes from GM oilseed rape. For transgene introgression to occur, the critical step which must be realized, is the formation of an F1 hybrid. Concerns exist that hybrid populations could be more vigorous and competitive compared to the parental species. This study examines the effect of simulated herbivory and interspecific competition on the vegetative and reproductive performance of non-transgenic F1 hybrids and their parental lines. Several vegetative and reproductive performance measures were used to determine the effect of simulated herbivory and competition on the Brassica lines, including leaf length and biomass for herbivory and seedling height and biomass for competition. For defoliation experiments, B. rapa showed little response in terms of leaf length but B. napus and the F1 hybrid responded negatively. Brassica rapa showed elevated biomass responses, but B. napus and the hybrid demonstrated negative responses to defoliation. Defoliation at the cotyledon stage had a slight effect upon final biomass with the F1 hybrid performing significantly worse than B. napus, although seed counts were not significantly different. For the series of competition experiments, hybrids seemed to be more similar to B. rapa in terms of early seedling growth and reproductive measures. The underperformance of hybrid plants when challenged by herbivory and competition, could potentially decrease survivorship and explain the rarity of hybrids in field surveys. However, should transgene introgression occur, the dynamics of hybrids could change radically thus increasing the risk of gene flow from a transgenic oilseed rape crop to the wild recipient.

  19. Weak population structure in European roe deer (Capreolus capreolus and evidence of introgressive hybridization with Siberian roe deer (C. pygargus in northeastern Poland.

    Directory of Open Access Journals (Sweden)

    Juanita Olano-Marin

    Full Text Available We investigated contemporary and historical influences on the pattern of genetic diversity of European roe deer (Capreolus capreolus. The study was conducted in northeastern Poland, a zone where vast areas of primeval forests are conserved and where the European roe deer was never driven to extinction. A total of 319 unique samples collected in three sampling areas were genotyped at 16 microsatellites and one fragment (610 bp of mitochondrial DNA (mtDNA control region. Genetic diversity was high, and a low degree of genetic differentiation among sampling areas was observed with both microsatellites and mtDNA. No evidence of genetic differentiation between roe deer inhabiting open fields and forested areas was found, indicating that the ability of the species to exploit these contrasting environments might be the result of its phenotypic plasticity. Half of the studied individuals carried an mtDNA haplotype that did not belong to C. capreolus, but to a related species that does not occur naturally in the area, the Siberian roe deer (C. pygargus. No differentiation between individuals with Siberian and European mtDNA haplotypes was detected at microsatellite loci. Introgression of mtDNA of Siberian roe deer into the genome of European roe deer has recently been detected in eastern Europe. Such introgression might be caused by human-mediated translocations of Siberian roe deer within the range of European roe deer or by natural hybridization between these species in the past.

  20. Morphological and Phylogenetic Characterization of New Gephyrocapsa Isolates Suggests Introgressive Hybridization in the Emiliania/Gephyrocapsa Complex (Haptophyta).

    Science.gov (United States)

    Bendif, El Mahdi; Probert, Ian; Young, Jeremy R; von Dassow, Peter

    2015-07-01

    The coccolithophore genus Gephyrocapsa contains a cosmopolitan assemblage of pelagic species, including the bloom-forming Gephyrocapsa oceanica, and is closely related to the emblematic coccolithophore Emiliania huxleyi within the Noëlaerhabdaceae. These two species have been extensively studied and are well represented in culture collections, whereas cultures of other species of this family are lacking. We report on three new strains of Gephyrocapsa isolated into culture from samples from the Chilean coastal upwelling zone using a novel flow cytometric single-cell sorting technique. The strains were characterized by morphological analysis using scanning electron microscopy and phylogenetic analysis of 6 genes (nuclear 18S and 28S rDNA, plastidial 16S and tufA, and mitochondrial cox1 and cox3 genes). Morphometric features of the coccoliths indicate that these isolates are distinct from G. oceanica and best correspond to G. muellerae. Surprisingly, both plastidial and mitochondrial gene phylogenies placed these strains within the E. huxleyi clade and well separated from G. oceanica isolates, making Emiliania appear polyphyletic. The only nuclear sequence difference, 1bp in the 28S rDNA region, also grouped E. huxleyi with the new Gephyrocapsa isolates and apart from G. oceanica. Specifically, the G. muellerae morphotype strains clustered with the mitochondrial β clade of E. huxleyi, which, like G. muellerae, has been associated with cold (temperate and sub-polar) waters. Among putative evolutionary scenarios that could explain these results we discuss the possibility that E. huxleyi is not a valid taxonomic unit, or, alternatively the possibility of past hybridization and introgression between each E. huxleyi clade and older Gephyrocapsa clades. In either case, the results support the transfer of Emiliania to Gephyrocapsa. These results have important implications for relating morphological species concepts to ecological and evolutionary units of diversity

  1. Evidence to support natural hybridization between Anopheles sinensis and Anopheles kleini (Diptera: Culicidae): possibly a significant mechanism for gene introgression in sympatric populations

    Science.gov (United States)

    2014-01-01

    Background Malaria caused by Plasmodium vivax is still a public health problem in the Republic of Korea (ROK), particularly regarding the recent re-emergence of this malarial species near the demilitarized zone in northwestern Paju City, Gyeonggi-do Province. Currently, at least 4 species (An. kleini, An. pullus, An. belenrae and An. lesteri) of the Hyrcanus Group are reported as possible natural vectors of vivax malaria in the ROK, and An. sinensis, which is the most dominant species, has long been incriminated as an important natural vector of this P. vivax. However, An. sinensis was ranked recently as a low potential vector. According to the discovery of natural hybrids between An. sinensis (a low potential vector for P. vivax) and An. kleini (a high potential vector for P. vivax) in Paju City, intensive investigation of this phenomenon is warranted under laboratory conditions. Methods Mosquitoes were collected during 2010-2012 from Paju City, ROK. Hybridization experiments used iso-female line colonies of these anophelines together with DNA analysis of ribosomal DNA [second internal transcribed spacer (ITS2)] and mitochondrial DNA [cytochrome c oxidase subunit I (COI)] of the parental colonies, F1-hybrids and repeated backcross progenies were performed intensively by using a PCR-based assay and pyrosequencing technology. Results The results from hybridization experiments and molecular investigations revealed that the mitochondrial COI gene was introgressed from An. sinensis into An. kleini. The An. sinensis progenies obtained from consecutive repeated backcrosses in both directions, i.e., F2-11 progeny [(An. sinensis x An. kleini) x An. sinensis] and F3-5 progeny [(An. kleini x An. sinensis) x An. kleini] provided good supportive evidence. Conclusions This study revealed introgression of the mitochondrial COI gene between An. sinensis and An. kleini through consecutive repeated backcrosses under laboratory conditions. This new body of knowledge will be

  2. Genomic divergence and lack of introgressive hybridization between two 13-year periodical cicadas support life cycle switching in the face of climate change.

    Science.gov (United States)

    Koyama, Takuya; Ito, Hiromu; Fujisawa, Tomochika; Ikeda, Hiroshi; Kakishima, Satoshi; Cooley, John R; Simon, Chris; Yoshimura, Jin; Sota, Teiji

    2016-11-01

    Life history evolution spurred by post-Pleistocene climatic change is hypothesized to be responsible for the present diversity in periodical cicadas (Magicicada), but the mechanism of life cycle change has been controversial. To understand the divergence process of 13-year and 17-year cicada life cycles, we studied genetic relationships between two synchronously emerging, parapatric 13-year periodical cicada species in the Decim group, Magicicada tredecim and M. neotredecim. The latter was hypothesized to be of hybrid origin or to have switched from a 17-year cycle via developmental plasticity. Phylogenetic analysis using restriction-site-associated DNA sequences for all Decim species and broods revealed that the 13-year M. tredecim lineage is genomically distinct from 17-year Magicicada septendecim but that 13-year M. neotredecim is not. We detected no significant introgression between M. tredecim and M. neotredecim/M. septendecim thus refuting the hypothesis that M. neotredecim are products of hybridization between M. tredecim and M. septendecim. Further, we found that introgressive hybridization is very rare or absent in the contact zone between the two 13-year species evidenced by segregation patterns in single nucleotide polymorphisms, mitochondrial lineage identity and head width and abdominal sternite colour phenotypes. Our study demonstrates that the two 13-year Decim species are of independent origin and nearly completely reproductively isolated. Combining our data with increasing observations of occasional life cycle change in part of a cohort (e.g. 4-year acceleration of emergence in 17-year species), we suggest a pivotal role for developmental plasticity in Magicicada life cycle evolution. © 2016 John Wiley & Sons Ltd.

  3. New insight into hybridization and unidirectional introgression between Ammodytes japonicus and Ammodytes heian (Trachiniformes, Ammodytidae.

    Directory of Open Access Journals (Sweden)

    Jin-Koo Kim

    Full Text Available Based on northern (NOL and southern (SOL mitochondrial lineages, recently, it proposed the new species Ammodytes heian and revived the species name Ammodytes japonicus to describe sand lances from the northwestern Pacific Ocean. This study used molecular methods to investigate genetic relationships between the two sand lance species in Korea and Japan. In total, 154 specimens were collected from four locations in Korea (Baengnyeongdo in the Yellow Sea, Tongyeong in the Korean Strait, and Jumunjin and Gijang in the East Sea, and 50 specimens were collected from a single location in Japan (Wakkanai in the Okhotsk Sea. Mitochondrial DNA analysis demonstrated that the individuals from Baengnyeongdo and Tongyeong all belonged to the SOL, whereas those from Gijang, Jumunjin, and Wakkanai included individuals from both the NOL and SOL (over 75% NOL. Population structure analyses were performed on the same individuals using seven microsatellite DNA markers. The population structure analysis based on 201 specimens identified two clusters (named as northern group and southern group, with the admixture proportion (q of < 0.1 for the northern group in the Backyeongdo and Tongyeong sand lances and < 0.1 for the southern group in the Wakkanai sand lances. The high heterogeneity indicated that the former was probably A. japonicus and the latter probably A. heian. However, the admixture proportion in the Jumunjin and Gijang sand lances was 0.71-0.75 for the southern group, indicating that hybridization and unidirectional introgression from SOL to NOL occurs in southwestern margin of the East Sea. Our findings illustrate the speciation process based on different patterns of gene flow between Korean and Japanese sand lance, which is strongly influenced by both the paleo-climatic change and the contemporary local oceanic current pattern.

  4. Alien DNA introgression and wheat DNA rearrangements in a stable wheat line derived from the early generation of distant hybridization.

    Science.gov (United States)

    Zhang, Lianquan; Liu, Dengcai; Yan, Zehong; Zheng, Youliang

    2005-10-01

    Polyploidy has been found to be common in plants. Bread or common wheat (Triticum aestivum L., 2n=42) is a good example of allopolyploid made up of three diploid genomes A, B and D. In recent years, by the study of mimicking the origination of common wheat, it was found that changes of DNA sequence and gene expression occurred at the early stages of artificial allohexaploid between tetraploid wheat and Aegilops tauschii, which was probably favorable to genetic diploidization of new synthetic hexaploid wheat. Common wheat 99L2 is a new line stable in genetic, which was derived from the early self-pollinated generation of wide hybrids between common wheat and rye. In this study, it was found that at least two rye DNA segments had been introgressed into 99L2. This result suggested that a mechanism of alien DNA introgression may exist, which was different from the traditional mechanism of chromosome pairing and DNA recombination between wheat and alien species. Meanwhile, during the introgression process of alien rye DNA segments, the changes in DNA sequences of wheat itself occurred.

  5. Interspecific Hybridization in Pilot Whales and Asymmetric Genetic Introgression in Northern Globicephala melas under the Scenario of Global Warming.

    Science.gov (United States)

    Miralles, Laura; Oremus, Marc; Silva, Mónica A; Planes, Serge; Garcia-Vazquez, Eva

    2016-01-01

    Pilot whales are two cetacean species (Globicephala melas and G. macrorhynchus) whose distributions are correlated with water temperature and partially overlap in some areas like the North Atlantic Ocean. In the context of global warming, distribution range shifts are expected to occur in species affected by temperature. Consequently, a northward displacement of the tropical pilot whale G. macrorynchus is expected, eventually leading to increased secondary contact areas and opportunities for interspecific hybridization. Here, we describe genetic evidences of recurrent hybridization between pilot whales in northeast Atlantic Ocean. Based on mitochondrial DNA sequences and microsatellite loci, asymmetric introgression of G. macrorhynchus genes into G. melas was observed. For the latter species, a significant correlation was found between historical population growth rate estimates and paleotemperature oscillations. Introgressive hybridization, current temperature increases and lower genetic variation in G. melas suggest that this species could be at risk in its northern range. Under increasing environmental and human-mediated stressors in the North Atlantic Ocean, it seems recommendable to develop a conservation program for G. melas.

  6. Distinguishing between incomplete lineage sorting and genomic introgressions: complete fixation of allospecific mitochondrial DNA in a sexually reproducing fish (Cobitis; Teleostei, despite clonal reproduction of hybrids.

    Directory of Open Access Journals (Sweden)

    Lukas Choleva

    Full Text Available Distinguishing between hybrid introgression and incomplete lineage sorting causing incongruence among gene trees in that they exhibit topological differences requires application of statistical approaches that are based on biologically relevant models. Such study is especially challenging in hybrid systems, where usual vectors mediating interspecific gene transfers--hybrids with Mendelian heredity--are absent or unknown. Here we study a complex of hybridizing species, which are known to produce clonal hybrids, to discover how one of the species, Cobitis tanaitica, has achieved a pattern of mito-nuclear mosaic genome over the whole geographic range. We appplied three distinct methods, including the method using solely the information on gene tree topologies, and found that the contrasting mito-nuclear signal might not have resulted from the retention of ancestral polymorphism. Instead, we found two signs of hybridization events related to C. tanaitica; one concerning nuclear gene flow and the other suggested mitochondrial capture. Interestingly, clonal inheritance (gynogenesis of contemporary hybrids prevents genomic introgressions and non-clonal hybrids are either absent or too rare to be detected among European Cobitis. Our analyses therefore suggest that introgressive hybridizations are rather old episodes, mediated by previously existing hybrids whose inheritance was not entirely clonal. Cobitis complex thus supports the view that the type of resulting hybrids depends on a level of genomic divergence between sexual species.

  7. Evidence for introgressive hybridization of captive markhor (Capra falconeri) with domestic goat: cautions for reintroduction.

    Science.gov (United States)

    Hammer, Sabine E; Schwammer, Harald M; Suchentrunk, Franz

    2008-04-01

    Markhors (Capra falconeri) are among the most endangered mammal species, and several conservation measures, including ex situ breeding, are implemented to prevent their extinction. We studied sequence diversity and differentiation of the first hypervariable segment of the mitochondrial DNA control region among C. f. heptneri and C. f. megaceros kept in four zoos in relationship to lineages of other wild and domestic goats, to assess for the first time the level of molecular distinctness and variability among those subspecies, and to check for possible introgression by related Capra taxa, such as domestic goats. Levels of differentiation between some Capra falconeri lineages and modern domestic goats were similar to levels between other wild goat species (i.e., Capra aegagrus, Capra ibex) and domestic goats. Among pure markhor lineages, paraphyly was observed for C. f. heptneri, suggesting occurrence of shared ancestral polymorphism among markhor subspecies and/or ancient or recent gene exchange between subspecies. Interestingly, 35.7% of all studied markhors from three zoos are introgressed by the domestic goat. Furthermore, despite relatively small breeding group sizes, markhors have maintained a relatively high proportion of mtDNA variation within zoo groups. In any case, the existence of markhors introgressed with domestic goat DNA in zoos should be considered when selecting markhors for ex situ breeding programs with the aim of building up a stock for later reintroduction into the wild.

  8. Genetic and Epigenetic Alterations of Brassica nigra Introgression Lines from Somatic Hybridization: A Resource for Cauliflower Improvement.

    Science.gov (United States)

    Wang, Gui-Xiang; Lv, Jing; Zhang, Jie; Han, Shuo; Zong, Mei; Guo, Ning; Zeng, Xing-Ying; Zhang, Yue-Yun; Wang, You-Ping; Liu, Fan

    2016-01-01

    Broad phenotypic variations were obtained previously in derivatives from the asymmetric somatic hybridization of cauliflower "Korso" (Brassica oleracea var. botrytis, 2n = 18, CC genome) and black mustard "G1/1" (Brassica nigra, 2n = 16, BB genome). However, the mechanisms underlying these variations were unknown. In this study, 28 putative introgression lines (ILs) were pre-selected according to a series of morphological (leaf shape and color, plant height and branching, curd features, and flower traits) and physiological (black rot/club root resistance) characters. Multi-color fluorescence in situ hybridization revealed that these plants contained 18 chromosomes derived from "Korso." Molecular marker (65 simple sequence repeats and 77 amplified fragment length polymorphisms) analysis identified the presence of "G1/1" DNA segments (average 7.5%). Additionally, DNA profiling revealed many genetic and epigenetic differences among the ILs, including sequence alterations, deletions, and variation in patterns of cytosine methylation. The frequency of fragments lost (5.1%) was higher than presence of novel bands (1.4%), and the presence of fragments specific to Brassica carinata (BBCC 2n = 34) were common (average 15.5%). Methylation-sensitive amplified polymorphism analysis indicated that methylation changes were common and that hypermethylation (12.4%) was more frequent than hypomethylation (4.8%). Our results suggested that asymmetric somatic hybridization and alien DNA introgression induced genetic and epigenetic alterations. Thus, these ILs represent an important, novel germplasm resource for cauliflower improvement that can be mined for diverse traits of interest to breeders and researchers.

  9. Genetic and epigenetic alterations of Brassica nigra introgression lines from somatic hybridization: a resource for cauliflower improvement

    Directory of Open Access Journals (Sweden)

    Guixiang Wang

    2016-08-01

    Full Text Available Broad phenotypic variations were obtained previously in derivatives from the asymmetric somatic hybridization of cauliflower ‘Korso’ (Brassica oleracea var. botrytis, 2n = 18, CC genome and black mustard ‘G1/1’ (Brassica nigra, 2n = 16, BB genome. However, the mechanisms underlying these variations were unknown. In this study, 28 putative introgression lines (ILs were pre-selected according to a series of morphological (leaf shape and color, plant height and branching, curd features, and flower traits and physiological (black rot/club root resistance characters. Multi-color fluorescence in situ hybridization revealed that these plants contained 18 chromosomes derived from ‘Korso’. Molecular marker (65 simple sequence repeats and 77 amplified fragment length polymorphisms analysis identified the presence of ‘G1/1’ DNA segments (average 7.5%. Additionally, DNA profiling revealed many genetic and epigenetic differences among the ILs, including sequence alterations, deletions, and variation in patterns of cytosine methylation. The frequency of fragments lost (5.1% was significantly higher than presence of novel bands (1.4%, and the presence of fragments specific to B. carinata (BBCC 2n = 34 were common (average 15.5%. Methylation-sensitive amplified polymorphism analysis indicated that methylation changes were common and that hypermethylation (12.4% was more frequent than hypomethylation (4.8%. Our results suggested that asymmetric somatic hybridization and alien DNA introgression induced genetic and epigenetic alterations. Thus, these ILs represent an important, novel germplasm resource for cauliflower improvement that can be mined for diverse traits of interest to breeders and researchers.

  10. Reticulate phylogeny of gastropod-shell-breeding cichlids from Lake Tanganyika – the result of repeated introgressive hybridization

    Directory of Open Access Journals (Sweden)

    Blanc Michel

    2007-01-01

    Full Text Available Abstract Background The tribe Lamprologini is the major substrate breeding lineage of Lake Tanganyika's cichlid species flock. Among several different life history strategies found in lamprologines, the adaptation to live and breed in empty gastropod shells is probably the most peculiar. Although shell-breeding arose several times in the evolutionary history of the lamprologines, all obligatory and most facultative shell-breeders belong to the so called "ossified group", a monophyletic lineage within the lamprologine cichlids. Since their distinctive life style enables these species to live and breed in closest vicinity, we hypothesized that these cichlids might be particularly prone to accidental hybridization, and that introgression might have affected the evolutionary history of this cichlid lineage. Results Our analyses revealed discrepancies between phylogenetic hypotheses based on mitochondrial and nuclear (AFLP data. While the nuclear phylogeny was congruent with morphological, behavioral and ecological characteristics, several species – usually highly specialized shell-breeders – were placed at contradicting positions in the mitochondrial phylogeny. The discordant phylogenies strongly suggest repeated incidents of introgressive hybridization between several distantly related shell-breeding species, which reticulated the phylogeny of this group of cichlids. Long interior branches and high bootstrap support for many interior nodes in the mitochondrial phylogeny argue against a major effect of ancient incomplete lineage sorting on the phylogenetic reconstruction. Moreover, we provide morphological and genetic (mtDNA and microsatellites evidence for ongoing hybridization among distantly related shell-breeders. In these cases, the territorial males of the inferred paternal species are too large to enter the shells of their mate, such that they have to release their sperm over the entrance of the shell to fertilize the eggs. With sperm

  11. Fine scale mapping of genomic introgressions within the Drosophila yakuba clade.

    Science.gov (United States)

    Turissini, David A; Matute, Daniel R

    2017-09-01

    The process of speciation involves populations diverging over time until they are genetically and reproductively isolated. Hybridization between nascent species was long thought to directly oppose speciation. However, the amount of interspecific genetic exchange (introgression) mediated by hybridization remains largely unknown, although recent progress in genome sequencing has made measuring introgression more tractable. A natural place to look for individuals with admixed ancestry (indicative of introgression) is in regions where species co-occur. In west Africa, D. santomea and D. yakuba hybridize on the island of São Tomé, while D. yakuba and D. teissieri hybridize on the nearby island of Bioko. In this report, we quantify the genomic extent of introgression between the three species of the Drosophila yakuba clade (D. yakuba, D. santomea), D. teissieri). We sequenced the genomes of 86 individuals from all three species. We also developed and applied a new statistical framework, using a hidden Markov approach, to identify introgression. We found that introgression has occurred between both species pairs but most introgressed segments are small (on the order of a few kilobases). After ruling out the retention of ancestral polymorphism as an explanation for these similar regions, we find that the sizes of introgressed haplotypes indicate that genetic exchange is not recent (>1,000 generations ago). We additionally show that in both cases, introgression was rarer on X chromosomes than on autosomes which is consistent with sex chromosomes playing a large role in reproductive isolation. Even though the two species pairs have stable contemporary hybrid zones, providing the opportunity for ongoing gene flow, our results indicate that genetic exchange between these species is currently rare.

  12. Widespread hybridization and bidirectional introgression in sympatric species of coral reef fish

    KAUST Repository

    Harrison, Hugo B.; Berumen, Michael L.; Saenz-Agudelo, Pablo; Salas, Eva; Williamson, David H.; Jones, Geoffrey P.

    2017-01-01

    interspecific hybrids from a collection of 2,991 coral trout sampled in inshore and mid-shelf reefs of the southern Great Barrier Reef. Hybrids were ubiquitous among reefs, fertile and spanned multiple generations suggesting both ecological and evolutionary

  13. Specific down-regulation of spermatogenesis genes targeted by 22G RNAs in hybrid sterile males associated with an X-Chromosome introgression.

    Science.gov (United States)

    Li, Runsheng; Ren, Xiaoliang; Bi, Yu; Ho, Vincy Wing Sze; Hsieh, Chia-Ling; Young, Amanda; Zhang, Zhihong; Lin, Tingting; Zhao, Yanmei; Miao, Long; Sarkies, Peter; Zhao, Zhongying

    2016-09-01

    Hybrid incompatibility (HI) prevents gene flow between species, thus lying at the heart of speciation genetics. One of the most common HIs is male sterility. Two superficially contradictory observations exist for hybrid male sterility. First, an introgression on the X Chromosome is more likely to produce male sterility than on autosome (so-called large-X theory); second, spermatogenesis genes are enriched on the autosomes but depleted on the X Chromosome (demasculinization of X Chromosome). Analysis of gene expression in Drosophila hybrids suggests a genetic interaction between the X Chromosome and autosomes that is essential for male fertility. However, the prevalence of such an interaction and its underlying mechanism remain largely unknown. Here we examine the interaction in nematode species by contrasting the expression of both coding genes and transposable elements (TEs) between hybrid sterile males and its parental nematode males. We use two lines of hybrid sterile males, each carrying an independent introgression fragment from Caenorhabditis briggsae X Chromosome in an otherwise Caenorhabditis nigoni background, which demonstrate similar defects in spermatogenesis. We observe a similar pattern of down-regulated genes that are specific for spermatogenesis between the two hybrids. Importantly, the down-regulated genes caused by the X Chromosome introgressions show a significant enrichment on the autosomes, supporting an epistatic interaction between the X Chromosome and autosomes. We investigate the underlying mechanism of the interaction by measuring small RNAs and find that a subset of 22G RNAs specifically targeting the down-regulated spermatogenesis genes is significantly up-regulated in hybrids, suggesting that perturbation of small RNA-mediated regulation may contribute to the X-autosome interaction. © 2016 Li et al.; Published by Cold Spring Harbor Laboratory Press.

  14. Vocal communication in an avian hybrid zone

    NARCIS (Netherlands)

    Hartog, Paula Maria den

    2008-01-01

    Avian vocalizations function in mate attraction and territorial defence. Vocalizations can act as behavioural barriers and play an important role in speciation processes. Hybrid zones illustrate behavioural barriers are not always impermeable and provide a natural laboratory to examine the role of

  15. Introgressive hybridization in Iberian cyprinid fishes:a cytogenomic approach to homoploid Leuciscinae

    OpenAIRE

    Pereira, Carla Sofia Alves, 1983-

    2013-01-01

    Tese de doutoramento, Biologia (Biologia Evolutiva), Universidade de Lisboa, Faculdade de Ciências, 2013 Hybridization is currently a well-recognized process amongst animals responsible for biodiversity, evolution and speciation processes while defying most species concepts. Hybridization is prevalent among fishes, particularly cyprinids, which therefore constitute good models of study (1) to access general patterns of genomic variation, (2) to identify the genetic basis and the evolutiona...

  16. Courtship displays of introgressed, interspecific hybrid Nasonia males : Further investigations into the 'grandfather effect'

    NARCIS (Netherlands)

    Beukeboom, L.W.; Assem, J. van den

    Previously, we investigated courtship behaviour of bidirectional, interspecific hybrid males of two species of Nasonia (Beukeboom & van den Assem, 2001). Characteristics of the displays were intermediate between those of the parental species, but at the same time were biased towards the paternal

  17. Chemical communication, sexual selection, and introgression in wall lizards.

    Science.gov (United States)

    MacGregor, Hannah E A; Lewandowsky, Rachel A M; d'Ettorre, Patrizia; Leroy, Chloé; Davies, Noel W; While, Geoffrey M; Uller, Tobias

    2017-10-01

    Divergence in communication systems should influence the likelihood that individuals from different lineages interbreed, and consequently shape the direction and rate of hybridization. Here, we studied the role of chemical communication in hybridization, and its contribution to asymmetric and sexually selected introgression between two lineages of the common wall lizard (Podarcis muralis). Males of the two lineages differed in the chemical composition of their femoral secretions. Chemical profiles provided information regarding male secondary sexual characters, but the associations were variable and inconsistent between lineages. In experimental contact zones, chemical composition was weakly associated with male reproductive success, and did not predict the likelihood of hybridization. Consistent with these results, introgression of chemical profiles in a natural hybrid zone resembled that of neutral nuclear genetic markers overall, but one compound in particular (tocopherol methyl ether) matched closely the introgression of visual sexual characters. These results imply that associations among male chemical profiles, sexual characters, and reproductive success largely reflect transient and environmentally driven effects, and that genetic divergence in chemical composition is largely neutral. We therefore suggest that femoral secretions in wall lizards primarily provide information about residency and individual identity rather than function as sexual signals. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  18. Multi-locus estimates of population structure and migration in a fence lizard hybrid zone.

    Directory of Open Access Journals (Sweden)

    Adam D Leaché

    Full Text Available A hybrid zone between two species of lizards in the genus Sceloporus (S. cowlesi and S. tristichus on the Mogollon Rim in Arizona provides a unique opportunity to study the processes of lineage divergence and merging. This hybrid zone involves complex interactions between 2 morphologically and ecologically divergent subspecies, 3 chromosomal groups, and 4 mitochondrial DNA (mtDNA clades. The spatial patterns of divergence between morphology, chromosomes and mtDNA are discordant, and determining which of these character types (if any reflects the underlying population-level lineages that are of interest has remained impeded by character conflict. The focus of this study is to estimate the number of populations interacting in the hybrid zone using multi-locus nuclear data, and to then estimate the migration rates and divergence time between the inferred populations. Multi-locus estimates of population structure and gene flow were obtained from 12 anonymous nuclear loci sequenced for 93 specimens of Sceloporus. Population structure estimates support two populations, and this result is robust to changes to the prior probability distribution used in the Bayesian analysis and the use of spatially-explicit or non-spatial models. A coalescent analysis of population divergence suggests that gene flow is high between the two populations, and that the timing of divergence is restricted to the Pleistocene. The hybrid zone is more accurately described as involving two populations belonging to S. tristichus, and the presence of S. cowlesi mtDNA haplotypes in the hybrid zone is an anomaly resulting from mitochondrial introgression.

  19. Three genetically divergent lineages of the Oryx in eastern Africa: Evidence for an ancient introgressive hybridization

    DEFF Research Database (Denmark)

    Masembe, Charles; Muwanika, Vincent B.; Nyakaana, Silvester

    2006-01-01

    Phylogeographic and population genetic studies using sequence information are frequently used to infer species boundaries and history; and to assess hybridization and population level processes. In this study, partial mitochondrial DNA (mtDNA) control region (423 bp) and cytochrome b sequences (666...... bp) of Oryx beisa sampled from five isolated localities in its entire current range in Africa were analyzed to investigate the extent of genetic variation and differentiation between populations. We observed high nucleotide diversity at the control region in the total sample (6.3%) but within...... populations, it varied considerably ranging from 1.6% to 8.1%. Population pairwise genetic differentiation was generally significantly high (ranging from F ST¿=¿0.15, P

  20. The ecology of white-handed and pileated gibbons in a zone of overlap and hybridization in Thailand.

    Science.gov (United States)

    Asensio, Norberto; José-Domínguez, Juan Manuel; Kongrit, Chalita; Brockelman, Warren Y

    2017-08-01

    The study of related species in contact zones can elucidate what factors mediate species coexistence and geographical distributions. We investigated niche overlap and group interactions of two gibbon species and their hybrids co-occurring in a zone of overlap and hybridization. The location, composition and behavior of white-handed, pileated, and mixed-species gibbon groups were studied by following them during 31 consecutive months in a relatively large part of the contact zone. Twenty groups of white-handed gibbon were mapped followed by nine groups of pileated gibbons and five mixed-species groups. White-handed, pileated and mixed-species groups had similar sizes and composition, ate a high proportion of fruits, shared a large number of species in their diets, and presented similar habitat preferences. Group home range sizes did not differ between species and overlapped little with neighboring groups irrespective of species, and intraspecific and interspecific encounter rates were similar. Ecological similarities support that competition between the gibbon species exists and takes the form of interspecific territoriality. However, we could not find any clear mechanism of niche partitioning favoring coexistence between species. Our findings suggest that the contact zone is unstable and is maintained by dispersal inward from groups of the parental species. The relatively low numbers of mixed-species groups and hybrids found suggests a high degree of premating reproductive isolation, perhaps mediated by interspecific miscommunication. The existence of hybrids and backcrosses potentially undetectable from phenotypic characters alone raises the possibility of more widespread introgression than has been evident. Hence, while interspecific territoriality should reduce the rate of gene transfer, it would not necessarily present a barrier to introgression into contiguous populations of the opposite species. © 2017 Wiley Periodicals, Inc.

  1. Estimating the location and shape of hybrid zones

    DEFF Research Database (Denmark)

    Guedj, Benjamin; Guillot, Gilles

    2011-01-01

    We propose a new model to make use of georeferenced genetic data for inferring the location and shape of a hybrid zone. The model output includes the posterior distribution of a parameter that quantifies the width of the hybrid zone. The model proposed is implemented in the GUI and command‐line v...

  2. Hybridization between mouse lemurs in an ecological transition zone in southern Madagascar.

    Science.gov (United States)

    Gligor, M; Ganzhorn, J U; Rakotondravony, D; Ramilijaona, O R; Razafimahatratra, E; Zischler, H; Hapke, A

    2009-02-01

    Hybrid zones in ecotones can be useful model systems for the study of evolutionary processes that shape the distribution and discreteness of species. Such studies could be important for an improved understanding of the complex biogeography of Madagascar, which is renowned for its outstanding degree of small-scale endemism. Certain forest remnants in central Madagascar indicate that transitional corridors across the island could have connected microendemics in different forest types in the past. Evolutionary processes in such corridors are difficult to study because most of these corridors have disappeared due to deforestation in central Madagascar. We studied a hybrid zone in one of the few remaining ecotonal corridors between dry and humid forests in Madagascar, which connects two species of mouse lemurs, Microcebus griseorufus in dry spiny forest and Microcebus murinus in humid littoral forest. We sampled 162 mouse lemurs at nine sites across this boundary. Morphometric analyses revealed intermediate morphotypes of many individuals in transitional habitat. Bayesian clustering of microsatellite genotypes and assignment tests yielded evidence for a mixed ancestry of mouse lemurs in the ecotone, where we also observed significant linkage disequilibria and heterozygote deficiency. In contrast to these observations, mitochondrial haplotypes displayed a sharply delimited boundary at the eastern edge of spiny forest, which was noncoincident with the signals from microsatellite data. Among several alternative scenarios, we propose asymmetric nuclear introgression due to male-biased dispersal, divergent environmental selection, and an expansion of dry spiny forest in the course of aridification as a probable explanation of our observations.

  3. Sharp acoustic boundaries across an altitudinal avian hybrid zone despite asymmetric introgression

    NARCIS (Netherlands)

    Halfwerk, W.; Dingle, C.; Brinkhuizen, D.M.; Poelstra, J. W.; Komdeur, J.; Slabbekoorn, H.

    Birdsong is a sexually selected trait that could play an important evolutionary role when related taxa come into secondary contact. Many songbird species, however, learn their songs through copying one or more tutors, which complicates the evolutionary outcome of such contact. Two subspecies of a

  4. Clinal differentiation and putative hybridization in a contact zone of Pinus ponderosa and P. arizonica (Pinaceae).

    Science.gov (United States)

    Epperson, B K; Telewski, F W; Plovanich-Jones, A E; Grimes, J E

    2001-06-01

    The widely distributed Pinus subsection Ponderosae is a species complex that has a transition zone among taxa in the southwestern United States. In southern Arizona and New Mexico at least two recognized taxa, Pinus ponderosa var. scopulorum and Pinus arizonica or P. ponderosa var. arizonica, are known to coexist in close proximity. In this study, we report the existence of populations where the taxa are sympatric. One of the key characteristics distinguishing taxa is the number of needles per fascicle; P. ponderosa typically has three, P. arizonica has five. We examined the spatial distribution of needle-number types in a belt transect that covers a transition zone from nearly pure three-needle types at the top of Mount Lemmon to five-needle types downslope, in the Santa Catalina Mountains, Arizona. The spatial distribution is inconsistent with there being both free interbreeding among types and selective neutrality of types. Trees with intermediate types, having combinations of three, four, and five needles and/or mean numbers of needles between 3.0 and 5.0, are spatially concentrated in the middle of the transition zone. The spatial distribution supports the occurrence of hybridization and introgression, and this is consistent with reported crossabilities of the types. The results suggest that selection is acting, either on needle number per se or on other traits of the ecotype with which it may be in linkage disequilibrium, to maintain the observed steep clinal differentiation.

  5. Spatial genetic structure across a hybrid zone between European rabbit subspecies

    Directory of Open Access Journals (Sweden)

    Fernando Alda

    2014-09-01

    Full Text Available The Iberian Peninsula is the only region in the world where the two existing subspecies of the European rabbit (Oryctolagus cuniculus naturally occur and hybridize. In this study we explore the relative roles of historical and contemporary processes in shaping the spatial genetic structure of the rabbit across its native distribution range, and how they differently affect each subspecies and the hybrid zone. For that purpose we obtained multilocus genotypes and mitochondrial DNA data from 771 rabbits across most of the distribution range of the European rabbit in Spain. Based on the nuclear markers we observed a hierarchical genetic structure firstly comprised by two genetic groups, largely congruent with the mitochondrial lineages and subspecies distributions (O. c. algirus and O. c. cuniculus, which were subsequently subdivided into seven genetic groups. Geographic distance alone emerged as an important factor explaining genetic differentiation across the whole range, without the need to invoke for the effect for geographical barriers. Additionally, the significantly positive spatial correlation up to a distance of only 100 km supported the idea that differentiation at a local level is of greater importance when considering the species overall genetic structure. When looking at the subspecies, northern populations of O. c. cuniculus showed more spatial genetic structure and differentiation than O. c. algirus. This could be due to local geographic barriers, limited resources, soil type and/or social behavior limiting dispersal. The hybrid zone showed similar genetic structure to the southern populations but a larger introgression from the northern lineage genome. These differences have been attributed to selection against the hybrids rather than to behavioral differences between subspecies. Ultimately, the genetic structure of the rabbit in its native distribution range is the result of an ensemble of factors, from geographical and ecological

  6. Postglacial species displacement in Triturus newts deduced from asymmetrically introgressed mitochondrial DNA and ecological niche models

    Directory of Open Access Journals (Sweden)

    Wielstra Ben

    2012-08-01

    Full Text Available Abstract Background If the geographical displacement of one species by another is accompanied by hybridization, mitochondrial DNA can introgress asymmetrically, from the outcompeted species into the invading species, over a large area. We explore this phenomenon using the two parapatric crested newt species, Triturus macedonicus and T. karelinii, distributed on the Balkan Peninsula in south-eastern Europe, as a model. Results We first delimit a ca. 54,000 km2 area in which T. macedonicus contains T. karelinii mitochondrial DNA. This introgression zone bisects the range of T. karelinii, cutting off a T. karelinii enclave. The high similarity of introgressed mitochondrial DNA haplotypes with those found in T. karelinii suggests a recent transfer across the species boundary. We then use ecological niche modeling to explore habitat suitability of the location of the present day introgression zone under current, mid-Holocene and Last Glacial Maximum conditions. This area was inhospitable during the Last Glacial Maximum for both species, but would have been habitable at the mid-Holocene. Since the mid-Holocene, habitat suitability generally increased for T. macedonicus, whereas it decreased for T. karelinii. Conclusion The presence of a T. karelinii enclave suggests that T. karelinii was the first to colonize the area where the present day introgression zone is positioned after the Last Glacial Maximum. Subsequently, we propose T. karelinii was outcompeted by T. macedonicus, which captured T. karelinii mitochondrial DNA via introgressive hybridization in the process. Ecological niche modeling suggests that this replacement was likely facilitated by a shift in climate since the mid-Holocene. We suggest that the northwestern part of the current introgression zone was probably never inhabited by T. karelinii itself, and that T. karelinii mitochondrial DNA spread there through T. macedonicus exclusively. Considering the spatial distribution of the

  7. Species distribution and introgressive hybridization of two Avicennia species from the Western Hemisphere unveiled by phylogeographic patterns.

    Science.gov (United States)

    Mori, Gustavo M; Zucchi, Maria I; Sampaio, Iracilda; Souza, Anete P

    2015-04-10

    Mangrove plants grow in the intertidal zone in tropical and subtropical regions worldwide. The global latitudinal distribution of the mangrove is mainly influenced by climatic and oceanographic features. Because of current climate changes, poleward range expansions have been reported for the major biogeographic regions of mangrove forests in the Western and Eastern Hemispheres. There is evidence that mangrove forests also responded similarly after the last glaciation by expanding their ranges. In this context, the use of genetic tools is an informative approach for understanding how historical processes and factors impact the distribution of mangrove species. We investigated the phylogeographic patterns of two Avicennia species, A. germinans and A. schaueriana, from the Western Hemisphere using nuclear and chloroplast DNA markers. Our results indicate that, although Avicennia bicolor, A. germinans and A. schaueriana are independent lineages, hybridization between A. schaueriana and A. germinans is a relevant evolutionary process. Our findings also reinforce the role of long-distance dispersal in widespread mangrove species such as A. germinans, for which we observed signs of transatlantic dispersal, a process that has, most likely, contributed to the breadth of the distribution of A. germinans. However, along the southern coast of South America, A. schaueriana is the only representative of the genus. The distribution patterns of A. germinans and A. schaueriana are explained by their different responses to past climate changes and by the unequal historical effectiveness of relative gene flow by propagules and pollen. We observed that A. bicolor, A. germinans and A. schaueriana are three evolutionary lineages that present historical and ongoing hybridization on the American continent. We also inferred a new evidence of transatlantic dispersal for A. germinans, which may have contributed to its widespread distribution. Despite the generally wider distribution of A

  8. Assessing multilocus introgression patterns: a case study on the mouse X chromosome in Central Europe

    Czech Academy of Sciences Publication Activity Database

    Macholán, Miloš; Baird, S. J. E.; Dufková, Petra; Munclinger, P.; Vošlajerová Bímová, Barbora; Piálek, Jaroslav

    2011-01-01

    Roč. 65, č. 5 (2011), s. 1428-1446 ISSN 0014-3820 R&D Projects: GA ČR GA206/08/0640 Institutional research plan: CEZ:AV0Z50450515; CEZ:AV0Z60930519 Keywords : genetic conflict * hybrid zone movement * sex biased introgression * mice * X chromosome Subject RIV: EG - Zoology Impact factor: 5.146, year: 2011

  9. Cytological and morphological analysis of hybrids between Brassicoraphanus, and Brassica napus for introgression of clubroot resistant trait into Brassica napus L.

    Science.gov (United States)

    Zhan, Zongxiang; Nwafor, Chinedu Charles; Hou, Zhaoke; Gong, Jianfang; Zhu, Bin; Jiang, Yingfen; Zhou, Yongming; Wu, Jiangsheng; Piao, Zhongyun; Tong, Yue; Liu, Chao; Zhang, Chunyu

    2017-01-01

    Interspecific hybridization is a powerful tool for improvement of crop species, it has the potential to broaden the genetic base and create new plant forms for breeding programs. Synthetic allopolyploid is a widely-used model for the study of genetic recombination and fixed heterosis in Brassica. In Brassica napus breeding, identification and introgression of new sources of clubroot resistance trait from wild or related species into it by hybridization is a long-term crop management strategy for clubroot disease. Radish (Raphanus sativus L.) is a close relative of the Brassica and most radish accessions are immune to the clubroot disease. A synthesized allotetraploid Brassicoraphanus (RRCC, 2n = 36) between R. sativus cv. HQ-04 (2n = 18, RR) and Brassica oleracea var. alboglabra (L.H Bailey) (2n = 18, CC) proved resistant of multiple clubroot disease pathogen P. brassicae. To predict the possibility to transfer the clubroot resistance trait from the RR subgenome of allotetraploid Brassicoraphanus (RRCC, 2n = 36) into Brassica napus (AACC, 2n = 38), we analyzed the frequency of chromosome pairings in the F1 hybrids produced from a cross between B. napus cv. HS5 and the allotetraploid, characterize the genomic composition of some backcrossed progeny (BC1) using GISH, BAC-FISH and AFLP techniques. The level of intergenomic pairing between A and R genomes in the F1 hybrid was high, allosyndetic bivalents formed in 73.53% PMCs indicative of significant level of homeologous recombination between two genomes and high probability of incorporating chromosomal segments/genes from R-genome into A/C-genomes. The BC1 plants inherited variant extra R chromosomes or fragments from allotetraploid as revealed by GISH and AFLP analysis. 13.51% BC2 individuals were resistant to clubroot disease, and several resistance lines had high pollen fertility, Overall, the genetic material presented in this work represents a potential new genetic resource for practical use in breeding B. napus

  10. Hybridization in the Ensatina Ring Species, Strong selection against hybrids at a hybrid zone in the ensatina ring species complex and its evolutionary implications

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrino, Joao; Baird, Stuart J.E.; Lawson, Lucinda; Macey, J. Robert; Moritz, Craig; Wake, David B.

    2005-04-22

    The analysis of interactions between lineages at varying levels of genetic divergence can provide insights into the process of speciation through the accumulation of incompatible mutations. Ring species, and especially the Ensatina eschscholtzii system exemplify this approach. The plethodontid salamanders Ensatina eschscholtzii xanthoptica and Ensatina eschscholtzii platensis hybridize in the Central Sierran foothills of California. We compared the genetic structure across two transects (southern and northern Calaveras Co.), one of which was re-sampled over 20 years, and examined diagnostic molecular markers (eight allozyme loci and mitochondrial DNA) and a diagnostic quantitative trait (color pattern). Key results across all studies were: (i) cline centers for all markers were coincident and the zones were narrow, with width estimates of 730m to 2000m; (ii) cline centers at the northern Calaveras transect were coincident between 1981 and 2001, demonstrating repeatability over 5 generations; (iii) there are very few if any putative F1's, but a relatively high number of backcrossed individuals (57-86 percent) in the central portion of transects; (iv) we found substantial linkage disequilibrium in all three studies and strong heterozygote deficit both in northern Calaveras, in 2001, and southern Calaveras. Both linkage disequilibrium and heterozygote deficit show maximum values near the center of the zones (R and Fis, approx. equal to 0.5). Using estimates of cline width and dispersal, we infer strong selection against hybrids (s* approx. equal to 46-75 percent). This is sufficient to promote accumulation of differences at loci that are neutral or under divergent selection, but would still allow for introgression of adaptive alleles. The evidence for strong, but incomplete isolation across this centrally located contact is consistent with theory suggesting a gradual increase in postzygotic incompatibility between allopatric populations subject to divergent

  11. Successful Wide Hybridization and Introgression Breeding in a Diverse Set of Common Peppers (Capsicum annuum) Using Different Cultivated Ají (C. baccatum) Accessions as Donor Parents

    Science.gov (United States)

    2015-01-01

    Capsicum baccatum, commonly known as ají, has been reported as a source of variation for many different traits to improve common pepper (C. annuum), one of the most important vegetables in the world. However, strong interspecific hybridization barriers exist between them. A comparative study of two wide hybridization approaches for introgressing C. baccatum genes into C. annuum was performed: i) genetic bridge (GB) using C. chinense and C. frutescens as bridge species; and, ii) direct cross between C. annuum and C. baccatum combined with in vitro embryo rescue (ER). A diverse and representative collection of 18 accessions from four cultivated species of Capsicum was used, including C. annuum (12), C. baccatum (3), C. chinense (2), and C. frutescens (1). More than 5000 crosses were made and over 1000 embryos were rescued in the present study. C. chinense performed as a good bridge species between C. annuum and C. baccatum, with the best results being obtained with the cross combination [C. baccatum (♀) × C. chinense (♂)] (♀) × C. annuum (♂), while C. frutescens gave poor results as bridge species due to strong prezygotic and postzygotic barriers. Virus-like-syndrome or dwarfism was observed in F1 hybrids when both C. chinense and C. frutescens were used as female parents. Regarding the ER strategy, the best response was found in C. annuum (♀) × C. baccatum (♂) crosses. First backcrosses to C. annuum (BC1s) were obtained according to the crossing scheme [C. annuum (♀) × C. baccatum (♂)] (♀) × C. annuum (♂) using ER. Advantages and disadvantages of each strategy are discussed in relation to their application to breeding programmes. These results provide breeders with useful practical information for the regular utilization of the C. baccatum gene pool in C. annuum breeding. PMID:26642059

  12. Multilocus analysis of introgression between two sympatric sister species of Drosophila: Drosophila yakuba and D. santomea.

    Science.gov (United States)

    Llopart, Ana; Lachaise, Daniel; Coyne, Jerry A

    2005-09-01

    Drosophila yakuba is widely distributed in sub-Saharan Africa, while D. santomea is endemic to the volcanic island of São Tomé in the Atlantic Ocean, 280 km west of Gabon. On São Tomé, D. yakuba is found mainly in open lowland forests, and D. santomea is restricted to the wet misty forests at higher elevations. At intermediate elevations, the species form a hybrid zone where hybrids occur at a frequency of approximately 1%. To determine the extent of gene flow between these species we studied polymorphism and divergence patterns in 29 regions distributed throughout the genome, including mtDNA and three genes on the Y chromosome. This multilocus approach, together with the comparison to the two allopatric species D. mauritiana and D. sechellia, allowed us to distinguish between forces that should affect all genes and forces that should act on some genes (e.g., introgression). Our results show that D. yakuba mtDNA has replaced that of D. santomea and that there is also significant introgression for two nuclear genes, yellow and salr. The majority of genes, however, has remained distinct. These two species therefore do not form a "hybrid swarm" in which much of the genome shows substantial introgression while disruptive selection maintains distinctness for only a few traits (e.g., pigmentation and male genitalia).

  13. Effects of introgression on the genetic population structure of two ecologically and economically important conifer species: lodgepole pine (Pinus contorta var. latifolia) and jack pine (Pinus banksiana).

    Science.gov (United States)

    Cullingham, Catherine I; Cooke, Janice E K; Coltman, David W

    2013-10-01

    Forest trees exhibit a remarkable range of adaptations to their environment, but as a result of frequent and long-distance gene flow, populations are often only weakly differentiated. Lodgepole and jack pine hybridize in western Canada, which adds the opportunity for introgression through hybridization to contribute to population structure and (or) adaptive variation. Access to large sample size, high density SNP datasets for these species would improve our ability to resolve population structure, parameterize introgression, and separate the influence of demography from adaptation. To accomplish this, 454 transcriptome reads for lodgepole and jack pine were assembled using Newbler and MIRA, the assemblies mined for SNPs, and 1536 SNPs were selected for typing on lodgepole pine, jack pine, and their hybrids (N = 536). We identified population structure using both Bayesian clustering and discriminate analysis of principle components. Introgressed SNP loci were identified and their influence on observed population structure was assessed. We found that introgressed loci resulted in increased differentiation both within lodgepole and jack pine populations. These findings are timely given the recent mountain pine beetle population expansion in the hybrid zone, and will facilitate future studies of adaptive traits in these ecologically important species.

  14. Comparative transmission genetics of introgressed chromatin in Gossypium (cotton) polyploids.

    Science.gov (United States)

    Waghmare, Vijay N; Rong, Junkang; Rogers, Carl J; Bowers, John E; Chee, Peng W; Gannaway, John R; Katageri, Ishwarappa; Paterson, Andrew H

    2016-04-01

    Introgression is widely acknowledged as a potential source of valuable genetic variation, and growing effort is being invested in analysis of interspecific crosses conferring transgressive variation. Experimental backcross populations provide an opportunity to study transmission genetics following interspecific hybridization, identifying opportunities and constraints to introgressive crop improvement. The evolutionary consequences of introgression have been addressed at the theoretical level, however, issues related to levels and patterns of introgression among (plant) species remain inadequately explored, including such factors as polyploidization, subgenome interaction inhabiting a common nucleus, and the genomic distribution and linkage relationships of introgressant alleles. We analyze introgression into the polyploid Gossypium hirsutum (upland cotton) from its sister G. tomentosum and compare the level and pattern with that of G. barbadense representing a different clade tracing to the same polyploidization. Across the genome, recurrent backcrossing to Gossypium hirsutum yielded only one-third of the expected average frequency of the G. tomentosum allele, although one unusual region showed preferential introgression. Although a similar rate of introgression is found in the two subgenomes of polyploid (AtDt) G. hirsutum, a preponderance of multilocus interactions were largely within the Dt subgenome. Skewed G. tomentosum chromatin transmission is polymorphic among two elite G. hirsutum genotypes, which suggests that genetic background may profoundly affect introgression of particular chromosomal regions. Only limited correspondence is found between G. hirsutum chromosomal regions that are intolerant to introgression from the two species, G. barbadense and G. tomentosum, concentrated near possible inversion polymorphisms. Complex transmission of introgressed chromatin highlights the challenges to utilization of exotic germplasm in crop improvement. © 2016

  15. Interspecific introgression and changes in population structure in a flatfish species complex after the Prestige accident

    International Nuclear Information System (INIS)

    Crego-Prieto, V.; Danancher, D.; Campo, D.; Perez, J.; Garcia-Vazquez, E.; Roca, A.

    2013-01-01

    Highlights: • Impact of Prestige oil spill was studied on two sympatric megrim fish populations. • Samples before and nine years after the accident were genetically analyzed. • A large proportion of post-F1 interspecific hybrids was found in the polluted area. • Both species’ population structure was altered by introgression of foreign alleles. • The spillage likely promoted a hybrid zone for Lepidorhombus in the areas affected. -- Abstract: Oil spills cause aggressive impacts on marine ecosystems affecting immense areas and the species inhabiting them. If wastes are not cleaned up properly, the remnants may affect local populations for a long time. This work focuses on the long-term impacts of the Prestige spillage that occurred off Galician coast (Spain) in November 2002. Model species were two sympatric flatfish, the megrims Lepidorhombus whiffiagonis and Lepidorhombus boscii. Samples obtained before and nine years after the Prestige accident from affected and unaffected areas were genotyped for six hypervariable nuclear markers and for the mitochondrial D-loop sequence. The results revealed a high proportion of post-F1 interspecific hybrids in the area affected, and also increased intraspecific population differentiation likely due to such localized introgression of foreign genes. These changes suggest the appearance of a hybrid zone following the accident and emphasize the need of paying special attention to potential evolutionary impacts of oil spills

  16. Spatial sorting unlikely to promote maladaptive hybridization: response to Lowe, Muhlfeld, and Allendorf

    Czech Academy of Sciences Publication Activity Database

    Phillips, B. L.; Baird, Stuart J. E.

    2015-01-01

    Roč. 30, č. 10 (2015), s. 564-565 ISSN 0169-5347 Institutional support: RVO:68081766 Keywords : Spatial sorting * Maladaptive hybridisation * Moving hybrid zones * Introgression * Hybrid invasion Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 16.735, year: 2015

  17. Surgeons and suture zones: Hybridization among four surgeonfish species in the Indo-Pacific with variable evolutionary outcomes

    KAUST Repository

    DiBattista, Joseph; Whitney, Jonathan; Craig, Matthew T.; Hobbs, Jean-Paul A.; Rocha, Luiz A.; Feldheim, Kevin A.; Berumen, Michael L.; Bowen, Brian W.

    2016-01-01

    Closely related species can provide valuable insights into evolutionary processes through comparison of their ecology, geographic distribution and the history recorded in their genomes. In the Indo-Pacific, many reef fishes are divided into sister species that come into secondary contact at biogeographic borders, most prominently where Indian Ocean and Pacific Ocean faunas meet. It is unclear whether hybridization in this contact zone represents incomplete speciation, secondary contact, an evolutionary dead-end (for hybrids) or some combination of the above. To address these issues, we conducted comprehensive surveys of two widely-distributed surgeonfish species, Acanthurus leucosternon (N = 141) and A. nigricans (N = 412), with mtDNA cytochrome b sequences and ten microsatellite loci. These surgeonfishes are found primarily in the Indian and Pacific Oceans, respectively, but overlap at the Christmas and Cocos-Keeling Islands hybrid zone in the eastern Indian Ocean. We also sampled the two other Pacific members of this species complex, A. achilles (N = 54) and A. japonicus (N = 49), which are known to hybridize with A. nigricans where their ranges overlap. Our results indicate separation between the four species that range from the recent Pleistocene to late Pliocene (235,000 to 2.25 million years ago). The Pacific A. achilles is the most divergent (and possibly ancestral) species with mtDNA dcorr ≈ 0.04, whereas the other two Pacific species (A. japonicus and A. nigricans) are distinguishable only at a population or subspecies level (ΦST = 0.6533, P < 0.001). Little population structure was observed within species, with evidence of recent population expansion across all four geographic ranges. We detected sharing of mtDNA haplotypes between species and extensive hybridization based on microsatellites, consistent with later generation hybrids but also the effects of allele homoplasy. Despite extensive introgression, 98% of specimens had concordance between mt

  18. Surgeons and suture zones: Hybridization among four surgeonfish species in the Indo-Pacific with variable evolutionary outcomes.

    Science.gov (United States)

    DiBattista, Joseph D; Whitney, Jonathan; Craig, Matthew T; Hobbs, Jean-Paul A; Rocha, Luiz A; Feldheim, Kevin A; Berumen, Michael L; Bowen, Brian W

    2016-08-01

    Closely related species can provide valuable insights into evolutionary processes through comparison of their ecology, geographic distribution and the history recorded in their genomes. In the Indo-Pacific, many reef fishes are divided into sister species that come into secondary contact at biogeographic borders, most prominently where Indian Ocean and Pacific Ocean faunas meet. It is unclear whether hybridization in this contact zone represents incomplete speciation, secondary contact, an evolutionary dead-end (for hybrids) or some combination of the above. To address these issues, we conducted comprehensive surveys of two widely-distributed surgeonfish species, Acanthurus leucosternon (N=141) and A. nigricans (N=412), with mtDNA cytochrome b sequences and ten microsatellite loci. These surgeonfishes are found primarily in the Indian and Pacific Oceans, respectively, but overlap at the Christmas and Cocos-Keeling Islands hybrid zone in the eastern Indian Ocean. We also sampled the two other Pacific members of this species complex, A. achilles (N=54) and A. japonicus (N=49), which are known to hybridize with A. nigricans where their ranges overlap. Our results indicate separation between the four species that range from the recent Pleistocene to late Pliocene (235,000-2.25million years ago). The Pacific A. achilles is the most divergent (and possibly ancestral) species with mtDNA dcorr≈0.04, whereas the other two Pacific species (A. japonicus and A. nigricans) are distinguishable only at a population or subspecies level (ΦST=0.6533, P<0.001). Little population structure was observed within species, with evidence of recent population expansion across all four geographic ranges. We detected sharing of mtDNA haplotypes between species and extensive hybridization based on microsatellites, consistent with later generation hybrids but also the effects of allele homoplasy. Despite extensive introgression, 98% of specimens had concordance between mtDNA lineage and

  19. Surgeons and suture zones: Hybridization among four surgeonfish species in the Indo-Pacific with variable evolutionary outcomes

    KAUST Repository

    DiBattista, Joseph

    2016-04-30

    Closely related species can provide valuable insights into evolutionary processes through comparison of their ecology, geographic distribution and the history recorded in their genomes. In the Indo-Pacific, many reef fishes are divided into sister species that come into secondary contact at biogeographic borders, most prominently where Indian Ocean and Pacific Ocean faunas meet. It is unclear whether hybridization in this contact zone represents incomplete speciation, secondary contact, an evolutionary dead-end (for hybrids) or some combination of the above. To address these issues, we conducted comprehensive surveys of two widely-distributed surgeonfish species, Acanthurus leucosternon (N = 141) and A. nigricans (N = 412), with mtDNA cytochrome b sequences and ten microsatellite loci. These surgeonfishes are found primarily in the Indian and Pacific Oceans, respectively, but overlap at the Christmas and Cocos-Keeling Islands hybrid zone in the eastern Indian Ocean. We also sampled the two other Pacific members of this species complex, A. achilles (N = 54) and A. japonicus (N = 49), which are known to hybridize with A. nigricans where their ranges overlap. Our results indicate separation between the four species that range from the recent Pleistocene to late Pliocene (235,000 to 2.25 million years ago). The Pacific A. achilles is the most divergent (and possibly ancestral) species with mtDNA dcorr ≈ 0.04, whereas the other two Pacific species (A. japonicus and A. nigricans) are distinguishable only at a population or subspecies level (ΦST = 0.6533, P < 0.001). Little population structure was observed within species, with evidence of recent population expansion across all four geographic ranges. We detected sharing of mtDNA haplotypes between species and extensive hybridization based on microsatellites, consistent with later generation hybrids but also the effects of allele homoplasy. Despite extensive introgression, 98% of specimens had concordance between mt

  20. Origin and cross-century dynamics of an avian hybrid zone.

    Science.gov (United States)

    Morales-Rozo, Andrea; Tenorio, Elkin A; Carling, Matthew D; Cadena, Carlos Daniel

    2017-12-15

    Characterizations of the dynamics of hybrid zones in space and time can give insights about traits and processes important in population divergence and speciation. We characterized a hybrid zone between tanagers in the genus Ramphocelus (Aves, Thraupidae) located in southwestern Colombia. We evaluated whether this hybrid zone originated as a result of secondary contact or of primary differentiation, and described its dynamics across time using spatial analyses of molecular, morphological, and coloration data in combination with paleodistribution modeling. Models of potential historical distributions based on climatic data and genetic signatures of demographic expansion suggested that the hybrid zone likely originated following secondary contact between populations that expanded their ranges out of isolated areas in the Quaternary. Concordant patterns of variation in phenotypic characters across the hybrid zone and its narrow extent are suggestive of a tension zone, maintained by a balance between dispersal and selection against hybrids. Estimates of phenotypic cline parameters obtained using specimens collected over nearly a century revealed that, in recent decades, the zone appears to have moved to the east and to higher elevations, and may have become narrower. Genetic variation was not clearly structured along the hybrid zone, but comparisons between historical and contemporary specimens suggested that temporal changes in its genetic makeup may also have occurred. Our data suggest that the hybrid zone likey resulted from secondary contact between populations. The observed changes in the hybrid zone may be a result of sexual selection, asymmetric gene flow, or environmental change.

  1. Genome-wide mapping in a house mouse hybrid zone reveals hybrid sterility loci and Dobzhansky-Muller interactions.

    Science.gov (United States)

    Turner, Leslie M; Harr, Bettina

    2014-12-09

    Mapping hybrid defects in contact zones between incipient species can identify genomic regions contributing to reproductive isolation and reveal genetic mechanisms of speciation. The house mouse features a rare combination of sophisticated genetic tools and natural hybrid zones between subspecies. Male hybrids often show reduced fertility, a common reproductive barrier between incipient species. Laboratory crosses have identified sterility loci, but each encompasses hundreds of genes. We map genetic determinants of testis weight and testis gene expression using offspring of mice captured in a hybrid zone between M. musculus musculus and M. m. domesticus. Many generations of admixture enables high-resolution mapping of loci contributing to these sterility-related phenotypes. We identify complex interactions among sterility loci, suggesting multiple, non-independent genetic incompatibilities contribute to barriers to gene flow in the hybrid zone.

  2. Investigation of (n,γ) reaction in hybrid reactor zones

    Energy Technology Data Exchange (ETDEWEB)

    Guenay, Mehtap [Inoenue Univ., Malatya (Turkey). Physics Dept.

    2014-12-15

    In this study, the fluids were composed with increased mole fractions of a mixture of molten salt: heavy metals 99-95 % Li{sub 20}Sn{sub 80{sup -}}1-5 % SFG-Pu, 99-95 % Li{sub 20}Sn{sub 80{sup -}}1-5 % SFG-PuF{sub 4}, 99-95 % Li{sub 20}Sn{sub 80{sup -}}1-5 % SFG-PuO{sub 2}. In this study, the effect on conversion of each isotope ({sup 238-242}Pu) in spent fuel grade plutonium by (n,γ) reactions was investigated in liquid first wall, blanket and shield zones of the designed hybrid reactor system. Beryllium (Be) is the neutron multiplier by (n,2n) reactions. The Be zone used was 3 cm thick. 9Cr2WVT, a ferritic steel, is used as structural material. Three-dimensional nucleonic calculations were performed by using the most recent versions of the MCNPX-2.7.0 Monte Carlo code and the nuclear data library ENDF/B-VII.0.

  3. Investigation of (n,γ) reaction in hybrid reactor zones

    International Nuclear Information System (INIS)

    Guenay, Mehtap

    2014-01-01

    In this study, the fluids were composed with increased mole fractions of a mixture of molten salt: heavy metals 99-95 % Li 20 Sn 80 - 1-5 % SFG-Pu, 99-95 % Li 20 Sn 80 - 1-5 % SFG-PuF 4 , 99-95 % Li 20 Sn 80 - 1-5 % SFG-PuO 2 . In this study, the effect on conversion of each isotope ( 238-242 Pu) in spent fuel grade plutonium by (n,γ) reactions was investigated in liquid first wall, blanket and shield zones of the designed hybrid reactor system. Beryllium (Be) is the neutron multiplier by (n,2n) reactions. The Be zone used was 3 cm thick. 9Cr2WVT, a ferritic steel, is used as structural material. Three-dimensional nucleonic calculations were performed by using the most recent versions of the MCNPX-2.7.0 Monte Carlo code and the nuclear data library ENDF/B-VII.0.

  4. Oscillation of an anuran hybrid zone: morphological evidence spanning 50 years.

    Directory of Open Access Journals (Sweden)

    Jean-Sébastien Roy

    Full Text Available The hybrid zone between the primarily forest-dwelling American toad, Anaxyrus americanus, and the prairie-adapted Canadian toad, A. hemiophrys, in southeastern Manitoba is known to have shifted its position during the past 50 years. Hybrid zones are areas of interbreeding between species and their movement across a landscape should reflect their underlying dynamics and environmental change. However, empirical demonstrations of hybrid zone movements over long periods of time are rare. This hybrid zone is dominated by individuals of intermediate morphology and genetic composition. We sought to determine if it had continued to move and if that movement was associated with shifts in habitat, as predicted.We used variation in the toads' most diagnostic morphological feature, the separation between their interorbital cranial crests, to determine the geographic position of the hybrid zone center at four times between 1960 and 2009 using maximum likelihood methods. The hybrid zone center moved west by 38 km over 19 years and then east again by 10 km over the succeeding 29 years. The position of the hybrid zone did not track either the direction or the magnitude of movement of the forest-prairie habitat transition over the same time period.This is the first reported evidence of oscillation in the position of a hybrid zone. The back and forth movement indicates that neither species maintains a selective advantage over the other in the long term. However, the movement of the hybrid zone was not bounded by the breadth of the habitat transition. Its oscillation suggests that the hybrid zone is better described as being elastically tethered to the habitat transition.

  5. Cryptic genetic diversity in the mottled rabbitfish Siganus fuscescens with mitochondrial introgression at a contact zone in the South China Sea.

    Science.gov (United States)

    Ravago-Gotanco, Rachel; de la Cruz, Talna Lorena; Pante, Ma Josefa; Borsa, Philippe

    2018-01-01

    The taxonomy of the mottled rabbitfish Siganus fuscescens species complex has long been challenging. In this study, we analyzed microsatellite genotypes, mitochondrial lineages, and morphometric data from 373 S. fuscescens individuals sampled from the northern Philippines and Hong Kong (South China Sea, Philippine Sea and Sulu Sea basins), to examine putative species boundaries in samples comprising three co-occurring mitochondrial lineages previously reported to characterize S. fuscescens (Clade A and Clade B) or S. canaliculatus (Clade C). We report the existence of two cryptic species within S. fuscescens in the northeast region of the South China Sea and northern Philippine Sea, supported by genetic and morphological differences. Individual-based assignment methods recovered concordant groupings of individuals into two nuclear genotype clusters (Cluster 1, Cluster 2) with (1) limited gene flow, if any, between them (FST = 0.241; P South China Sea. Mitonuclear discordance due to introgression obscures phylogenetic relationships for recently-diverged lineages, and cautions against the use of mitochondrial markers alone for species identification within the mottled rabbitfish species complex in the South China Sea region.

  6. Adaptive traits are maintained on steep selective gradients despite gene flow and hybridization in the intertidal zone.

    Directory of Open Access Journals (Sweden)

    Gerardo I Zardi

    Full Text Available Gene flow among hybridizing species with incomplete reproductive barriers blurs species boundaries, while selection under heterogeneous local ecological conditions or along strong gradients may counteract this tendency. Congeneric, externally-fertilizing fucoid brown algae occur as distinct morphotypes along intertidal exposure gradients despite gene flow. Combining analyses of genetic and phenotypic traits, we investigate the potential for physiological resilience to emersion stressors to act as an isolating mechanism in the face of gene flow. Along vertical exposure gradients in the intertidal zone of Northern Portugal and Northwest France, the mid-low shore species Fucus vesiculosus, the upper shore species Fucus spiralis, and an intermediate distinctive morphotype of F. spiralis var. platycarpus were morphologically characterized. Two diagnostic microsatellite loci recovered 3 genetic clusters consistent with prior morphological assignment. Phylogenetic analysis based on single nucleotide polymorphisms in 14 protein coding regions unambiguously resolved 3 clades; sympatric F. vesiculosus, F. spiralis, and the allopatric (in southern Iberia population of F. spiralis var. platycarpus. In contrast, the sympatric F. spiralis var. platycarpus (from Northern Portugal was distributed across the 3 clades, strongly suggesting hybridization/introgression with both other entities. Common garden experiments showed that physiological resilience following exposure to desiccation/heat stress differed significantly between the 3 sympatric genetic taxa; consistent with their respective vertical distribution on steep environmental clines in exposure time. Phylogenetic analyses indicate that F. spiralis var. platycarpus is a distinct entity in allopatry, but that extensive gene flow occurs with both higher and lower shore species in sympatry. Experimental results suggest that strong selection on physiological traits across steep intertidal exposure gradients

  7. Repeated adaptive introgression at a gene under multiallelic balancing selection.

    Directory of Open Access Journals (Sweden)

    Vincent Castric

    2008-08-01

    Full Text Available Recently diverged species typically have incomplete reproductive barriers, allowing introgression of genetic material from one species into the genomic background of the other. The role of natural selection in preventing or promoting introgression remains contentious. Because of genomic co-adaptation, some chromosomal fragments are expected to be selected against in the new background and resist introgression. In contrast, natural selection should favor introgression for alleles at genes evolving under multi-allelic balancing selection, such as the MHC in vertebrates, disease resistance, or self-incompatibility genes in plants. Here, we test the prediction that negative, frequency-dependent selection on alleles at the multi-allelic gene controlling pistil self-incompatibility specificity in two closely related species, Arabidopsis halleri and A. lyrata, caused introgression at this locus at a higher rate than the genomic background. Polymorphism at this gene is largely shared, and we have identified 18 pairs of S-alleles that are only slightly divergent between the two species. For these pairs of S-alleles, divergence at four-fold degenerate sites (K = 0.0193 is about four times lower than the genomic background (K = 0.0743. We demonstrate that this difference cannot be explained by differences in effective population size between the two types of loci. Rather, our data are most consistent with a five-fold increase of introgression rates for S-alleles as compared to the genomic background, making this study the first documented example of adaptive introgression facilitated by balancing selection. We suggest that this process plays an important role in the maintenance of high allelic diversity and divergence at the S-locus in flowering plant families. Because genes under balancing selection are expected to be among the last to stop introgressing, their comparison in closely related species provides a lower-bound estimate of the time since the

  8. Structure of herbivore communities in two oak (Quercus spp.) hybrid zones.

    Science.gov (United States)

    Boecklen, William J; Spellenberg, Richard

    1990-11-01

    We examined patterns of density and species diversity for leaf-mining Lepidopterans and gall-forming Hymenopterans in two oak (Quercus spp.) hybrid zones: Quercus depressipes x Q. rugosa and Q. emoryi x Q. coccolobifolia. In both species complexes, hybrid hosts typically supported significantly lower densities and species diversity of parasites than did parental types. This contradicts the findings of Whitham (1989) that suggested that hybrid hosts may act as parasite sinks both in ecological and evolutionary time. We discuss features of hybrid zones that are likely to influence patterns of herbivory.

  9. Countering Gray-Zone Hybrid Threats: An Analysis of Russias New Generation Warfare and Implications for the US Army

    Science.gov (United States)

    2016-10-18

    Threats 21 Laws and Cultural Norms as a Weapons System : When operating in the gray zone, aggressors try to use... Operational Phases 26 Countering Gray-Zone Hybrid Threats 4 Abstract The gray zone is an operating environment in...Countering Gray-Zone Hybrid Threats 6 Criminal Organizations and Networks,

  10. Influence of environment and mitochondrial heritage on the ecological characteristics of fish in a hybrid zone.

    Directory of Open Access Journals (Sweden)

    Nicolas Stolzenberg

    2009-06-01

    Full Text Available Ecological characteristics (growth, morphology, reproduction arise from the interaction between environmental factors and genetics. Genetic analysis of individuals' life history traits might be used to improve our understanding of mechanisms that form and maintain a hybrid zone.A fish hybrid zone was used to characterize the process of natural selection. Data were collected during two reproductive periods (2001 and 2002 and 1117 individuals (nase, Chondrostama nasus nasus, sofie C. toxostoma toxostoma and hybrids were sampled. Reproductive dates of the two parental species overlapped at sympatric sites. The nase had an earlier reproductive period than the sofie; males had longer reproductive periods for both species. Hybridisation between female nase and male sofie was the most likely. Hybrids had a reproductive period similar to the inherited parental mitochondrial type. Growth and reproductive information from different environments has been synthesised following a bayesian approach of the von Bertalanffy model. Hybrid life history traits appear to link with maternal heritage. Hybrid size from the age of two and size at first maturity appeared to be closer to the size of the maternal origin species (nase or sofie. Median growth rates for hybrids were similar and intermediate between those of the parental species. We observed variable life history traits for hybrids and pure forms in the different parts of the hybrid zone. Geometrical analysis of the hybrid fish shape gave evidence of two main morphologies with a link to maternal heritage.Selective mating seemed to be the underlying process which, with mitochondrial heritage, could explain the evolution of the studied hybrid zone. More generally, we showed the importance of studies on hybrid zones and specifically the study of individuals' ecological characteristics, to improve our understanding of speciation.

  11. Influence of environment and mitochondrial heritage on the ecological characteristics of fish in a hybrid zone.

    Science.gov (United States)

    Stolzenberg, Nicolas; Nguyen The, Bénédicte; Salducci, Marie Dominique; Cavalli, Laurent

    2009-06-18

    Ecological characteristics (growth, morphology, reproduction) arise from the interaction between environmental factors and genetics. Genetic analysis of individuals' life history traits might be used to improve our understanding of mechanisms that form and maintain a hybrid zone. A fish hybrid zone was used to characterize the process of natural selection. Data were collected during two reproductive periods (2001 and 2002) and 1117 individuals (nase, Chondrostama nasus nasus, sofie C. toxostoma toxostoma and hybrids) were sampled. Reproductive dates of the two parental species overlapped at sympatric sites. The nase had an earlier reproductive period than the sofie; males had longer reproductive periods for both species. Hybridisation between female nase and male sofie was the most likely. Hybrids had a reproductive period similar to the inherited parental mitochondrial type. Growth and reproductive information from different environments has been synthesised following a bayesian approach of the von Bertalanffy model. Hybrid life history traits appear to link with maternal heritage. Hybrid size from the age of two and size at first maturity appeared to be closer to the size of the maternal origin species (nase or sofie). Median growth rates for hybrids were similar and intermediate between those of the parental species. We observed variable life history traits for hybrids and pure forms in the different parts of the hybrid zone. Geometrical analysis of the hybrid fish shape gave evidence of two main morphologies with a link to maternal heritage. Selective mating seemed to be the underlying process which, with mitochondrial heritage, could explain the evolution of the studied hybrid zone. More generally, we showed the importance of studies on hybrid zones and specifically the study of individuals' ecological characteristics, to improve our understanding of speciation.

  12. Introgression Browser: High throughput whole-genome SNP visualization

    NARCIS (Netherlands)

    Aflitos, S.A.; Sanchez Perez, G.F.; Ridder, de D.; Fransz, P.; Schranz, M.E.; Jong, de J.H.S.G.M.; Peters, S.A.

    2015-01-01

    Breeding by introgressive hybridization is a pivotal strategy to broaden the genetic basis of crops. Usually, the desired traits are monitored in consecutive crossing generations by marker-assisted selection, but their analyses fail in chromosome regions where crossover recombinants are rare or not

  13. Introgression browser: high-throughput whole-genome SNP visualization

    NARCIS (Netherlands)

    Alves Aflitos, S.; Sanchez-Perez, G.; de Ridder, D.; Fransz, P.; Schranz, M.E.; de Jong, H.; Peters, S.A.

    2015-01-01

    Breeding by introgressive hybridization is a pivotal strategy to broaden the genetic basis of crops. Usually, the desired traits are monitored in consecutive crossing generations by marker-assisted selection, but their analyses fail in chromosome regions where crossover recombinants are rare or not

  14. New evidence for hybrid zones of forest and savanna elephants in Central and West Africa

    DEFF Research Database (Denmark)

    Mondol, Samrat; Moltke, Ida; Hart, John

    2015-01-01

    unsampled areas of Africa. Novel statistical methods applied to these data identify 46 hybrid samples - many more than have been previously identified - only two of which are from the Garamba region. The remaining 44 are from three other geographically distinct locations: a major hybrid zone along...

  15. Narrow hybrid zone between two subspecies of big sagebrush (Artemisia tridentata: Asteraceae): XI. Plant-insect interactions in reciprocal transplant gardens

    Science.gov (United States)

    John H. Graham; E. Durant McArthur; D. Carl Freeman

    2001-01-01

    Basin big sagebrush (Artemisia tridentata ssp. tridentata) and mountain big sagebrush (A. t. ssp. vaseyana) hybridize in a narrow zone near Salt Creek, Utah. Reciprocal transplant experiments in this hybrid zone demonstrate that hybrids are more fit than either parental subspecies, but only in the hybrid zone. Do hybrids experience greater, or lesser, use by...

  16. Ongoing movement of the hermit warbler X Townsend's warbler hybrid zone.

    Directory of Open Access Journals (Sweden)

    Meade Krosby

    Full Text Available BACKGROUND: Movements of hybrid zones - areas of overlap and interbreeding between species - are difficult to document empirically. This is true because moving hybrid zones are expected to be rare, and because movement may proceed too slowly to be measured directly. Townsend's warblers (Dendroica townsendi hybridize with hermit warblers (D. occidentalis where their ranges overlap in Washington and Oregon. Previous morphological, behavioral, and genetic studies of this hybrid zone suggest that it has been steadily moving into the geographical range of hermit warblers, with the more aggressive Townsend's warblers replacing hermit warblers along ∼2000 km of the Pacific coast of Canada and Alaska. Ongoing movement of the zone, however, has yet to be empirically demonstrated. METHODOLOGY/PRINCIPAL FINDINGS: We compared recently sampled hybrid zone specimens to those collected 10-20 years earlier, to test directly the long-standing hypothesis of hybrid zone movement between these species. Newly sampled specimens were more Townsend's-like than historical specimens, consistent with ongoing movement of the zone into the geographical range of hermit warblers. CONCLUSIONS/SIGNIFICANCE: While movement of a hybrid zone may be explained by several possible mechanisms, in this case a wealth of existing evidence suggests that movement is being driven by the competitive displacement of hermit warblers by Townsend's warblers. That no ecological differences have been found between these species, and that replacement of hermit warblers by Townsend's warblers is proceeding downward in latitude and elevation - opposite the directions of range shifts predicted by recent climate change - further support that this movement is not being driven by alternative environmental factors. If the mechanism of competitive displacement is correct, whether this process will ultimately lead to the extinction of hermit warblers will depend on the continued maintenance of the

  17. The high Andes, gene flow and a stable hybrid zone shape the genetic structure of a wide-ranging South American parrot

    Directory of Open Access Journals (Sweden)

    Schaefer H Martin

    2011-06-01

    Full Text Available Abstract Background While the gene flow in some organisms is strongly affected by physical barriers and geographical distance, other highly mobile species are able to overcome such constraints. In southern South America, the Andes (here up to 6,900 m may constitute a formidable barrier to dispersal. In addition, this region was affected by cycles of intercalating arid/moist periods during the Upper/Late Pleistocene and Holocene. These factors may have been crucial in driving the phylogeographic structure of the vertebrate fauna of the region. Here we test these hypotheses in the burrowing parrot Cyanoliseus patagonus (Aves, Psittaciformes across its wide distributional range in Chile and Argentina. Results Our data show a Chilean origin for this species, with a single migration event across the Andes during the Upper/Late Pleistocene, which gave rise to all extant Argentinean mitochondrial lineages. Analyses suggest a complex population structure for burrowing parrots in Argentina, which includes a hybrid zone that has remained stable for several thousand years. Within this zone, introgression by expanding haplotypes has resulted in the evolution of an intermediate phenotype. Multivariate regressions show that present day climatic variables have a strong influence on the distribution of genetic heterogeneity, accounting for almost half of the variation in the data. Conclusions Here we show how huge barriers like the Andes and the regional environmental conditions imposed constraints on the ability of a parrot species to colonise new habitats, affecting the way in which populations diverged and thus, genetic structure. When contact between divergent populations was re-established, a stable hybrid zone was formed, functioning as a channel for genetic exchange between populations.

  18. Mating, hybridisation and introgression in Lasius ants (Hymenoptera: Formicidae)

    DEFF Research Database (Denmark)

    Van der Have, Tom; Pedersen, Jes Søe; Boomsma, Jacobus Jan

    2011-01-01

    Recent reviews have shown that hybridisation among ant species is likely to be more common than previously appreci-ated, but that documented cases of introgression remain rare. After molecular phylogenetic work had shown that Euro-pean Lasius niger (LINNAEUS, 1758) and L. psammophilus SEIFERT, 1992...... (formerly L. alienus (FOERSTER, 1850)) are unlikely to be very closely related, we decided to analyse an old data set confirming the conclusion by PEARSON (1983) that these two ants can indeed form viable hybrids. We show that signatures of introgression can be detected in a Danish site...... sympatrically. This would imply that multiple accessible field sites are available to study the molecular details of hybridisation and in-trogression between two ant species that have variable degrees of sympatry throughout their distributional ranges...

  19. Barrier to gene flow between two ecologically divergent Populus species, P. alba (white poplar) and P. tremula (European aspen): the role of ecology and life history in gene introgression.

    Science.gov (United States)

    Lexer, C; Fay, M F; Joseph, J A; Nica, M-S; Heinze, B

    2005-04-01

    The renewed interest in the use of hybrid zones for studying speciation calls for the identification and study of hybrid zones across a wide range of organisms, especially in long-lived taxa for which it is often difficult to generate interpopulation variation through controlled crosses. Here, we report on the extent and direction of introgression between two members of the "model tree" genus Populus: Populus alba (white poplar) and Populus tremula (European aspen), across a large zone of sympatry located in the Danube valley. We genotyped 93 hybrid morphotypes and samples from four parental reference populations from within and outside the zone of sympatry for a genome-wide set of 20 nuclear microsatellites and eight plastid DNA restriction site polymorphisms. Our results indicate that introgression occurs preferentially from P. tremula to P. alba via P. tremula pollen. This unidirectional pattern is facilitated by high levels of pollen vs. seed dispersal in P. tremula (pollen/seed flow = 23.9) and by great ecological opportunity in the lowland floodplain forest in proximity to P. alba seed parents, which maintains gene flow in the direction of P. alba despite smaller effective population sizes (N(e)) in this species (P. alba N(e)c. 500-550; P. tremula N(e)c. 550-700). Our results indicate that hybrid zones will be valuable tools for studying the genetic architecture of the barrier to gene flow between these two ecologically divergent Populus species.

  20. Sex− and species−biased gene flow in a spotted eagle hybrid zone

    Directory of Open Access Journals (Sweden)

    Väli Ülo

    2011-04-01

    Full Text Available Abstract Background Recent theoretical and empirical work points toward a significant role for sex-chromosome linked genes in the evolution of traits that induce reproductive isolation and for traits that evolve under influence of sexual selection. Empirical studies including recently diverged (Pleistocene, short-lived avian species pairs with short generation times have found that introgression occurs on the autosomes but not on the Z-chromosome. Here we study genetic differentiation and gene flow in the long-lived greater spotted eagle (Aquila clanga and lesser spotted eagle (A. pomarina, two species with comparatively long generation times. Results Our data suggest that there is a directional bias in migration rates between hybridizing spotted eagles in eastern Europe. We find that a model including post divergence gene flow fits our data best for both autosomal and Z-chromosome linked loci but, for the Z-chromosome, the rate is reduced in the direction from A. pomarina to A. clanga. Conclusions The fact that some introgression still occurs on the Z-chromosome between these species suggests that the differentiation process is in a more premature phase in our study system than in previously studied avian species pairs and that could be explained by a shorter divergence time and/or a longer average generation time in the spotted eagles. The results are in agreement with field observations and provide further insight into the role of sex-linked loci for the build-up of barriers to gene flow among diverging populations and species.

  1. Introgression of mitochondrial DNA among Myodes voles: consequences for energetics?

    Directory of Open Access Journals (Sweden)

    Boratyński Zbyszek

    2011-12-01

    Full Text Available Abstract Background Introgression of mitochondrial DNA (mtDNA is among the most frequently described cases of reticulate evolution. The tendency of mtDNA to cross interspecific barriers is somewhat counter-intuitive considering the key function of enzymes that it encodes in the oxidative-phosphorylation process, which could give rise to hybrid dysfunction. How mtDNA reticulation affects the evolution of metabolic functions is, however, uncertain. Here we investigated how morpho-physiological traits vary in natural populations of a common rodent (the bank vole, Myodes glareolus and whether this variation could be associated with mtDNA introgression. First, we confirmed that M. glareolus harbour mtDNA introgressed from M. rutilus by analyzing mtDNA (cytochrome b, 954 bp and nuclear DNA (four markers; 2333 bp in total sequence variation and reconstructing loci phylogenies among six natural populations in Finland. We then studied geographic variation in body size and basal metabolic rate (BMR among the populations of M. glareolus and tested its relationship with mtDNA type. Results Myodes glareolus and its arctic neighbour, M. rutilus, are reciprocally monophyletic at the analyzed nuclear DNA loci. In contrast, the two northernmost populations of M. glareolus have a fixed mitotype that is shared with M. rutilus, likely due to introgressive hybridization. The analyses of phenotypic traits revealed that the body mass and whole-body, but not mass corrected, BMR are significantly reduced in M. glareolus females from northern Finland that also have the introgressed mitotype. Restricting the analysis to the single population where the mitotypes coexist, the association of mtDNA type with whole-body BMR remained but those with mass corrected BMR and body mass did not. Mitochondrial sequence variation in the introgressed haplotypes is compatible with demographic growth of the populations, but may also be a result of positive selection. Conclusion Our

  2. Testing the 'hybrid susceptibility' and 'phenological sink' hypotheses using the P. balsamifera - P. deltoides hybrid zone and septoria leaf spot [Septoria musiva].

    Science.gov (United States)

    LeBoldus, Jared M; Isabel, Nathalie; Floate, Kevin D; Blenis, Peter; Thomas, Barb R

    2013-01-01

    Hybrid genotypes that arise between plant species frequently have increased susceptibility to arthropod pests and fungal pathogens. This pattern has been attributed to the breakdown of plant defenses ('Hybrid susceptibility' hypothesis) and (or) to extended periods of susceptibility attributed to plant phenologies in zones of species overlap and (or) hybridization ('phenological sink' hypothesis). We examined these hypotheses by assessing the susceptibility of parental and hybrid Populus host genotypes to a leaf spot disease caused by the fungal pathogen Septoria musiva. For this purpose, 214 genotypes were obtained from morphologically pure zones of P. balsamifera and P. deltoides, and from an intervening zone of overlap and hybridization on the drainage of the Red Deer River, Alberta, Canada. Genotypes were identified as P. balsamifera, P. deltoides, or hybrid using a suite of 27 species-specific SNP markers. Initially the genetic structure of the hybrid zone was characterized with 27.7% of trees classified as admixed individuals. To test the hybrid susceptibility hypothesis, a subset of 52 genotypes was inoculated with four isolates of S. musiva. Levels of susceptibility were P. balsamifera > F1 hybrid > P. deltoides. A further 53 genotypes were grown in a common garden to assess the effect of genotype on variation in leaf phenology. Leaf phenology was more variable within the category of hybrid genotypes than within categories of either parental species. Leaf phenology was also more variable for the category of trees originating in the hybrid (P. balsamifera - P. deltoides [hybrid and parental genotypes combined]) zone than in adjacent pure zones of the parental species. The results from the inoculation experiment support the hybrid intermediacy hypothesis. The results from the common garden experiment support the 'phenological sink' hypothesis. These findings have greatly increased our understanding of the epidemiology and ecology of fungal pathogens in plant

  3. Testing the 'hybrid susceptibility' and 'phenological sink' hypotheses using the P. balsamifera - P. deltoides hybrid zone and septoria leaf spot [Septoria musiva].

    Directory of Open Access Journals (Sweden)

    Jared M LeBoldus

    Full Text Available Hybrid genotypes that arise between plant species frequently have increased susceptibility to arthropod pests and fungal pathogens. This pattern has been attributed to the breakdown of plant defenses ('Hybrid susceptibility' hypothesis and (or to extended periods of susceptibility attributed to plant phenologies in zones of species overlap and (or hybridization ('phenological sink' hypothesis. We examined these hypotheses by assessing the susceptibility of parental and hybrid Populus host genotypes to a leaf spot disease caused by the fungal pathogen Septoria musiva. For this purpose, 214 genotypes were obtained from morphologically pure zones of P. balsamifera and P. deltoides, and from an intervening zone of overlap and hybridization on the drainage of the Red Deer River, Alberta, Canada. Genotypes were identified as P. balsamifera, P. deltoides, or hybrid using a suite of 27 species-specific SNP markers. Initially the genetic structure of the hybrid zone was characterized with 27.7% of trees classified as admixed individuals. To test the hybrid susceptibility hypothesis, a subset of 52 genotypes was inoculated with four isolates of S. musiva. Levels of susceptibility were P. balsamifera > F1 hybrid > P. deltoides. A further 53 genotypes were grown in a common garden to assess the effect of genotype on variation in leaf phenology. Leaf phenology was more variable within the category of hybrid genotypes than within categories of either parental species. Leaf phenology was also more variable for the category of trees originating in the hybrid (P. balsamifera - P. deltoides [hybrid and parental genotypes combined] zone than in adjacent pure zones of the parental species. The results from the inoculation experiment support the hybrid intermediacy hypothesis. The results from the common garden experiment support the 'phenological sink' hypothesis. These findings have greatly increased our understanding of the epidemiology and ecology of fungal

  4. Hybridization between three crested newt species (Triturus cristatus superspecies) in the Czech Republic and Slovakia: comparison of nuclear markers and mitochondrial DNA

    Czech Academy of Sciences Publication Activity Database

    Mikulíček, Peter; Horák, Aleš; Zavadil, V.; Kautman, J.; Piálek, Jaroslav

    2012-01-01

    Roč. 61, 3-4 (2012), s. 202-218 ISSN 0139-7893 R&D Projects: GA ČR GA206/01/0695 Institutional support: RVO:68081766 ; RVO:60077344 Keywords : hybrid zone * introgression * mtDNA * microsatellites * RAPD * Salamandridae Subject RIV: EG - Zoology Impact factor: 0.494, year: 2012

  5. Para-allopatry in hybridizing fire-bellied toads (Bombina bombina and B. variegata): Inference from transcriptome-wide coalescence analyses

    Czech Academy of Sciences Publication Activity Database

    Nürnberger, Beate; Fijarczyk, A.; Lohse, K.; Szymura, J. M.; Blaxter, M. L.

    2016-01-01

    Roč. 70, č. 8 (2016), s. 1803-1818 ISSN 0014-3820 Institutional support: RVO:68081766 Keywords : ecological speciation * genome-wide coalescence * hybrid zone * introgression * RNA-seq. Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.201, year: 2016

  6. Tangled trios? Characterizing a hybrid zone in Castilleja (Orobanchaceae)

    Science.gov (United States)

    Erika l. Hersch-Green; Richard. Cronn

    2009-01-01

    Hybridization and polyploidization are exceedingly important processes because both influence the ecological envelope and evolutionary trajectory of land plants. These processes are frequently invoked for Castilleja (Indian paintbrushes) as contributors to morphological and genetic novelty and as complicating factors in species delimitations. Here...

  7. Economic analysis of hybrid power systems (PV/diesel) in different climatic zones of Tamil Nadu

    International Nuclear Information System (INIS)

    Suresh Kumar, U.; Manoharan, P.S.

    2014-01-01

    Highlights: • Investigation on economic feasibility of PV/diesel system in various climatic zones. • HOMER is used to solve economic feasibility analysis. • By the sensitivity analysis, the net present cost is reduced. • Optimum climatic zone in Tamil Nadu, India is recommended. - Abstract: With the increasing threat to environment and the fast depleting fossil fuel resources, hybrid power systems consisting of two or more renewable energy sources such as solar PV, wind, biomass, ocean thermal-with or without the back up of diesel generator have come to the forefront. These hybrid systems are normally integrated with battery banks for total reliability; such systems have brought about better quality of life in remote areas of developing economics. The remote areas in the state of Tamil Nadu in India possess excellent renewable energy sources. These areas fall under different climatic zones, are sparsely populated and are in the process of development. Though these areas are connected to the grid, Tamil Nadu grid is not stable; it is currently experiencing 40% short fall in generation. Thus grid power is available to these remote areas only for 10 h a day and even when available, there are voltage frequency problems. This paper analyses the economic feasibility of installing and operating hybrid systems in these areas. The areas are divided into different climatic zones and the hybrid system economy is analyzed for each climatic zone on the basis of NPC (net present cost), consumption of diesel and renewable fraction for all climate zones. The analysis indicates that the interior climatic zone – the area would be the optimum climatic zone to install HPS PV/diesel. The sensitivity analysis proves that the NPC of such a system can be reduced. It is suggested that due to high initial cost, government subsidy is necessary to adopt the system on a large scale. Such a profit will encourage development of renewable energy utilization and bring about rapid

  8. Quantifying introgression risk with realistic population genetics

    OpenAIRE

    Ghosh, Atiyo; Meirmans, Patrick G.; Haccou, Patsy

    2012-01-01

    Introgression is the permanent incorporation of genes from the genome of one population into another. This can have severe consequences, such as extinction of endemic species, or the spread of transgenes. Quantification of the risk of introgression is an important component of genetically modified crop regulation. Most theoretical introgression studies aimed at such quantification disregard one or more of the most important factors concerning introgression: realistic genetical mechanisms, rep...

  9. An HMM-based comparative genomic framework for detecting introgression in eukaryotes.

    Directory of Open Access Journals (Sweden)

    Kevin J Liu

    2014-06-01

    Full Text Available One outcome of interspecific hybridization and subsequent effects of evolutionary forces is introgression, which is the integration of genetic material from one species into the genome of an individual in another species. The evolution of several groups of eukaryotic species has involved hybridization, and cases of adaptation through introgression have been already established. In this work, we report on PhyloNet-HMM-a new comparative genomic framework for detecting introgression in genomes. PhyloNet-HMM combines phylogenetic networks with hidden Markov models (HMMs to simultaneously capture the (potentially reticulate evolutionary history of the genomes and dependencies within genomes. A novel aspect of our work is that it also accounts for incomplete lineage sorting and dependence across loci. Application of our model to variation data from chromosome 7 in the mouse (Mus musculus domesticus genome detected a recently reported adaptive introgression event involving the rodent poison resistance gene Vkorc1, in addition to other newly detected introgressed genomic regions. Based on our analysis, it is estimated that about 9% of all sites within chromosome 7 are of introgressive origin (these cover about 13 Mbp of chromosome 7, and over 300 genes. Further, our model detected no introgression in a negative control data set. We also found that our model accurately detected introgression and other evolutionary processes from synthetic data sets simulated under the coalescent model with recombination, isolation, and migration. Our work provides a powerful framework for systematic analysis of introgression while simultaneously accounting for dependence across sites, point mutations, recombination, and ancestral polymorphism.

  10. Molecular, Physicochemical and Rheological Characteristics of Introgressive Triticale/Triticum monococcum ssp. monococcum Lines with Wheat 1D/1A Chromosome Substitution

    Directory of Open Access Journals (Sweden)

    Lidia Błaszczyk

    2013-07-01

    Full Text Available Three sets of hexaploid introgressive triticale lines, with Triticum monococcum ssp. monococcum (cultivated einkorn wheat genes and a bread wheat chromosome 1D substituted for chromosome 1A, and one set of secondary triticale lines were evaluated for grain and flour physicochemical and dough rheological characteristics in two generations (F7 and F8. Genomic in situ hybridization (GISH and fluorescence in situ hybridization (FISH confirmed the 1D/1A chromosome substitution. The presence or absence of einkorn high-molecular-weight (HMW glutenin subunits and the wheat Glu-D1d locus encoding the 5 + 10 subunits was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE, capillary zone electrophoresis, and allele-specific molecular markers. Significant differences were found among physicochemical properties (with the exception of the Hagberg falling number of all introgressive Triticale/T. monococcum lines and the secondary triticale lines. The wheat 1D/1A chromosome substitution also affected these properties. The results showed that in all introgressive triticale lines, the protein and gluten content, Zeleny sedimentation value, and water absorption capacity, were increased. The rheological parameters estimated using micro-farinograph, reomixer, and Kieffer dough extensibility systems also showed an appreciable increase in dough-mixing properties, maximum resistance to extension (Rmax, and dough extensibility. Introgressive Triticale/T. monococcum lines with 5 + 10 subunits have particularly favorable rheological parameters. The results obtained in this study suggest that the cultivated einkorn genome Am, in the context of hexaploid secondary triticale lines and with a wheat 1D/1A substitution, has the potential to improve gluten polymer interactions and be a valuable genetic resource for triticale quality improvement.

  11. Hybridization among wild boars, local breeds and commercial breeds - preliminary results

    DEFF Research Database (Denmark)

    Iacolina, Laura; Bakan, Jana; Cubric-Curik, Vlatka

    . Hybridization with the domestic pig is known to occur in Europe, however the degree and extent of the phenomenon is not fully understood yet. Introgression is considered to be a treat to biodiversity and could lead to loss of local adaptation or introgression in the wild population of human selected genes....... A better understanding of the hybridization levels at European scale would provide an important tool for the development of management plans aimed at reducing human conflict but also at preserving biodiversity and genetic differentiation. Additionally, this information would provide new perspectives...... gradients in variability levels among the analysed wild and domestic populations. This preliminary results will be further investigated to address the possible presence of hybrid zone(s) in Europe and the possible implications for conservation and management of both wild populations and local pig breeds...

  12. Population diversity and evidence of introgression among the black oaks of California

    Science.gov (United States)

    Richard S. Dodd; Nasser Kashani; Zara Afzal-Rafii

    2002-01-01

    The black oaks of California include 4 tree species (California black oak, coast live oak, Shreve oak, interior live oak) that are known to hybridize. Complex patterns of population variation within each species are likely to result from these hybrid combinations and from subsequent introgressions. We have been studying population variation using biochemical and...

  13. Supervised machine learning reveals introgressed loci in the genomes of Drosophila simulans and D. sechellia.

    Science.gov (United States)

    Schrider, Daniel R; Ayroles, Julien; Matute, Daniel R; Kern, Andrew D

    2018-04-01

    Hybridization and gene flow between species appears to be common. Even though it is clear that hybridization is widespread across all surveyed taxonomic groups, the magnitude and consequences of introgression are still largely unknown. Thus it is crucial to develop the statistical machinery required to uncover which genomic regions have recently acquired haplotypes via introgression from a sister population. We developed a novel machine learning framework, called FILET (Finding Introgressed Loci via Extra-Trees) capable of revealing genomic introgression with far greater power than competing methods. FILET works by combining information from a number of population genetic summary statistics, including several new statistics that we introduce, that capture patterns of variation across two populations. We show that FILET is able to identify loci that have experienced gene flow between related species with high accuracy, and in most situations can correctly infer which population was the donor and which was the recipient. Here we describe a data set of outbred diploid Drosophila sechellia genomes, and combine them with data from D. simulans to examine recent introgression between these species using FILET. Although we find that these populations may have split more recently than previously appreciated, FILET confirms that there has indeed been appreciable recent introgression (some of which might have been adaptive) between these species, and reveals that this gene flow is primarily in the direction of D. simulans to D. sechellia.

  14. Assortative mating and differential male mating success in an ash hybrid zone population

    Directory of Open Access Journals (Sweden)

    Frascaria-Lacoste Nathalie

    2006-11-01

    Full Text Available Abstract Background The structure and evolution of hybrid zones depend mainly on the relative importance of dispersal and local adaptation, and on the strength of assortative mating. Here, we study the influence of dispersal, temporal isolation, variability in phenotypic traits and parasite attacks on the male mating success of two parental species and hybrids by real-time pollen flow analysis. We focus on a hybrid zone population between the two closely related ash species Fraxinus excelsior L. (common ash and F. angustifolia Vahl (narrow-leaved ash, which is composed of individuals of the two species and several hybrid types. This population is structured by flowering time: the F. excelsior individuals flower later than the F. angustifolia individuals, and the hybrid types flower in-between. Hybrids are scattered throughout the population, suggesting favorable conditions for their local adaptation. We estimate jointly the best-fitting dispersal kernel, the differences in male fecundity due to variation in phenotypic traits and level of parasite attack, and the strength of assortative mating due to differences in flowering phenology. In addition, we assess the effect of accounting for genotyping error on these estimations. Results We detected a very high pollen immigration rate and a fat-tailed dispersal kernel, counter-balanced by slight phenological assortative mating and short-distance pollen dispersal. Early intermediate flowering hybrids, which had the highest male mating success, showed optimal sex allocation and increased selfing rates. We detected asymmetry of gene flow, with early flowering trees participating more as pollen donors than late flowering trees. Conclusion This study provides striking evidence that long-distance gene flow alone is not sufficient to counter-act the effects of assortative mating and selfing. Phenological assortative mating and short-distance dispersal can create temporal and spatial structuring that appears

  15. A matter of genes? Possible consequences of genetic introgression from domestic forms in two problematic species

    DEFF Research Database (Denmark)

    Scandura, Massimo; Canu, Antonio; Bassi, Elena

    wildlife managers and public administrations. Here, we present an updated review on the extent and the possible effects of hybridization in the two species. Specifically, we will focus on i) the methods to track introgression and their main limitations, ii) the life-history traits possibly affected...... by the introgression, iii) the conditions for introgressive hybridization to occur and iv) the management implications. After its historical minimum in the early XX century, the wild boar came back to be a common presence in the Italian countryside, becoming a pest. Crossbreeding between wild boar and domestic pigs...... has been historically important and is likely to have shaped the present-day genetic make-up of both forms. Although intensive farming has reduced the chance of hybridization in nature, gene flow between wild and domestic S. scrofa still takes place either spontaneously in areas where open-air pig...

  16. Quantifying introgression risk with realistic population genetics.

    Science.gov (United States)

    Ghosh, Atiyo; Meirmans, Patrick G; Haccou, Patsy

    2012-12-07

    Introgression is the permanent incorporation of genes from the genome of one population into another. This can have severe consequences, such as extinction of endemic species, or the spread of transgenes. Quantification of the risk of introgression is an important component of genetically modified crop regulation. Most theoretical introgression studies aimed at such quantification disregard one or more of the most important factors concerning introgression: realistic genetical mechanisms, repeated invasions and stochasticity. In addition, the use of linkage as a risk mitigation strategy has not been studied properly yet with genetic introgression models. Current genetic introgression studies fail to take repeated invasions and demographic stochasticity into account properly, and use incorrect measures of introgression risk that can be manipulated by arbitrary choices. In this study, we present proper methods for risk quantification that overcome these difficulties. We generalize a probabilistic risk measure, the so-called hazard rate of introgression, for application to introgression models with complex genetics and small natural population sizes. We illustrate the method by studying the effects of linkage and recombination on transgene introgression risk at different population sizes.

  17. Characterisation of the joining zone of serially arranged hybrid semi-finished components

    Science.gov (United States)

    Behrens, B.-A.; Chugreev, A.; Matthias, T.

    2018-05-01

    Forming of already joined semi-finished products is an innovative approach to manufacture components which are well-adapted to external loads. This approach results in an economically and ecologically improved production by the targeted use of high-quality materials in component areas, which undergo high stresses. One possible production method for hybrid semi-finished products is friction welding. This welding method allows for the production of hybrid semi-finished products made of aluminium and steel as well as steel and steel. In this paper, the thermomechanical tensile and shear stresses causing a failure of the joined zone are experimentally determined through tension tests. These tests are performed with specimens whose joint zones are aligned with different angles to the load direction.

  18. Introgression in interspecific hybrids of lily

    NARCIS (Netherlands)

    Tuyl, van J.M.; Maas, I.W.G.M.; Lim, K.B.

    2002-01-01

    In order to introduce new desirable characters into the cultivar assortment of lily a range of interspecific crossing barriers has to be overcome. By using various pollination and embryo rescue techniques pre- and postfertilization barriers were overcome and a range of wide interspecific lily

  19. Measures of linkage disequilibrium among neighbouring SNPs indicate asymmetries across the house mouse hybrid zone

    Czech Academy of Sciences Publication Activity Database

    Wang, L.; Luzynski, K.; Pool, J. E.; Janoušek, V.; Dufková, Petra; Vyskočilová, Martina; Teeter, K. C.; Nachman, M. W.; Munclinger, P.; Macholán, Miloš; Piálek, Jaroslav; Tucker, P. K.

    2011-01-01

    Roč. 20, č. 14 (2011), s. 2985-3000 ISSN 0962-1083 R&D Projects: GA ČR GA206/08/0640 Grant - others:NSF(US) DEB0746560 Institutional research plan: CEZ:AV0Z60930519; CEZ:AV0Z50450515 Keywords : house mouse * hybrid zones * linkage disequilibrium * SNP markers Subject RIV: EG - Zoology Impact factor: 5.522, year: 2011

  20. Detecting slow introgression of invasive alleles in an extensively restocked game bird

    Directory of Open Access Journals (Sweden)

    Ines eSanchez-Donoso

    2014-04-01

    Full Text Available Interbreeding of two species in the wild implies introgression of alleles from one species into the other only when admixed individuals survive and successfully backcross with the parental species. Consequently, estimating the proportion of first generation hybrids in a population may not inform about the evolutionary impact of hybridization. Samples obtained over a long time span may offer a more accurate view of the spreading of introgressed alleles in a species’ gene pool. Common quail (Coturnix coturnix populations in Europe have been restocked extensively with farm quails of hybrid origin (crosses with Japanese quails, C. japonica. We genetically monitored a common quail population over 15 years to investigate whether genetic introgression is occurring and used simulations to investigate our power to detect it. Our results revealed that some introgression has occurred, but we did not observe a significant increase over time in the proportion of admixed individuals. However, simulations showed that the degree of admixture may be larger than anticipated due to the limited power of analyses over a short time span, and that observed data was compatible with a low rate of introgression, probably resulting from reduced fitness of admixed individuals. Simulations predicted this could result in extensive admixture in the near future.

  1. Root activity and soil feeding zones of some Bajra hybrids (Pennisetum typhoids Stapf.)

    International Nuclear Information System (INIS)

    Shriniwas

    1980-01-01

    Root activity and soil feeding zones of five bajra hybrids (Hybrid D-356, HB-3, HB-4, HB-1 and Bil-3B) were determined under natural field conditions by placement of 32 P labelled superphosphate enclosed in gelatinous capsules at different soil locations around the plant. Percent root activity varied significantly from one depth to another and it decreased with increase in depths and lateral distances. More than 44 percent of the root activity occurred in a soil feeding zone consisting of 0-15 cm depth having double of this much lateral distance. Percent root activity in HB-3 and HB-4 was almost found identical both horizontally and vertically. Hybrid D-356 and HB-1 approximated more than 38 percent root activity in a soil feeding zone of 0-15 cm in depth and 0-10 cm in lateral distance. 32 P placement in capsules appeared to hold promise over Hall's technique since it overcomes the differences caused by disturbance of the feeding activity of roots at the point of 32 P injection into the soil. (author)

  2. Bibliography of studies on hybrid zones of the common shrew chromosome races distributed in Russia

    Directory of Open Access Journals (Sweden)

    Rena Nadjafova

    2013-11-01

    Full Text Available The common shrew, Sorex araneus Linnaeus, 1758, has become a model species for cytogenetical and evolutionary studies after discovery of extraordinary Robertsonian polymorphism at the within-species level. Development of differential staining techniques (Q-, R-and G-banding made it possible to identify the chromosomal arms and their combination in racial karyotypes. Entering into contact with each other, the chromosomal races might form hybrid zones which represent a great interest for understanding of the process of speciation. Until recently all known hybrid zones of S. araneus were localized in Western Europe and only one was identified in Siberia (Russia between Novosibirsk and Tomsk races (Aniskin and Lukianova 1989, Searle and Wójcik 1998, Polyakov et al. 2011. However, rapidly growing number of reports on discovery of interracial hybrid zones of Sorex araneus in the European part of Russia and neighboring territories appeared lately. The aim of the present work is to compile the bibliography of all studies covering this topic regardless of the original language and the publishing source which hopefully could make research data more accessible to international scientists.It could also be a productive way to save current history of Sorex araneus researches in full context of the ISACC (International Sorex araneus Cytogenetics Committee heritage (Searle et al. 2007, Zima 2008.

  3. Interploidal hybridization and mating patterns in the Sphagnum subsecundum complex.

    Science.gov (United States)

    Ricca, M; Szövényi, P; Temsch, E M; Johnson, M G; Shaw, A J

    2011-08-01

    Polyploidization is thought to result in instant sympatric speciation, but several cases of hybrid zones between one of the parental species and its polyploid derivative have been documented. Previous work showed that diploid Sphagnum lescurii is an allopolyploid derived from the haploids S. lescurii (maternal progenitor) and S. subsecundum (paternal progenitor). Here, we report the results from analyses of a population where allodiploid and haploid S. lescurii co-occur and produce sporophytes. We tested (i) whether haploids and diploids form hybrid triploid sporophytes; (ii) how hybrid and nonhybrid sporophytes compare in fitness; (iii) whether hybrid sporophytes form viable spores; (iv) the ploidy of any viable gametophyte offspring from hybrid sporophytes; (v) the relative viability of sporelings derived from hybrid and nonhybrid sporophytes; and (vi) if interploidal hybridization results in introgression between the allopolyploid and its haploid progenitor. We found that triploid hybrid sporophytes do occur and are larger than nonhybrid sporophytes, but exhibit very low germination percentages and produce sporelings that develop more slowly than those from nonhybrid sporophytes. All sporophytes attached to haploid gametophytes were triploid and were sired by diploid males, but all sporophytes attached to diploid gametophytes were tetraploid. This asymmetric pattern of interploidal hybridization is related to an absence of haploid male gametophytes in the population. Surprisingly, all sporelings from triploid sporophytes were triploid, yet were genetically variable, suggesting some form of aberrant meiosis that warrants further study. There was limited (but some) evidence of introgression between allodiploid and haploid S. lescurii. © 2011 Blackwell Publishing Ltd.

  4. Predicting Freeway Work Zone Delays and Costs with a Hybrid Machine-Learning Model

    Directory of Open Access Journals (Sweden)

    Bo Du

    2017-01-01

    Full Text Available A hybrid machine-learning model, integrating an artificial neural network (ANN and a support vector machine (SVM model, is developed to predict spatiotemporal delays, subject to road geometry, number of lane closures, and work zone duration in different periods of a day and in the days of a week. The model is very user friendly, allowing the least inputs from the users. With that the delays caused by a work zone on any location of a New Jersey freeway can be predicted. To this end, tremendous amounts of data from different sources were collected to establish the relationship between the model inputs and outputs. A comparative analysis was conducted, and results indicate that the proposed model outperforms others in terms of the least root mean square error (RMSE. The proposed hybrid model can be used to calculate contractor penalty in terms of cost overruns as well as incentive reward schedule in case of early work competition. Additionally, it can assist work zone planners in determining the best start and end times of a work zone for developing and evaluating traffic mitigation and management plans.

  5. A protected area influences genotype-specific survival and the structure of a Canis hybrid zone.

    Science.gov (United States)

    Benson, John F; Patterson, Brent R; Mahoney, Peter J

    2014-02-01

    It is widely recognized that protected areas can strongly influence ecological systems and that hybridization is an important conservation issue. However, previous studies have not explicitly considered the influence of protected areas on hybridization dynamics. Eastern wolves are a species of special concern and their distribution is largely restricted to a protected population in Algonquin Provincial Park (APP), Ontario, Canada, where they are the numerically dominant canid. We studied intrinsic and extrinsic factors influencing survival and cause-specific mortality of hybrid and parental canids in the three-species hybrid zone between eastern wolves, eastern coyotes, and gray wolves in and adjacent to APP. Mortality risk for eastern wolves in areas adjacent to APP was significantly higher than for other sympatric Canis types outside of APP, and for eastern wolves and other canids within APP. Outside of APP, the annual mortality rate of all canids by harvest (24%) was higher than for other causes of death (4-7%). Furthermore, eastern wolves (hazard ratio = 3.5) and nonresidents (transients and dispersing animals, hazard ratio = 2.7) were more likely to die from harvest relative to other Canis types and residents, respectively. Thus, eastern wolves dispersing from APP were especially vulnerable to harvest mortality. For residents, eastern wolf survival was more negatively influenced by increased road density than for other Canis types, further highlighting the sensitivity of eastern wolves to human disturbance. A cycle of dispersal from APP followed by high rates of mortality and hybridization appears to maintain eastern wolves at low density adjacent to APP, limiting the potential for expansion beyond the protected area. However, high survival and numerical dominance of eastern wolves within APP suggest that protected areas can allow rare hybridizing species to persist even if their demographic performance is compromised and barriers to hybridization are largely

  6. Chromosomal rearrangements and gene flow over time in an inter-specific hybrid zone of the Sorex araneus group.

    Science.gov (United States)

    Yannic, G; Basset, P; Hausser, J

    2009-06-01

    Most hybrid zones have existed for hundreds or thousands of years but have generally been observed for only a short time period. Studies extending over periods long enough to track evolutionary changes in the zones or assess the ultimate outcome of hybridization are scarce. Here, we describe the evolution over time of the level of genetic isolation between two karyotypically different species of shrews (Sorex araneus and Sorex antinorii) at a hybrid zone located in the Swiss Alps. We first evaluated hybrid zone movement by contrasting patterns of gene flow and changes in cline parameters (centre and width) using 24 microsatellite loci, between two periods separated by 10 years apart. Additionally, we tested the role of chromosomal rearrangements on gene flow by analysing microsatellite loci located on both rearranged and common chromosomes to both species. We did not detect any movement of the hybrid zone during the period analysed, suggesting that the zone is a typical tension zone. However, the gene flow was significantly lower among the rearranged than the common chromosomes for the second period, whereas the difference was only marginally significant for the first period. This further supports the role of chromosomal rearrangements on gene flow between these taxa.

  7. Phylogeny with introgression in Habronattus jumping spiders (Araneae: Salticidae).

    Science.gov (United States)

    Leduc-Robert, Geneviève; Maddison, Wayne P

    2018-02-22

    Habronattus is a diverse clade of jumping spiders with complex courtship displays and repeated evolution of Y chromosomes. A well-resolved species phylogeny would provide an important framework to study these traits, but has not yet been achieved, in part because the few genes available in past studies gave conflicting signals. Such discordant gene trees could be the result of incomplete lineage sorting (ILS) in recently diverged parts of the phylogeny, but there are indications that introgression could be a source of conflict. To infer Habronattus phylogeny and investigate the cause of gene tree discordance, we assembled transcriptomes for 34 Habronattus species and 2 outgroups. The concatenated 2.41 Mb of nuclear data (1877 loci) resolved phylogeny by Maximum Likelihood (ML) with high bootstrap support (95-100%) at most nodes, with some uncertainty surrounding the relationships of H. icenoglei, H. cambridgei, H. oregonensis, and Pellenes canadensis. Species tree analyses by ASTRAL and SVDQuartets gave almost completely congruent results. Several nodes in the ML phylogeny from 12.33 kb of mitochondrial data are incongruent with the nuclear phylogeny and indicate possible mitochondrial introgression: the internal relationships of the americanus and the coecatus groups, the relationship between the altanus, decorus, banksi, and americanus group, and between H. clypeatus and the coecatus group. To determine the relative contributions of ILS and introgression, we analyzed gene tree discordance for nuclear loci longer than 1 kb using Bayesian Concordance Analysis (BCA) for the americanus group (679 loci) and the VCCR clade (viridipes/clypeatus/coecatus/roberti groups) (517 loci) and found signals of introgression in both. Finally, we tested specifically for introgression in the concatenated nuclear matrix with Patterson's D statistics and D FOIL . We found nuclear introgression resulting in substantial admixture between americanus group species, between H. roberti

  8. The Tomato Hybrid Proline-Rich Protein regulates the abcission zone competence to respond to ethylene signals

    Science.gov (United States)

    The Tomato Hybrid Proline-Rich Protein (THyPRP) gene was specifically expressed in the tomato (Solanum lycopersicum) flower abscission zone (FAZ), and its stable antisense silencing under the control of an abscission zone (AZ)-specific promoter, Tomato Abscission Polygalacturonase4,significantly inh...

  9. Hybrid Approach of Aortic Diseases: Zone 1 Delivery and Volumetric Analysis on the Descending Aorta

    Directory of Open Access Journals (Sweden)

    José Augusto Duncan

    Full Text Available Abstract Introduction: Conventional techniques of surgical correction of arch and descending aortic diseases remains as high-risk procedures. Endovascular treatments of abdominal and descending thoracic aorta have lower surgical risk. Evolution of both techniques - open debranching of the arch and endovascular approach of the descending aorta - may extend a less invasive endovascular treatment for a more extensive disease with necessity of proximal landing zone in the arch. Objective: To evaluate descending thoracic aortic remodeling by means of volumetric analysis after hybrid approach of aortic arch debranching and stenting the descending aorta. Methods: Retrospective review of seven consecutive patients treated between September 2014 and August 2016 for diseases of proximal descending aorta (aneurysms and dissections by hybrid approach to deliver the endograft at zone 1. Computed tomography angiography were analyzed using a specific software to calculate descending thoracic aorta volumes pre- and postoperatively. Results: Follow-up was done in 100% of patients with a median time of 321 days (range, 41-625 days. No deaths or permanent neurological complications were observed. There were no endoleaks or stent migrations. Freedom from reintervention was 100% at 300 days and 66% at 600 days. Median volume reduction was of 45.5 cm3, representing a median volume shrinkage by 9.3%. Conclusion: Hybrid approach of arch and descending thoracic aorta diseases is feasible and leads to a favorable aortic remodeling with significant volume reduction.

  10. Quantifying introgression risk with realistic population genetics

    NARCIS (Netherlands)

    Ghosh, A.; Meirmans, P.G.; Haccou, P.

    2012-01-01

    Introgression is the permanent incorporation of genes from the genome of one population into another. This can have severe consequences, such as extinction of endemic species, or the spread of transgenes. Quantification of the risk of introgression is an important component of genetically modified

  11. Widespread introgression of mountain hare genes into Fennoscandian brown hare populations.

    Directory of Open Access Journals (Sweden)

    Riikka Levänen

    Full Text Available In Fennoscandia, mountain hare (Lepus timidus and brown hare (Lepus europaeus hybridize and produce fertile offspring, resulting in gene flow across the species barrier. Analyses of maternally inherited mitochondrial DNA (mtDNA show that introgression occur frequently, but unavailability of appropriate nuclear DNA markers has made it difficult to evaluate the scale- and significance for the species. The extent of introgression has become important as the brown hare is continuously expanding its range northward, at the apparent expense of the mountain hare, raising concerns about possible competition. We report here, based on analysis of 6833 SNP markers, that the introgression is highly asymmetrical in the direction of gene flow from mountain hare to brown hare, and that the levels of nuclear gene introgression are independent of mtDNA introgression. While it is possible that brown hares obtain locally adapted alleles from the resident mountain hares, the low levels of mountain hare alleles among allopatric brown hares suggest that hybridization is driven by stochastic processes. Interspecific geneflow with the brown hare is unlikely to have major impacts on mountain hare in Fennoscandia, but direct competition may.

  12. Testing parasite "intimacy": the whipworm Trichuris muris in the European house mouse hybrid zone

    Czech Academy of Sciences Publication Activity Database

    Wasimuddin, Wasimuddin; Bryja, Josef; Ribas, A.; Baird, Stuart J. E.; Piálek, Jaroslav; Goüy de Bellocq, Joëlle

    2016-01-01

    Roč. 6, č. 9 (2016), s. 2688-2701 ISSN 2045-7758 R&D Projects: GA ČR GA206/08/0640; GA MŠk EE2.3.35.0026; GA MŠk EE2.3.20.0303; GA ČR(CZ) GA16-20049S Institutional support: RVO:68081766 Keywords : Hybrid zones * Mus musculus * parasite life history traits * phylogeography * population structure Subject RIV: EG - Zoology OBOR OECD: Ecology Impact factor: 2.440, year: 2016

  13. Multi-Zone hybrid model for failure detection of the stable ventilation systems

    DEFF Research Database (Denmark)

    Gholami, Mehdi; Schiøler, Henrik; Soltani, Mohsen

    2010-01-01

    In this paper, a conceptual multi-zone model for climate control of a live stock building is elaborated. The main challenge of this research is to estimate the parameters of a nonlinear hybrid model. A recursive estimation algorithm, the Extended Kalman Filter (EKF) is implemented for estimation....... Since the EKF is sensitive to the initial guess, in the following the estimation process is split up into simple parts and approximate parameters are found with a non recursive least squares method in order to provide good initial values. Results based on experiments from a real life stable facility...

  14. Stable Heliconius butterfly hybrid zones are correlated with a local rainfall peak at the edge of the Amazon basin.

    Science.gov (United States)

    Rosser, Neil; Dasmahapatra, Kanchon K; Mallet, James

    2014-12-01

    Multilocus clines between Müllerian mimetic races of Heliconius butterflies provide a classic example of the maintenance of hybrid zones and their importance in speciation. Concordant hybrid zones in the mimics Heliconius erato and H. melpomene in northern Peru were carefully documented in the 1980s, and this prior work now permits a historical analysis of the movement or stasis of the zones. Previous work predicted that these zones might be moving toward the Andes due to selective asymmetry. Extensive deforestation and climate change might also be expected to affect the positions and widths of the hybrid zones. We show that the positions and shapes of these hybrid zones have instead remained remarkably stable between 1985 and 2012. The stability of this interaction strongly implicates continued selection, rather than neutral mixing following secondary contact. The stability of cline widths and strong linkage disequilibria (gametic correlation coefficients Rmax = 0.35-0.56 among unlinked loci) over 25 years suggest that mimetic selection pressures on each color pattern locus have remained approximately constant (s ≈ 0.13-0.40 per locus in both species). Exceptionally high levels of precipitation at the edge of the easternmost Andes may act as a population density trough for butterflies, trapping the hybrid zones at the foot of the mountains, and preventing movement. As such, our results falsify one prediction of the Pleistocene Refugium theory: That the ranges of divergent species or subspecies should be centered on regions characterized by maxima of rainfall, with hybrid zones falling in more arid regions between them. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  15. .i.Daphnia./i. hybridization along ecological gradients in pelagic environments: the potential for the presence of hybrid zones in plankton

    Czech Academy of Sciences Publication Activity Database

    Petrusek, A.; Seďa, Jaromír; Macháček, Jiří; Ruthová, Š.; Šmilauer, P.

    2008-01-01

    Roč. 363, č. 1505 (2008), s. 2931-2941 ISSN 0962-8436 R&D Projects: GA ČR(CZ) GA206/04/0190 Institutional research plan: CEZ:AV0Z60170517 Keywords : interspecific hybridization * Daphnia longispina complex * hybrid zones * canyon-shaped reservoirs * ITS-RFLP * allozyme electrophoresis Subject RIV: EH - Ecology, Behaviour Impact factor: 5.556, year: 2008

  16. Species distribution models contribute to determine the effect of climate and interspecific interactions in moving hybrid zones.

    Science.gov (United States)

    Engler, J O; Rödder, D; Elle, O; Hochkirch, A; Secondi, J

    2013-11-01

    Climate is a major factor delimiting species' distributions. However, biotic interactions may also be prominent in shaping geographical ranges, especially for parapatric species forming hybrid zones. Determining the relative effect of each factor and their interaction of the contact zone location has been difficult due to the lack of broad scale environmental data. Recent developments in species distribution modelling (SDM) now allow disentangling the relative contributions of climate and species' interactions in hybrid zones and their responses to future climate change. We investigated the moving hybrid zone between the breeding ranges of two parapatric passerines in Europe. We conducted SDMs representing the climatic conditions during the breeding season. Our results show a large mismatch between the realized and potential distributions of the two species, suggesting that interspecific interactions, not climate, account for the present location of the contact zone. The SDM scenarios show that the southerly distributed species, Hippolais polyglotta, might lose large parts of its southern distribution under climate change, but a similar gain of novel habitat along the hybrid zone seems unlikely, because interactions with the other species (H. icterina) constrain its range expansion. Thus, whenever biotic interactions limit range expansion, species may become 'trapped' if range loss due to climate change is faster than the movement of the contact zone. An increasing number of moving hybrid zones are being reported, but the proximate causes of movement often remain unclear. In a global context of climate change, we call for more interest in their interactions with climate change. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  17. Study of male–mediated gene flow across a hybrid zone in the common shrew (Sorex araneus using Y chromosome

    Directory of Open Access Journals (Sweden)

    Andrei V. Polyakov

    2017-06-01

    Full Text Available Despite many studies, the impact of chromosome rearrangements on gene flow between chromosome races of the common shrew (Sorex araneus Linnaeus, 1758 remains unclear. Interracial hybrids form meiotic chromosome complexes that are associated with reduced fertility. Nevertheless comprehensive investigations of autosomal and mitochondrial markers revealed weak or no barrier to gene flow between chromosomally divergent populations. In a narrow zone of contact between the Novosibirsk and Tomsk races hybrids are produced with extraordinarily complex configurations at meiosis I. Microsatellite markers have not revealed any barrier to gene flow, but the phenotypic differentiation between races is greater than may be expected if gene flow was unrestricted. To explore this contradiction we analyzed the distribution of the Y chromosome SNP markers within this hybrid zone. The Y chromosome variants in combination with race specific autosome complements allow backcrosses to be distinguished and their proportion among individuals within the hybrid zone to be evaluated. The balanced ratio of the Y variants observed among the pure race individuals as well as backcrosses reveals no male mediated barrier to gene flow. The impact of reproductive unfitness of backcrosses on gene flow is discussed as a possible mechanism of the preservation of race-specific morphology within the hybrid zone.

  18. Systematic design for trait introgression projects

    OpenAIRE

    Cameron, John N.; Han, Ye; Wang, Lizhi; Beavis, William D.

    2017-01-01

    Key message Using an Operations Research approach, we demonstrate design of optimal trait introgression projects with respect to competing objectives. Abstract We demonstrate an innovative approach for designing Trait Introgression (TI) projects based on optimization principles from Operations Research. If the designs of TI projects are based on clear and measurable objectives, they can be translated into mathematical models with decision variables and constraints that can be translated into ...

  19. The mouse hybrid zone in Central Europe: from morphology to molecules

    Czech Academy of Sciences Publication Activity Database

    Ďureje, Ľudovít; Macholán, Miloš; Baird, Stuart J. E.; Piálek, Jaroslav

    2012-01-01

    Roč. 61, 3-4 (2012), s. 308-318 ISSN 0139-7893 R&D Projects: GA ČR GA206/08/0640 Institutional support: RVO:68081766 ; RVO:67985904 Keywords : geography * introgression * mtDNA * Mus musculus musculus * Mus musculus domesticus * X chromosome * Y chromosome Subject RIV: EG - Zoology; EB - Genetics ; Molecular Biology (UZFG-Y) Impact factor: 0.494, year: 2012

  20. A suite of molecular markers for identifying species, detecting introgression and describing population structure in spadefoot toads (Spea spp.).

    Science.gov (United States)

    Pfennig, Karin S; Allenby, Ashley; Martin, Ryan A; Monroy, Anaïs; Jones, Corbin D

    2012-09-01

    Two congeneric species of spadefoot toad, Spea multiplicata and Spea bombifrons, have been the focus of hybridization studies since the 1970s. Because complex hybrids are not readily distinguished phenotypically, genetic markers are needed to identify introgressed individuals. We therefore developed a set of molecular markers (amplified fragment length polymorphism, polymerase chain reaction-restriction fragment length polymorphism and single nucleotide polymorphism) for identifying pure-species, F1 hybrids and more complex introgressed types. To do so, we tested a series of markers across both species and known hybrids using populations in both allopatry and sympatry. We retained those markers that differentiated the two pure-species and also consistently identified known species hybrids. These markers are well suited for identifying hybrids between these species. Moreover, those markers that show variation within each species can be used in conjunction with existing molecular markers in studies of population structure and gene flow. © 2012 Blackwell Publishing Ltd.

  1. Analysis of stability and adaptability of QPM hybrids of maize growing in different Colombian agroecological zones

    Directory of Open Access Journals (Sweden)

    Ever Andrés vargas Escobar

    2016-01-01

    Full Text Available Energy is maize´s biggest contribution for humans and animals. Scientist have been trying to increase its protein level since 1896, it wasn´t until the 60´s when the opaque gene O2 was discovered. In its recessive state, the gene causes the quality of the maize protein to increase, due to the growth of the Globulin protein and the reduction of Zein protein. Known as Quality Protein Maize (QPM, they can double the essential amino acids Lysine and Tryptophan´s percentages when compared with normal maize endosperm. In a commercial scenario, there is a need for high yielding genotypes adapted to different environments; it is also desirable to have a better protein quality. In the present study, 9 yellow endosperm QPM hybrids, developed by FENALCE from CIMMYT´s germoplasm and a normal commercial endosperm check were tested in 6 agro ecological zones: Wet Caribbean, Dry Caribbean, Orinoco, Valley of the Cauca River, Valley of the Magdalena River and the Coffee Growing Zone. A randomized complete block design was used in 17 environments and four repetitions. Variables concerning the plant and yield components were measured, but for this study the grain yield was the only taken. Additionally samples were taken to assess the content of Tryptophan. The stability and adaptability analysis was made using the Eberhart and Russell, Lin and Binns and AMMI models. The QPM hybrid that stood out for all the environments was QPM 303 and QPM 305 for unfavorable environments. Both retain their biochemical characteristics of protein quality and are stable in the evaluated environments according to the statistical models that were used.

  2. Testing parasite 'intimacy': the whipworm Trichuris muris in the European house mouse hybrid zone.

    Science.gov (United States)

    Wasimuddin; Bryja, Josef; Ribas, Alexis; Baird, Stuart J E; Piálek, Jaroslav; Goüy de Bellocq, Joëlle

    2016-05-01

    Host-parasite interaction studies across hybrid zones often focus on host genetic variation, treating parasites as homogeneous. 'Intimately' associated hosts and parasites might be expected to show similar patterns of genetic structure. In the literature, factors such as no intermediate host and no free-living stage have been proposed as 'intimacy' factors likely constraining parasites to closely follow the evolutionary history of their hosts. To test whether the whipworm, Trichuris muris, is intimately associated with its house mouse host, we studied its population genetics across the European house mouse hybrid zone (HMHZ) which has a strong central barrier to gene flow between mouse taxa. T. muris has a direct life cycle and nonmobile free stage: if these traits constrain the parasite to an intimate association with its host we expect a geographic break in the parasite genetic structure across the HMHZ. We genotyped 205 worms from 56 localities across the HMHZ and additionally T. muris collected from sympatric woodmice (Apodemus spp.) and allopatric murine species, using mt-COX1, ITS1-5.8S-ITS2 rDNA and 10 microsatellites. We show four haplogroups of mt-COX1 and three clear ITS1-5.8S-ITS2 clades in the HMHZ suggesting a complex demographic/phylogeographic history. Microsatellites show strong structure between groups of localities. However, no marker type shows a break across the HMHZ. Whipworms from Apodemus in the HMHZ cluster, and share mitochondrial haplotypes, with those from house mice. We conclude Trichuris should not be regarded as an 'intimate' parasite of the house mouse: while its life history might suggest intimacy, passage through alternate hosts is sufficiently common to erase signal of genetic structure associated with any particular host taxon.

  3. Evidence of cryptic introgression in tomato (Solanum lycopersicum L.) based on wild tomato species alleles.

    Science.gov (United States)

    Labate, Joanne A; Robertson, Larry D

    2012-08-07

    Many highly beneficial traits (e.g. disease or abiotic stress resistance) have been transferred into crops through crosses with their wild relatives. The 13 recognized species of tomato (Solanum section Lycopersicon) are closely related to each other and wild species genes have been extensively used for improvement of the crop, Solanum lycopersicum L. In addition, the lack of geographical barriers has permitted natural hybridization between S. lycopersicum and its closest wild relative Solanum pimpinellifolium in Ecuador, Peru and northern Chile. In order to better understand patterns of S. lycopersicum diversity, we sequenced 47 markers ranging in length from 130 to 1200 bp (total of 24 kb) in genotypes of S. lycopersicum and wild tomato species S. pimpinellifolium, Solanum arcanum, Solanum peruvianum, Solanum pennellii and Solanum habrochaites. Between six and twelve genotypes were comparatively analyzed per marker. Several of the markers had previously been hypothesized as carrying wild species alleles within S. lycopersicum, i.e., cryptic introgressions. Each marker was mapped with high confidence (etomato whole genome shotgun chromosomes (SL2.40) database. Neighbor-joining trees showed high mean bootstrap support (86.8 ± 2.34%) for distinguishing red-fruited from green-fruited taxa for 38 of the markers. Hybridization and parsimony splits networks, genomic map positions of markers relative to documented introgressions, and historical origins of accessions were used to interpret evolutionary patterns at nine markers with putatively introgressed alleles. Of the 47 genetic markers surveyed in this study, four were involved in linkage drag on chromosome 9 during introgression breeding, while alleles at five markers apparently originated from natural hybridization with S. pimpinellifolium and were associated with primitive genotypes of S. lycopersicum. The positive identification of introgressed genes within crop species such as S. lycopersicum will help

  4. Hybridization of mouse lemurs: different patterns under different ecological conditions

    Directory of Open Access Journals (Sweden)

    Rosenkranz David

    2011-10-01

    Full Text Available Abstract Background Several mechanistic models aim to explain the diversification of the multitude of endemic species on Madagascar. The island's biogeographic history probably offered numerous opportunities for secondary contact and subsequent hybridization. Existing diversification models do not consider a possible role of these processes. One key question for a better understanding of their potential importance is how they are influenced by different environmental settings. Here, we characterized a contact zone between two species of mouse lemurs, Microcebus griseorufus and M. murinus, in dry spiny bush and mesic gallery forest that border each other sharply without intermediate habitats between them. We performed population genetic analyses based on mtDNA sequences and nine nuclear microsatellites and compared the results to a known hybrid zone of the same species in a nearby wide gradient from dry spiny bush over transitional forest to humid littoral forest. Results In the spiny-gallery system, Microcebus griseorufus is restricted to the spiny bush; Microcebus murinus occurs in gallery forest and locally invades the dryer habitat of its congener. We found evidence for bidirectional introgressive hybridization, which is closely linked to increased spatial overlap within the spiny bush. Within 159 individuals, we observed 18 hybrids with mitochondrial haplotypes of both species. Analyses of simulated microsatellite data indicate that we identified hybrids with great accuracy and that we probably underestimated their true number. We discuss short-term climatic fluctuations as potential trigger for the dynamic of invasion and subsequent hybridization. In the gradient hybrid zone in turn, long-term aridification could have favored unidirectional nuclear introgression from Microcebus griseorufus into M. murinus in transitional forest. Conclusions Madagascar's southeastern transitional zone harbors two very different hybrid zones of mouse lemurs

  5. Genotype, soil type, and locale effects on reciprocal transplant vigor, endophyte growth, and microbial functional diversity of a narrow sagebrush hybrid zone in Salt Creek Canyon, Utah

    Science.gov (United States)

    Miglia, K.J.; McArthur, E.D.; Redman, R.S.; Rodriguez, R.J.; Zak, J.C.; Freeman, D.C.

    2007-01-01

    When addressing the nature of ecological adaptation and environmental factors limiting population ranges and contributing to speciation, it is important to consider not only the plant's genotype and its response to the environment, but also any close interactions that it has with other organisms, specifically, symbiotic microorganisms. To investigate this, soils and seedlings were reciprocally transplanted into common gardens of the big sagebrush hybrid zone in Salt Creek Canyon, Utah, to determine location and edaphic effects on the fitness of parental and hybrid plants. Endophytic symbionts and functional microbial diversity of indigenous and transplanted soils and sagebrush plants were also examined. Strong selection occurred against the parental genotypes in the middle hybrid zone garden in middle hybrid zone soil; F1 hybrids had the highest fitness under these conditions. Neither of the parental genotypes had superior fitness in their indigenous soils and habitats; rather F1 hybrids with the nonindigenous maternal parent were superiorly fit. Significant garden-by-soil type interactions indicate adaptation of both plant and soil microorganisms to their indigenous soils and habitats, most notably in the middle hybrid zone garden in middle hybrid zone soil. Contrasting performances of F1 hybrids suggest asymmetrical gene flow with mountain, rather than basin, big sagebrush acting as the maternal parent. We showed that the microbial community impacted the performance of parental and hybrid plants in different soils, likely limiting the ranges of the different genotypes.

  6. Selection against recombinant hybrids maintains reproductive isolation in hybridizing Populus species despite F1 fertility and recurrent gene flow.

    Science.gov (United States)

    Christe, Camille; Stölting, Kai N; Bresadola, Luisa; Fussi, Barbara; Heinze, Berthold; Wegmann, Daniel; Lexer, Christian

    2016-06-01

    Natural hybrid zones have proven to be precious tools for understanding the origin and maintenance of reproductive isolation (RI) and therefore species. Most available genomic studies of hybrid zones using whole- or partial-genome resequencing approaches have focused on comparisons of the parental source populations involved in genome admixture, rather than exploring fine-scale patterns of chromosomal ancestry across the full admixture gradient present between hybridizing species. We have studied three well-known European 'replicate' hybrid zones of Populus alba and P. tremula, two widespread, ecologically divergent forest trees, using up to 432 505 single-nucleotide polymorphisms (SNPs) from restriction site-associated DNA (RAD) sequencing. Estimates of fine-scale chromosomal ancestry, genomic divergence and differentiation across all 19 poplar chromosomes revealed strikingly contrasting results, including an unexpected preponderance of F1 hybrids in the centre of genomic clines on the one hand, and genomically localized, spatially variable shared variants consistent with ancient introgression between the parental species on the other. Genetic ancestry had a significant effect on survivorship of hybrid seedlings in a common garden trial, pointing to selection against early-generation recombinants. Our results indicate a role for selection against recombinant genotypes in maintaining RI in the face of apparent F1 fertility, consistent with the intragenomic 'coadaptation' model of barriers to introgression upon secondary contact. Whole-genome resequencing of hybridizing populations will clarify the roles of specific genetic pathways in RI between these model forest trees and may reveal which loci are affected most strongly by its cyclic breakdown. © 2016 John Wiley & Sons Ltd.

  7. Heritability studies for seed quality traits in introgressed segregating populations of brassica

    International Nuclear Information System (INIS)

    Farhatullah, S.; Nasim, A.; Fayyaz, L.

    2014-01-01

    Estimation of genetic parameters in the context of trait characterization is an essential component of future targeted crop improvement programs. Collection of knowledge about genetic behavior such as genetic variability and heritability etc., of the germplasm is the basic step for initiation of any breeding program. Genetic variability and Broad sense heritability for various seed quality traits in 10 brassica genotypes and their 12 F2 progenies comprising of introgressed hybrids were studied. The genotypes had highly significant variation for oil content, protein, glucosinolates contents, oleic, linolenic and erucic acid contents. Glucosinolates content and erucic acid showed high heritability in all F2 populations, while rest of the traits showed variable trends. The cross combination 547 x 118 (B. napus x B. campestris) proved to be a good interspecific hybrid that had high proportion of introgression and has high heritability for beneficial traits. The individual plants having combination of desirable traits were also identified from the F2 populations. (author)

  8. New hybrid genetic particle swarm optimization algorithm to design multi-zone binary filter.

    Science.gov (United States)

    Lin, Jie; Zhao, Hongyang; Ma, Yuan; Tan, Jiubin; Jin, Peng

    2016-05-16

    The binary phase filters have been used to achieve an optical needle with small lateral size. Designing a binary phase filter is still a scientific challenge in such fields. In this paper, a hybrid genetic particle swarm optimization (HGPSO) algorithm is proposed to design the binary phase filter. The HGPSO algorithm includes self-adaptive parameters, recombination and mutation operations that originated from the genetic algorithm. Based on the benchmark test, the HGPSO algorithm has achieved global optimization and fast convergence. In an easy-to-perform optimizing procedure, the iteration number of HGPSO is decreased to about a quarter of the original particle swarm optimization process. A multi-zone binary phase filter is designed by using the HGPSO. The long depth of focus and high resolution are achieved simultaneously, where the depth of focus and focal spot transverse size are 6.05λ and 0.41λ, respectively. Therefore, the proposed HGPSO can be applied to the optimization of filter with multiple parameters.

  9. Yield Potential of Ten Peanut Introgression Lines derived from Crosses between Arachis cardenassii and A. hypogaea

    Directory of Open Access Journals (Sweden)

    AHMAD RIDUAN

    2005-09-01

    Full Text Available Diploid species of peanut (Arachis cardenasii showed no symptoms of PStV infection when mechanically inoculated with PStV. Some introgression lines derived from A. cardenasii and A. hypogaea hybridization have been introduced to Indonesia. Evaluation of their adaptability and yield potential were necessary before pursuing further utilization of these introgression lines. The objectives of this research were to determine yield potential of the introgression lines of peanut in green house and field conditions and to evaluate incidence of PStV infection in the field. Peanut plants were grown in the green house and in the field according to standard procedures for raising peanut. Results of the experiments showed that growth and developmental characters of the tested lines were similar between field and green house grown plants. The introgression lines generally exhibited higher secondary branches and longer to flower and harvest as compared to peanut cv. Gajah and Kelinci. The NC-CS30 line was identfied as having higher yield and bigger seed size as compared to standard peanut cultivars (Gajah and Kelinci. Therefore, NC-CS30 germplasm may be further developed as commercial peanut cultivar or be used as donor for peanut breeding in Indonesia.

  10. Mining for Candidate Genes in an Introgression Line by Using RNA Sequencing: The Anthocyanin Overaccumulation Phenotype in Brassica

    Directory of Open Access Journals (Sweden)

    Lulu Xie

    2016-08-01

    Full Text Available Introgression breeding is a widely used method for the genetic improvement of crop plants; however, the mechanism underlying candidate gene flow patterns during hybridization is poorly understood. In this study, we used a powerful pipeline to investigate a Chinese cabbage (Brassica rapa L. ssp. pekinensis introgression line with the anthocyanin overaccumulation phenotype. Our purpose was to analyze the gene flow patterns during hybridization and elucidate the genetic factors responsible for the accumulation of this important pigment compound. We performed RNA-seq analysis by using two pipelines, one with and one without a reference sequence, to obtain transcriptome data. We identified 930 significantly differentially expressed genes (DEGs between the purple-leaf introgression line and B. rapa green cultivar, namely, 389 up-regulated and 541 down-regulated DEGs that mapped to the B. rapa reference genome. Since only one anthocyanin pathway regulatory gene was identified, i.e., Bra037887 (bHLH, we mined unmapped reads, revealing 2,031 de novo assembled unigenes, including c3563g1i2. Phylogenetic analysis suggested that c3563g1i2, which was transferred from the Brassica B genome of the donor parental line Brassica juncea, may represent an R2R3-MYB transcription factor that participates in the ternary transcriptional activation complex responsible for the anthocyanin overaccumulation phenotype of the B. rapa introgression line. We also identified genes involved in cold and light reaction pathways that were highly upregulated in the introgression line, as confirmed using quantitative real-time PCR analysis. The results of this study shed light on the mechanisms underlying the purple leaf trait in Brassica plants and may facilitate the use of introgressive hybridization for many traits of interest.

  11. Mating, hybridisation and introgression in Lasius ants

    NARCIS (Netherlands)

    Have, van der T.M.; Pedersen, J.S.; Boomsma, J.J.

    2011-01-01

    Recent reviews have shown that hybridisation among ant species is likely to be more common than previously appreciated. but that documented cases of introgression remain rare. After molecular phylogenetic work had shown that European Lasius niger (LINNAEUS, 1758) and L. psammophilus SEIFERT, 1992

  12. Introgression in Lake Malaŵi

    DEFF Research Database (Denmark)

    Stauffer, Jay R.; Madsen, Henry; Rollinson, David

    2014-01-01

    with the indigenous strain of S. haematobium, which ultimately produced via introgression a strain that can use both B. globosus and B. nyassanus as intermediate hosts. This actively evolving situation involving intermediate snail-host switching and decline of Trematocranus placodon, a natural cichlid snail predator...

  13. Number of genes controlling a quantitative trait in a hybrid zone of the aposematic frog Ranitomeya imitator

    DEFF Research Database (Denmark)

    Vestergaard, Jacob Schack; Twomey, Evan; Larsen, Rasmus

    2015-01-01

    The number of genes controlling mimetic traits has been a topic of much research and discussion. In this paper, we examine a mimetic, dendrobatid frog Ranitomeya imitator, which harbours extensive phenotypic variation with multiple mimetic morphs, not unlike the celebrated Heliconius system...... and apply it to the R. imitator system. We show that probably one or two, or at most three genes, control the mimetic phenotype segregating in a R. imitator hybrid zone identified using image analyses....

  14. Floral traits and pollination ecology of European Arum hybrids.

    Science.gov (United States)

    Chartier, Marion; Liagre, Suzanne; Weiss-Schneeweiss, Hanna; Kolano, Bozena; Bessière, Jean-Marie; Schönenberger, Jürg; Gibernau, Marc

    2016-02-01

    Hybridisation is common in plants and can affect the genetic diversity and ecology of sympatric parental populations. Hybrids may resemble the parental species in their ecology, leading to competition and/or gene introgression; alternatively, they may diverge from the parental phenotypes, possibly leading to the colonisation of new ecological niches and to speciation. Here, we describe inflorescence morphology, ploidy levels, pollinator attractive scents, and pollinator guilds of natural hybrids of Arum italicum and A. maculatum (Araceae) from a site with sympatric parental populations in southern France to determine how these traits affect the hybrid pollination ecology. Hybrids were characterised by inflorescences with a size and a number of flowers more similar to A. italicum than to A. maculatum. In most cases, hybrid stamens were purple, as in A. maculatum, and spadix appendices yellow, as in A. italicum. Hybrid floral scent was closer to that of A. italicum, but shared some compounds with A. maculatum and comprised unique compounds. Also, the pollinator guild of the hybrids was similar to that of A. italicum. Nevertheless, the hybrids attracted a high proportion of individuals of the main pollinator of A. maculatum. We discuss the effects of hybridisation in sympatric parental zones in which hybrids exhibit low levels of reproductive success, the establishment of reproductive barriers between parental species, the role of the composition of floral attractive scents in the differential attraction of pollinators and in the competition between hybrids and their parental species, and the potential of hybridisation to give rise to new independent lineages.

  15. Genetic structure of Miscanthus sinensis and Miscanthus sacchariflorus in Japan indicates a gradient of bidirectional but asymmetric introgression

    Science.gov (United States)

    Clark, Lindsay V.; Stewart, J. Ryan; Nishiwaki, Aya; Toma, Yo; Kjeldsen, Jens Bonderup; Jørgensen, Uffe; Zhao, Hua; Peng, Junhua; Yoo, Ji Hye; Heo, Kweon; Yu, Chang Yeon; Yamada, Toshihiko

    2015-01-01

    Unilateral introgression from diploids to tetraploids has been hypothesized to be an important evolutionary mechanism in plants. However, few examples have been definitively identified, perhaps because data of sufficient depth and breadth were difficult to obtain before the advent of affordable high-density genotyping. Throughout Japan, tetraploid Miscanthus sacchariflorus and diploid Miscanthus sinensis are common, and occasionally hybridize. In this study, 667 M. sinensis and 78 M. sacchariflorus genotypes from Japan were characterized using 20 704 SNPs and ten plastid microsatellites. Similarity of SNP genotypes between diploid and tetraploid M. sacchariflorus indicated that the tetraploids originated through autopolyploidy. Structure analysis indicated a gradient of introgression from diploid M. sinensis into tetraploid M. sacchariflorus throughout Japan; most tetraploids had some M. sinensis DNA. Among phenotypically M. sacchariflorus tetraploids, M. sinensis ancestry averaged 7% and ranged from 1–39%, with introgression greatest in southern Japan. Unexpectedly, rare (~1%) diploid M. sinensis individuals from northern Japan were found with 6–27% M. sacchariflorus ancestry. Population structure of M. sinensis in Japan included three groups, and was driven primarily by distance, and secondarily by geographic barriers such as mountains and straits. Miscanthus speciation is a complex and dynamic process. In contrast to limited introgression between diploid M. sacchariflorus and M. sinensis in northern China, selection for adaptation to a moderate maritime climate probably favoured cross-ploidy introgressants in southern Japan. These results will help guide the selection of Miscanthus accessions for the breeding of biomass cultivars. PMID:25618143

  16. Introgression of a Block of Genome Under Infinitesimal Selection.

    Science.gov (United States)

    Sachdeva, Himani; Barton, Nicholas H

    2018-06-12

    Adaptive introgression is common in nature and can be driven by selection acting on multiple, linked genes. We explore the effects of polygenic selection on introgression under the infinitesimal model with linkage. This model assumes that the introgressing block has an effectively infinite number of loci, each with an infinitesimal effect on the trait under selection. The block is assumed to introgress under directional selection within a native population that is genetically homogeneous. We use individual-based simulations and a branching process approximation to compute various statistics of the introgressing block, and explore how these depend on parameters such as the map length and initial trait value associated with the introgressing block, the genetic variability along the block, and the strength of selection. Our results show that the introgression dynamics of a block under infinitesimal selection are qualitatively different from the dynamics of neutral introgression. We also find that in the long run, surviving descendant blocks are likely to have intermediate lengths, and clarify how their length is shaped by the interplay between linkage and infinitesimal selection. Our results suggest that it may be difficult to distinguish the long-term introgression of a block of genome with a single strongly selected locus from the introgression of a block with multiple, tightly linked and weakly selected loci. Copyright © 2018, Genetics.

  17. Male mating strategy and the introgression of a growth hormone transgene.

    Science.gov (United States)

    Valosaari, Kata-Riina; Aikio, Sami; Kaitala, Veijo

    2008-11-01

    Escaped transgenic organisms (GMO's) may threaten the populations of their wild relatives if able to hybridize with each other. The introgression of a growth enhancement transgene into a wild Atlantic salmon population may be affected by the transgene's effects not only on fitness parameters, but also on mating behaviour. Large anadromous GMO males are most preferred in mating, but a transgene can also give the large sneakers a reproductive advantage over the smaller wild individuals. With a simulation model, we studied whether the increase in the proportion and mating success of sneakers in transgenic and hybrid genotypes could facilitate the introgression of a transgene into wild population after the release of GMOs. The model combines population dynamics and Mendelian inheritance of a transgenic trait. We found that the introgression of the transgene is strongly affected by the greater mating preference of large GMO males. Furthermore, the difference in reproductive success between the anadromous versus sneaker strategy defines how much GMO's have to be preferred to be able to invade. These results emphasize the importance of detailed knowledge of reproductive systems and the effect of a transgene on the phenotype and behaviour of GMOs when assessing the consequences of their release or escape to the wild.

  18. X-y interactions underlie sperm head abnormality in hybrid male house mice.

    Science.gov (United States)

    Campbell, Polly; Nachman, Michael W

    2014-04-01

    The genetic basis of hybrid male sterility in house mice is complex, highly polygenic, and strongly X linked. Previous work suggested that there might be interactions between the Mus musculus musculus X and the M. m. domesticus Y with a large negative effect on sperm head morphology in hybrid males with an F1 autosomal background. To test this, we introgressed the M. m. domesticus Y onto a M. m. musculus background and measured the change in sperm morphology, testis weight, and sperm count across early backcross generations and in 11th generation backcross males in which the opportunity for X-autosome incompatibilities is effectively eliminated. We found that abnormality in sperm morphology persists in M. m. domesticus Y introgression males, and that this phenotype is rescued by M. m. domesticus introgressions on the X chromosome. In contrast, the severe reductions in testis weight and sperm count that characterize F1 males were eliminated after one generation of backcrossing. These results indicate that X-Y incompatibilities contribute specifically to sperm morphology. In contrast, X-autosome incompatibilities contribute to low testis weight, low sperm count, and sperm morphology. Restoration of normal testis weight and sperm count in first generation backcross males suggests that a small number of complex incompatibilities between loci on the M. m. musculus X and the M. m. domesticus autosomes underlie F1 male sterility. Together, these results provide insight into the genetic architecture of F1 male sterility and help to explain genome-wide patterns of introgression across the house mouse hybrid zone.

  19. Introgression of mountain hare (Lepus timidus mitochondrial DNA into wild brown hares (Lepus europaeus in Denmark

    Directory of Open Access Journals (Sweden)

    Villesen Palle

    2006-11-01

    Full Text Available Abstract Background In Europe the mountain hare (Lepus timidus exists in Great Britain, Norway, Sweden, Finland, parts of the Alps and in Eastern Europe, but not in Denmark. Interspecific hybridization has been demonstrated between native Swedish mountain hares and introduced brown hares (Lepus europaeus. During the data collection in a study concerning Danish brown hares we identified 16 hares with a single very divergent haplotype. Results Phylogenetic analysis shows that the divergent Danish haplotype is most closely related to the Swedish mountain hare. The frequency of Lepus timidus mtDNA haplotype in the Eastern Danish hare populations is estimated to 6%. Conclusion In contrast to what is known, the Danish hare populations are not pure L. europaeus populations but include introgressed brown hares with Swedish L. timidus mtDNA. The most probable explanation of this is natural migration or translocation of introgressed brown hares from Sweden. The impurity of hare populations has implications for conservation and population genetics.

  20. Systematic design for trait introgression projects.

    Science.gov (United States)

    Cameron, John N; Han, Ye; Wang, Lizhi; Beavis, William D

    2017-10-01

    Using an Operations Research approach, we demonstrate design of optimal trait introgression projects with respect to competing objectives. We demonstrate an innovative approach for designing Trait Introgression (TI) projects based on optimization principles from Operations Research. If the designs of TI projects are based on clear and measurable objectives, they can be translated into mathematical models with decision variables and constraints that can be translated into Pareto optimality plots associated with any arbitrary selection strategy. The Pareto plots can be used to make rational decisions concerning the trade-offs between maximizing the probability of success while minimizing costs and time. The systematic rigor associated with a cost, time and probability of success (CTP) framework is well suited to designing TI projects that require dynamic decision making. The CTP framework also revealed that previously identified 'best' strategies can be improved to be at least twice as effective without increasing time or expenses.

  1. Molecular data reveal complex hybridization and a cryptic species of neotropical wild cat.

    Science.gov (United States)

    Trigo, Tatiane C; Schneider, Alexsandra; de Oliveira, Tadeu G; Lehugeur, Livia M; Silveira, Leandro; Freitas, Thales R O; Eizirik, Eduardo

    2013-12-16

    Hybridization among animal species has recently become more recognized as an important phenomenon, especially in the context of recent radiations. Here we show that complex hybridization has led to contrasting patterns of genomic composition among closely related species of the Neotropical cat genus Leopardus. We show strong evidence of ancient hybridization and introgression between the pampas cat (L. colocolo) and northeastern populations of tigrina (L. tigrinus), leading to remarkable cytonuclear discordance in the latter. In contrast, southern tigrina populations show recent and continuing hybridization with Geoffroy's cat (L. geoffroyi), leading to extreme levels of interspecific admixture at their contact zone. Finally, we demonstrate that two seemingly continuous Brazilian tigrina populations show no evidence of ongoing gene flow between them, leading us to support their formal recognition as distinct species, namely L. tigrinus in the northeast and L. guttulus in the south. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Semi-permeable species boundaries in the coral genus Madracis: introgression in a brooding coral system.

    Science.gov (United States)

    Frade, P R; Reyes-Nivia, M C; Faria, J; Kaandorp, J A; Luttikhuizen, P C; Bak, R P M

    2010-12-01

    Introgressive hybridization is described in several phylogenetic studies of mass-spawning corals. However, the prevalence of this process among brooding coral species is unclear. We used a mitochondrial (mtDNA: nad5) and two nuclear (nDNA: ATPSα and SRP54) intron markers to explore species barriers in the coral genus Madracis and address the role of hybridization in brooding systems. Specimens of six Caribbean Madracis morphospecies were collected from 5 to 60 m depth at Buoy One, Curaçao, supplemented by samples from Aruba, Trinidad & Tobago and Bermuda. Polymerase chain reaction and denaturing gradient gel electrophoresis were coupled to detect distinct alleles within single colonies. The recurrent nDNA phylogenetic non-monophyly among taxa is only challenged by Madracis senaria, the single monophyletic species within the genus. nDNA AMOVAs indicated overall statistical divergence (0.1% significance level) among species but pairwise comparisons of genetic differentiation revealed some gene exchange between Madracis taxa. mtDNA sequences clustered in two main groups representing typical shallow and deep water Madracis species. Madracis pharensis shallow and deep colonies (with threshold at about 23-24 m) clustered in different mtDNA branches, together with their depth-sympatric congenerics. This divergence was repeated for the nDNA (ATPSα) suggestive of distinct M. pharensis depth populations. These matched the vertical distribution of the dinoflagellate symbionts hosted by M. pharensis, with Symbiodinium ITS2 type B7 in the shallows but type B15 in the deep habitats, suggesting symbiont-related disruptive selection. Recurrent non-monophyly of Madracis taxa and high levels of shared polymorphism reflected in ambiguous phylogenetic networks indicate that hybridization is likely to have played a role in the evolution of the genus. Using coalescent forward-in-time simulations, lineage sorting alone was rejected as an explanation to the SRP54 genetic variation

  3. Application of a hybrid multiscale approach to simulate hydrologic and biogeochemical processes in the river-groundwater interaction zone.

    Energy Technology Data Exchange (ETDEWEB)

    Hammond, Glenn Edward; Yang, Xiaofan; Song, Xuehang; Song, Hyun-Seob; Hou, Zhangshuan; Chen, Xingyuan; Liu, Yuanyuan; Scheibe, Tim

    2017-03-01

    The groundwater-surface water interaction zone (GSIZ) plays an important role in riverine and watershed ecosystems as the exchange of waters of variable composition and temperature (hydrologic exchange flows) stimulate microbial activity and associated biogeochemical reactions. Variable temporal and spatial scales of hydrologic exchange flows, heterogeneity of the subsurface environment, and complexity of biogeochemical reaction networks in the GSIZ present challenges to incorporation of fundamental process representations and model parameterization across a range of spatial scales (e.g. from pore-scale to field scale). This paper presents a novel hybrid multiscale simulation approach that couples hydrologic-biogeochemical (HBGC) processes between two distinct length scales of interest.

  4. Estimating the right allocation of resources on weekends and public holidays in Green Zone using hybrid methods

    Science.gov (United States)

    Yusoff, Nazhatul Sahima Mohd; Liong, Choong-Yeun; Ismail, Wan Rosmanira; Noh, Abu Yazid Md; Noor, Nur Amalina Mohd

    2018-04-01

    Long patient waiting time and congestion is a major problem faced by Green Zone in Emergency Department at Hospital Universiti Sains Malaysia (EDHUSM) especially during weekends and public holidays. Even though the Green Zone is servicing only the non-critical patients, patient waiting time, causing the department fails to achieve its Key Performance Indicator (KPI). The long waiting time is due to the insufficient resources provided during the weekends and public holidays versus the large number of patients. Currently, only two doctors supported by two nurses are scheduled for every shift during weekends and public holidays. The numbers of patients are higher during weekends and public holidays as compared to weekdays, but the scheduled number of doctors and nurses are the same as weekdays. Therefore, this study presents a hybrid method to estimate the right number of doctors and nurses for improving the services of the Green Zone during weekends and public holidays. Fifty scenarios based on current and proposed schedules of doctors and nurses are simulated and analysed using the hybrid method of Discrete Event Simulation (DES) and Data Envelopment Analysis (DEA). Banker, Charnes and Cooper (BCC) input-oriented model and Super-Efficiency models of DEA were used to analyse the efficiency of the scenarios. The results show that the best schedule is a combination of four doctors supported by four nurses in every shift during weekends and public holidays for the Green Zone. The findings show that such schedule will not only help the department to achieve its KPI but also enable a more optimal utilization of the resources.

  5. Adaptability of grades and hybrids of tangerine in a subtropical zone of Russia

    Directory of Open Access Journals (Sweden)

    Julia Abilphazova

    2015-08-01

    Full Text Available Results of researches of various cultivars and hybrids of tangerine growing in the conditions of the humid subtropics of Russia and possessing valuable physiological and biochemical markers are presented in article. The stress factors limiting cultivation of tangerine culture in Krasnodar region are defined. The assessment of the water saving and enzymes activity in tangerine leaves is given. Changes of physiological parameters at influence of a stressful factor are shown. The analysis of water deficiency is revealed existence of essential distinctions between cultivars and hybrids. Change of thickness of a leaf blade of tangerine is the important diagnostic characteristic testifying the ability of leaf tissues to accumulate and keep water. Researches are showing that difference between catalase action of cultivars and hybrids are insignificant. Strengthening of enzyme activity can testify to bigger violation of a functional state of plant cultivars in comparison with the hybrides. Water deficiency and drought resistance coefficient can be used for diagnostics of stability of tangerine to hydrothermal factors. Correlation coefficients between the studied markers were calculated and regression models of their interrelation were given. So, there was a high correlation between thickness of a leaf blade and water deficiency index; close correlation between water deficiency and thickness of a leaf blade, as well as dependence of average degree on water deficiency and catalase activity were noted. There were revealed tangerine cultivars and hybrids which are stable in in the changing environmental conditions and have high biochemical value of fruits.

  6. Unexpected ancestry of Populus seedlings from a hybrid zone implies a large role for postzygotic selection in the maintenance of species.

    Science.gov (United States)

    Lindtke, Dorothea; Gompert, Zachariah; Lexer, Christian; Buerkle, C Alex

    2014-09-01

    In the context of potential interspecific gene flow, the integrity of species will be maintained by reproductive barriers that reduce genetic exchange, including traits associated with prezygotic isolation or poor performance of hybrids. Hybrid zones can be used to study the importance of different reproductive barriers, particularly when both parental species and hybrids occur in close spatial proximity. We investigated the importance of barriers to gene flow that act early vs. late in the life cycle of European Populus by quantifying the prevalence of homospecific and hybrid matings within a mosaic hybrid zone. We obtained genotypic data for 11 976 loci from progeny and their maternal parents and constructed a Bayesian model to estimate individual admixture proportions and hybrid classes for sampled trees and for the unsampled pollen parent. Matings that included one or two hybrid parents were common, resulting in admixture proportions of progeny that spanned the whole range of potential ancestries between the two parental species. This result contrasts strongly with the distribution of admixture proportions in adult trees, where intermediate hybrids and each of the parental species are separated into three discrete ancestry clusters. The existence of the full range of hybrids in seedlings is consistent with weak reproductive isolation early in the life cycle of Populus. Instead, a considerable amount of selection must take place between the seedling stage and maturity to remove many hybrid seedlings. Our results highlight that high hybridization rates and appreciable hybrid fitness do not necessarily conflict with the maintenance of species integrity. © 2014 John Wiley & Sons Ltd.

  7. [Identification of a novel WART-like chromosome rearrangement in complex heterozygotes in an interracial hybrid zone of the common shrew Sorex araneus L].

    Science.gov (United States)

    Pavlova, S V; Bulatova, N Sh

    2010-09-01

    Karyotypes uncharacteristic of pure races or hybrids were identified in the interracial hybrid zones of the common shrew Sorex araneus L. that were recently discovered in the European part of Russia. This suggests the actual existence in natural populations of WART-like rearrangements (whole-arm reciprocal translocations) along with Robertsonian fusions of acrocentrics. Demonstration of new and still rare chromosome variants is the aim of this communication.

  8. Genomic diversity and introgression in O. sativa reveal the impact of domestication and breeding on the rice genome.

    Directory of Open Access Journals (Sweden)

    Keyan Zhao

    2010-05-01

    Full Text Available The domestication of Asian rice (Oryza sativa was a complex process punctuated by episodes of introgressive hybridization among and between subpopulations. Deep genetic divergence between the two main varietal groups (Indica and Japonica suggests domestication from at least two distinct wild populations. However, genetic uniformity surrounding key domestication genes across divergent subpopulations suggests cultural exchange of genetic material among ancient farmers.In this study, we utilize a novel 1,536 SNP panel genotyped across 395 diverse accessions of O. sativa to study genome-wide patterns of polymorphism, to characterize population structure, and to infer the introgression history of domesticated Asian rice. Our population structure analyses support the existence of five major subpopulations (indica, aus, tropical japonica, temperate japonica and GroupV consistent with previous analyses. Our introgression analysis shows that most accessions exhibit some degree of admixture, with many individuals within a population sharing the same introgressed segment due to artificial selection. Admixture mapping and association analysis of amylose content and grain length illustrate the potential for dissecting the genetic basis of complex traits in domesticated plant populations.Genes in these regions control a myriad of traits including plant stature, blast resistance, and amylose content. These analyses highlight the power of population genomics in agricultural systems to identify functionally important regions of the genome and to decipher the role of human-directed breeding in refashioning the genomes of a domesticated species.

  9. Introgression and selection shaped the evolutionary history of sympatric sister-species of coral reef fishes (genus: Haemulon)

    KAUST Repository

    Bernal, Moisé s A.; Gaither, Michelle R.; Simison, W. Brian; Rocha, Luiz A.

    2016-01-01

    Closely related marine species with large overlapping ranges provide opportunities to study mechanisms of speciation, particularly when there is evidence of gene flow between such lineages. Here, we focus on a case of hybridization between the sympatric sister-species Haemulon maculicauda and H. flaviguttatum, using Sanger sequencing of mitochondrial and nuclear loci, as well as 2422 single nucleotide polymorphisms (SNPs) obtained via restriction site-associated DNA sequencing (RADSeq). Mitochondrial markers revealed a shared haplotype for COI and low divergence for CytB and CR between the sister-species. On the other hand, complete lineage sorting was observed at the nuclear loci and most of the SNPs. Under neutral expectations, the smaller effective population size of mtDNA should lead to fixation of mutations faster than nDNA. Thus, these results suggest that hybridization in the recent past (0.174-0.263Ma) led to introgression of the mtDNA, with little effect on the nuclear genome. Analyses of the SNP data revealed 28 loci potentially under divergent selection between the two species. The combination of mtDNA introgression and limited nuclear DNA introgression provides a mechanism for the evolution of independent lineages despite recurrent hybridization events. This study adds to the growing body of research that exemplifies how genetic divergence can be maintained in the presence of gene flow between closely related species.

  10. Introgression and selection shaped the evolutionary history of sympatric sister-species of coral reef fishes (genus: Haemulon)

    KAUST Repository

    Bernal, Moisés A.

    2016-11-22

    Closely related marine species with large overlapping ranges provide opportunities to study mechanisms of speciation, particularly when there is evidence of gene flow between such lineages. Here, we focus on a case of hybridization between the sympatric sister-species Haemulon maculicauda and H. flaviguttatum, using Sanger sequencing of mitochondrial and nuclear loci, as well as 2422 single nucleotide polymorphisms (SNPs) obtained via restriction site-associated DNA sequencing (RADSeq). Mitochondrial markers revealed a shared haplotype for COI and low divergence for CytB and CR between the sister-species. On the other hand, complete lineage sorting was observed at the nuclear loci and most of the SNPs. Under neutral expectations, the smaller effective population size of mtDNA should lead to fixation of mutations faster than nDNA. Thus, these results suggest that hybridization in the recent past (0.174-0.263Ma) led to introgression of the mtDNA, with little effect on the nuclear genome. Analyses of the SNP data revealed 28 loci potentially under divergent selection between the two species. The combination of mtDNA introgression and limited nuclear DNA introgression provides a mechanism for the evolution of independent lineages despite recurrent hybridization events. This study adds to the growing body of research that exemplifies how genetic divergence can be maintained in the presence of gene flow between closely related species.

  11. A hybrid model of swash-zone longshore sediment transport on refelctive beaches

    NARCIS (Netherlands)

    Jiang, A.W.; Hughes, M.; Cowell, P.; Gordon, A.; Savioli, J.C.; Ranasinghe, R.W.M.R.J.B.

    2010-01-01

    The hydrodynamics and sediment transport in the swash zone is currently outside the domain of coastal-area models, which is a significant limitation in obtaining littoral sediment-transport estimates, especially on steep reflective beaches where the waves practically break on the beachface. In this

  12. The Dynamics of Two Hybrid Zones in Appalachian Salamanders of the Genus Plethodon

    Science.gov (United States)

    Nelson G. Hairston; R. Haven Wiley; Charles K. Smith; Kenneth A. Kneidel

    1992-01-01

    Two zones of intergradation between populations of Plethodon have been studied for 18 and 20 years, respectively. The data consist of systematic scores of colors, made at least twice annually. Near Heintooga Overlook in the Balsam Mountains (Great Smoky Mountains National Park), the salamanders' cheeks are gray. Proceeding north toward the...

  13. Reduced range of the endangered crested capuchin monkey (Sapajus robustus) and a possible hybrid zone with Sapajus nigritus.

    Science.gov (United States)

    Martins, Waldney Pereira; Lynch Alfaro, Jessica; Rylands, Anthony B

    2017-10-01

    The crested capuchin monkey (Sapajus robustus) is an endangered species endemic to the highly fragmented Atlantic Forest of Brazil. Surveys for S. robustus were carried out over a 25-month period (2003-2005) to obtain more precise geographical limits for the western range of the species. Previously published localities for S. robustus were mapped, and each point was given a 25-km radius "buffer zone." The largest forest remnants in the buffer zones (>300 ha) in Minas Gerais were visited in order to interview the local people and/or survey the forests directly using playback recordings of S. robustus. Camera traps were used in key localities if interviews suggested the presence of capuchins but no animals were sighted during the surveys. Of 127 valid interviews, only 39 people reported the presence of Sapajus in nearby forest fragments. We confirmed the presence of Sapajus in only 19 of these. S. robustus occurred in four, and S. libidinosus, S. nigritus, S. xanthosternos, or S. robustus × S. nigritus (hybrids?) occurred in the remaining 15. Based on our study, the estimated geographical distribution of S. robustus is 119,654 km 2 , which represents a reduction of more than 70,000 km 2 when compared to its formerly described range. The geographical limits as defined in this study are: northeast-the Jequitinhonha River; northwest and west-the Jequitinhonha River; southwest-the Suaçuí Grande River and the Espinhaço mountains; southeast-the Doce River; east-the Atlantic Ocean. A probable hybrid zone where capuchin monkeys have morphological features of both S. nigritus and S. robustus was found between the Santo Antônio and the Suaçuí Grande rivers. The elucidation of the geographical distribution of S. robustus is important for its conservation, facilitating the delineation of priority areas for the creation of reserves and the initiation of studies of the species' ecology and behavior. © 2017 Wiley Periodicals, Inc.

  14. Climate-Driven Reshuffling of Species and Genes: Potential Conservation Roles for Species Translocations and Recombinant Hybrid Genotypes

    Directory of Open Access Journals (Sweden)

    Jon Mark Scriber

    2013-12-01

    Full Text Available Comprising 50%–75% of the world’s fauna, insects are a prominent part of biodiversity in communities and ecosystems globally. Biodiversity across all levels of biological classifications is fundamentally based on genetic diversity. However, the integration of genomics and phylogenetics into conservation management may not be as rapid as climate change. The genetics of hybrid introgression as a source of novel variation for ecological divergence and evolutionary speciation (and resilience may generate adaptive potential and diversity fast enough to respond to locally-altered environmental conditions. Major plant and herbivore hybrid zones with associated communities deserve conservation consideration. This review addresses functional genetics across multi-trophic-level interactions including “invasive species” in various ecosystems as they may become disrupted in different ways by rapid climate change. “Invasive genes” (into new species and populations need to be recognized for their positive creative potential and addressed in conservation programs. “Genetic rescue” via hybrid translocations may provide needed adaptive flexibility for rapid adaptation to environmental change. While concerns persist for some conservationists, this review emphasizes the positive aspects of hybrids and hybridization. Specific implications of natural genetic introgression are addressed with a few examples from butterflies, including transgressive phenotypes and climate-driven homoploid recombinant hybrid speciation. Some specific examples illustrate these points using the swallowtail butterflies (Papilionidae with their long-term historical data base (phylogeographical diversity changes and recent (3-decade climate-driven temporal and genetic divergence in recombinant homoploid hybrids and relatively recent hybrid speciation of Papilio appalachiensis in North America. Climate-induced “reshuffling” (recombinations of species composition, genotypes

  15. Climate-Driven Reshuffling of Species and Genes: Potential Conservation Roles for Species Translocations and Recombinant Hybrid Genotypes.

    Science.gov (United States)

    Scriber, Jon Mark

    2013-12-24

    Comprising 50%-75% of the world's fauna, insects are a prominent part of biodiversity in communities and ecosystems globally. Biodiversity across all levels of biological classifications is fundamentally based on genetic diversity. However, the integration of genomics and phylogenetics into conservation management may not be as rapid as climate change. The genetics of hybrid introgression as a source of novel variation for ecological divergence and evolutionary speciation (and resilience) may generate adaptive potential and diversity fast enough to respond to locally-altered environmental conditions. Major plant and herbivore hybrid zones with associated communities deserve conservation consideration. This review addresses functional genetics across multi-trophic-level interactions including "invasive species" in various ecosystems as they may become disrupted in different ways by rapid climate change. "Invasive genes" (into new species and populations) need to be recognized for their positive creative potential and addressed in conservation programs. "Genetic rescue" via hybrid translocations may provide needed adaptive flexibility for rapid adaptation to environmental change. While concerns persist for some conservationists, this review emphasizes the positive aspects of hybrids and hybridization. Specific implications of natural genetic introgression are addressed with a few examples from butterflies, including transgressive phenotypes and climate-driven homoploid recombinant hybrid speciation. Some specific examples illustrate these points using the swallowtail butterflies (Papilionidae) with their long-term historical data base (phylogeographical diversity changes) and recent (3-decade) climate-driven temporal and genetic divergence in recombinant homoploid hybrids and relatively recent hybrid speciation of Papilio appalachiensis in North America. Climate-induced "reshuffling" (recombinations) of species composition, genotypes, and genomes may become

  16. Hybrid numerical-experimental optical investigation of the contact zone of ultrasonic motors

    Science.gov (United States)

    Ostasevicius, Vytautas; Palevicius, Arvydas; Ragulskis, Minvydas; Janusas, Giedrius; Pilkauskas, Kestutis

    2005-09-01

    Ultrasonic motors have seen application in areas needing compact, efficient, and intermittent motion. Such applications include: camera auto focus lenses, watch motors, compact paper handling, microrobots, medicine and etc.. They are characterized by high torque at low rotational speed, simple mechanical design and good controllability. Compared with electromagnetic actuators, there is no danger of interference due to electromagnetic induction because no magnetic field is used and ultrasonic motors are more quiet since speed-reduction gears are not required. A polarization vector of the piezoceramic element and location of excitation electrodes on its surface determine the resonance modes of the high frequency vibration exciter. In its turn the modes of vibration play a key role in the functionality of ultrasonic motor. There are analyzed two different regimes of operation--when the contact zone of the resonator performs elliptic and unidirectional motions. Though the mechanical characteristics of the ultrasonic motor in both cases are comparable, detailed analysis of the contact surface shows very different wears. Laser holography is used to identify and control the regimes of motion of actuator. Experimental results are compared with computer simulations. Contact surfaces are analyzed by atomic force microscope (AFM) before experiment, after 10 minutes and after 50 minutes of operation.

  17. Genetic population structure of turbot ( Scophthalmus maximus L.) supports the presence of multiple hybrid zones for marine fishes in the transition zone between the Baltic Sea and the North Sea

    DEFF Research Database (Denmark)

    Eg Nielsen, Einar; Nielsen, P.H.; Meldrup, Dorte

    2004-01-01

    Sea, suggesting high gene flow among populations in these areas. In contrast, there was a sharp cline in genetic differentiation going from the low saline Baltic Sea to the high saline North Sea. The data were explained best by two divergent populations connected by a hybrid zone; however......, a mechanical mixing model could not be ruled out. A significant part of the genetic variance could be ascribed to variation among years within locality. Nevertheless, the population structure was relatively stable over time, suggesting that the observed pattern of genetic differentiation is biologically...... significant. This study suggests that hybrid zones are a common phenomenon for marine fishes in the transition area between the North Sea and the Baltic Sea and highlights the importance of using interspecific comparisons for inferring population structure in high gene flow species such as most marine fishes....

  18. Genomewide variation in an introgression line of rice-Zizania revealed by whole-genome re-sequencing.

    Directory of Open Access Journals (Sweden)

    Zhen-Hui Wang

    Full Text Available BACKGROUND: Hybridization between genetically diverged organisms is known as an important avenue that drives plant genome evolution. The possible outcomes of hybridization would be the occurrences of genetic instabilities in the resultant hybrids. It remained under-investigated however whether pollination by alien pollens of a closely related but sexually "incompatible" species could evoke genomic changes and to what extent it may result in phenotypic novelties in the derived progenies. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we have re-sequenced the genomes of Oryza sativa ssp. japonica cv. Matsumae and one of its derived introgressant RZ35 that was obtained from an introgressive hybridization between Matsumae and Zizanialatifolia Griseb. in general, 131 millions 90 base pair (bp paired-end reads were generated which covered 13.2 and 21.9 folds of the Matsumae and RZ35 genomes, respectively. Relative to Matsumae, a total of 41,724 homozygous single nucleotide polymorphisms (SNPs and 17,839 homozygous insertions/deletions (indels were identified in RZ35, of which 3,797 SNPs were nonsynonymous mutations. Furthermore, rampant mobilization of transposable elements (TEs was found in the RZ35 genome. The results of pathogen inoculation revealed that RZ35 exhibited enhanced resistance to blast relative to Matsumae. Notably, one nonsynonymous mutation was found in the known blast resistance gene Pid3/Pi25 and real-time quantitative (q RT-PCR analysis revealed constitutive up-regulation of its expression, suggesting both altered function and expression of Pid3/Pi25 may be responsible for the enhanced resistance to rice blast by RZ35. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that introgressive hybridization by Zizania has provoked genomewide, extensive genomic changes in the rice genome, and some of which have resulted in important phenotypic novelties. These findings suggest that introgressive hybridization by alien pollens of even a

  19. Crop to wild introgression in lettuce: following the fate of crop genome segments in backcross populations.

    Science.gov (United States)

    Uwimana, Brigitte; Smulders, Marinus J M; Hooftman, Danny A P; Hartman, Yorike; van Tienderen, Peter H; Jansen, Johannes; McHale, Leah K; Michelmore, Richard W; Visser, Richard G F; van de Wiel, Clemens C M

    2012-03-26

    After crop-wild hybridization, some of the crop genomic segments may become established in wild populations through selfing of the hybrids or through backcrosses to the wild parent. This constitutes a possible route through which crop (trans)genes could become established in natural populations. The likelihood of introgression of transgenes will not only be determined by fitness effects from the transgene itself but also by the crop genes linked to it. Although lettuce is generally regarded as self-pollinating, outbreeding does occur at a low frequency. Backcrossing to wild lettuce is a likely pathway to introgression along with selfing, due to the high frequency of wild individuals relative to the rarely occurring crop-wild hybrids. To test the effect of backcrossing on the vigour of inter-specific hybrids, Lactuca serriola, the closest wild relative of cultivated lettuce, was crossed with L. sativa and the F(1) hybrid was backcrossed to L. serriola to generate BC(1) and BC(2) populations. Experiments were conducted on progeny from selfed plants of the backcrossing families (BC(1)S(1) and BC(2)S(1)). Plant vigour of these two backcrossing populations was determined in the greenhouse under non-stress and abiotic stress conditions (salinity, drought, and nutrient deficiency). Despite the decreasing contribution of crop genomic blocks in the backcross populations, the BC(1)S(1) and BC(2)S(1) hybrids were characterized by a substantial genetic variation under both non-stress and stress conditions. Hybrids were identified that performed equally or better than the wild genotypes, indicating that two backcrossing events did not eliminate the effect of the crop genomic segments that contributed to the vigour of the BC(1) and BC(2) hybrids. QTLs for plant vigour under non-stress and the various stress conditions were detected in the two populations with positive as well as negative effects from the crop. As it was shown that the crop contributed QTLs with either a positive

  20. Crop to wild introgression in lettuce: following the fate of crop genome segments in backcross populations

    Directory of Open Access Journals (Sweden)

    Uwimana Brigitte

    2012-03-01

    Full Text Available Abstract Background After crop-wild hybridization, some of the crop genomic segments may become established in wild populations through selfing of the hybrids or through backcrosses to the wild parent. This constitutes a possible route through which crop (transgenes could become established in natural populations. The likelihood of introgression of transgenes will not only be determined by fitness effects from the transgene itself but also by the crop genes linked to it. Although lettuce is generally regarded as self-pollinating, outbreeding does occur at a low frequency. Backcrossing to wild lettuce is a likely pathway to introgression along with selfing, due to the high frequency of wild individuals relative to the rarely occurring crop-wild hybrids. To test the effect of backcrossing on the vigour of inter-specific hybrids, Lactuca serriola, the closest wild relative of cultivated lettuce, was crossed with L. sativa and the F1 hybrid was backcrossed to L. serriola to generate BC1 and BC2 populations. Experiments were conducted on progeny from selfed plants of the backcrossing families (BC1S1 and BC2S1. Plant vigour of these two backcrossing populations was determined in the greenhouse under non-stress and abiotic stress conditions (salinity, drought, and nutrient deficiency. Results Despite the decreasing contribution of crop genomic blocks in the backcross populations, the BC1S1 and BC2S1 hybrids were characterized by a substantial genetic variation under both non-stress and stress conditions. Hybrids were identified that performed equally or better than the wild genotypes, indicating that two backcrossing events did not eliminate the effect of the crop genomic segments that contributed to the vigour of the BC1 and BC2 hybrids. QTLs for plant vigour under non-stress and the various stress conditions were detected in the two populations with positive as well as negative effects from the crop. Conclusion As it was shown that the crop

  1. Crop to wild introgression in lettuce: following the fate of crop genome segments in backcross populations

    Science.gov (United States)

    2012-01-01

    Background After crop-wild hybridization, some of the crop genomic segments may become established in wild populations through selfing of the hybrids or through backcrosses to the wild parent. This constitutes a possible route through which crop (trans)genes could become established in natural populations. The likelihood of introgression of transgenes will not only be determined by fitness effects from the transgene itself but also by the crop genes linked to it. Although lettuce is generally regarded as self-pollinating, outbreeding does occur at a low frequency. Backcrossing to wild lettuce is a likely pathway to introgression along with selfing, due to the high frequency of wild individuals relative to the rarely occurring crop-wild hybrids. To test the effect of backcrossing on the vigour of inter-specific hybrids, Lactuca serriola, the closest wild relative of cultivated lettuce, was crossed with L. sativa and the F1 hybrid was backcrossed to L. serriola to generate BC1 and BC2 populations. Experiments were conducted on progeny from selfed plants of the backcrossing families (BC1S1 and BC2S1). Plant vigour of these two backcrossing populations was determined in the greenhouse under non-stress and abiotic stress conditions (salinity, drought, and nutrient deficiency). Results Despite the decreasing contribution of crop genomic blocks in the backcross populations, the BC1S1 and BC2S1 hybrids were characterized by a substantial genetic variation under both non-stress and stress conditions. Hybrids were identified that performed equally or better than the wild genotypes, indicating that two backcrossing events did not eliminate the effect of the crop genomic segments that contributed to the vigour of the BC1 and BC2 hybrids. QTLs for plant vigour under non-stress and the various stress conditions were detected in the two populations with positive as well as negative effects from the crop. Conclusion As it was shown that the crop contributed QTLs with either a

  2. Effects of asymmetric nuclear introgression, introgressive mitochondrial sweep, and purifying selection on phylogenetic reconstruction and divergence estimates in the Pacific clade of Locustella warblers.

    Science.gov (United States)

    Drovetski, Sergei V; Semenov, Georgy; Red'kin, Yaroslav A; Sotnikov, Vladimir N; Fadeev, Igor V; Koblik, Evgeniy A

    2015-01-01

    When isolated but reproductively compatible populations expand geographically and meet, simulations predict asymmetric introgression of neutral loci from a local to invading taxon. Genetic introgression may affect phylogenetic reconstruction by obscuring topology and divergence estimates. We combined phylogenetic analysis of sequences from one mtDNA and 12 nuDNA loci with analysis of gene flow among 5 species of Pacific Locustella warblers to test for presence of genetic introgression and its effects on tree topology and divergence estimates. Our data showed that nuDNA introgression was substantial and asymmetrical among all members of superspecies groups whereas mtDNA showed no introgression except a single species pair where the invader's mtDNA was swept by mtDNA of the local species. This introgressive sweep of mtDNA had the opposite direction of the nuDNA introgression and resulted in the paraphyly of the local species' mtDNA haplotypes with respect to those of the invader. Тhe multilocus nuDNA species tree resolved all inter- and intraspecific relationships despite substantial introgression. However, the node ages on the species tree may be underestimated as suggested by the differences in node age estimates based on non-introgressing mtDNA and introgressing nuDNA. In turn, the introgressive sweep and strong purifying selection appear to elongate internal branches in the mtDNA gene tree.

  3. A Novel Hybrid Intelligent Indoor Location Method for Mobile Devices by Zones Using Wi-Fi Signals.

    Science.gov (United States)

    Castañón-Puga, Manuel; Salazar, Abby Stephanie; Aguilar, Leocundo; Gaxiola-Pacheco, Carelia; Licea, Guillermo

    2015-12-02

    The increasing use of mobile devices in indoor spaces brings challenges to location methods. This work presents a hybrid intelligent method based on data mining and Type-2 fuzzy logic to locate mobile devices in an indoor space by zones using Wi-Fi signals from selected access points (APs). This approach takes advantage of wireless local area networks (WLANs) over other types of architectures and implements the complete method in a mobile application using the developed tools. Besides, the proposed approach is validated by experimental data obtained from case studies and the cross-validation technique. For the purpose of generating the fuzzy rules that conform to the Takagi-Sugeno fuzzy system structure, a semi-supervised data mining technique called subtractive clustering is used. This algorithm finds centers of clusters from the radius map given by the collected signals from APs. Measurements of Wi-Fi signals can be noisy due to several factors mentioned in this work, so this method proposed the use of Type-2 fuzzy logic for modeling and dealing with such uncertain information.

  4. A Novel Hybrid Intelligent Indoor Location Method for Mobile Devices by Zones Using Wi-Fi Signals

    Directory of Open Access Journals (Sweden)

    Manuel Castañón–Puga

    2015-12-01

    Full Text Available The increasing use of mobile devices in indoor spaces brings challenges to location methods. This work presents a hybrid intelligent method based on data mining and Type-2 fuzzy logic to locate mobile devices in an indoor space by zones using Wi-Fi signals from selected access points (APs. This approach takes advantage of wireless local area networks (WLANs over other types of architectures and implements the complete method in a mobile application using the developed tools. Besides, the proposed approach is validated by experimental data obtained from case studies and the cross-validation technique. For the purpose of generating the fuzzy rules that conform to the Takagi–Sugeno fuzzy system structure, a semi-supervised data mining technique called subtractive clustering is used. This algorithm finds centers of clusters from the radius map given by the collected signals from APs. Measurements of Wi-Fi signals can be noisy due to several factors mentioned in this work, so this method proposed the use of Type-2 fuzzy logic for modeling and dealing with such uncertain information.

  5. The Causes and Evolutionary Consequences of Mixed Singing in Two Hybridizing Songbird Species (Luscinia spp.)

    Science.gov (United States)

    Vokurková, Jana; Petrusková, Tereza; Reifová, Radka; Kozman, Alexandra; Mořkovský, Libor; Kipper, Silke; Weiss, Michael; Reif, Jiří; Dolata, Paweł T.; Petrusek, Adam

    2013-01-01

    Bird song plays an important role in the establishment and maintenance of prezygotic reproductive barriers. When two closely related species come into secondary contact, song convergence caused by acquisition of heterospecific songs into the birds’ repertoires is often observed. The proximate mechanisms responsible for such mixed singing, and its effect on the speciation process, are poorly understood. We used a combination of genetic and bioacoustic analyses to test whether mixed singing observed in the secondary contact zone of two passerine birds, the Thrush Nightingale (Luscinia luscinia) and the Common Nightingale (L. megarhynchos), is caused by introgressive hybridization. We analysed song recordings of both species from allopatric and sympatric populations together with genotype data from one mitochondrial and seven nuclear loci. Semi-automated comparisons of our recordings with an extensive catalogue of Common Nightingale song types confirmed that most of the analysed sympatric Thrush Nightingale males were ‘mixed singers’ that use heterospecific song types in their repertoires. None of these ‘mixed singers’ possessed any alleles introgressed from the Common Nightingale, suggesting that they were not backcross hybrids. We also analysed songs of five individuals with intermediate phenotype, which were identified as F1 hybrids between the Thrush Nightingale female and the Common Nightingale male by genetic analysis. Songs of three of these hybrids corresponded to the paternal species (Common Nightingale) but the remaining two sung a mixed song. Our results suggest that although hybridization might increase the tendency for learning songs from both parental species, interspecific cultural transmission is the major proximate mechanism explaining the occurrence of mixed singers among the sympatric Thrush Nightingales. We also provide evidence that mixed singing does not substantially increase the rate of interspecific hybridization and discuss the

  6. Experimental investigations on the state of the friction-welded joint zone in steel hybrid components after process-relevant thermo-mechanical loadings

    Science.gov (United States)

    Behrens, B.-A.; Bouguecha, A.; Vucetic, M.; Peshekhodov, I.; Matthias, T.; Kolbasnikov, N.; Sokolov, S.; Ganin, S.

    2016-10-01

    As a part of the newly established Collaborative Research Center 1153 (SFB 1153) "Process chain for the manufacturing of hybrid high-performance components by tailored forming" at the Leibniz Universität Hannover, the Institute of Forming Technology and Machines (IFUM) examines the influence of thermo-mechanical stresses on the reduced Young's modulus as well as the hardness of hybrid (steel-steel compound) joined semi-finished products. Currently the expertise in the production of bulk metal formed parts is limited to mono-materials. For manufacturing parts of hybrid materials and also for the methods of the new process routes, practical experience has to be gained. The subproject C1 within the collaborative research center 1153 with the short title "Failure Prediction" deals with the question, if the hybrid semi-finished products fulfill the thermo-mechanical demands or if they fail at the joining zone (JZ) during forging. For this purpose, stresses similar to those in the process were imposed on hybrid semi-finished products by torsion tests by using the thermo-mechanical test system Gleeble 3800. Afterwards, the specimens were examined metallographically and by nanoindentations with the help of a TriboIndenter TI950. Thus, first knowledge on the behaviour of thermo-mechanical stresses on the reduced Young's modulus and the hardness of hybrid joined semi-finished parts was gained.

  7. Mutualism, hybrid inviability and speciation in a tropical ant-plant.

    Science.gov (United States)

    Léotard, G; Saltmarsh, A; Kjellberg, F; McKey, D

    2008-07-01

    Although biotic interactions are particularly intricate in the tropics, few studies have examined whether divergent adaptations to biotic interactions lead to speciation in tropical organisms. Ant-plant mutualisms are widespread in the tropics. Within Leonardoxa africana, two subspecies present contrasting defences against herbivores. Young leaves of subsp. africana are defended by mutualistic ants, whereas subsp. gracilicaulis satiates herbivores by synchronized leaf production. Subsp. africana possesses hollow internodes and many large foliar nectaries, housing and feeding ants. We detected no genetic introgression between the two subspecies in the contact zone between them. F1 hybrids were present. They were intermediate in phenotype, expressing reduced, nonfunctional but costly myrmecophilic traits. However, they suffered more herbivory than their parents. Hybrids remained small, failing to reach reproductive size, probably due to their maladapted defence phenotype. Hence, there could be a direct link between adaptation to mutualism and reproductive isolation: biotic interactions could be a driver of tropical diversity.

  8. Revealing the distinct habitat ranges and hybrid zone of genetic sub-populations within Pseudo-nitzschia pungens (Bacillariophyceae) in the West Pacific area.

    Science.gov (United States)

    Kim, Jin Ho; Wang, Pengbin; Park, Bum Soo; Kim, Joo-Hwan; Patidar, Shailesh Kumar; Han, Myung-Soo

    2018-03-01

    Genetic sub-populations (clades) of cosmopolitan marine diatom Pseudo-nitzschia pungens might have distinct habitats, and their hybrid zone is suspected in higher latitude area of the West Pacific area, however, it is still unrevealed because of technical difficulties and lack of evidences in natural environments. The aim of this study is to investigate the habitat characteristics of each clade of P. pungens on geographical distribution with the habitat temperature ranges of each clade and to reveal their hybrid zone in the West Pacific area. We employed the 137 number of nucleotide sequences of P. pungens and its sampling data (spatial and temporal scale) originated from the West Pacific area, and used field application of qPCR assay for intra-specific level of P. pungens. Only two genotypes, clade I and III, were identified in the West Pacific area. Clade I was distributed from 39 to 32.3°N, and clade III were from 1.4 to 34.4°N. The estimated habitat temperature for the clade I and clade III ranges were 8.1-26.9 °C and 24.2-31.2 °C, respectively. The latitudinal distributions and temperature ranges of each clade were significantly different. The qPCR assay employed, and results suggested that the hybrid zone for clade I and III has been observed in the southern Korean coasts, and clade III might be introduced from the Southern Pacific area. The cell abundances of clade III were strongly related with the higher seawater temperature and warm current force. This study has defined distinct habitat characteristics of genetically different sub-populations of P. pungens, and revealed its hybrid zone in natural environment for the first time. We also provided strong evidences about dispersion of the population of clade III to higher latitude in the West Pacific area. Copyright © 2018. Published by Elsevier B.V.

  9. Introgression of A- and B-genome of tetraploid triticale chromatin into tetraploid rye.

    Science.gov (United States)

    Wiśniewska, H; Kwiatek, M; Kulak-Książczyk, S; Apolinarska, B

    2013-11-01

    An improvement of rye is one of the mainstream goals of current breeding. Our study is concerned with the introduction of the tetraploid triticale (ABRR) into the 4x rye (RRRR) using classical methods of distant crossing. One hundred fifty BC1F9 hybrid plants [(4x rye × 4x triticales) × 4x rye] obtained from a backcrossing program were studied. The major aim of this work was to verify the presence of an introgressed A- and B- genome chromatin of triticale in a collection of the 4x rye-tiritcale hybrids and to determine their chromosome compositions. In the present study, karyotypes of the previously reported BC1F2s and BC1F3s were compared with that of the BC1F9 generation as obtained after several subsequent open pollinations. The genomic in situ hybridisation (GISH) allowed us to identify 133 introgression forms in which chromosome numbers ranged between 26 and 32. Using four DNA probes (5S rDNA, 25S rDNA, pSc119.2 and pAs1), the fluorescence in situ hybridisation (FISH) was carried out to facilitate an exact chromosome identification in the hybrid plants. The combination of the multi-colour GISH with the repetitive DNA FISH singled out five types of translocated chromosomes: 2A.2R, 4A.4R, 5A.5R, 5B.5R and 7A.7R among the examined BC1F9s. The reported translocation lines could serve as valuable sources of wheat chromatin suitable for further improvements of rye.

  10. Genome-wide signatures of complex introgression and adaptive evolution in the big cats

    Science.gov (United States)

    Figueiró, Henrique V.; Li, Gang; Trindade, Fernanda J.; Assis, Juliana; Pais, Fabiano; Fernandes, Gabriel; Santos, Sarah H. D.; Hughes, Graham M.; Komissarov, Aleksey; Antunes, Agostinho; Trinca, Cristine S.; Rodrigues, Maíra R.; Linderoth, Tyler; Bi, Ke; Silveira, Leandro; Azevedo, Fernando C. C.; Kantek, Daniel; Ramalho, Emiliano; Brassaloti, Ricardo A.; Villela, Priscilla M. S.; Nunes, Adauto L. V.; Teixeira, Rodrigo H. F.; Morato, Ronaldo G.; Loska, Damian; Saragüeta, Patricia; Gabaldón, Toni; Teeling, Emma C.; O’Brien, Stephen J.; Nielsen, Rasmus; Coutinho, Luiz L.; Oliveira, Guilherme; Murphy, William J.; Eizirik, Eduardo

    2017-01-01

    The great cats of the genus Panthera comprise a recent radiation whose evolutionary history is poorly understood. Their rapid diversification poses challenges to resolving their phylogeny while offering opportunities to investigate the historical dynamics of adaptive divergence. We report the sequence, de novo assembly, and annotation of the jaguar (Panthera onca) genome, a novel genome sequence for the leopard (Panthera pardus), and comparative analyses encompassing all living Panthera species. Demographic reconstructions indicated that all of these species have experienced variable episodes of population decline during the Pleistocene, ultimately leading to small effective sizes in present-day genomes. We observed pervasive genealogical discordance across Panthera genomes, caused by both incomplete lineage sorting and complex patterns of historical interspecific hybridization. We identified multiple signatures of species-specific positive selection, affecting genes involved in craniofacial and limb development, protein metabolism, hypoxia, reproduction, pigmentation, and sensory perception. There was remarkable concordance in pathways enriched in genomic segments implicated in interspecies introgression and in positive selection, suggesting that these processes were connected. We tested this hypothesis by developing exome capture probes targeting ~19,000 Panthera genes and applying them to 30 wild-caught jaguars. We found at least two genes (DOCK3 and COL4A5, both related to optic nerve development) bearing significant signatures of interspecies introgression and within-species positive selection. These findings indicate that post-speciation admixture has contributed genetic material that facilitated the adaptive evolution of big cat lineages. PMID:28776029

  11. Identification of Mutant Genes and Introgressed Tiger Salamander DNA in the Laboratory Axolotl, Ambystoma mexicanum.

    Science.gov (United States)

    Woodcock, M Ryan; Vaughn-Wolfe, Jennifer; Elias, Alexandra; Kump, D Kevin; Kendall, Katharina Denise; Timoshevskaya, Nataliya; Timoshevskiy, Vladimir; Perry, Dustin W; Smith, Jeramiah J; Spiewak, Jessica E; Parichy, David M; Voss, S Randal

    2017-01-31

    The molecular genetic toolkit of the Mexican axolotl, a classic model organism, has matured to the point where it is now possible to identify genes for mutant phenotypes. We used a positional cloning-candidate gene approach to identify molecular bases for two historic axolotl pigment phenotypes: white and albino. White (d/d) mutants have defects in pigment cell morphogenesis and differentiation, whereas albino (a/a) mutants lack melanin. We identified in white mutants a transcriptional defect in endothelin 3 (edn3), encoding a peptide factor that promotes pigment cell migration and differentiation in other vertebrates. Transgenic restoration of Edn3 expression rescued the homozygous white mutant phenotype. We mapped the albino locus to tyrosinase (tyr) and identified polymorphisms shared between the albino allele (tyr a ) and tyr alleles in a Minnesota population of tiger salamanders from which the albino trait was introgressed. tyr a has a 142 bp deletion and similar engineered alleles recapitulated the albino phenotype. Finally, we show that historical introgression of tyr a significantly altered genomic composition of the laboratory axolotl, yielding a distinct, hybrid strain of ambystomatid salamander. Our results demonstrate the feasibility of identifying genes for traits in the laboratory Mexican axolotl.

  12. Production of antihypertensive peptides by enzymatic zein hydrolysate from maize-zea mays ssp. mexicana introgression line

    International Nuclear Information System (INIS)

    Wang, L.; Zhang, X.; Qiao, Y.; Qu, M.

    2014-01-01

    Teosintes are essential gene reservoir for maize breeding improvement, among which Zea mays ssp. mexicana has many valuable traits deserved to be transferred into maize genetic background. In this study, one maize-teosinte introgression line SD00100 was selected from the population of Zea mays ssp. mexicana as wild parent. This introgression line manifested the outstanding agricultural traits similar to maize parent Ye 515 and alien genetic material was identified by genomic in situ hybridization (GISH). To produce bioactive peptides with potent angiotensin converting enzyme (ACE) inhibitory activity, zein extracted from endosperm meal was then undergone enzymatic hydrolysis with thermolysin and the hydrolysate was then filtered through a 3 kDa cut-off membrane. ACE inhibitory activity of permeate from Ye 515 and SD00100 was evaluated by RP-HPLC. The IC50 values of the peptides obtained from maize parent and the introgression line were 96.9 micro g/ml and 22.9 micro g/ml, respectively, with significant difference between them. Our results showed that an outstanding inbred maize line was obtained for production of antihypertensive peptides as well as for further development of functional food. (author)

  13. The eastern migratory caribou: the role of genetic introgression in ecotype evolution.

    Science.gov (United States)

    Klütsch, Cornelya F C; Manseau, Micheline; Trim, Vicki; Polfus, Jean; Wilson, Paul J

    2016-02-01

    Understanding the evolutionary history of contemporary animal groups is essential for conservation and management of endangered species like caribou (Rangifer tarandus). In central Canada, the ranges of two caribou subspecies (barren-ground/woodland caribou) and two woodland caribou ecotypes (boreal/eastern migratory) overlap. Our objectives were to reconstruct the evolutionary history of the eastern migratory ecotype and to assess the potential role of introgression in ecotype evolution. STRUCTURE analyses identified five higher order groups (i.e. three boreal caribou populations, eastern migratory ecotype and barren-ground). The evolutionary history of the eastern migratory ecotype was best explained by an early genetic introgression from barren-ground into a woodland caribou lineage during the Late Pleistocene and subsequent divergence of the eastern migratory ecotype during the Holocene. These results are consistent with the retreat of the Laurentide ice sheet and the colonization of the Hudson Bay coastal areas subsequent to the establishment of forest tundra vegetation approximately 7000 years ago. This historical reconstruction of the eastern migratory ecotype further supports its current classification as a conservation unit, specifically a Designatable Unit, under Canada's Species at Risk Act. These findings have implications for other sub-specific contact zones for caribou and other North American species in conservation unit delineation.

  14. Development and bin mapping of gene-associated interspecific SNPs for cotton (Gossypium hirsutum L.) introgression breeding efforts.

    Science.gov (United States)

    Hulse-Kemp, Amanda M; Ashrafi, Hamid; Zheng, Xiuting; Wang, Fei; Hoegenauer, Kevin A; Maeda, Andrea B V; Yang, S Samuel; Stoffel, Kevin; Matvienko, Marta; Clemons, Kimberly; Udall, Joshua A; Van Deynze, Allen; Jones, Don C; Stelly, David M

    2014-10-30

    Cotton (Gossypium spp.) is the largest producer of natural fibers for textile and is an important crop worldwide. Crop production is comprised primarily of G. hirsutum L., an allotetraploid. However, elite cultivars express very small amounts of variation due to the species monophyletic origin, domestication and further bottlenecks due to selection. Conversely, wild cotton species harbor extensive genetic diversity of prospective utility to improve many beneficial agronomic traits, fiber characteristics, and resistance to disease and drought. Introgression of traits from wild species can provide a natural way to incorporate advantageous traits through breeding to generate higher-producing cotton cultivars and more sustainable production systems. Interspecific introgression efforts by conventional methods are very time-consuming and costly, but can be expedited using marker-assisted selection. Using transcriptome sequencing we have developed the first gene-associated single nucleotide polymorphism (SNP) markers for wild cotton species G. tomentosum, G. mustelinum, G. armourianum and G. longicalyx. Markers were also developed for a secondary cultivated species G. barbadense cv. 3-79. A total of 62,832 non-redundant SNP markers were developed from the five wild species which can be utilized for interspecific germplasm introgression into cultivated G. hirsutum and are directly associated with genes. Over 500 of the G. barbadense markers have been validated by whole-genome radiation hybrid mapping. Overall 1,060 SNPs from the five different species have been screened and shown to produce acceptable genotyping assays. This large set of 62,832 SNPs relative to cultivated G. hirsutum will allow for the first high-density mapping of genes from five wild species that affect traits of interest, including beneficial agronomic and fiber characteristics. Upon mapping, the markers can be utilized for marker-assisted introgression of new germplasm into cultivated cotton and in

  15. Broadening the genetic base of Abyssinian mustard (Brassica carinata A. Braun through introgression of genes from related allotetraploid species

    Directory of Open Access Journals (Sweden)

    Farooq A. Sheikh

    2014-07-01

    Full Text Available Brassica carinata (BBCC, 2n=34 has still to emerge as a major oilseed crop owing to poor agronomic attributes like long stature, long maturity duration and low seed yield. The restricted amount of genetic variability available in natural B. carinata necessitates utilization of new sources of variability for broadening its genetic base. Interspecific hybridization followed by selection in selfed and back cross progenies was employed to generate useful variability into B. carinata cv ˈPC5ˈ from elite lines of Brassica napus (AACC, 2n=38 and Brassica juncea (AABB, 2n=36. The morphological evaluation of 24 stable introgressed progenies revealed wide range of variability for key economic traits. The progenies with mean maturity duration of 161 ± 2.1 days, short stature of 139.5 ± 6.5 cm and seed yield per plant of 18.6 ± 2.0 g in comparison to the corresponding figures of 168 ± 4.6 days, 230.6 ± 12.7 cm and 12.0 ± 2.4 g in ˈPC5ˈ (recurrent parent were recovered. Diversity analysis at morphological level revealed that 22 out of 24 stable introgressed progenies were grouped with B. carinata ˈPC5ˈ at average taxonomic distance of 1.19. The diversity at molecular level using 25 polymorphic and reproducible RAPD primers revealed that 19 out of 21 introgressed progenies grouped with B. carinata ˈPC5ˈ at a similarity coefficient of 0.68. The clusters in general represent a wide range of genetic diversity in the back cross lines of B. carinata as a result of introgression of genes from elite lines of B. napus and B. juncea parents.

  16. Multilocus analysis of divergence and introgression in sympatric and allopatric sibling species of the Lutzomyia longipalpis complex in Brazil.

    Science.gov (United States)

    Araki, Alejandra S; Ferreira, Gabriel E M; Mazzoni, Camila J; Souza, Nataly A; Machado, Ricardo C; Bruno, Rafaela V; Peixoto, Alexandre A

    2013-01-01

    Lutzomyia longipalpis, the main vector of visceral leishmaniasis in Latin America, is a complex of sibling species. In Brazil, a number of very closely related sibling species have been revealed by the analyses of copulation songs, sex pheromones and molecular markers. However, the level of divergence and gene flow between the sibling species remains unclear. Brazilian populations of this vector can be divided in two main groups: one producing Burst-type songs and the Cembrene-1 pheromone and a second more diverse group producing various Pulse song subtypes and different pheromones. We analyzed 21 nuclear loci in two pairs of Brazilian populations: two sympatric populations from the Sobral locality (1S and 2S) in northeastern Brazil and two allopatric populations from the Lapinha and Pancas localities in southeastern Brazil. Pancas and Sobral 2S are populations of the Burst/Cembrene-1 species while Lapinha and Sobral 1S are two putative incipient species producing the same pheromone and similar Pulse song subtypes. The multilocus analysis strongly suggests the occurrence of gene flow during the divergence between the sibling species, with different levels of introgression between loci. Moreover, this differential introgression is asymmetrical, with estimated gene flow being higher in the direction of the Burst/Cembrene-1 species. The results indicate that introgressive hybridization has been a crucial phenomenon in shaping the genome of the L. longipalpis complex. This has possible epidemiological implications and is particularly interesting considering the potential for increased introgression caused by man-made environmental changes and the current trend of leishmaniasis urbanization in Brazil.

  17. Multilocus Analysis of Divergence and Introgression in Sympatric and Allopatric Sibling Species of the Lutzomyia longipalpis Complex in Brazil

    Science.gov (United States)

    Mazzoni, Camila J.; Souza, Nataly A.; Machado, Ricardo C.; Bruno, Rafaela V.

    2013-01-01

    Background Lutzomyia longipalpis, the main vector of visceral leishmaniasis in Latin America, is a complex of sibling species. In Brazil, a number of very closely related sibling species have been revealed by the analyses of copulation songs, sex pheromones and molecular markers. However, the level of divergence and gene flow between the sibling species remains unclear. Brazilian populations of this vector can be divided in two main groups: one producing Burst-type songs and the Cembrene-1 pheromone and a second more diverse group producing various Pulse song subtypes and different pheromones. Methodology/Principal Findings We analyzed 21 nuclear loci in two pairs of Brazilian populations: two sympatric populations from the Sobral locality (1S and 2S) in northeastern Brazil and two allopatric populations from the Lapinha and Pancas localities in southeastern Brazil. Pancas and Sobral 2S are populations of the Burst/Cembrene-1 species while Lapinha and Sobral 1S are two putative incipient species producing the same pheromone and similar Pulse song subtypes. The multilocus analysis strongly suggests the occurrence of gene flow during the divergence between the sibling species, with different levels of introgression between loci. Moreover, this differential introgression is asymmetrical, with estimated gene flow being higher in the direction of the Burst/Cembrene-1 species. Conclusions/Significance The results indicate that introgressive hybridization has been a crucial phenomenon in shaping the genome of the L. longipalpis complex. This has possible epidemiological implications and is particularly interesting considering the potential for increased introgression caused by man-made environmental changes and the current trend of leishmaniasis urbanization in Brazil. PMID:24147172

  18. Genetic architecture of autosome-mediated hybrid male sterility in Drosophila.

    Science.gov (United States)

    Marín, I

    1996-04-01

    Several estimators have been developed for assessing the number of sterility factors in a chromosome based on the sizes of fertile and sterile introgressed fragments. Assuming that two factors are required for producing sterility, simulations show that one of these, twice the inverse of the relative size of the largest fertile fragment, provides good average approximations when as few as five fertile fragments are analyzed. The estimators have been used for deducing the number of factors from previous data on several pairs of species. A particular result contrasts with the authors' interpretations: instead of the high number of sterility factors suggested, only a few per autosome are estimated in both reciprocal crosses involving Drosophila buzzatii and D. koepferae. It has been possible to map these factors, between three and six per chromosome, in the autosomes 3 and 4 of these species. Out of 203 introgressions of different fragments or combinations of fragments, the outcome of at least 192 is explained by the mapped zones. These results suggest that autosome-mediated sterility in the male hybrids of these species is mediated by a few epistatic factors, similarly to X-mediated sterility in the hybrids of other Drosophila species.

  19. Genetic analysis of post-mating reproductive barriers in hybridizing European Populus species.

    Science.gov (United States)

    Macaya-Sanz, D; Suter, L; Joseph, J; Barbará, T; Alba, N; González-Martínez, S C; Widmer, A; Lexer, C

    2011-10-01

    Molecular genetic analyses of experimental crosses provide important information on the strength and nature of post-mating barriers to gene exchange between divergent populations, which are topics of great interest to evolutionary geneticists and breeders. Although not a trivial task in long-lived organisms such as trees, experimental interspecific recombinants can sometimes be created through controlled crosses involving natural F(1)'s. Here, we used this approach to understand the genetics of post-mating isolation and barriers to introgression in Populus alba and Populus tremula, two ecologically divergent, hybridizing forest trees. We studied 86 interspecific backcross (BC(1)) progeny and >350 individuals from natural populations of these species for up to 98 nuclear genetic markers, including microsatellites, indels and single nucleotide polymorphisms, and inferred the origin of the cytoplasm of the cross with plastid DNA. Genetic analysis of the BC(1) revealed extensive segregation distortions on six chromosomes, and >90% of these (12 out of 13) favored P. tremula donor alleles in the heterospecific genomic background. Since selection was documented during early diploid stages of the progeny, this surprising result was attributed to epistasis, cyto-nuclear coadaptation, heterozygote advantage at nuclear loci experiencing introgression or a combination of these. Our results indicate that gene flow across 'porous' species barriers affects these poplars and aspens beyond neutral, Mendelian expectations and suggests the mechanisms responsible. Contrary to expectations, the Populus sex determination region is not protected from introgression. Understanding the population dynamics of the Populus sex determination region will require tests based on natural interspecific hybrid zones.

  20. Interspecific introgression in cetaceans: DNA markers reveal post-F1 status of a pilot whale.

    Directory of Open Access Journals (Sweden)

    Laura Miralles

    Full Text Available Visual species identification of cetacean strandings is difficult, especially when dead specimens are degraded and/or species are morphologically similar. The two recognised pilot whale species (Globicephala melas and Globicephala macrorhynchus are sympatric in the North Atlantic Ocean. These species are very similar in external appearance and their morphometric characteristics partially overlap; thus visual identification is not always reliable. Genetic species identification ensures correct identification of specimens. Here we have employed one mitochondrial (D-Loop region and eight nuclear loci (microsatellites as genetic markers to identify six stranded pilot whales found in Galicia (Northwest Spain, one of them of ambiguous phenotype. DNA analyses yielded positive amplification of all loci and enabled species identification. Nuclear microsatellite DNA genotypes revealed mixed ancestry for one individual, identified as a post-F1 interspecific hybrid employing two different Bayesian methods. From the mitochondrial sequence the maternal species was Globicephala melas. This is the first hybrid documented between Globicephala melas and G. macrorhynchus, and the first post-F1 hybrid genetically identified between cetaceans, revealing interspecific genetic introgression in marine mammals. We propose to add nuclear loci to genetic databases for cetacean species identification in order to detect hybrid individuals.

  1. Historical introgression drives pervasive mitochondrial admixture between two species of pelagic sharks.

    Science.gov (United States)

    Corrigan, Shannon; Maisano Delser, Pierpaolo; Eddy, Corey; Duffy, Clinton; Yang, Lei; Li, Chenhong; Bazinet, Adam L; Mona, Stefano; Naylor, Gavin J P

    2017-05-01

    We use a genomic sampling of both nuclear and mitochondrial DNA markers to examine a pattern of genetic admixture between Carcharhinus galapagensis (Galapagos sharks) and Carcharhinus obscurus (dusky sharks), two well-known and closely related sharks that have been recognized as valid species for more than 100years. We describe widespread mitochondrial-nuclear discordance in which these species are readily distinguishable based on 2152 nuclear single nucleotide polymorphisms from 910 independent autosomal regions, but show pervasive mitochondrial admixture. The species are superficially morphologically cryptic as adults but show marked differences in internal anatomy, as well as niche separation. There was no indication of ongoing hybridization between the species. We conclude that the observed mitochondrial-nuclear discordance is likely due to historical mitochondrial introgression following a range expansion. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Application of Genomic In Situ Hybridization in Horticultural Science

    Directory of Open Access Journals (Sweden)

    Fahad Ramzan

    2017-01-01

    Full Text Available Molecular cytogenetic techniques, such as in situ hybridization methods, are admirable tools to analyze the genomic structure and function, chromosome constituents, recombination patterns, alien gene introgression, genome evolution, aneuploidy, and polyploidy and also genome constitution visualization and chromosome discrimination from different genomes in allopolyploids of various horticultural crops. Using GISH advancement as multicolor detection is a significant approach to analyze the small and numerous chromosomes in fruit species, for example, Diospyros hybrids. This analytical technique has proved to be the most exact and effective way for hybrid status confirmation and helps remarkably to distinguish donor parental genomes in hybrids such as Clivia, Rhododendron, and Lycoris ornamental hybrids. The genome characterization facilitates in hybrid selection having potential desirable characteristics during the early hybridization breeding, as this technique expedites to detect introgressed sequence chromosomes. This review study epitomizes applications and advancements of genomic in situ hybridization (GISH techniques in horticultural plants.

  3. A molecular cytogenetic analysis of introgression in Alstroemeria

    NARCIS (Netherlands)

    Kamstra, S.A.

    1999-01-01

    This thesis describes the results of a molecular cytogenetic investigation of the process of introgression in Alstroemeria . The aim of this study was to transfer chromosomes or genes from one Alstroemeria species into another. For this, two

  4. Hybridization, mitochondrial DNA phylogeography, and prediction of the early stages of reproductive isolation: lessons from New Zealand cicadas (genus Kikihia).

    Science.gov (United States)

    Marshall, David C; Hill, Kathy B R; Cooley, John R; Simon, Chris

    2011-07-01

    One of the major tenets of the modern synthesis is that genetic differentiation among subpopulations is translated over time into genetic differentiation among species. Phylogeographic exploration is therefore essential to the study of speciation because it can reveal the presence of subpopulations that may go on to become species or that may already represent cryptic species. Acoustic species-specific mating signals provide a significant advantage for the recognition of cryptic or incipient species. Because the majority of species do not have such easily recognized premating signals, data from acoustically signaling species can serve as a valuable heuristic tool. Acoustic signals are also convenient tools for recognizing hybridization events. Here, we demonstrate that evidence of hybridization in the form of intermediate song phenotypes is present in many contact zones between species of the New Zealand grass cicadas of the Kikihia muta species complex and that recurring mitochondrial DNA (mtDNA) introgression has created misleading patterns that make it difficult to identify certain taxa using song or mtDNA alone. In one case, introgression appears to have occurred between allopatric taxa by dispersal of introgressed populations of an intermediary species ("hybridization by proxy"). We also present a comparison of mtDNA-tree- and song-based taxonomies obtained for the K. muta complex. We find that 12 mtDNA candidate species are identified using shifts in phylogenetic branching rate found by a single-threshold mixed Yule-coalescent lineage model, while only 7 candidate species are identified using songs. Results from the Yule-coalescent model are dependent on factors such as the number of modeled thresholds and the inclusion of duplicate haplotypes. Genetic distances within song species reach a maximum at about 0.028 substitutions/site when likely cases of hybridization and introgression are excluded. Large genetic breaks or "gaps" are not observed between some

  5. Genetic susceptibility to infectious disease in East African Shorthorn Zebu: a genome-wide analysis of the effect of heterozygosity and exotic introgression.

    Science.gov (United States)

    Murray, Gemma G R; Woolhouse, Mark E J; Tapio, Miika; Mbole-Kariuki, Mary N; Sonstegard, Tad S; Thumbi, Samuel M; Jennings, Amy E; van Wyk, Ilana Conradie; Chase-Topping, Margo; Kiara, Henry; Toye, Phil; Coetzer, Koos; deC Bronsvoort, Barend M; Hanotte, Olivier

    2013-11-09

    Positive multi-locus heterozygosity-fitness correlations have been observed in a number of natural populations. They have been explained by the correlation between heterozygosity and inbreeding, and the negative effect of inbreeding on fitness (inbreeding depression). Exotic introgression in a locally adapted population has also been found to reduce fitness (outbreeding depression) through the breaking-up of co-adapted genes, or the introduction of non-locally adapted gene variants. In this study we examined the inter-relationships between genome-wide heterozygosity, introgression, and death or illness as a result of infectious disease in a sample of calves from an indigenous population of East African Shorthorn Zebu (crossbred Bos taurus x Bos indicus) in western Kenya. These calves were observed from birth to one year of age as part of the Infectious Disease in East African Livestock (IDEAL) project. Some of the calves were found to be genetic hybrids, resulting from the recent introgression of European cattle breed(s) into the indigenous population. European cattle are known to be less well adapted to the infectious diseases present in East Africa. If death and illness as a result of infectious disease have a genetic basis within the population, we would expect both a negative association of these outcomes with introgression and a positive association with heterozygosity. In this indigenous livestock population we observed negative associations between heterozygosity and both death and illness as a result of infectious disease and a positive association between European taurine introgression and episodes of clinical illness. We observe the effects of both inbreeding and outbreeding depression in the East African Shorthorn Zebu, and therefore find evidence of a genetic component to vulnerability to infectious disease. These results indicate that the significant burden of infectious disease in this population could, in principle, be reduced by altered breeding

  6. Study of local-zone microstructure, strength and fracture toughness of hybrid laser-metal-inert-gas-welded A7N01 aluminum alloy joint

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaomin, E-mail: xmwang991011@163.com [School of Life Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China); Li, Bo [School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China); Li, Mingxing; Huang, Cui [School of Life Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China); Chen, Hui [School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China)

    2017-03-14

    Mechanical properties of hybrid laser-metal-inert-gas-welded A7N01-T5 aluminum alloy joints were studied by using local samples that were extracted from the base metal (BM), heat-affected zone (HAZ), and fusion zone (FZ) of the joint to investigate the triangular relationship of microstructure, strength and fracture toughness of the local zones. The BM had the highest yield strength, ultimate tensile strength (UTS) and lowest elongation, which contrasts with the FZ. The yield strength of the HAZ is lower than that of the BM, whereas its UTS is very close to that of the BM, and its elongation is higher than that of the BM. The fracture toughness of the three local zones decreased as HAZ>BM>FZ. To analyze differences in local mechanical behavior, the detailed microstructure of the three local zones was studied by optical microscopy and electron backscattered diffraction, whereas the fracture surface and precipitation were studied by scanning and transmission electron microscopy. The variation of grain size, especially the morphology and distribution of strengthening phase in HAZ in welding process is the key factor that leads to its different mechanical properties from that of BM, which can be elucidated by different dislocation mechanism, sheared mechanism or Orowan mechanism. The as-cast microstructure and second-phase particles that segregate between dendritic branches provide the FZ with the lowest yield strength and UTS. The factors including area fraction of the precipitates, the difference of strength between the matrix and the grain boundaries, the precipitate-free zone along grain boundaries, as well as the grain boundaries angle are taken into account to explain the difference of fracture toughness among BM, HAZ and FZ, and their fracture modes.

  7. Demonstration of variation in chondrocyte activity in different zones of articular cartilage: an assessment of the value of in-situ hybridization.

    Science.gov (United States)

    Marles, P J; Hoyland, J A; Parkinson, R; Freemont, A J

    1991-04-01

    Several methods have been described for investigating chondrocyte metabolism in vitro. In this study, in-situ hybridization (ISH) using an oligonucleotide probe (i.e. a poly-d(T) probe) to detect total messenger RNA (mRNA) in cartilage explants has been compared with radiosulphate and radioleucine uptake studies in an attempt to assess the value of ISH in investigating chondrocyte metabolism. The relative results of the three parameters indicate qualitative similarities in cells in the intermediate, deep and calcified zones but differences in the superficial zone. The relative levels of mRNA and leucine and sulphate uptake in the midzone areas could be construed as indicating that the bulk of cellular activity was directed towards the synthesis of proteoglycans. A similar relation between the three parameters, but at a lower level, was seen in chondrocytes in the calcified zone demonstrating that these cells are viable and biosynthetic. Both quantitative and qualitative differences between the three methods were observed in the superficial chondrocytes regarding the amount of mRNA compared to sulphate and leucine uptake. The results suggest that ISH can detect differences in the amount of mRNA present in chondrocytes in differing zones of cartilage and, like the radioleucine and radiosulphate studies, particularly emphasizes their functional heterogeneity.

  8. Introgression of genetic material from Zea mays ssp. Mexicana into cultivated maize was facilitated by tissue culture

    International Nuclear Information System (INIS)

    Wang, L.; Gu, X.; Qu, M.; Luan, J.; Zhang, J.

    2012-01-01

    Zea mays ssp. mexicana, a wild relative of cultivated maize (Z. mays ssp. mays), is a useful gene resource for maize breeding. In this study, two populations were generated by conventional breeding scheme (population I) or tissue culture regime (population II), respectively, to introgress genetic material of Z. mays ssp. mexicana into maize. Karyotype analysis showed that the arm ratios of 10 pairs of chromosomes in parent maize Ye515 and derivative lines from 2 different populations with 26% and 38% chromosome variation frequencies, respectively. Alien chromatin was detected in the root tip cells of progeny plants through genomic in situ hybridization (GISH). There were 3.3 chromosomes carrying alien chromatin on average in population I and 6.5 in population II. The hybridization signals were located mainly at the terminal or sub terminal regions of the chromosomes and the sizes were notably variant among lines. Based on those results, it is concluded that the introgression of genetic material from Z. mays ssp. mexicana into cultivated maize was facilitated by tissue culture, and subsequently some excellent materials for maize breeding were created. (author)

  9. THE LESSONIA NIGRESCENS SPECIES COMPLEX (LAMINARIALES, PHAEOPHYCEAE) SHOWS STRICT PARAPATRY AND COMPLETE REPRODUCTIVE ISOLATION IN A SECONDARY CONTACT ZONE(1).

    Science.gov (United States)

    Tellier, Florence; Tapia, Javier; Faugeron, Sylvain; Destombe, Christophe; Valero, Myriam

    2011-08-01

    During secondary contact between phylogenetically closely related species (sibling species) having diverged in allopatry, the maintenance of species integrity depends on intrinsic and extrinsic reproductive barriers. In kelps (Phaeophyceae), the observations of hybrids in laboratory conditions suggest that reproductive isolation is incomplete. However, not all interspecific crosses are successful, and very few hybrids have been observed in nature, despite the co-occurrence of many kelp species in sympatry. This suggests that there are reproductive barriers that maintain species integrity. In this study, we characterized the fine genetic structure of a secondary contact zone to clarify the extent of reproductive isolation between two sister species. In Lessonia nigrescens Bory (Laminariales, Phaeophyta) species complex, two cryptic species have been recently found out from gene phylogenies, and-waiting for a formal taxonomic description-we used their geographic distribution to name them (northern and southern species). We studied 12 populations, distributed along 50 km of coastline, and employed two molecular approaches, assigning individuals to phylogenetic species according to a diagnostic mitochondrial marker (351 individuals analyzed) and quantifying interspecific gene flow with four microsatellite markers (248 individuals analyzed). No hybridization or introgression was revealed, indicating complete reproductive isolation in natural conditions. Unexpectedly, our study demonstrated that the two species were strictly segregated in space. This absence of co-occurrence along the contact zone can partially explain the lack of hybridization, raising new interesting questions as to the mechanisms that limit sympatry at small spatial scales. © 2011 Phycological Society of America.

  10. Introgression Between Cultivars and Wild Populations of Momordica charantia L. (Cucurbitaceae) in Taiwan

    Science.gov (United States)

    Liao, Pei-Chun; Tsai, Chi-Chu; Chou, Chang-Hung; Chiang, Yu-Chung

    2012-01-01

    The landrace strains of Momordica charantia are widely cultivated vegetables throughout the tropics and subtropics, but not in Taiwan, a continental island in Southeast Asia, until a few hundred years ago. In contrast, the related wild populations with smaller fruit sizes are native to Taiwan. Because of the introduction of cultivars for agricultural purposes, these two accessions currently exhibit a sympatric or parapatric distribution in Taiwan. In this study, the cultivars and wild samples from Taiwan, India, and Korea were collected for testing of their hybridization and evolutionary patterns. The cpDNA marker showed a clear distinction between accessions of cultivars and wild populations of Taiwan and a long divergence time. In contrast, an analysis of eight selectively neutral nuclear microsatellite loci did not reveal a difference between the genetic structures of these two accessions. A relatively short divergence time and frequent but asymmetric gene flows were estimated based on the isolation-with-migration model. Historical and current introgression from cultivars to wild populations of Taiwan was also inferred using MIGRATE-n and BayesAss analyses. Our results showed that these two accessions shared abundant common ancestral polymorphisms, and the timing of the divergence and colonization of the Taiwanese wild populations is consistent with the geohistory of the Taiwan Strait land bridge of the Last Glacial Maximum (LGM). Long-term and recurrent introgression between accessions indicated the asymmetric capacity to receive foreign genes from other accessions. The modern introduction of cultivars of M. charantia during the colonization of Taiwan by the Han Chinese ethnic group enhanced the rate of gene replacement in the native populations and resulted in the loss of native genes. PMID:22754378

  11. Introgression between cultivars and wild populations of Momordica charantia L. (Cucurbitaceae) in Taiwan.

    Science.gov (United States)

    Liao, Pei-Chun; Tsai, Chi-Chu; Chou, Chang-Hung; Chiang, Yu-Chung

    2012-01-01

    The landrace strains of Momordica charantia are widely cultivated vegetables throughout the tropics and subtropics, but not in Taiwan, a continental island in Southeast Asia, until a few hundred years ago. In contrast, the related wild populations with smaller fruit sizes are native to Taiwan. Because of the introduction of cultivars for agricultural purposes, these two accessions currently exhibit a sympatric or parapatric distribution in Taiwan. In this study, the cultivars and wild samples from Taiwan, India, and Korea were collected for testing of their hybridization and evolutionary patterns. The cpDNA marker showed a clear distinction between accessions of cultivars and wild populations of Taiwan and a long divergence time. In contrast, an analysis of eight selectively neutral nuclear microsatellite loci did not reveal a difference between the genetic structures of these two accessions. A relatively short divergence time and frequent but asymmetric gene flows were estimated based on the isolation-with-migration model. Historical and current introgression from cultivars to wild populations of Taiwan was also inferred using MIGRATE-n and BayesAss analyses. Our results showed that these two accessions shared abundant common ancestral polymorphisms, and the timing of the divergence and colonization of the Taiwanese wild populations is consistent with the geohistory of the Taiwan Strait land bridge of the Last Glacial Maximum (LGM). Long-term and recurrent introgression between accessions indicated the asymmetric capacity to receive foreign genes from other accessions. The modern introduction of cultivars of M. charantia during the colonization of Taiwan by the Han Chinese ethnic group enhanced the rate of gene replacement in the native populations and resulted in the loss of native genes.

  12. Archaic adaptive introgression in TBX15/WARS2

    DEFF Research Database (Denmark)

    Racimo, Fernando; Gokhman, David; Fumagalli, Matteo

    2017-01-01

    A recent study conducted the first genome-wide scan for selection in Inuit from Greenland using SNP chip data. Here, we report that selection in the region with the second most extreme signal of positive selection in Greenlandic Inuit favored a deeply divergent haplotype that is closely related...... to the sequence in the Denisovan genome, and was likely introgressed from an archaic population. The region contains two genes, WARS2 and TBX15, and has previously been associated with adipose tissue differentiation and body-fat distribution in humans. We show that the adaptively introgressed allele has been...... under selection in a much larger geographic region than just Greenland. Furthermore, it is associated with changes in expression of WARS2 and TBX15 in multiple tissues including the adrenal gland and subcutaneous adipose tissue, and with regional DNA methylation changes in TBX15....

  13. Introgression between ecologically distinct species following increased salinity in the Colorado Delta- Worldwide implications for impacted estuary diversity

    Directory of Open Access Journals (Sweden)

    Clive L.F. Lau

    2017-12-01

    Full Text Available We investigate hybridization and introgression between ecologically distinct sister species of silverside fish in the Gulf of California through combined analysis of morphological, sequence, and genotypic data. Water diversions in the past century turned the Colorado River Delta from a normal estuary to a hypersaline inverse estuary, raising concerns for the local fauna, much of which is endangered. Salinity differences are known to generate ecological species pairs and we anticipated that loss of the fresher-water historic salinity regime could alter the adaptive factors maintaining distinction between the broadly distributed Gulf-endemic Colpichthys regis and the narrowly restricted Delta-endemic Colpichthys hubbsi, the species that experienced dramatic environmental change. In this altered environmental context, these long-isolated species (as revealed by Cytochrome b sequences show genotypic (RAG1, microsatellites evidence of active hybridization where the species ranges abut, as well as directional introgression from C. regis into the range center of C. hubbsi. Bayesian group assignment (STRUCTURE on six microsatellite loci and multivariate analyses (DAPC on both microsatellites and phenotypic data further support substantial recent admixture between the sister species. Although we find no evidence for recent population decline in C. hubbsi based on mitochondrial sequence, introgression may be placing an ancient ecological species at risk of extinction. Such introgressive extinction risk should also pertain to other ecological species historically sustained by the now changing Delta environment. More broadly, salinity gradient associated ecological speciation is evident in silverside species pairs in many estuarine systems around the world. Ecological species pairs among other taxa in such systems are likely poorly understood or cryptic. As water extraction accelerates in river systems worldwide, salinity gradients will necessarily be

  14. Introgression between ecologically distinct species following increased salinity in the Colorado Delta- Worldwide implications for impacted estuary diversity.

    Science.gov (United States)

    Lau, Clive L F; Jacobs, David K

    2017-01-01

    We investigate hybridization and introgression between ecologically distinct sister species of silverside fish in the Gulf of California through combined analysis of morphological, sequence, and genotypic data. Water diversions in the past century turned the Colorado River Delta from a normal estuary to a hypersaline inverse estuary, raising concerns for the local fauna, much of which is endangered. Salinity differences are known to generate ecological species pairs and we anticipated that loss of the fresher-water historic salinity regime could alter the adaptive factors maintaining distinction between the broadly distributed Gulf-endemic Colpichthys regis and the narrowly restricted Delta-endemic Colpichthys hubbsi , the species that experienced dramatic environmental change. In this altered environmental context, these long-isolated species (as revealed by Cytochrome b sequences) show genotypic (RAG1, microsatellites) evidence of active hybridization where the species ranges abut, as well as directional introgression from C. regis into the range center of C. hubbsi . Bayesian group assignment (STRUCTURE) on six microsatellite loci and multivariate analyses (DAPC) on both microsatellites and phenotypic data further support substantial recent admixture between the sister species. Although we find no evidence for recent population decline in C. hubbsi based on mitochondrial sequence, introgression may be placing an ancient ecological species at risk of extinction. Such introgressive extinction risk should also pertain to other ecological species historically sustained by the now changing Delta environment. More broadly, salinity gradient associated ecological speciation is evident in silverside species pairs in many estuarine systems around the world. Ecological species pairs among other taxa in such systems are likely poorly understood or cryptic. As water extraction accelerates in river systems worldwide, salinity gradients will necessarily be altered, impacting

  15. The lodgepole × jack pine hybrid zone in Alberta, Canada: a stepping stone for the mountain pine beetle on its journey East across the boreal forest?

    Science.gov (United States)

    Lusebrink, Inka; Erbilgin, Nadir; Evenden, Maya L

    2013-09-01

    Historical data show that outbreaks of the tree killing mountain pine beetle are often preceded by periods of drought. Global climate change impacts drought frequency and severity and is implicated in the range expansion of the mountain pine beetle into formerly unsuitable habitats. Its expanded range has recently reached the lodgepole × jack pine hybrid zone in central Alberta, Canada, which could act as a transition from its historical lodgepole pine host to a jack pine host present in the boreal forest. This field study tested the effects of water limitation on chemical defenses of mature trees against mountain pine beetle-associated microorganisms and on beetle brood success in lodgepole × jack pine hybrid trees. Tree chemical defenses as measured by monoterpene emission from tree boles and monoterpene concentration in needles were greater in trees that experienced water deficit compared to well-watered trees. Myrcene was identified as specific defensive compound, since it significantly increased upon inoculation with dead mountain pine beetles. Beetles reared in bolts from trees that experienced water deficit emerged with a higher fat content, demonstrating for the first time experimentally that drought conditions benefit mountain pine beetles. Further, our study demonstrated that volatile chemical emission from tree boles and phloem chemistry place the hybrid tree chemotype in-between lodgepole pine and jack pine, which might facilitate the host shift from lodgepole pine to jack pine.

  16. Les hybridations interspecifiques dans le genre Phaseolus ...

    African Journals Online (AJOL)

    La réussite de l'introgression de caractères utiles chez le haricot commun P. vulgaris à partir des deux espèces P. coccineus et P. polyanthus dépend en partie des génotypes utilisés. Ce travail vise à identifier des génotypes de Phaseolus compatibles lors des hybridations interspécifiques et à identifier les hybrides issus ...

  17. SNP Discovery for mapping alien introgressions in wheat

    Science.gov (United States)

    2014-01-01

    Background Monitoring alien introgressions in crop plants is difficult due to the lack of genetic and molecular mapping information on the wild crop relatives. The tertiary gene pool of wheat is a very important source of genetic variability for wheat improvement against biotic and abiotic stresses. By exploring the 5Mg short arm (5MgS) of Aegilops geniculata, we can apply chromosome genomics for the discovery of SNP markers and their use for monitoring alien introgressions in wheat (Triticum aestivum L). Results The short arm of chromosome 5Mg of Ae. geniculata Roth (syn. Ae. ovata L.; 2n = 4x = 28, UgUgMgMg) was flow-sorted from a wheat line in which it is maintained as a telocentric chromosome. DNA of the sorted arm was amplified and sequenced using an Illumina Hiseq 2000 with ~45x coverage. The sequence data was used for SNP discovery against wheat homoeologous group-5 assemblies. A total of 2,178 unique, 5MgS-specific SNPs were discovered. Randomly selected samples of 59 5MgS-specific SNPs were tested (44 by KASPar assay and 15 by Sanger sequencing) and 84% were validated. Of the selected SNPs, 97% mapped to a chromosome 5Mg addition to wheat (the source of t5MgS), and 94% to 5Mg introgressed from a different accession of Ae. geniculata substituting for chromosome 5D of wheat. The validated SNPs also identified chromosome segments of 5MgS origin in a set of T5D-5Mg translocation lines; eight SNPs (25%) mapped to TA5601 [T5DL · 5DS-5MgS(0.75)] and three (8%) to TA5602 [T5DL · 5DS-5MgS (0.95)]. SNPs (gsnp_5ms83 and gsnp_5ms94), tagging chromosome T5DL · 5DS-5MgS(0.95) with the smallest introgression carrying resistance to leaf rust (Lr57) and stripe rust (Yr40), were validated in two released germplasm lines with Lr57 and Yr40 genes. Conclusion This approach should be widely applicable for the identification of species/genome-specific SNPs. The development of a large number of SNP markers will facilitate the precise introgression and

  18. SNP Discovery for mapping alien introgressions in wheat.

    Science.gov (United States)

    Tiwari, Vijay K; Wang, Shichen; Sehgal, Sunish; Vrána, Jan; Friebe, Bernd; Kubaláková, Marie; Chhuneja, Praveen; Doležel, Jaroslav; Akhunov, Eduard; Kalia, Bhanu; Sabir, Jamal; Gill, Bikram S

    2014-04-10

    Monitoring alien introgressions in crop plants is difficult due to the lack of genetic and molecular mapping information on the wild crop relatives. The tertiary gene pool of wheat is a very important source of genetic variability for wheat improvement against biotic and abiotic stresses. By exploring the 5Mg short arm (5MgS) of Aegilops geniculata, we can apply chromosome genomics for the discovery of SNP markers and their use for monitoring alien introgressions in wheat (Triticum aestivum L). The short arm of chromosome 5Mg of Ae. geniculata Roth (syn. Ae. ovata L.; 2n = 4x = 28, UgUgMgMg) was flow-sorted from a wheat line in which it is maintained as a telocentric chromosome. DNA of the sorted arm was amplified and sequenced using an Illumina Hiseq 2000 with ~45x coverage. The sequence data was used for SNP discovery against wheat homoeologous group-5 assemblies. A total of 2,178 unique, 5MgS-specific SNPs were discovered. Randomly selected samples of 59 5MgS-specific SNPs were tested (44 by KASPar assay and 15 by Sanger sequencing) and 84% were validated. Of the selected SNPs, 97% mapped to a chromosome 5Mg addition to wheat (the source of t5MgS), and 94% to 5Mg introgressed from a different accession of Ae. geniculata substituting for chromosome 5D of wheat. The validated SNPs also identified chromosome segments of 5MgS origin in a set of T5D-5Mg translocation lines; eight SNPs (25%) mapped to TA5601 [T5DL · 5DS-5MgS(0.75)] and three (8%) to TA5602 [T5DL · 5DS-5MgS (0.95)]. SNPs (gsnp_5ms83 and gsnp_5ms94), tagging chromosome T5DL · 5DS-5MgS(0.95) with the smallest introgression carrying resistance to leaf rust (Lr57) and stripe rust (Yr40), were validated in two released germplasm lines with Lr57 and Yr40 genes. This approach should be widely applicable for the identification of species/genome-specific SNPs. The development of a large number of SNP markers will facilitate the precise introgression and monitoring of alien segments in crop

  19. Genetic and epigenetic status of triple exotic consanguinity cotton introgression lines.

    Science.gov (United States)

    He, S P; Sun, J L; Du, X M

    2011-10-03

    Introgression lines are some of the most important germplasm for breeding applications and other research conducted on cotton crops. The DNA methylation level among 10 introgression lines of cotton (Gossypium hirsutum) and three exotic parental species (G. arboreum, G. thurberi and G. barbadense) were assessed by methylation-sensitive amplified polymorphism (MSAP) technology. The methylation level in the introgression lines ranged from 33.3 to 51.5%. However, the lines PD0111 and PD0113 had the lowest methylation level (34.6 and 33.3%, respectively) due to demethylation of most non-coding sequences. Amplified fragment length polymorphism (AFLP) was used to evaluate the genetic polymorphism in the cotton introgression lines. A high degree of polymorphism was observed in all introgression lines (mean 47.2%) based on AFLP and MSAP analyses. This confirmed the effects of genetic improvement on cotton introgression lines. The low methylation varieties, PD0111 and PD0113 (introgression lines), clustered outside of the introgression lines based on MSAP data, which was incongruent with an AFLP-based dendrogram. This phenomenon could be caused by environmental changes or introgression of exotic DNA fragments.

  20. Extracted Venom and Cuticular Compounds of Imported Fire Ants, Solenopsis spp., and Chemotaxonomic Applications Across a Persistent Hybrid Zone

    Science.gov (United States)

    Characterization of cuticular biomolecular assemblages for imported fire ants permit basic distinctions among colonies of S. invicta, S. richteri, and their hybrids; thus, providing opportunities to investigate details of landscape ecology for this species complex as well as to assess levels of inva...

  1. The genomic landscape at a late stage of stickleback speciation: High genomic divergence interspersed by small localized regions of introgression.

    Directory of Open Access Journals (Sweden)

    Mark Ravinet

    2018-05-01

    Full Text Available Speciation is a continuous process and analysis of species pairs at different stages of divergence provides insight into how it unfolds. Previous genomic studies on young species pairs have revealed peaks of divergence and heterogeneous genomic differentiation. Yet less known is how localised peaks of differentiation progress to genome-wide divergence during the later stages of speciation in the presence of persistent gene flow. Spanning the speciation continuum, stickleback species pairs are ideal for investigating how genomic divergence builds up during speciation. However, attention has largely focused on young postglacial species pairs, with little knowledge of the genomic signatures of divergence and introgression in older stickleback systems. The Japanese stickleback species pair, composed of the Pacific Ocean three-spined stickleback (Gasterosteus aculeatus and the Japan Sea stickleback (G. nipponicus, which co-occur in the Japanese islands, is at a late stage of speciation. Divergence likely started well before the end of the last glacial period and crosses between Japan Sea females and Pacific Ocean males result in hybrid male sterility. Here we use coalescent analyses and Approximate Bayesian Computation to show that the two species split approximately 0.68-1 million years ago but that they have continued to exchange genes at a low rate throughout divergence. Population genomic data revealed that, despite gene flow, a high level of genomic differentiation is maintained across the majority of the genome. However, we identified multiple, small regions of introgression, occurring mainly in areas of low recombination rate. Our results demonstrate that a high level of genome-wide divergence can establish in the face of persistent introgression and that gene flow can be localized to small genomic regions at the later stages of speciation with gene flow.

  2. The genomic landscape at a late stage of stickleback speciation: High genomic divergence interspersed by small localized regions of introgression.

    Science.gov (United States)

    Ravinet, Mark; Yoshida, Kohta; Shigenobu, Shuji; Toyoda, Atsushi; Fujiyama, Asao; Kitano, Jun

    2018-05-01

    Speciation is a continuous process and analysis of species pairs at different stages of divergence provides insight into how it unfolds. Previous genomic studies on young species pairs have revealed peaks of divergence and heterogeneous genomic differentiation. Yet less known is how localised peaks of differentiation progress to genome-wide divergence during the later stages of speciation in the presence of persistent gene flow. Spanning the speciation continuum, stickleback species pairs are ideal for investigating how genomic divergence builds up during speciation. However, attention has largely focused on young postglacial species pairs, with little knowledge of the genomic signatures of divergence and introgression in older stickleback systems. The Japanese stickleback species pair, composed of the Pacific Ocean three-spined stickleback (Gasterosteus aculeatus) and the Japan Sea stickleback (G. nipponicus), which co-occur in the Japanese islands, is at a late stage of speciation. Divergence likely started well before the end of the last glacial period and crosses between Japan Sea females and Pacific Ocean males result in hybrid male sterility. Here we use coalescent analyses and Approximate Bayesian Computation to show that the two species split approximately 0.68-1 million years ago but that they have continued to exchange genes at a low rate throughout divergence. Population genomic data revealed that, despite gene flow, a high level of genomic differentiation is maintained across the majority of the genome. However, we identified multiple, small regions of introgression, occurring mainly in areas of low recombination rate. Our results demonstrate that a high level of genome-wide divergence can establish in the face of persistent introgression and that gene flow can be localized to small genomic regions at the later stages of speciation with gene flow.

  3. Source-sink estimates of genetic introgression show influence of hatchery strays on wild chum salmon populations in Prince William Sound, Alaska.

    Directory of Open Access Journals (Sweden)

    James R Jasper

    Full Text Available The extent to which stray, hatchery-reared salmon affect wild populations is much debated. Although experiments show that artificial breeding and culture influence the genetics of hatchery salmon, little is known about the interaction between hatchery and wild salmon in a natural setting. Here, we estimated historical and contemporary genetic population structures of chum salmon (Oncorhynchus keta in Prince William Sound (PWS, Alaska, with 135 single nucleotide polymorphism (SNP markers. Historical population structure was inferred from the analysis of DNA from fish scales, which had been archived since the late 1960's for several populations in PWS. Parallel analyses with microsatellites and a test based on Hardy-Weinberg proportions showed that about 50% of the fish-scale DNA was cross-contaminated with DNA from other fish. These samples were removed from the analysis. We used a novel application of the classical source-sink model to compare SNP allele frequencies in these archived fish-scales (1964-1982 with frequencies in contemporary samples (2008-2010 and found a temporal shift toward hatchery allele frequencies in some wild populations. Other populations showed markedly less introgression, despite moderate amounts of hatchery straying. The extent of introgression may reflect similarities in spawning time and life-history traits between hatchery and wild fish, or the degree that hybrids return to a natal spawning area. The source-sink model is a powerful means of detecting low levels of introgression over several generations.

  4. Genetic evidence for hybrid trait speciation in heliconius butterflies.

    Directory of Open Access Journals (Sweden)

    Camilo Salazar

    2010-04-01

    Full Text Available Homoploid hybrid speciation is the formation of a new hybrid species without change in chromosome number. So far, there has been a lack of direct molecular evidence for hybridization generating novel traits directly involved in animal speciation. Heliconius butterflies exhibit bright aposematic color patterns that also act as cues in assortative mating. Heliconius heurippa has been proposed as a hybrid species, and its color pattern can be recreated by introgression of the H. m. melpomene red band into the genetic background of the yellow banded H. cydno cordula. This hybrid color pattern is also involved in mate choice and leads to reproductive isolation between H. heurippa and its close relatives. Here, we provide molecular evidence for adaptive introgression by sequencing genes across the Heliconius red band locus and comparing them to unlinked wing patterning genes in H. melpomene, H. cydno, and H. heurippa. 670 SNPs distributed among 29 unlinked coding genes (25,847bp showed H. heurippa was related to H. c. cordula or the three species were intermixed. In contrast, among 344 SNPs distributed among 13 genes in the red band region (18,629bp, most showed H. heurippa related with H. c. cordula, but a block of around 6,5kb located in the 3' of a putative kinesin gene grouped H. heurippa with H. m. melpomene, supporting the hybrid introgression hypothesis. Genealogical reconstruction showed that this introgression occurred after divergence of the parental species, perhaps around 0.43Mya. Expression of the kinesin gene is spatially restricted to the distal region of the forewing, suggesting a mechanism for pattern regulation. This gene therefore constitutes the first molecular evidence for adaptive introgression during hybrid speciation and is the first clear candidate for a Heliconius wing patterning locus.

  5. A hybrid hydrologic-geophysical inverse technique for the assessment and monitoring of leachates in the vadose zone. 1997 annual progress report

    International Nuclear Information System (INIS)

    Alumbaugh, D.L.

    1997-01-01

    'It is the objective of this proposed study to develop and field test a new, integrated Hybrid Hydrologic-Geophysical Inverse Technique (HHGIT) for characterization of the vadose zone at contaminated sites. This fundamentally new approach to site characterization and monitoring will provide detailed knowledge about hydrological properties, geological heterogeneity and the extent and movement of contamination. HHGIT combines electrical resistivity tomography (ERT) to geophysically sense a 3D volume, statistical information about fabric of geological formations, and sparse data on moisture and contaminant distributions. Combining these three types of information into a single inversion process will provide much better estimates of spatially varied hydraulic properties and three-dimensional contaminant distributions than could be obtained from interpreting the data types individually. Furthermore, HHGIT will be a geostatistically based estimation technique; the estimates represent conditional mean hydraulic property fields and contaminant distributions. Thus, this method will also quantify the uncertainty of the estimates as well as the estimates themselves. The knowledge of this uncertainty is necessary to determine the likelihood of success of remediation efforts and the risk posed by hazardous materials. Controlled field experiments will be conducted to provide critical data sets for evaluation of these methodologies, for better understanding of mechanisms controlling contaminant movement in the vadose zone, and for evaluation of the HHGIT method as a long term monitoring strategy.'

  6. Progressive introgression between ¤Brassica napus¤ (oilseed rape) and ¤B-rapa¤

    DEFF Research Database (Denmark)

    Hansen, L.B.; Siegismund, H.R.; Bagger Jørgensen, Rikke

    2003-01-01

    We have earlier shown extensive introgression between oilseed rape (Brassica napus) and B. rapa in a weedy population using AFLP markers specific for the nuclear genomes. In order to describe the progress of this introgression, we examined 117 offspring from 12 maternal plants from the introgress...

  7. Molecular ecology of the big brown bat (Eptesicus fuscus): Genetic and natural history variation in a hybrid zone

    Science.gov (United States)

    Neubaum, M.A.; Douglas, M.R.; Douglas, M.E.; O'Shea, T.J.

    2007-01-01

    Several geographically distinct mitochondrial DNA (mtDNA) lineages of the big brown bat (Eptesicus fuscus) have been documented in North America. Individuals from 2 of these lineages, an eastern and a western form, co-occur within maternity colonies in Colorado. The discovery of 2 divergent mtDNA lineages in sympatry prompted a set of questions regarding possible biological differences between haplotypes. We captured big brown bats at maternity roosts in Colorado and recorded data on body size, pelage color, litter size, roosting and overwintering behaviors, and local distributions. Wing biopsies were collected for genetic analysis. The ND2 region of the mtDNA molecule was used to determine lineage of the bats. In addition, nuclear DNA (nDNA) intron 1 of the ??-globin gene was used to determine if mtDNA lineages are hybridizing. Eastern and western mtDNA lineages differed by 10.3% sequence divergence and examination of genetic data suggests recent population expansion for both lineages. Differences in distribution occur along the Colorado Front Range, with an increasing proportion of western haplotypes farther south. Results from nDNA analyses demonstrated hybridization between the 2 lineages. Additionally, no outstanding distinctiveness was found between the mtDNA lineages in natural history characters examined. We speculate that historical climate changes separated this species into isolated eastern and western populations, and that secondary contact with subsequent interbreeding was facilitated by European settlement. ?? 2007 American Society of Mammalogists.

  8. Rapid male-specific regulatory divergence and down regulation of spermatogenesis genes in Drosophila species hybrids.

    Directory of Open Access Journals (Sweden)

    Jennifer Ferguson

    Full Text Available In most crosses between closely related species of Drosophila, the male hybrids are sterile and show postmeiotic abnormalities. A series of gene expression studies using genomic approaches have found significant down regulation of postmeiotic spermatogenesis genes in sterile male hybrids. These results have led some to suggest a direct relationship between down regulation in gene expression and hybrid sterility. An alternative explanation to a cause-and-effect relationship between misregulation of gene expression and male sterility is rapid divergence of male sex regulatory elements leading to incompatible interactions in an interspecies hybrid genome. To test the effect of regulatory divergence in spermatogenesis gene expression, we isolated 35 fertile D. simulans strains with D. mauritiana introgressions in either the X, second or third chromosome. We analyzed gene expression in these fertile hybrid strains for a subset of spermatogenesis genes previously reported as significantly under expressed in sterile hybrids relative to D. simulans. We found that fertile autosomal introgressions can cause levels of gene down regulation similar to that of sterile hybrids. We also found that X chromosome heterospecific introgressions cause significantly less gene down regulation than autosomal introgressions. Our results provide evidence that rapid male sex gene regulatory divergence can explain misexpression of spermatogenesis genes in hybrids.

  9. Hybridization between ecotypes in a phenotypically and ecologically heterogeneous population of Iris savannarum (Iridaceae) in Florida.

    Science.gov (United States)

    Iris series Hexagonae is a small, monophyletic complex of 5 species and associated hybrid populations, popularly known as the “Louisiana irises.” The Hexagonae alliance of Iris have been recognized as a textbook case of introgressive hybridization based on numerous studies in Louisiana. We previou...

  10. Studies of a new hybrid taxon in the Artemisia tridentata (Asteraceae: Anthemideae) complex

    Science.gov (United States)

    Heather D. Garrison; Leila M. Shultz; E. Durant McArthur

    2013-01-01

    Members of the Artemisia tridentata complex (ASTERACEAE: Anthemideae: Artemisia subgen. Tridentatae) have adapted to changing environmental conditions through geographic migration, introgression, and hybridization. These processes have resulted in morphologic and genetic variation. A presumed hybrid ("Bonneville" big sagebrush) of the complex occurs in the...

  11. Evidence for suppression of immunity as a driver for genomic introgressions and host range expansion in races of Albugo candida, a generalist parasite

    DEFF Research Database (Denmark)

    McMullan, Mark; Gardiner, Anastasia; Bailey, Kate

    2015-01-01

    How generalist parasites with wide host ranges can evolve is a central question in parasite evolution. Albugo candida is an obligate biotrophic parasite that consists of many physiological races that each specialize on distinct Brassicaceae host species. By analyzing genome sequence assemblies...... by normally non-infecting races. This facilitates introgression and the exchange of effector repertoires, and may enable the evolution of novel races that can undergo clonal population expansion on new hosts. We discuss recent studies on hybridization in other eukaryotes such as yeast, Heliconius butterflies...

  12. Genetic introgression and the survival of Florida panther kittens

    Science.gov (United States)

    Hostetler, Jeffrey A.; Onorato, David P.; Nichols, James D.; Johnson, Warren E.; Roelke, Melody E.; O'Brien, Stephen J.; Jansen, Deborah; Oli, Madan K.

    2010-01-01

    Estimates of survival for the young of a species are critical for population models. These models can often be improved by determining the effects of management actions and population abundance on this demographic parameter. We used multiple sources of data collected during 1982–2008 and a live-recapture dead-recovery modeling framework to estimate and model survival of Florida panther (Puma concolor coryi) kittens (age 0–1 year). Overall, annual survival of Florida panther kittens was 0.323 ± 0.071 (SE), which was lower than estimates used in previous population models. In 1995, female pumas from Texas (P. c. stanleyana) were released into occupied panther range as part of an intentional introgression program to restore genetic variability. We found that kitten survival generally increased with degree of admixture: F1 admixed and backcrossed to Texas kittens survived better than canonical Florida panther and backcrossed to canonical kittens. Average heterozygosity positively influenced kitten and older panther survival, whereas index of panther abundance negatively influenced kitten survival. Our results provide strong evidence for the positive population-level impact of genetic introgression on Florida panthers. Our approach to integrate data from multiple sources was effective at improving robustness as well as precision of estimates of Florida panther kitten survival, and can be useful in estimating vital rates for other elusive species with sparse data.

  13. When and how did Bos indicus introgress into Mongolian cattle?

    Science.gov (United States)

    Yue, Xiangpeng; Li, Ran; Liu, Li; Zhang, Yunsheng; Huang, Jieping; Chang, Zhenhua; Dang, Ruihua; Lan, Xianyong; Chen, Hong; Lei, Chuzhao

    2014-03-10

    The Mongolian cattle are one of the most widespread breeds with strictly Bos taurus morphological features in northern China. In our current study, we presented a diversity of mitochondrial DNA (mtDNA) D-loop region and Y chromosome SNP markers in 25 male and 8 female samples of Mongolian cattle from the Xinjiang Uygur autonomous region in Western China, and detected 21 B. taurus and four Bos indicus (zebu) mtDNA haplotypes. Among four B. indicus mtDNA haplotypes, two haplotypes belonged to I1 haplogroup and the remaining two haplotypes belonged to I2 haplogroup. In contrast, all 25 male Mongolian cattle samples revealed B. taurus Y chromosome haplotype and no B. indicus haplotypes were found. Historical and archeological records indicate that B. taurus was introduced to Xinjiang during the second millennium BC and B. indicus appeared in this region by the second century AD. The two types of cattle coexisted for many centuries in Xinjiang, as depicted in clay and wooden figurines unearthed in the Astana cemetery in Turfan (3rd-8th century AD). Multiple lines of evidence suggest that the earliest B. indicus introgression in the Mongolian cattle may have occurred during the 2nd-7th centuries AD through the Silk Road around the Xinjiang region. This conclusion differs from the previous hypothesis that zebu introgression to Mongolian cattle happened during the Mongol Empire era in the 13th century. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Scientific management of Mediterranean coastal zone: a hybrid ocean forecasting system for oil spill and search and rescue operations.

    Science.gov (United States)

    Jordi, A; Ferrer, M I; Vizoso, G; Orfila, A; Basterretxea, G; Casas, B; Alvarez, A; Roig, D; Garau, B; Martínez, M; Fernández, V; Fornés, A; Ruiz, M; Fornós, J J; Balaguer, P; Duarte, C M; Rodríguez, I; Alvarez, E; Onken, R; Orfila, P; Tintoré, J

    2006-01-01

    The oil spill from Prestige tanker showed the importance of scientifically based protocols to minimize the impacts on the environment. In this work, we describe a new forecasting system to predict oil spill trajectories and their potential impacts on the coastal zone. The system is formed of three main interconnected modules that address different capabilities: (1) an operational circulation sub-system that includes nested models at different scales, data collection with near-real time assimilation, new tools for initialization or assimilation based on genetic algorithms and feature-oriented strategic sampling; (2) an oil spill coastal sub-system that allows simulation of the trajectories and fate of spilled oil together with evaluation of coastal zone vulnerability using environmental sensitivity indexes; (3) a risk management sub-system for decision support based on GIS technology. The system is applied to the Mediterranean Sea where surface currents are highly variable in space and time, and interactions between local, sub-basin and basin scale increase the non-linear interactions effects which need to be adequately resolved at each one of the intervening scales. Besides the Mediterranean Sea is a complex reduced scale ocean representing a real scientific and technological challenge for operational oceanography and particularly for oil spill response and search and rescue operations.

  15. Repair boundary for parent tube indications within the upper joint zone of hybrid expansion joint (HEJ) sleeved tubes

    International Nuclear Information System (INIS)

    Cullen, W.K.; Keating, R.F.

    1997-01-01

    In the Spring and Fall of 1994, and the Spring of 1995, crack-like indications were found in the upper hybrid expansion joint (HEJ) region of Steam Generator (S/G) tubes which had been sleeved using Westinghouse HEJ sleeves. As a result of these findings, analytic and test evaluations were performed to assess the effect of the degradation on the structural, and leakage, integrity of the sleeve/tube joint relative to the requirements of the United States Nuclear Regulatory Commission's (NRC) draft Regulatory Guide (RG) 1.121. The results of these evaluations demonstrated that tubes with implied or known crack-like circumferential parent tube indications (PTIs) located 1.1 inches or farther below the bottom of the hardroll upper transition, have sufficient, and significant, integrity relative to the requirements of RG 1.121. Thus, the purpose of this report is to provide background information related to the justification of the modified tube repair boundary

  16. Introgression of a Tombusvirus Resistance Locus from Nicotiana edwardsonii var. Columbia to N. clevelandii.

    Science.gov (United States)

    Schoelz, James E; Wiggins, B Elizabeth; Wintermantel, William M; Ross, Kathleen

    2006-05-01

    ABSTRACT A new variety of Nicotiana, N. edwardsonii var. Columbia, was evaluated for its capacity to serve as a new source for virus resistance genes. Columbia was developed from a hybridization between N. glutinosa and N. clevelandii, the same parents used for the formation of the original N. edwardsonii. However, in contrast to the original N. edwardsonii, crosses between Columbia and either of its parents are fertile. Thus, the inheritance of virus resistance genes present in N. glutinosa could be characterized by using Columbia as a bridge plant in crosses with the susceptible parent, N. clevelandii. To determine how virus resistance genes would segregate in interspecific crosses between Columbia and N. clevelandii, we followed the fate of the N gene, a single dominant gene that specifies resistance to Tobacco mosaic virus (TMV). Our genetic evidence indicated that the entire chromosome containing the N gene was introgressed into N. clevelandii to create an addition line, designated N. clevelandii line 19. Although line 19 was homozygous for resistance to TMV, it remained susceptible to Tomato bushy stunt virus (TBSV) and Cauliflower mosaic virus (CaMV) strain W260, indicating that resistance to these viruses must reside on other N. glutinosa chromosomes. We also developed a second addition line, N. clevelandii line 36, which was homozygous for resistance to TBSV. Line 36 was susceptible to TMV and CaMV strain W260, but was resistant to other tombusviruses, including Cucumber necrosis virus, Cymbidium ringspot virus, Lettuce necrotic stunt virus, and Carnation Italian ringspot virus.

  17. Impacts of Neanderthal-Introgressed Sequences on the Landscape of Human Gene Expression.

    Science.gov (United States)

    McCoy, Rajiv C; Wakefield, Jon; Akey, Joshua M

    2017-02-23

    Regulatory variation influencing gene expression is a key contributor to phenotypic diversity, both within and between species. Unfortunately, RNA degrades too rapidly to be recovered from fossil remains, limiting functional genomic insights about our extinct hominin relatives. Many Neanderthal sequences survive in modern humans due to ancient hybridization, providing an opportunity to assess their contributions to transcriptional variation and to test hypotheses about regulatory evolution. We developed a flexible Bayesian statistical approach to quantify allele-specific expression (ASE) in complex RNA-seq datasets. We identified widespread expression differences between Neanderthal and modern human alleles, indicating pervasive cis-regulatory impacts of introgression. Brain regions and testes exhibited significant downregulation of Neanderthal alleles relative to other tissues, consistent with natural selection influencing the tissue-specific regulatory landscape. Our study demonstrates that Neanderthal-inherited sequences are not silent remnants of ancient interbreeding but have measurable impacts on gene expression that contribute to variation in modern human phenotypes. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Hybridization within a Pilosella population: a morphometric analysis

    Czech Academy of Sciences Publication Activity Database

    Urfus, Tomáš; Krahulec, František; Krahulcová, Anna

    2014-01-01

    Roč. 49, č. 2 (2014), s. 223-238 ISSN 1211-9520 R&D Projects: GA ČR GA206/08/0890 Institutional research plan: CEZ:AV0Z60050516 Institutional support: RVO:67985939 Keywords : hybridization * introgression * multivariate morphometrics Subject RIV: EF - Botanics Impact factor: 1.778, year: 2014

  19. From hybrid swarms to swarms of hybrids

    Science.gov (United States)

    Stohlgren, Thomas J.; Szalanski, Allen L; Gaskin, John F.; Young, Nicholas E.; West, Amanda; Jarnevich, Catherine S.; Tripodi, Amber

    2014-01-01

    Science has shown that the introgression or hybridization of modern humans (Homo sapiens) with Neanderthals up to 40,000 YBP may have led to the swarm of modern humans on earth. However, there is little doubt that modern trade and transportation in support of the humans has continued to introduce additional species, genotypes, and hybrids to every country on the globe. We assessed the utility of species distributions modeling of genotypes to assess the risk of current and future invaders. We evaluated 93 locations of the genus Tamarix for which genetic data were available. Maxent models of habitat suitability showed that the hybrid, T. ramosissima x T. chinensis, was slightly greater than the parent taxa (AUCs > 0.83). General linear models of Africanized honey bees, a hybrid cross of Tanzanian Apis mellifera scutellata and a variety of European honey bee including A. m. ligustica, showed that the Africanized bees (AUC = 0.81) may be displacing European honey bees (AUC > 0.76) over large areas of the southwestern U.S. More important, Maxent modeling of sub-populations (A1 and A26 mitotypes based on mDNA) could be accurately modeled (AUC > 0.9), and they responded differently to environmental drivers. This suggests that rapid evolutionary change may be underway in the Africanized bees, allowing the bees to spread into new areas and extending their total range. Protecting native species and ecosystems may benefit from risk maps of harmful invasive species, hybrids, and genotypes.

  20. Increased Mycoplasma hyopneumoniae Disease Prevalence in Domestic Hybrids Among Free-Living Wild Boar.

    Science.gov (United States)

    Goedbloed, Daniel J; van Hooft, Pim; Lutz, Walburga; Megens, Hendrik-Jan; van Wieren, Sip E; Ydenberg, Ron C; Prins, Herbert H T

    2015-12-01

    Wildlife immune genes are subject to natural selection exerted by pathogens. In contrast, domestic immune genes are largely protected from pathogen selection by veterinary care. Introgression of domestic alleles into the wild could lead to increased disease susceptibility, but observations are scarce due to low introgression rates, low disease prevalence and reduced survival of domestic hybrids. Here we report the first observation of a deleterious effect of domestic introgression on disease prevalence in a free-living large mammal. A fraction of 462 randomly sampled free-living European wild boar (Sus scrofa) was genetically identified as recent wild boar-domestic pig hybrids based on 351 SNP data. Analysis of antibody prevalence against the bacterial pathogen Mycoplasma hyopneumoniae (Mhyo) showed an increased Mhyo prevalence in wild-domestic hybrids. We argue that the most likely mechanism explaining the observed association between domestic hybrid status and Mhyo antibody prevalence would be introgression of deleterious domestic alleles. We hypothesise that large-scale use of antibiotics in the swine breeding sector may have played a role in shaping the relatively deleterious properties of domestic swine immune genes and that domestic introgression may also lead to increased wildlife disease susceptibility in the case of other species.

  1. Hybridisation among groupers (genus Cephalopholis) at the eastern Indian Ocean suture zone: taxonomic and evolutionary implications

    Science.gov (United States)

    Payet, Samuel D.; Hobbs, Jean-Paul A.; DiBattista, Joseph D.; Newman, Stephen J.; Sinclair-Taylor, Tane; Berumen, Michael L.; McIlwain, Jennifer L.

    2016-12-01

    Hybridisation is a significant evolutionary process that until recently was considered rare in the marine environment. A suture zone in the eastern Indian Ocean is home to numerous hybridising sister species, providing an ideal opportunity to determine how hybridisation affects speciation and biodiversity in coral reef fishes. At this location, hybridisation between two grouper (Epinephelidae) species: Cephalopholis urodeta (Pacific Ocean) and C. nigripinnis (Indian Ocean) was investigated to determine the genetic basis of hybridisation and to compare the ecology and life history of hybrids and their parent species. This approach aimed to provide insights into the taxonomic and evolutionary consequences of hybridisation. Despite clear phenotypic differences, multiple molecular markers revealed hybrids, and their parent species were genetically homogenous within and (thousands of kilometres) outside of the hybrid zone. Hybrids were at least as fit as their parent species (in terms of growth, reproduction, and abundance) and were observed in a broad range of intermediate phenotypes. The two species appear to be interbreeding at Christmas Island due to inherent biological and ecological compatibilities, and the lack of genetic structure may be explained by three potential scenarios: (1) hybridisation and introgression; (2) discordance between morphology and genetics; and (3) incomplete lineage sorting. Further molecular analyses are necessary to discriminate these scenarios. Regardless of which applies, C. urodeta and C. nigripinnis are unlikely to evolve in reproductive isolation as they cohabit where they are common (Christmas Island) and will source congeneric mates where they are rare (Cocos Keeling Islands). Our results add to the growing body of evidence that hybridisation among coral reef fishes is a dynamic evolutionary factor.

  2. Hybridisation among groupers (genus Cephalopholis) at the eastern Indian Ocean suture zone: taxonomic and evolutionary implications

    KAUST Repository

    Payet, Samuel D.; Hobbs, Jean-Paul A.; DiBattista, Joseph; Newman, Stephen J.; Sinclair-Taylor, Tane; Berumen, Michael L.; McIlwain, Jennifer L.

    2016-01-01

    Hybridisation is a significant evolutionary process that until recently was considered rare in the marine environment. A suture zone in the eastern Indian Ocean is home to numerous hybridising sister species, providing an ideal opportunity to determine how hybridisation affects speciation and biodiversity in coral reef fishes. At this location, hybridisation between two grouper (Epinephelidae) species: Cephalopholis urodeta (Pacific Ocean) and C. nigripinnis (Indian Ocean) was investigated to determine the genetic basis of hybridisation and to compare the ecology and life history of hybrids and their parent species. This approach aimed to provide insights into the taxonomic and evolutionary consequences of hybridisation. Despite clear phenotypic differences, multiple molecular markers revealed hybrids, and their parent species were genetically homogenous within and (thousands of kilometres) outside of the hybrid zone. Hybrids were at least as fit as their parent species (in terms of growth, reproduction, and abundance) and were observed in a broad range of intermediate phenotypes. The two species appear to be interbreeding at Christmas Island due to inherent biological and ecological compatibilities, and the lack of genetic structure may be explained by three potential scenarios: (1) hybridisation and introgression; (2) discordance between morphology and genetics; and (3) incomplete lineage sorting. Further molecular analyses are necessary to discriminate these scenarios. Regardless of which applies, C. urodeta and C. nigripinnis are unlikely to evolve in reproductive isolation as they cohabit where they are common (Christmas Island) and will source congeneric mates where they are rare (Cocos Keeling Islands). Our results add to the growing body of evidence that hybridisation among coral reef fishes is a dynamic evolutionary factor. © 2016 Springer-Verlag Berlin Heidelberg

  3. Hybridisation among groupers (genus Cephalopholis) at the eastern Indian Ocean suture zone: taxonomic and evolutionary implications

    KAUST Repository

    Payet, Samuel D.

    2016-08-05

    Hybridisation is a significant evolutionary process that until recently was considered rare in the marine environment. A suture zone in the eastern Indian Ocean is home to numerous hybridising sister species, providing an ideal opportunity to determine how hybridisation affects speciation and biodiversity in coral reef fishes. At this location, hybridisation between two grouper (Epinephelidae) species: Cephalopholis urodeta (Pacific Ocean) and C. nigripinnis (Indian Ocean) was investigated to determine the genetic basis of hybridisation and to compare the ecology and life history of hybrids and their parent species. This approach aimed to provide insights into the taxonomic and evolutionary consequences of hybridisation. Despite clear phenotypic differences, multiple molecular markers revealed hybrids, and their parent species were genetically homogenous within and (thousands of kilometres) outside of the hybrid zone. Hybrids were at least as fit as their parent species (in terms of growth, reproduction, and abundance) and were observed in a broad range of intermediate phenotypes. The two species appear to be interbreeding at Christmas Island due to inherent biological and ecological compatibilities, and the lack of genetic structure may be explained by three potential scenarios: (1) hybridisation and introgression; (2) discordance between morphology and genetics; and (3) incomplete lineage sorting. Further molecular analyses are necessary to discriminate these scenarios. Regardless of which applies, C. urodeta and C. nigripinnis are unlikely to evolve in reproductive isolation as they cohabit where they are common (Christmas Island) and will source congeneric mates where they are rare (Cocos Keeling Islands). Our results add to the growing body of evidence that hybridisation among coral reef fishes is a dynamic evolutionary factor. © 2016 Springer-Verlag Berlin Heidelberg

  4. An improved hybrid multi-criteria/multidimensional model for strategic industrial location selection: Casablanca industrial zones as a case study.

    Science.gov (United States)

    Boutkhoum, Omar; Hanine, Mohamed; Agouti, Tarik; Tikniouine, Abdessadek

    2015-01-01

    In this paper, we examine the issue of strategic industrial location selection in uncertain decision making environments for implanting new industrial corporation. In fact, the industrial location issue is typically considered as a crucial factor in business research field which is related to many calculations about natural resources, distributors, suppliers, customers, and most other things. Based on the integration of environmental, economic and social decisive elements of sustainable development, this paper presents a hybrid decision making model combining fuzzy multi-criteria analysis with analytical capabilities that OLAP systems can provide for successful and optimal industrial location selection. The proposed model mainly consists in three stages. In the first stage, a decision-making committee has been established to identify the evaluation criteria impacting the location selection process. In the second stage, we develop fuzzy AHP software based on the extent analysis method to assign the importance weights to the selected criteria, which allows us to model the linguistic vagueness, ambiguity, and incomplete knowledge. In the last stage, OLAP analysis integrated with multi-criteria analysis employs these weighted criteria as inputs to evaluate, rank and select the strategic industrial location for implanting new business corporation in the region of Casablanca, Morocco. Finally, a sensitivity analysis is performed to evaluate the impact of criteria weights and the preferences given by decision makers on the final rankings of strategic industrial locations.

  5. The problem of the use the hybrid and photovoltaic systems in insular zones with climatic siversity in Madeira; A problematica da utilizacao de sistemas fotovoltaicos e hibridos em zonas insulares de diversidade climatica-ILHA da Madeira

    Energy Technology Data Exchange (ETDEWEB)

    Magro, J. C. E.

    2004-07-01

    Project PAUER contemplates the evaluation and utilization of renewable energy in insular zones with climatic diversity, situated on the Archipelago of Madeira. The project has three main areas of intervention: prospecting and evaluating energetic resources; creation of data bases of climatic data for application in energetic studies and other areas; the installation of twenty autonomous photovoltaic or hybrid systems in isolated localities. This communication presents some data from meteorological observations made up until the present date, following appropriate statistical analysis. Characteristics of some installed photovoltaic and hybrid systems as well as some of the principal problems encountered in the field are also given. (Author)

  6. A hybrid machine learning model to estimate nitrate contamination of production zone groundwater in the Central Valley, California

    Science.gov (United States)

    Ransom, K.; Nolan, B. T.; Faunt, C. C.; Bell, A.; Gronberg, J.; Traum, J.; Wheeler, D. C.; Rosecrans, C.; Belitz, K.; Eberts, S.; Harter, T.

    2016-12-01

    A hybrid, non-linear, machine learning statistical model was developed within a statistical learning framework to predict nitrate contamination of groundwater to depths of approximately 500 m below ground surface in the Central Valley, California. A database of 213 predictor variables representing well characteristics, historical and current field and county scale nitrogen mass balance, historical and current landuse, oxidation/reduction conditions, groundwater flow, climate, soil characteristics, depth to groundwater, and groundwater age were assigned to over 6,000 private supply and public supply wells measured previously for nitrate and located throughout the study area. The machine learning method, gradient boosting machine (GBM) was used to screen predictor variables and rank them in order of importance in relation to the groundwater nitrate measurements. The top five most important predictor variables included oxidation/reduction characteristics, historical field scale nitrogen mass balance, climate, and depth to 60 year old water. Twenty-two variables were selected for the final model and final model errors for log-transformed hold-out data were R squared of 0.45 and root mean square error (RMSE) of 1.124. Modeled mean groundwater age was tested separately for error improvement in the model and when included decreased model RMSE by 0.5% compared to the same model without age and by 0.20% compared to the model with all 213 variables. 1D and 2D partial plots were examined to determine how variables behave individually and interact in the model. Some variables behaved as expected: log nitrate decreased with increasing probability of anoxic conditions and depth to 60 year old water, generally decreased with increasing natural landuse surrounding wells and increasing mean groundwater age, generally increased with increased minimum depth to high water table and with increased base flow index value. Other variables exhibited much more erratic or noisy behavior in

  7. Male meiosis and gametogenesis in wild house mice (Mus musculus domesticus) from a chromosomal hybrid zone; a comparison between "simple" Robertsonian heterozygotes and homozygotes.

    Science.gov (United States)

    Wallace, B M; Searle, J B; Everett, C A

    1992-01-01

    Wild male house mice Mus musculus domesticus were collected from the hybrid zone between the John o'Groats race (2n = 32) and the standard race (2n = 40) in northern Scotland. Meiosis in both homozygotes (2n = 32, 36, and 40) and single Robertsonian heterozygotes (2n = 33, 35, and 37) was found to be orderly. At prophase/metaphase I in heterozygotes, a trivalent was formed from the metacentric and two homologous acrocentrics. At pachytene, this trivalent usually had a single side arm at the position of the centromeres, as a result of nonhomologous pairing of the acrocentrics. This side arm persisted into diplotene. Generally only a single chiasma was formed between each acrocentric and the metacentric. Anaphase I nondisjunction frequencies were estimated as 1.5% for the homozygotes and 2.7% for the heterozygotes. The extent of germ cell death between the pachytene and round spermatid stages was 18% greater in heterozygotes than in homozygotes. Our results concur with previous studies which indicate that single Robertsonian heterozygotes in wild house mice have near-normal fertility.

  8. Identification of exotic genetic components and DNA methylation pattern analysis of three cotton introgression lines from Gossypium bickii.

    Science.gov (United States)

    He, Shou-Pu; Sun, Jun-Ling; Zhang, Chao; Du, Xiong-Ming

    2011-01-01

    The impact of alien DNA fragments on plant genome has been studied in many species. However, little is known about the introgression lines of Gossypium. To study the consequences of introgression in Gossypium, we investigated 2000 genomic and 800 epigenetic sites in three typical cotton introgression lines, as well as their cultivar (Gossypium hirsutum) and wild parents (Gossypium bickii), by amplified fragment length polymorphism (AFLP) and methylation-sensitive amplified polymorphism (MSAP). The results demonstrate that an average of 0.5% of exotic DNA segments from wild cotton is transmitted into the genome of each introgression line, with the addition of other forms of genetic variation. In total, an average of 0.7% of genetic variation sites is identified in introgression lines. Simultaneously, the overall cytosine methylation level in each introgression line is very close to that of the upland cotton parent (an average of 22.6%). Further dividing patterns reveal that both hypomethylation and hypermethylation occurred in introgression lines in comparison with the upland cotton parent. Sequencing of nine methylation polymorphism fragments showed that most (7 of 9) of the methylation alternations occurred in the noncoding sequences. The molecular evidence of introgression from wild cotton into introgression lines in our study is identified by AFLP. Moreover, the causes of petal variation in introgression lines are discussed.

  9. Evaluation of sugarcane introgression lines for resistance to brown rust disease caused by Puccinia melanocephala

    OpenAIRE

    Wang, Xiao-Yan; Wen-Feng, Li; Ying-Kun, Huang; Xin, Lu; Zhi-Ming, Luo; Jiong, Yin; Hong-Li, Shan; Rong-Yue, Zhang

    2013-01-01

    Sugarcane brown rust disease caused by Puccinia melanocephala is one of the important fungal diseases affecting sugarcane yield around the world. Cultivar resistance is the most appropriate control method for this disease. In this study, 62 introgression lines chosen from the crossing Saccharum officinarum L. cv. Ludashi x Erianthus rockii Yunnan 95-19 were evaluated for brown rust resistance using artificial inoculation. More than 30% of the introgression lines were identified as resistant. ...

  10. Introgression Between Cultivars and Wild Populations of Momordica charantia L. (Cucurbitaceae in Taiwan

    Directory of Open Access Journals (Sweden)

    Yu-Chung Chiang

    2012-05-01

    Full Text Available The landrace strains of Momordica charantia are widely cultivated vegetables throughout the tropics and subtropics, but not in Taiwan, a continental island in Southeast Asia, until a few hundred years ago. In contrast, the related wild populations with smaller fruit sizes are native to Taiwan. Because of the introduction of cultivars for agricultural purposes, these two accessions currently exhibit a sympatric or parapatric distribution in Taiwan. In this study, the cultivars and wild samples from Taiwan, India, and Korea were collected for testing of their hybridization and evolutionary patterns. The cpDNA marker showed a clear distinction between accessions of cultivars and wild populations of Taiwan and a long divergence time. In contrast, an analysis of eight selectively neutral nuclear microsatellite loci did not reveal a difference between the genetic structures of these two accessions. A relatively short divergence time and frequent but asymmetric gene flows were estimated based on the isolation-with-migration model. Historical and current introgression from cultivars to wild populations of Taiwan was also inferred using MIGRATE-n and BayesAss analyses. Our results showed that these two accessions shared abundant common ancestral polymorphisms, and the timing of the divergence and colonization of the Taiwanese wild populations is consistent with the geohistory of the Taiwan Strait land bridge of the Last Glacial Maximum (LGM. Long-term and recurrent introgression between accessions indicated the asymmetric capacity to receive foreign genes from other accessions. The modern introduction of cultivars of M. charantia during the colonization of Taiwan by the Han Chinese ethnic group enhanced the rate of gene replacement in the native populations and resulted in the loss of native genes.

  11. Locus-dependent selection in crop-wild hybrids of lettuce under field conditions and its implication for GM crop development

    OpenAIRE

    Hooftman, D.A.P.; Flavell, A.J.; Jansen, J.; Nijs, den, J.C.M.; Syed, N.H.; Sorensen, A.P.; Wengel, ter, P.O.; Wiel, van de, C.C.M.

    2011-01-01

    Gene escape from crops has gained much attention in the last two decades, as transgenes introgressing into wild populations could affect the latter's ecological characteristics. However, different genes have different likelihoods of introgression. The mixture of selective forces provided by natural conditions creates an adaptive mosaic of alleles from both parental species. We investigated segregation patterns after hybridization between lettuce (Lactuca sativa) and its wild relative, L. serr...

  12. Meiosis in elephant grass (Pennisetum purpureum), pearl millet (Pennisetum glaucum) (Poaceae, Poales) and their interspecific hybrids

    OpenAIRE

    Techio, Vânia Helena; Davide, Lisete Chamma; Pereira, Antônio Vander

    2006-01-01

    The cultivated and sexually compatible species Pennisetum purpureum (elephant grass, 2n = 4x = 28) and Pennisetum glaucum (pearl millet, 2n = 2x = 14) can undergo hybridization which favors the amplification of their genetic background and the introgression of favorable alleles into breeding programs. The main problem with interspecific hybrids of these species is infertility due to triploidy (2n = 3x = 21). This study describes meiosis in elephant grass x pearl millet hybrids and their proge...

  13. Biomass carbon, nitrogen and phosphorus stocks in hybrid poplar buffers, herbaceous buffers and natural woodlots in the riparian zone on agricultural land.

    Science.gov (United States)

    Fortier, Julien; Truax, Benoit; Gagnon, Daniel; Lambert, France

    2015-05-01

    In many temperate agricultural areas, riparian forests have been converted to cultivated land, and only narrow strips of herbaceous vegetation now buffer many farm streams. The afforestation of these riparian zones has the potential to increase carbon (C) storage in agricultural landscapes by creating a new biomass sink for atmospheric CO2. Occurring at the same time, the storage of nitrogen (N) and phosphorus (P) in plant biomass, is an important water quality function that may greatly vary with types of riparian vegetation. The objectives of this study were (1) to compare C, N and P storage in aboveground, belowground and detrital biomass for three types of riparian vegetation cover (9-year-old hybrid poplar buffers, herbaceous buffers and natural woodlots) across four agricultural sites and (2) to determine potential vegetation cover effects on soil nutrient supply rate in the riparian zone. Site level comparisons suggest that 9-year-old poplar buffers have stored 9-31 times more biomass C, 4-10 times more biomass N, and 3-7 times more biomass P than adjacent non managed herbaceous buffers, with the largest differences observed on the more fertile sites. The conversion of these herbaceous buffers to poplar buffers could respectively increase C, N and P storage in biomass by 3.2-11.9 t/ha/yr, 32-124 kg/ha/yr and 3.2-15.6 kg/ha/yr, over 9 years. Soil NO3 and P supply rates during the summer were respectively 57% and 66% lower in poplar buffers than in adjacent herbaceous buffers, potentially reflecting differences in nutrient storage and cycling between the two buffer types. Biomass C ranged 49-160 t/ha in woodlots, 33-110 t/ha in poplar buffers and 3-4 t/ha in herbaceous buffers. Similar biomass C stocks were found in the most productive poplar buffer and three of the four woodlots studied. Given their large and varied biomass C stocks, conservation of older riparian woodlots is equally important for C balance management in farmland. In addition, the

  14. Targeted introgression of a wheat stem rust resistance gene by DNA marker-assisted chromosome engineering.

    Science.gov (United States)

    Niu, Zhixia; Klindworth, Daryl L; Friesen, Timothy L; Chao, Shiaoman; Jin, Yue; Cai, Xiwen; Xu, Steven S

    2011-04-01

    Chromosome engineering is a useful strategy for transfer of alien genes from wild relatives into modern crops. However, this strategy has not been extensively used for alien gene introgression in most crops due to low efficiency of conventional cytogenetic techniques. Here, we report an improved scheme of chromosome engineering for efficient elimination of a large amount of goatgrass (Aegilops speltoides) chromatin surrounding Sr39, a gene that provides resistance to multiple stem rust races, including Ug99 (TTKSK) in wheat. The wheat ph1b mutation, which promotes meiotic pairing between homoeologous chromosomes, was employed to induce recombination between wheat chromosome 2B and goatgrass 2S chromatin using a backcross scheme favorable for inducing and detecting the homoeologous recombinants with small goatgrass chromosome segments. Forty recombinants with Sr39 with reduced surrounding goatgrass chromatin were quickly identified from 1048 backcross progenies through disease screening and molecular marker analysis. Four of the recombinants carrying Sr39 with a minimal amount of goatgrass chromatin (2.87-9.15% of the translocated chromosomes) were verified using genomic in situ hybridization. Approximately 97% of the goatgrass chromatin was eliminated in one of the recombinants, in which a tiny goatgrass chromosome segment containing Sr39 was retained in the wheat genome. Localization of the goatgrass chromatin in the recombinants led to rapid development of three molecular markers tightly linked to Sr39. The new wheat lines and markers provide useful resources for the ongoing global effort to combat Ug99. This study has demonstrated great potential of chromosome engineering in genome manipulation for plant improvement.

  15. Evolution of postmating reproductive isolation: measuring the fitness effects of chromosomal regions containing hybrid male sterility factors.

    Science.gov (United States)

    Johnson, N A; Wu, C I

    1993-08-01

    At least six regions of the X chromosome can cause male sterility when introgressed from Drosophila mauritiana into Drosophila simulans. In this article, we present the results of the other fitness effects caused by two X-linked regions that contain hybrid male sterility factors. In both regions, females that are heterozygous for an introgression with such a sterility factor produce substantially-fewer offspring than females heterozygous for an introgression that lacks the sterility factor. Thus, the hybrid male sterility factors, or other genes nearby, have substantial effects on female productivity. In contrast, hybrid male sterility factors have little or no effect on the relative viabilities of either sex. The evolutionary implications of these findings are discussed.

  16. Introgression of Black Rot Resistance from Brassica carinata to Cauliflower (Brassica oleracea botrytis Group) through Embryo Rescue

    Science.gov (United States)

    Sharma, Brij B.; Kalia, Pritam; Singh, Dinesh; Sharma, Tilak R.

    2017-01-01

    Black rot caused by Xanthomonas campestris pv. campestris (Xcc) is a very important disease of cauliflower (Brassica oleracea botrytis group) resulting into 10–50% yield losses every year. Since there is a dearth of availability of resistance to black rot disease in B. oleracea (C genome), therefore exploration of A and B genomes was inevitable as they have been reported to be potential reservoirs of gene(s) for resistance to black rot. To utilize these sources, interspecific hybrid and backcross progeny (B1) were generated between cauliflower “Pusa Sharad” and Ethiopian mustard “NPC-9” employing in vitro embryo rescue technique. Direct ovule culture method was better than siliqua culture under different temperature regime periods. Hybridity testing of F1 inter-specific plants was carried out using co-dominant SSR marker and Brassica B and C genome-specific (DB and DC) primers. Meiosis in the di-genomic (BCC) interspecific hybrid of B. oleracea botrytis group (2n = 18, CC) × B. carinata (2n = 4x = 34, BBCC) was higly disorganized and cytological analysis of pollen mother cells revealed chromosomes 2n = 26 at metaphase-I. Fertile giant pollen grain formation was observed frequently in interspecific F1 hybrid and BC1 plants. The F1 inter-specific plants were found to be resistant to Xcc race 1. Segregation distortion was observed in BC1 generation for black rot resistance and different morphological traits. The At1g70610 marker analysis confirmed successful introgression of black rot resistance in interspecific BC1 population. This effort will go a long way in pyramiding gene(s) for resistance against black rot in Cole crops, especially cauliflower and cabbage for developing durable resistance, thus minimize dependency on bactericides. PMID:28769959

  17. Introgression of Black Rot Resistance from Brassica carinata to Cauliflower (Brassica oleracea botrytis Group through Embryo Rescue

    Directory of Open Access Journals (Sweden)

    Brij B. Sharma

    2017-07-01

    Full Text Available Black rot caused by Xanthomonas campestris pv. campestris (Xcc is a very important disease of cauliflower (Brassica oleracea botrytis group resulting into 10–50% yield losses every year. Since there is a dearth of availability of resistance to black rot disease in B. oleracea (C genome, therefore exploration of A and B genomes was inevitable as they have been reported to be potential reservoirs of gene(s for resistance to black rot. To utilize these sources, interspecific hybrid and backcross progeny (B1 were generated between cauliflower “Pusa Sharad” and Ethiopian mustard “NPC-9” employing in vitro embryo rescue technique. Direct ovule culture method was better than siliqua culture under different temperature regime periods. Hybridity testing of F1 inter-specific plants was carried out using co-dominant SSR marker and Brassica B and C genome-specific (DB and DC primers. Meiosis in the di-genomic (BCC interspecific hybrid of B. oleracea botrytis group (2n = 18, CC × B. carinata (2n = 4x = 34, BBCC was higly disorganized and cytological analysis of pollen mother cells revealed chromosomes 2n = 26 at metaphase-I. Fertile giant pollen grain formation was observed frequently in interspecific F1 hybrid and BC1 plants. The F1 inter-specific plants were found to be resistant to Xcc race 1. Segregation distortion was observed in BC1 generation for black rot resistance and different morphological traits. The At1g70610 marker analysis confirmed successful introgression of black rot resistance in interspecific BC1 population. This effort will go a long way in pyramiding gene(s for resistance against black rot in Cole crops, especially cauliflower and cabbage for developing durable resistance, thus minimize dependency on bactericides.

  18. Introgression of Black Rot Resistance from Brassica carinata to Cauliflower (Brassica oleracea botrytis Group) through Embryo Rescue.

    Science.gov (United States)

    Sharma, Brij B; Kalia, Pritam; Singh, Dinesh; Sharma, Tilak R

    2017-01-01

    Black rot caused by Xanthomonas campestris pv. campestris ( Xcc ) is a very important disease of cauliflower ( Brassica oleracea botrytis group) resulting into 10-50% yield losses every year. Since there is a dearth of availability of resistance to black rot disease in B. oleracea (C genome), therefore exploration of A and B genomes was inevitable as they have been reported to be potential reservoirs of gene(s) for resistance to black rot. To utilize these sources, interspecific hybrid and backcross progeny (B 1 ) were generated between cauliflower "Pusa Sharad" and Ethiopian mustard "NPC-9" employing in vitro embryo rescue technique. Direct ovule culture method was better than siliqua culture under different temperature regime periods. Hybridity testing of F 1 inter-specific plants was carried out using co-dominant SSR marker and Brassica B and C genome-specific (DB and DC) primers. Meiosis in the di-genomic (BCC) interspecific hybrid of B. oleracea botrytis group (2 n = 18, CC) × B. carinata (2 n = 4x = 34, BBCC) was higly disorganized and cytological analysis of pollen mother cells revealed chromosomes 2 n = 26 at metaphase-I. Fertile giant pollen grain formation was observed frequently in interspecific F 1 hybrid and BC 1 plants. The F 1 inter-specific plants were found to be resistant to Xcc race 1. Segregation distortion was observed in BC 1 generation for black rot resistance and different morphological traits. The At1g70610 marker analysis confirmed successful introgression of black rot resistance in interspecific BC 1 population. This effort will go a long way in pyramiding gene(s) for resistance against black rot in Cole crops, especially cauliflower and cabbage for developing durable resistance, thus minimize dependency on bactericides.

  19. Genetic analysis of a novel broad-spectrum powdery mildew resistance gene from the wheat-Agropyron cristatum introgression line Pubing 74.

    Science.gov (United States)

    Lu, Yuqing; Yao, Miaomiao; Zhang, Jinpeng; Song, Liqiang; Liu, Weihua; Yang, Xinming; Li, Xiuquan; Li, Lihui

    2016-09-01

    A novel broad-spectrum powdery mildew resistance gene PmPB74 was identified in wheat- Agropyron cristatum introgression line Pubing 74. Development of wheat cultivars with broad-spectrum, durable resistance to powdery mildew has been restricted by lack of superior genetic resources. In this study, a wheat-A. cristatum introgression line Pubing 74, originally selected from a wide cross between the common wheat cultivar Fukuhokomugi (Fukuho) and Agropyron cristatum (L.) Gaertn (2n = 4x = 28; genome PPPP), displayed resistance to powdery mildew at both the seedling and adult stages. The putative alien chromosomal fragment in Pubing 74 was below the detection limit of genomic in situ hybridization (GISH), but evidence for other non-GISH-detectable introgressions was provided by the presence of three STS markers specific to A. cristatum. Genetic analysis indicated that Pubing 74 carried a single dominant gene for powdery mildew resistance, temporarily designated PmPB74. Molecular mapping showed that PmPB74 was located on wheat chromosome arm 5DS, and flanked by markers Xcfd81 and HRM02 at genetic distances of 2.5 and 1.7 cM, respectively. Compared with other lines with powdery mildew resistance gene(s) on wheat chromosome arm 5DS, Pubing 74 was resistant to all 28 Blumeria graminis f. sp tritici (Bgt) isolates from different wheat-producing regions of northern China. Allelism tests indicated that PmPB74 was not allelic to PmPB3558 or Pm2. Our work showed that PmPB74 is a novel gene with broad resistance to powdery mildew, and hence will be helpful in broadening the genetic basis of powdery mildew resistance in wheat.

  20. Genetic complexity underlying hybrid male sterility in Drosophila.

    Science.gov (United States)

    Sawamura, Kyoichi; Roote, John; Wu, Chung-I; Yamamoto, Masa-Toshi

    2004-02-01

    Recent genetic analyses of closely related species of Drosophila have indicated that hybrid male sterility is the consequence of highly complex synergistic effects among multiple genes, both conspecific and heterospecific. On the contrary, much evidence suggests the presence of major genes causing hybrid female sterility and inviability in the less-related species, D. melanogaster and D. simulans. Does this contrast reflect the genetic distance between species? Or, generally, is the genetic basis of hybrid male sterility more complex than that of hybrid female sterility and inviability? To clarify this point, the D. simulans introgression of the cytological region 34D-36A to the D. melanogaster genome, which causes recessive male sterility, was dissected by recombination, deficiency, and complementation mapping. The 450-kb region between two genes, Suppressor of Hairless and snail, exhibited a strong effect on the sterility. Males are (semi-)sterile if this region of the introgression is made homozygous or hemizygous. But no genes in the region singly cause the sterility; this region has at least two genes, which in combination result in male sterility. Further, the males are less fertile when heterozygous with a larger introgression, which suggests that dominant modifiers enhance the effects of recessive genes of male sterility. Such an epistatic view, even in the less-related species, suggests that the genetic complexity is special to hybrid male sterility.

  1. Development and Identification of Introgression Lines from Cross of Oryza sativa and Oryza minuta

    Institute of Scientific and Technical Information of China (English)

    GUO Si-bin; WEI Yu; LI Xiao-qiong; LIU Kai-qiang; HUANG Feng-kuan; CHEN Cai-hong; GAO Guo-qing

    2013-01-01

    Introgression line population is effectively used in mapping quantitative trait loci (QTLs),identifying favorable genes,discovering hidden genetic variation,evaluating the action or interaction of QTLs in multiple conditions and providing the favorable experimental materials for plant breeding and genetic research.In this study,an advanced backcross and consecutive selfing strategy was used to develop introgression lines (ILs),which derived from an accession of Oryza minuta (accession No.101133) with BBCC genome,as the donor,and an elite indica cultivar IR24 (O.sativa),as the recipient.Introgression segments from O.minuta were screened using 164 polymorphic simple sequence repeat (SSR) markers in the genome of each IL.Introgressed segments carried by 131 ILs covered the whole O.sativa genome.The average number of homozygous O.minuta segments per introgression line was about 9.99.The average length of introgressed segments was approximate 14.78 cM,and about 79.64%of these segments had sizes less than 20 cM.In the genome of each introgression line,the O.minuta chromosomal segments harbored chromosomal fragments of O.sativa ranging from 1.15% to 27.6%,with an overall average of 8.57%.At each locus,the ratio of substitution of O.minuta alleles had a range of 1.5%-25.2%,with an average of 8.3% Based on the evaluation of the phenotype of these ILs,a wide range of alterations in morphological and yield-related traits were found.After inoculation,ILs 41,11 and 7 showed high resistance to bacterial blight,brown planthopper and whitebacked planthopper,respectively.These O.minuta-O.sativa ILs will serve as genetic materials for identifying and using favorable genes from O.minuta.

  2. Introgression from cultivated rice alters genetic structures of wild relative populations: implications for in situ conservation

    Science.gov (United States)

    Jin, Xin; Chen, Yu; Liu, Ping; Li, Chen; Cai, Xingxing; Rong, Jun

    2018-01-01

    Abstract Maintaining genetic integrity is essential for in situ and ex situ conservation of crop wild relative (CWR) species. However, introgression of crop alleles into CWR species/populations may change their genetic structure and diversity, resulting in more invasive weeds or, in contrast, the extinction of endangered populations. To determine crop-wild introgression and its consequences, we examined the genetic structure and diversity of six wild rice (Oryza rufipogon) populations under in situ conservation in China. Thirty-four simple sequence repeat (SSR) and 34 insertion/deletion markers were used to genotype the wild rice populations and two sets of rice cultivars (O. sativa), corresponding to the two types of molecular markers. Shared alleles and STRUCTURE analyses suggested a variable level of crop-wild introgression and admixture. Principal coordinates and cluster analyses indicated differentiation of wild rice populations, which was associated with the spatial distances to cultivated rice fields. The level of overall genetic diversity was comparable between wild rice populations and rice cultivars, but a great number of wild-specific alleles was detected in the wild populations. We conclude based on the results that crop-wild introgression can considerably alter the pattern of genetic structure and relationships of CWR populations. Appropriate measures should be taken for effective in situ conservation of CWR species under the scenario of crop-wild introgression. PMID:29308123

  3. Introgressing subgenome components from Brassica rapa and B. carinata to B. juncea for broadening its genetic base and exploring intersubgenomic heterosis

    Directory of Open Access Journals (Sweden)

    Zili Wei

    2016-11-01

    Full Text Available Brassica juncea (AjAjBjBj, is an allotetraploid that arose from two diploid species, B. rapa (ArAr and B. nigra (BnBn. It is an old oilseed crop with unique favorable traits, but the genetic improvement on this species is limited. We developed an approach to broaden its genetic base within several generations by intensive selection. The Ar subgenome from the Asian oil crop B. rapa (ArAr and the Bc subgenome from the African oil crop B. carinata (BcBcCcCc were combined in a synthesized allohexaploid (ArArBcBcCcCc, which was crossed with traditional B. juncea to generate pentaploid F1 hybrids (ArAjBcBjCc, with subsequent self-pollination to obtain newly synthesized B. juncea (Ar/jAr/jBc/jBc/j. After intensive cytological screening and phenotypic selection of fertility and agronomic traits, a population of new-type B. juncea was obtained and was found to be genetically stable at the F6 generation. The new-type B. juncea possesses good fertility and rich genetic diversity and is distinctly divergent but not isolated from traditional B. juncea, as revealed by population genetic analysis with molecular markers. More than half of its genome was modified, showing exotic introgression and novel variation. In addition to the improvement in some traits of the new-type B. juncea lines, a considerable potential for heterosis was observed in inter-subgenomic hybrids between new-type B. juncea lines and traditional B. juncea accessions. The new-type B. juncea exhibited a stable chromosome number and a novel genome composition through multiple generations, providing insight into how to significantly broaden the genetic base of crops with subgenome introgression from their related species and the potential of exploring inter-subgenomic heterosis for hybrid breeding.

  4. Localizing introgression on the chromosome of rice by genomic in ...

    African Journals Online (AJOL)

    USER

    2010-07-26

    Jul 26, 2010 ... ... preparation. Newly emerged roots (1 – 2 cm) from field grown F1 hybrid plants ... The slides were screened with fluorescence micro- ... Brar DS, Dalmacio R, Eloloran R, Aggarwal R, Angels R, Khush GS. (1996).

  5. A general method for identifying major hybrid male sterility genes in Drosophila.

    Science.gov (United States)

    Zeng, L W; Singh, R S

    1995-10-01

    The genes responsible for hybrid male sterility in species crosses are usually identified by introgressing chromosome segments, monitored by visible markers, between closely related species by continuous backcrosses. This commonly used method, however, suffers from two problems. First, it relies on the availability of markers to monitor the introgressed regions and so the portion of the genome examined is limited to the marked regions. Secondly, the introgressed regions are usually large and it is impossible to tell if the effects of the introgressed regions are the result of single (or few) major genes or many minor genes (polygenes). Here we introduce a simple and general method for identifying putative major hybrid male sterility genes which is free of these problems. In this method, the actual hybrid male sterility genes (rather than markers), or tightly linked gene complexes with large effects, are selectively introgressed from one species into the background of another species by repeated backcrosses. This is performed by selectively backcrossing heterozygous (for hybrid male sterility gene or genes) females producing fertile and sterile sons in roughly equal proportions to males of either parental species. As no marker gene is required for this procedure, this method can be used with any species pairs that produce unisexual sterility. With the application of this method, a small X chromosome region of Drosophila mauritiana which produces complete hybrid male sterility (aspermic testes) in the background of D. simulans was identified. Recombination analysis reveals that this region contains a second major hybrid male sterility gene linked to the forked locus located at either 62.7 +/- 0.66 map units or at the centromere region of the X chromosome of D. mauritiana.

  6. Existence of vigorous lineages of crop-wild hybrids in Lettuce under field conditions

    NARCIS (Netherlands)

    Hooftman, D.A.P.; Hartman, Y.; Oostermeijer, J.G.B.; den Nijs, J.C.M.

    2009-01-01

    Plant to plant gene flow is a route of environmental exposure for GM plants specifically since crosses with wild relatives could lead to the formation of more vigorous hybrids, which could increase the rate of introgression and the environmental impact. Here, we test the first step in the process of

  7. Molecular cytogenetic characterization of alien introgressions with gene Fhb3 for resistance to Fusarium head blight disease of wheat

    Science.gov (United States)

    Fusarium head blight (FHB) resistance was identified in the alien species Leymus racemosus, and wheat-Leymus introgression lines with FHB resistance were reported previously. Detailed molecular cytogenetic analysis of alien introgressions T01, T09, and T14 and the mapping of Fhb3, a new gene for FHB...

  8. Introgression from domestic goat generated variation at the major histocompatibility complex of Alpine ibex.

    Directory of Open Access Journals (Sweden)

    Christine Grossen

    2014-06-01

    Full Text Available The major histocompatibility complex (MHC is a crucial component of the vertebrate immune system and shows extremely high levels of genetic polymorphism. The extraordinary genetic variation is thought to be ancient polymorphisms maintained by balancing selection. However, introgression from related species was recently proposed as an additional mechanism. Here we provide evidence for introgression at the MHC in Alpine ibex (Capra ibex ibex. At a usually very polymorphic MHC exon involved in pathogen recognition (DRB exon 2, Alpine ibex carried only two alleles. We found that one of these DRB alleles is identical to a DRB allele of domestic goats (Capra aegagrus hircus. We sequenced 2489 bp of the coding and non-coding regions of the DRB gene and found that Alpine ibex homozygous for the goat-type DRB exon 2 allele showed nearly identical sequences (99.8% to a breed of domestic goats. Using Sanger and RAD sequencing, microsatellite and SNP chip data, we show that the chromosomal region containing the goat-type DRB allele has a signature of recent introgression in Alpine ibex. A region of approximately 750 kb including the DRB locus showed high rates of heterozygosity in individuals carrying one copy of the goat-type DRB allele. These individuals shared SNP alleles both with domestic goats and other Alpine ibex. In a survey of four Alpine ibex populations, we found that the region surrounding the DRB allele shows strong linkage disequilibria, strong sequence clustering and low diversity among haplotypes carrying the goat-type allele. Introgression at the MHC is likely adaptive and introgression critically increased MHC DRB diversity in the genetically impoverished Alpine ibex. Our finding contradicts the long-standing view that genetic variability at the MHC is solely a consequence of ancient trans-species polymorphism. Introgression is likely an underappreciated source of genetic diversity at the MHC and other loci under balancing selection.

  9. Introgression from Domestic Goat Generated Variation at the Major Histocompatibility Complex of Alpine Ibex

    Science.gov (United States)

    Grossen, Christine; Keller, Lukas; Biebach, Iris; Croll, Daniel

    2014-01-01

    The major histocompatibility complex (MHC) is a crucial component of the vertebrate immune system and shows extremely high levels of genetic polymorphism. The extraordinary genetic variation is thought to be ancient polymorphisms maintained by balancing selection. However, introgression from related species was recently proposed as an additional mechanism. Here we provide evidence for introgression at the MHC in Alpine ibex (Capra ibex ibex). At a usually very polymorphic MHC exon involved in pathogen recognition (DRB exon 2), Alpine ibex carried only two alleles. We found that one of these DRB alleles is identical to a DRB allele of domestic goats (Capra aegagrus hircus). We sequenced 2489 bp of the coding and non-coding regions of the DRB gene and found that Alpine ibex homozygous for the goat-type DRB exon 2 allele showed nearly identical sequences (99.8%) to a breed of domestic goats. Using Sanger and RAD sequencing, microsatellite and SNP chip data, we show that the chromosomal region containing the goat-type DRB allele has a signature of recent introgression in Alpine ibex. A region of approximately 750 kb including the DRB locus showed high rates of heterozygosity in individuals carrying one copy of the goat-type DRB allele. These individuals shared SNP alleles both with domestic goats and other Alpine ibex. In a survey of four Alpine ibex populations, we found that the region surrounding the DRB allele shows strong linkage disequilibria, strong sequence clustering and low diversity among haplotypes carrying the goat-type allele. Introgression at the MHC is likely adaptive and introgression critically increased MHC DRB diversity in the genetically impoverished Alpine ibex. Our finding contradicts the long-standing view that genetic variability at the MHC is solely a consequence of ancient trans-species polymorphism. Introgression is likely an underappreciated source of genetic diversity at the MHC and other loci under balancing selection. PMID:24945814

  10. Molecular data highlight hybridization in squirrel monkeys (Saimiri, Cebidae

    Directory of Open Access Journals (Sweden)

    Jeferson Carneiro

    Full Text Available Abstract Hybridization has been reported increasingly frequently in recent years, fueling the debate on its role in the evolutionary history of species. Some studies have shown that hybridization is very common in captive New World primates, and hybrid offspring have phenotypes and physiological responses distinct from those of the "pure" parents, due to gene introgression. Here we used the TA15 Alu insertion to investigate hybridization in the genus Saimiri. Our results indicate the hybridization of Saimiri boliviensis peruviensis with S. sciureus macrodon, and S. b. boliviensis with S. ustus. Unexpectedly, some hybrids of both S. boliviensis peruviensis and S. b. boliviensis were homozygous for the absence of the insertion, which indicates that the hybrids were fertile.

  11. Spatial sorting promotes the spread of maladaptive hybridization

    Science.gov (United States)

    Lowe, Winsor H.; Muhlfeld, Clint C.; Allendorf, Fred W.

    2015-01-01

    Invasive hybridization is causing loss of biodiversity worldwide. The spread of such introgression can occur even when hybrids have reduced Darwinian fitness, which decreases the frequency of hybrids due to low survival or reproduction through time. This paradox can be partially explained by spatial sorting, where genotypes associated with dispersal increase in frequency at the edge of expansion, fueling further expansion and allowing invasive hybrids to increase in frequency through space rather than time. Furthermore, because all progeny of a hybrid will be hybrids (i.e., will possess genes from both parental taxa), nonnative admixture in invaded populations can increase even when most hybrid progeny do not survive. Broader understanding of spatial sorting is needed to protect native biodiversity.

  12. A new hybrid two-zone/crucible furnace process for the growth of epitaxial Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8} superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Siegal, M.P.; Overmyer, D.L.; Venturini, E.L.; Dominguez, F.; Padilla, R.R. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States)

    1998-12-01

    Epitaxial Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8} (Tl-2212) films {approximately}5500 {Angstrom} thick are grown on LaAlO{sub 3}(100) substrates using a new hybrid two-zone/crucible furnace process enabling precise control of thallination. This method combines the best features of both conventional crucible and two-zone processing for the first time: superb film properties and reduced handling of hazardous Tl-oxide powders. Single-phase, highly {ital c}-axis oriented Tl-2212 films are grown with smooth morphology, Meissner transition {approximately}103 K, and critical current density {approximately}1.1{times}10{sup 7}A/cm{sup 2} at 5 K for twenty consecutive runs without having to change or add to the Tl-oxide source. {copyright} {ital 1998 Materials Research Society.}

  13. A new Neotibicen cicada subspecies (Hemiptera: Cicadidae) from the southeastern USA forms hybrid zones with a widespread relative despite a divergent male calling song.

    Science.gov (United States)

    Marshall, David C; Hill, Kathy B R

    2017-05-31

    A morphologically cryptic subspecies of Neotibicen similaris (Smith and Grossbeck) is described from forests of the Apalachicola region of the southeastern United States. Although the new form exhibits a highly distinctive male calling song, it hybridizes extensively where it meets populations of the nominate subspecies in parapatry, by which it is nearly surrounded. This is the first reported example of hybridization between North American nonperiodical cicadas. Acoustic and morphological characters are added to the original description of the nominate subspecies, and illustrations of complex hybrid song phenotypes are presented. The biogeography of N. similaris is discussed in light of historical changes in forest composition on the southeastern Coastal Plain.

  14. Characterizing haploinsufficiency of SHELL gene to improve fruit form prediction in introgressive hybrids of oil palm

    OpenAIRE

    Teh, Chee Keng; Muaz, Siti Dalila; Tangaya, Praveena; Fong, Po-Yee; Ong, Ai Ling; Mayes, Sean; Chew, Fook Tim; Kulaveerasingam, Harikrishna; Appleton, David Ross

    2017-01-01

    The fundamental trait in selective breeding of oil palm (Eleais guineensis Jacq.) is the shell thickness surrounding the kernel. The monogenic shell thickness is inversely correlated to mesocarp thickness, where the crude palm oil accumulates. Commercial thin-shelled tenera derived from thick-shelled dura???shell-less pisifera generally contain 30% higher oil per bunch. Two mutations, sh MPOB (M1) and sh AVROS (M2) in the SHELL gene ? a type II MADS-box transcription factor mainly present in ...

  15. Assessing rates and patterns of hybridization between wild boar and domestic pig in Europe

    DEFF Research Database (Denmark)

    Canu, Antonio; Iacolina, Laura; Apollonio, Marco

    genetic marker systems and the potentiality of newly developed markers across a range of European wild boar populations. Maternally inherited mitochondrial DNA alleles are by large shared between wild and domestic stocks, and the most reliable indicator of introgression is commonly considered the presence....... However, despite the availability of multiple molecular markers, with different inheritance systems and undergoing different selective pressures, the analysis on the extent and impact of introgressive hybridization in Europe remains challenging. Here we show the outcome of the application of different...

  16. When biogeographical provinces collide: Hybridization of reef fishes at the crossroads of marine biogeographical provinces in the Arabian Sea

    KAUST Repository

    DiBattista, Joseph

    2015-04-01

    Aim: Suture zones are areas where closely related species from different biogeographical regions come into contact and interbreed. This concept originated from the study of terrestrial ecosystems but it remains unclear whether a similar phenomenon occurs in the marine environment. Here we investigate a potential suture zone from a previously unknown hybrid hotspot at the Socotra Archipelago (Yemen), located in the Arabian Sea, where fauna from the Red Sea, Gulf of Aden, Arabian Sea, western Indian Ocean and greater Indo-Polynesian Province intersect. Location: Red Sea, Gulf of Aden, Arabian Sea and Indian Ocean. Methods: Putative hybrid reef fish were identified based on intermediate coloration and morphology. Underwater observations and collections were conducted to determine: (1) whether parent species form heterospecific social groups or breeding pairs; (2) the sex and reproductive status of morphologically intermediate individuals; and (3) whether parent species were forming mixed species associations owing to a dearth of conspecific partners. To support hybrid status, morphologically intermediate and parental individuals were genotyped using mitochondrial DNA cytochrome c oxidase subunit I (COI), nuclear recombination-activating gene 2 (RAG2) and the nuclear TMO-4C4 (TMO) gene. Results: We observed putative hybrids involving 14 species from four reef fish families at Socotra. Most cases involved a parental species with a restricted distribution (e.g. Red Sea or Arabian Sea) and a broadly distributed Indo-Pacific species. In most cases, at least one of the parent species was rare at Socotra. Hybrid gene flow was largely unidirectional, and although introgression was rare, we found evidence that some butterflyfish and surgeonfish hybrids were fertile and formed breeding groups with parental species. Main conclusions: The rate of hybrid discovery at Socotra is much greater than that recorded elsewhere in the marine environment and involved both allopatric and

  17. Genetics of hybrid male sterility between drosophila sibling species: a complex web of epistasis is revealed in interspecific studies.

    Science.gov (United States)

    Palopoli, M F; Wu, C I

    1994-10-01

    To study the genetic differences responsible for the sterility of their male hybrids, we introgressed small segments of an X chromosome from Drosophila simulans into a pure Drosophila mauritiana genetic background, then assessed the fertility of males carrying heterospecific introgressions of varying size. Although this analysis examined less than 20% of the X chromosome (roughly 5% of the euchromatic portion of the D. simulans genome), and the segments were introgressed in only one direction, a minimum of four factors that contribute to hybrid male sterility were revealed. At least two of the factors exhibited strong epistasis: males carrying either factor alone were consistently fertile, whereas males carrying both factors together were always sterile. Distinct spermatogenic phenotypes were observed for sterile introgressions of different lengths, and it appeared that an interaction between introgressed segments also influenced the stage of spermatogenic defect. Males with one category of introgression often produced large quantities of motile sperm and were observed copulating, but never inseminated females. Evidently these two species have diverged at a large number of loci which have varied effects on hybrid male fertility. By extrapolation, we estimate that there are at least 40 such loci on the X chromosome alone. Because these species exhibit little DNA-sequence divergence at arbitrarily chosen loci, it seems unlikely that the extensive functional divergence observed could be due mainly to random genetic drift. Significant epistasis between conspecific genes appears to be a common component of hybrid sterility between recently diverged species of Drosophila. The linkage relationships of interacting factors could shed light on the role played by epistatic selection in the dynamics of the allele substitutions responsible for reproductive barriers between species.

  18. Yield QTL analysis of Oryza sativa x O. glumaepatula introgression lines

    Directory of Open Access Journals (Sweden)

    Priscila Nascimento Rangel

    2013-03-01

    Full Text Available The objective of this work was to evaluate the yield performance of two generations (BC2F2 and BC2F9 of introgression lines developed from the interspecific cross between Oryza sativa and O. glumaepatula, and to identify the SSR markers associated to yield. The wild accession RS‑16 (O. glumaepatula was used as donor parent in the backcross with the high yielding cultivar Cica‑8 (O. sativa. A set of 114 BC2F1 introgression lines was genotyped with 141 polymorphic SSR loci distributed across the whole rice genome. Molecular analysis showed that in average 22% of the O. glumaepatula genome was introgressed into BC2F1 generation. Nine BC2F9 introgression lines had a significantly higher yield than the genitor Cica‑8, thus showing a positive genome interaction among cultivated rice and the wild O. glumaepatula. Seven QTL were identified in the overall BC2F2, with one marker interval (4879‑EST20 of great effect on yield. The alleles with positive effect on yield came from the cultivated parent Cica‑8.

  19. The elusive nature of adaptive mitochondrial DNA evolution of an Arctic lineage prone to frequent introgression

    DEFF Research Database (Denmark)

    Melo-Ferreira, Jose; Vilela, Joana; Fonseca, Miguel M.

    2014-01-01

    understood. Hares (Lepus spp.) are privileged models to study the impact of natural selection on mitogenomic evolution because 1) species are adapted to contrasting environments, including arctic, with different metabolic pressures, and 2) mtDNA introgression from arctic into temperate species is widespread...

  20. Introgression of a leaf rust resistance gene from Aegilops caudata to ...

    Indian Academy of Sciences (India)

    tance genes (Lr) and 48 stripe rust resistance genes (Yr) have .... Leaf rust reaction of the parents, wheat – Ae. caudata introgression lines and representative F2 plants developed from the cross: .... segregation ratio, which is otherwise a serious problem with ... Financial assistance was provided by the USDA-ARS under the.

  1. Chromosome engineering for alien gene introgression in wheat: Progress and prospective

    Science.gov (United States)

    Chromosome engineering is a useful strategy for introgression of desirable genes from wild relatives into cultivated wheat. However, it has been a challenge to transfer a small amount of alien chromatin containing the gene of interest from one genome to another non-homologous genome through classic...

  2. Observations préliminaires sur la répartition et les fluctuations de l'ichtyomasse exploitable dans les différentes zones écologiques du lac Ihema (bassin moyen de l'Akagera, Rwanda

    Directory of Open Access Journals (Sweden)

    Mughanda, M.

    1988-01-01

    Full Text Available Preliminary considerations on distribution and changes in fishable ichtyomass in the ecological areas of lake Ihema (Akagera middle, Foodplain, Rwanda. Since 1981, commercial fishing is accomplished in lake Ihema with gillnets of 50 mm meshes and a mean of 175 tons of fish was caught per year during the first three years. Simultaneously, experimental fishing was introduced since 1982, for which ten gillnets of different meshes are used. Fishes of the two general Tilapia and Clarias are captured in commercial fishing, but in experimental one, about ten taxons of fish are caught. For this paper, we examined statistics obtained from experimental catches during 1982 and 1983. Apart from Tilapia and Clarias, small Cichlidae of Haplochromis group, two species of Mormyridae and Synodontis spp represent a potential which may be exploited with other kinds of gear. Concerning productiveness of fishing areas in lake Ihema, littoral zones (= inshore are more rich than pelagic (= offshore ones and the northern sector in which Akagera river enters the lake is the most productive. Species of fish are differently represented in ecological zones, following the kind of their food (planctonophagous, detritivorous or carnivorous and the places they can reproduce. Catches fluctuate monthly and annually probably because of natural changes in fish stock according to fluctuations of climatic conditions, but also because of increasing intensity of commercial fishing. For Tilapia, reduction in the quantity captured may also be due to introgressive hybridization and competition between T. macrochir, T. nilotica and their hybrids.

  3. Species-specific SSR alleles for studies of hybrid cattails (Typha latifolia × T. angustifolia; Typhaceae) in North America

    Czech Academy of Sciences Publication Activity Database

    Snow, A. A.; Travis, S. E.; Wildová, Radka; Fér, T.; Sweeney, P. M.; Marburger, J. E.; Windels, S.; Kubátová, B.; Goldberg, D. E.; Mutegi, E.

    2010-01-01

    Roč. 97, č. 12 (2010), s. 2061-2067 ISSN 0002-9122 Institutional research plan: CEZ:AV0Z60050516 Keywords : gene flow * hybrid * introgression * invasive species * molecular markers Subject RIV: EF - Botanics Impact factor: 3.052, year: 2010

  4. Ecological differentiation, lack of hybrids involving diploids, and asymmetric gene flow between polyploids in narrow contact zones of Senecio carniolicus (syn. Jacobaea carniolica, Asteraceae)

    Czech Academy of Sciences Publication Activity Database

    Hülber, K.; Sonnleitner, M.; Suda, Jan; Krejčíková, J.; Schönswetter, P.; Schneeweiss, G. M.; Winkler, M.

    2015-01-01

    Roč. 5, č. 6 (2015), s. 1224-1234 ISSN 2045-7758 R&D Projects: GA ČR GB14-36079G Institutional support: RVO:67985939 Keywords : gene flow * hybridization * polyploidy Subject RIV: EF - Botanics Impact factor: 2.537, year: 2015

  5. Genome-wide architecture of reproductive isolation in a naturally occurring hybrid zone between Mus musculus musculus and M. m. domesticus

    Czech Academy of Sciences Publication Activity Database

    Janoušek, V.; Wang, L.; Luzynski, K.; Dufková, Petra; Mrkvicová Vyskočilová, Martina; Nachman, M. W.; Munclinger, P.; Macholán, Miloš; Piálek, Jaroslav; Tucker, P. K.

    2012-01-01

    Roč. 21, č. 12 (2012), s. 3032-3047 ISSN 0962-1083 R&D Projects: GA ČR GA206/08/0640 Institutional support: RVO:68081766 ; RVO:67985904 Keywords : genomics * proteomics * hybridization * mammals * speciation Subject RIV: EG - Zoology Impact factor: 6.275, year: 2012

  6. Adaptive consequences of human-mediated introgression for indigenous tree species: the case of a relict Pinus pinaster population.

    Science.gov (United States)

    Ramírez-Valiente, José Alberto; Robledo-Arnuncio, Juan José

    2014-12-01

    , a potential early selective advantage of exotic and hybrid genotypes would enhance initial steps of introgression of non-native genes into the study relict population of P. pinaster. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Assessment of stability and plasticity of new hybrids of maize (Zea mays L. under the conditions of Polissia and Steppe zones of Ukraine

    Directory of Open Access Journals (Sweden)

    Л. М. Присяжнюк

    2016-05-01

    Full Text Available Purpose. To select promising high productive maize hyb­rids of middle-early maturity group in terms of stability and plasticity of main economic characters. Methods. Field study, laboratory test, analytical procedure and statistical evaluation. Results. 14 maize hybrids recorded in the State Register of Plant Varieties Suitable for Dissemination in Ukraine in 2015 were studied for plasticity and stability of such traits as productivity, protein and starch content. Intensive highly-plastic hybrid ‘SI Tiptop’ was selected among the studied ones for productivity trait that can respond properly to changes of growing conditions. It was defined that for the starch content such hybrids as ‘SI Tiptop’, ‘SI Enigma’, ‘SI Arioso’, ‘Svich 38’, ‘Svich 35’, ‘HU 8653’, ‘Zdobutok’ and ‘SI Contrakt’ belonged to the intensive type and combined rather high values and the stability of the studied trait under variable conditions. The following hybrids as ‘NS 2642’, ‘DK S3016’, ‘Svich 38’, ‘NS 2632’ were qualified as intensive for protein content and appeared to be highly-plastic but stability values of this trait were low. ‘Svich 38’ hybrid was intensive simultaneously for two traits such as protein and starch content and showed rather high values of plasticity. ‘SI Tiptop’, ‘SI Enigma’ and ‘Svich 35’ were defined as hybrids of extensive type that provided stable protein content in adverse cultivation conditions. Conclusions. On the condition that intensive crop growing technologies should be used, for obtaining stable yields it is advisable to sow only highly-plastic hybrids that can adapt to unfavorable environmental factors, including ‘SI Tiptop’ – for productivity trait, ‘Zdobutok’ and ‘SI Kontrakt’ – for starch content, ‘MAC 24N‘, ‘NA 2642‘ and ‘Danubio’ – for protein content.

  8. Hybridization rates between lettuce (Lactuca sativa) and its wild relative (L. serriola) under field conditions

    OpenAIRE

    D'Andrea, Luigi; Felber, François; Guadagnuolo, Roberto

    2008-01-01

    Hybridization and introgression between crops and wild relatives may have important evolutionary and ecological consequences such as gene swamping or increased invasiveness. In the present study, we investigated hybridization under field conditions between crop lettuce (Lactuca sativa) and its wild relative prickly lettuce (L. serriola), two cross-compatible, predominantly autogamous and insect pollinated species. In 2003 and 2004, we estimated the rates of hybridization between L. sativa and...

  9. Natural hybridization and reproductive isolation between two Primula speciesFA

    Institute of Scientific and Technical Information of China (English)

    Yanping Xie; Xingfu Zhu; Yongpeng Ma; Jianli Zhao; Li Li; Qingjun Li

    2017-01-01

    Natural hybridization frequently occurs in plants and can facilitate gene flow between species,possibly resulting in species refusion.However,various reproductive barriers block the formation of hybrids and maintain species integrity.Here,we conducted a field survey to examine natural hybridization and reproductive isolation (RI) between sympatric populations of Primula secundiflora and P.poissonii using ten nuclear simple sequence repeat (SSR) loci.Although introgressive hybridization occurred,species boundaries between P.secundiflora and P.poissonii were maintained through nearly complete reproductive isolation.These interfertile species provide an excellent model for studying the RI mechanisms and evolutionary forces that maintain species boundaries.

  10. Metazoan parasite communities: support for the biological invasion of Barbus barbus and its hybridization with the endemic Barbus meridionalis

    Directory of Open Access Journals (Sweden)

    L. Gettová

    2016-11-01

    Full Text Available Abstract Background Recently, human intervention enabled the introduction of Barbus barbus from the Rhône River basin into the Barbus meridionalis habitats of the Argens River. After an introduction event, parasite loss and lower infection can be expected in non-native hosts in contrast to native species. Still, native species might be endangered by hybridization with the incomer and the introduction of novel parasite species. In our study, we aimed to examine metazoan parasite communities in Barbus spp. populations in France, with a special emphasis on the potential threat posed by the introduction of novel parasite species by invasive B. barbus to local B. meridionalis. Methods Metazoan parasite communities were examined in B. barbus, B. meridionalis and their hybrids in three river basins in France. Microsatellites were used for the species identification of individual fish. Parasite abundance, prevalence, and species richness were compared. Effects of different factors on parasite infection levels and species richness were tested using GLM. Results Metazoan parasites followed the expansion range of B. barbus and confirmed its introduction into the Argens River. Here, the significantly lower parasite number and lower levels of infection found in B. barbus in contrast to B. barbus from the Rhône River supports the enemy release hypothesis. Barbus barbus × B. meridionalis hybridization in the Argens River basin was confirmed using both microsatellites and metazoan parasites, as hybrids were infected by parasites of both parental taxa. Trend towards higher parasite diversity in hybrids when compared to parental taxa, and similarity between parasite communities from the Barbus hybrid zone suggest that hybrids might represent “bridges” for parasite infection between B. barbus and B. meridionalis. Risk of parasite transmission from less parasitized B. barbus to more parasitized B. meridionalis indicated from our study in the Argens River

  11. Growth, morphology, and developmental instability of rainbow trout, Yellowstone cutthroat trout, and four hybrid generations

    Science.gov (United States)

    Ostberg, C.O.; Duda, J.J.; Graham, J.H.; Zhang, S.; Haywood, K. P.; Miller, B.; Lerud, T.L.

    2011-01-01

    Hybridization of cutthroat trout Oncorhynchus clarkii with nonindigenous rainbow trout O. mykiss contributes to the decline of cutthroat trout subspecies throughout their native range. Introgression by rainbow trout can swamp the gene pools of cutthroat trout populations, especially if there is little selection against hybrids. We used rainbow trout, Yellowstone cutthroat trout O. clarkii bouvieri, and rainbow trout × Yellowstone cutthroat trout F1 hybrids as parents to construct seven different line crosses: F1 hybrids (both reciprocal crosses), F2 hybrids, first-generation backcrosses (both rainbow trout and Yellowstone cutthroat trout), and both parental taxa. We compared growth, morphology, and developmental instability among these seven crosses reared at two different temperatures. Growth was related to the proportion of rainbow trout genome present within the crosses. Meristic traits were influenced by maternal, additive, dominant, overdominant, and (probably) epistatic genetic effects. Developmental stability, however, was not disturbed in F1 hybrids, F2 hybrids, or backcrosses. Backcrosses were morphologically similar to their recurrent parent. The lack of developmental instability in hybrids suggests that there are few genetic incompatibilities preventing introgression. Our findings suggest that hybrids are not equal: that is, growth, development, character traits, and morphology differ depending on the genomic contribution from each parental species as well as the hybrid generation.

  12. Genetic Evidence of Hybridization between the Endangered Native Species Iguana delicatissima and the Invasive Iguana iguana (Reptilia, Iguanidae) in the Lesser Antilles: Management Implications.

    Science.gov (United States)

    Vuillaume, Barbara; Valette, Victorien; Lepais, Olivier; Grandjean, Frédéric; Breuil, Michel

    2015-01-01

    The worldwide increase of hybridization in different groups is thought to have become more important with the loss of isolating barriers and the introduction of invasive species. This phenomenon could result in the extinction of endemic species. This study aims at investigating the hybridization dynamics between the endemic and threatened Lesser Antillean iguana (Iguana delicatissima) and the invasive common green iguana (Iguana iguana) in the Lesser Antilles, as well as assessing the impact of interspecific hybridization on the decline of I. delicatissima. 59 I. delicatissima (5 localities), 47 I. iguana (12 localities) and 27 hybrids (5 localities), who were all identified based on morphological characters, have been genotyped at 15 microsatellites markers. We also sequenced hybrids using ND4 mitochondrial loci to further investigate mitochondrial introgression. The genetic clustering of species and hybrid genetic assignment were performed using a comparative approach, through the implementation of a Discriminant Analysis of Principal Component (DAPC) based on statistics, as well as genetic clustering approaches based on the genetic models of several populations (Structure, NewHybrids and HIest), in order to get full characterization of hybridization patterns and introgression dynamics across the islands. The iguanas identified as hybrids in the wild, thanks to morphological analysis, were all genetically F1, F2, or backcrosses. A high proportion of individuals were also the result of a longer-term admixture. The absence of reproductive barriers between species leads to hybridization when species are in contact. Yet morphological and behavioral differences between species could explain why males I. iguana may dominate I. delicatissima, thus resulting in short-term species displacement and extinction by hybridization and recurrent introgression from I. iguana toward I. delicatissima. As a consequence, I. delicatissima gets eliminated through introgression, as

  13. Genetic Evidence of Hybridization between the Endangered Native Species Iguana delicatissima and the Invasive Iguana iguana (Reptilia, Iguanidae) in the Lesser Antilles: Management Implications

    Science.gov (United States)

    Vuillaume, Barbara; Valette, Victorien; Lepais, Olivier; Grandjean, Frédéric; Breuil, Michel

    2015-01-01

    The worldwide increase of hybridization in different groups is thought to have become more important with the loss of isolating barriers and the introduction of invasive species. This phenomenon could result in the extinction of endemic species. This study aims at investigating the hybridization dynamics between the endemic and threatened Lesser Antillean iguana (Iguana delicatissima) and the invasive common green iguana (Iguana iguana) in the Lesser Antilles, as well as assessing the impact of interspecific hybridization on the decline of I. delicatissima. 59 I. delicatissima (5 localities), 47 I. iguana (12 localities) and 27 hybrids (5 localities), who were all identified based on morphological characters, have been genotyped at 15 microsatellites markers. We also sequenced hybrids using ND4 mitochondrial loci to further investigate mitochondrial introgression. The genetic clustering of species and hybrid genetic assignment were performed using a comparative approach, through the implementation of a Discriminant Analysis of Principal Component (DAPC) based on statistics, as well as genetic clustering approaches based on the genetic models of several populations (Structure, NewHybrids and HIest), in order to get full characterization of hybridization patterns and introgression dynamics across the islands. The iguanas identified as hybrids in the wild, thanks to morphological analysis, were all genetically F1, F2, or backcrosses. A high proportion of individuals were also the result of a longer-term admixture. The absence of reproductive barriers between species leads to hybridization when species are in contact. Yet morphological and behavioral differences between species could explain why males I. iguana may dominate I. delicatissima, thus resulting in short-term species displacement and extinction by hybridization and recurrent introgression from I. iguana toward I. delicatissima. As a consequence, I. delicatissima gets eliminated through introgression, as

  14. Genetic Evidence of Hybridization between the Endangered Native Species Iguana delicatissima and the Invasive Iguana iguana (Reptilia, Iguanidae in the Lesser Antilles: Management Implications.

    Directory of Open Access Journals (Sweden)

    Barbara Vuillaume

    Full Text Available The worldwide increase of hybridization in different groups is thought to have become more important with the loss of isolating barriers and the introduction of invasive species. This phenomenon could result in the extinction of endemic species. This study aims at investigating the hybridization dynamics between the endemic and threatened Lesser Antillean iguana (Iguana delicatissima and the invasive common green iguana (Iguana iguana in the Lesser Antilles, as well as assessing the impact of interspecific hybridization on the decline of I. delicatissima. 59 I. delicatissima (5 localities, 47 I. iguana (12 localities and 27 hybrids (5 localities, who were all identified based on morphological characters, have been genotyped at 15 microsatellites markers. We also sequenced hybrids using ND4 mitochondrial loci to further investigate mitochondrial introgression. The genetic clustering of species and hybrid genetic assignment were performed using a comparative approach, through the implementation of a Discriminant Analysis of Principal Component (DAPC based on statistics, as well as genetic clustering approaches based on the genetic models of several populations (Structure, NewHybrids and HIest, in order to get full characterization of hybridization patterns and introgression dynamics across the islands. The iguanas identified as hybrids in the wild, thanks to morphological analysis, were all genetically F1, F2, or backcrosses. A high proportion of individuals were also the result of a longer-term admixture. The absence of reproductive barriers between species leads to hybridization when species are in contact. Yet morphological and behavioral differences between species could explain why males I. iguana may dominate I. delicatissima, thus resulting in short-term species displacement and extinction by hybridization and recurrent introgression from I. iguana toward I. delicatissima. As a consequence, I. delicatissima gets eliminated through

  15. Development of a genetic sexing strain in Bactrocera carambolae (Diptera: Tephritidae) by introgression of sex sorting components from B. dorsalis, Salaya1 strain.

    Science.gov (United States)

    Isasawin, Siriwan; Aketarawong, Nidchaya; Lertsiri, Sittiwat; Thanaphum, Sujinda

    2014-01-01

    The carambola fruit fly, Bactrocera carambolae Drew & Hancock is a high profile key pest that is widely distributed in the southwestern ASEAN region. In addition, it has trans-continentally invaded Suriname, where it has been expanding east and southward since 1975. This fruit fly belongs to Bactrocera dorsalis species complex. The development and application of a genetic sexing strain (Salaya1) of B. dorsalis sensu stricto (s.s.) (Hendel) for the sterile insect technique (SIT) has improved the fruit fly control. However, matings between B. dorsalis s.s. and B. carambolae are incompatible, which hinder the application of the Salaya1 strain to control the carambola fruit fly. To solve this problem, we introduced genetic sexing components from the Salaya1 strain into the B. carambolae genome by interspecific hybridization. Morphological characteristics, mating competitiveness, male pheromone profiles, and genetic relationships revealed consistencies that helped to distinguish Salaya1 and B. carambolae strains. A Y-autosome translocation linking the dominant wild-type allele of white pupae gene and a free autosome carrying a recessive white pupae homologue from the Salaya1 strain were introgressed into the gene pool of B. carambolae. A panel of Y-pseudo-linked microsatellite loci of the Salaya1 strain served as markers for the introgression experiments. This resulted in a newly derived genetic sexing strain called Salaya5, with morphological characteristics corresponding to B. carambolae. The rectal gland pheromone profile of Salaya5 males also contained a distinctive component of B. carambolae. Microsatellite DNA analyses confirmed the close genetic relationships between the Salaya5 strain and wild B. carambolae populations. Further experiments showed that the sterile males of Salaya5 can compete with wild males for mating with wild females in field cage conditions. Introgression of sex sorting components from the Salaya1 strain to a closely related B. carambolae

  16. Detecting genetic introgression: high levels of intersubspecific recombination found in Xylella fastidiosa in Brazil.

    Science.gov (United States)

    Nunney, Leonard; Yuan, Xiaoli; Bromley, Robin E; Stouthamer, Richard

    2012-07-01

    Documenting the role of novel mutation versus homologous recombination in bacterial evolution, and especially in the invasion of new hosts, is central to understanding the long-term dynamics of pathogenic bacteria. We used multilocus sequence typing (MLST) to study this issue in Xylella fastidiosa subsp. pauca from Brazil, a bacterium causing citrus variegated chlorosis (CVC) and coffee leaf scorch (CLS). All 55 citrus isolates typed (plus one coffee isolate) defined three similar sequence types (STs) dominated by ST11 (85%), while the remaining 22 coffee isolates defined two STs, mainly ST16 (74%). This low level of variation masked unusually large allelic differences (>1% divergence with no intermediates) at five loci (leuA, petC, malF, cysG, and holC). We developed an introgression test to detect whether these large differences were due to introgression via homologous recombination from another X. fastidiosa subspecies. Using additional sequencing around these loci, we established that the seven randomly chosen MLST targets contained seven regions of introgression totaling 2,172 bp of 4,161 bp (52%), only 409 bp (10%) of which were detected by other recombination tests. This high level of introgression suggests the hypothesis that X. fastidiosa subsp. pauca became pathogenic on citrus and coffee (crops cultivated in Brazil for several hundred years) only recently after it gained genetic variation via intersubspecific recombination, facilitating a switch from native hosts. A candidate donor is the subspecies infecting plum in the region since 1935 (possibly X. fastidiosa subsp. multiplex). This hypothesis predicts that nonrecombinant native X. fastidiosa subsp. pauca (not yet isolated) does not cause disease in citrus or coffee.

  17. Evolutionary analyses of non-genealogical bonds produced by introgressive descent.

    Science.gov (United States)

    Bapteste, Eric; Lopez, Philippe; Bouchard, Frédéric; Baquero, Fernando; McInerney, James O; Burian, Richard M

    2012-11-06

    All evolutionary biologists are familiar with evolutionary units that evolve by vertical descent in a tree-like fashion in single lineages. However, many other kinds of processes contribute to evolutionary diversity. In vertical descent, the genetic material of a particular evolutionary unit is propagated by replication inside its own lineage. In what we call introgressive descent, the genetic material of a particular evolutionary unit propagates into different host structures and is replicated within these host structures. Thus, introgressive descent generates a variety of evolutionary units and leaves recognizable patterns in resemblance networks. We characterize six kinds of evolutionary units, of which five involve mosaic lineages generated by introgressive descent. To facilitate detection of these units in resemblance networks, we introduce terminology based on two notions, P3s (subgraphs of three nodes: A, B, and C) and mosaic P3s, and suggest an apparatus for systematic detection of introgressive descent. Mosaic P3s correspond to a distinct type of evolutionary bond that is orthogonal to the bonds of kinship and genealogy usually examined by evolutionary biologists. We argue that recognition of these evolutionary bonds stimulates radical rethinking of key questions in evolutionary biology (e.g., the relations among evolutionary players in very early phases of evolutionary history, the origin and emergence of novelties, and the production of new lineages). This line of research will expand the study of biological complexity beyond the usual genealogical bonds, revealing additional sources of biodiversity. It provides an important step to a more realistic pluralist treatment of evolutionary complexity.

  18. High-throughput phenotyping to detect drought tolerance QTL in wild barley introgression lines.

    Directory of Open Access Journals (Sweden)

    Nora Honsdorf

    Full Text Available Drought is one of the most severe stresses, endangering crop yields worldwide. In order to select drought tolerant genotypes, access to exotic germplasm and efficient phenotyping protocols are needed. In this study the high-throughput phenotyping platform "The Plant Accelerator", Adelaide, Australia, was used to screen a set of 47 juvenile (six week old wild barley introgression lines (S42ILs for drought stress responses. The kinetics of growth development was evaluated under early drought stress and well watered treatments. High correlation (r=0.98 between image based biomass estimates and actual biomass was demonstrated, and the suitability of the system to accurately and non-destructively estimate biomass was validated. Subsequently, quantitative trait loci (QTL were located, which contributed to the genetic control of growth under drought stress. In total, 44 QTL for eleven out of 14 investigated traits were mapped, which for example controlled growth rate and water use efficiency. The correspondence of those QTL with QTL previously identified in field trials is shown. For instance, six out of eight QTL controlling plant height were also found in previous field and glasshouse studies with the same introgression lines. This indicates that phenotyping juvenile plants may assist in predicting adult plant performance. In addition, favorable wild barley alleles for growth and biomass parameters were detected, for instance, a QTL that increased biomass by approximately 36%. In particular, introgression line S42IL-121 revealed improved growth under drought stress compared to the control Scarlett. The introgression line showed a similar behavior in previous field experiments, indicating that S42IL-121 may be an attractive donor for breeding of drought tolerant barley cultivars.

  19. High-throughput phenotyping to detect drought tolerance QTL in wild barley introgression lines

    KAUST Repository

    Honsdorf, Nora

    2014-05-13

    Drought is one of the most severe stresses, endangering crop yields worldwide. In order to select drought tolerant genotypes, access to exotic germplasm and efficient phenotyping protocols are needed. In this study the high-throughput phenotyping platform "The Plant Accelerator", Adelaide, Australia, was used to screen a set of 47 juvenile (six week old) wild barley introgression lines (S42ILs) for drought stress responses. The kinetics of growth development was evaluated under early drought stress and well watered treatments. High correlation (r = 0.98) between image based biomass estimates and actual biomass was demonstrated, and the suitability of the system to accurately and non-destructively estimate biomass was validated. Subsequently, quantitative trait loci (QTL) were located, which contributed to the genetic control of growth under drought stress. In total, 44 QTL for eleven out of 14 investigated traits were mapped, which for example controlled growth rate and water use efficiency. The correspondence of those QTL with QTL previously identified in field trials is shown. For instance, six out of eight QTL controlling plant height were also found in previous field and glasshouse studies with the same introgression lines. This indicates that phenotyping juvenile plants may assist in predicting adult plant performance. In addition, favorable wild barley alleles for growth and biomass parameters were detected, for instance, a QTL that increased biomass by approximately 36%. In particular, introgression line S42IL-121 revealed improved growth under drought stress compared to the control Scarlett. The introgression line showed a similar behavior in previous field experiments, indicating that S42IL-121 may be an attractive donor for breeding of drought tolerant barley cultivars. © 2014 Honsdorf et al.

  20. Detection of alien genetic introgressions in bread wheat using dot-blot genomic hybridisation.

    Science.gov (United States)

    Rey, María-Dolores; Prieto, Pilar

    2017-01-01

    Simple, reliable methods for the identification of alien genetic introgressions are required in plant breeding programmes. The use of genomic dot-blot hybridisation allows the detection of small Hordeum chilense genomic introgressions in the descendants of genetic crosses between wheat and H. chilense addition or substitution lines in wheat when molecular markers are difficult to use. Based on genomic in situ hybridisation, DNA samples from wheat lines carrying putatively H. chilense introgressions were immobilised on a membrane, blocked with wheat genomic DNA and hybridised with biotin-labelled H. chilense genomic DNA as a probe. This dot-blot screening reduced the number of plants necessary to be analysed by molecular markers or in situ hybridisation, saving time and money. The technique was sensitive enough to detect a minimum of 5 ng of total genomic DNA immobilised on the membrane or about 1/420 dilution of H. chilense genomic DNA in the wheat background. The robustness of the technique was verified by in situ hybridisation. In addition, the detection of other wheat relative species such as Hordeum vulgare , Secale cereale and Agropyron cristatum in the wheat background was also reported .

  1. The myth of natural barriers. Is transgene introgression by genetically modified crops an environmental risk?

    Science.gov (United States)

    Guarnieri, Vincenzo; Benessia, Alice; Camino, Elena; Barbiero, Giuseppe

    2008-01-01

    Genetically modified (GM) crops under open field conditions are a complex and controversial issue. Ecologists are discussing about the possibility that a transgene belonging to GM plants could spread to native populations through a process known as introgression the stable incorporation of a gene in the host genome able to generate a differentiated population. The ecological consequences of a transgene introgression in plants or bacteria are not yet well understood, but could be significant. In this critical review we consider vertical and horizontal introgression. We analyse the biochemical and genetic constraints, and environmental factors that limit the possibility of transgene spread; meanwhile we show cases in which the natural barriers are overcome. Then we discuss the overall management of GM crops, noting the shortcomings and approximations of risk assessment based on linear thinking typical of the biomolecular approach. Finally we suggest to explicitly weight facts together with values and we encourage the undertaking of an ecological perspective, encompassing the complexity of (non-linear) relations between organisms and the environment.

  2. Genetic introgression of ethylene-suppressed transgenic tomatoes with higher-polyamines trait overcomes many unintended effects due to reduced ethylene on the primary metabolome

    Directory of Open Access Journals (Sweden)

    Anatoly P Sobolev

    2014-12-01

    Full Text Available Ethylene regulates a myriad physiological and biochemical processes in ripening fruits and is accepted as the ripening hormone for the climacteric fruits. However, its effects on metabolome and resulting fruit quality are not yet fully understood, particularly when some of the ripening-associated biochemical changes are independent of ethylene action. We have generated a homozygous transgenic tomato genotype (2AS-AS that exhibits reduced ethylene production as a result of impaired expression of 1-aminocyclopropane-1-carboxylate synthase 2 gene by its antisense RNA and had a longer shelf life. Double transgenic hybrid (2AS-AS x 579HO developed through a genetic cross between 2AS-AS and 579HO (Mehta et al., 2002 lines resulted in significantly higher ethylene production than either the WT or 2AS-AS fruit. To determine the effects of reduced ethylene and introgression of higher polyamines’ trait, the metabolic profiles of ripening fruits from WT (556AZ, 2AS-AS, and 2AS-AS x 579HO lines were determined using 1H-NMR spectroscopy. The levels of Glu, Asp, AMP, Adenosine, Nucl1 and Nucl2 increased during ripening of the WT fruit. The increases in Glu, Asp, and AMP levels were attenuated in 2AS-AS fruit but recovered in the double hybrid with higher ethylene and polyamine levels. The ripening-associated decreases in Ala, Tyr, Val, Ile, Phe, malate and myo-inositol levels in the 2AS-AS line were not reversed in the double hybrid line suggesting a developmental/ripening regulated accumulation of these metabolites independent of ethylene. Significant increases in the levels of fumarate, formate, choline, Nucl1 and Nucl2 at most stages of ripening fruit were found in the double transgenic line due to introgression with higher-polyamines trait. Taken together these results show that the ripening-associated metabolic changes are both ethylene dependent and independent, and that the fruit metabolome is under the control of multiple regulators, including

  3. Genome patterns of selection and introgression of haplotypes in natural populations of the house mouse (Mus musculus.

    Directory of Open Access Journals (Sweden)

    Fabian Staubach

    Full Text Available General parameters of selection, such as the frequency and strength of positive selection in natural populations or the role of introgression, are still insufficiently understood. The house mouse (Mus musculus is a particularly well-suited model system to approach such questions, since it has a defined history of splits into subspecies and populations and since extensive genome information is available. We have used high-density single-nucleotide polymorphism (SNP typing arrays to assess genomic patterns of positive selection and introgression of alleles in two natural populations of each of the subspecies M. m. domesticus and M. m. musculus. Applying different statistical procedures, we find a large number of regions subject to apparent selective sweeps, indicating frequent positive selection on rare alleles or novel mutations. Genes in the regions include well-studied imprinted loci (e.g. Plagl1/Zac1, homologues of human genes involved in adaptations (e.g. alpha-amylase genes or in genetic diseases (e.g. Huntingtin and Parkin. Haplotype matching between the two subspecies reveals a large number of haplotypes that show patterns of introgression from specific populations of the respective other subspecies, with at least 10% of the genome being affected by partial or full introgression. Using neutral simulations for comparison, we find that the size and the fraction of introgressed haplotypes are not compatible with a pure migration or incomplete lineage sorting model. Hence, it appears that introgressed haplotypes can rise in frequency due to positive selection and thus can contribute to the adaptive genomic landscape of natural populations. Our data support the notion that natural genomes are subject to complex adaptive processes, including the introgression of haplotypes from other differentiated populations or species at a larger scale than previously assumed for animals. This implies that some of the admixture found in inbred strains of mice

  4. Existence of vigorous lineages of crop-wild hybrids in Lettuce under field conditions.

    Science.gov (United States)

    Hooftman, Danny A P; Hartman, Yorike; Oostermeijer, J Gerard B; Den Nijs, Hans J C M

    2009-01-01

    Plant to plant gene flow is a route of environmental exposure for GM plants specifically since crosses with wild relatives could lead to the formation of more vigorous hybrids, which could increase the rate of introgression and the environmental impact. Here, we test the first step in the process of potential transgene introgression: whether hybrid vigor can be inherited to the next generation, which could lead to fixation of altered, i.e., elevated, quantitative traits. The potential for a permanent elevated fitness was tested using individual autogamous progeny lineages of hybrids between the crop Lactuca sativa (Lettuce) and the wild species Lactuca serriola (Prickly Lettuce). We compared progeny from motherplants grown under either greenhouse or field conditions. The survival of young plants depended strongly on maternal environment. Furthermore, we observed that offspring reproductive fitness components were correlated with maternal fitness. Our study demonstrates that post-zygotic genotypic sorting at the young plants stage reduces the number of genotypes non-randomly, leading to inheritance of high levels of reproductive traits in the surviving hybrid lineages, compared to the pure wild relatives. Consequently, directional selection could lead to displacement of the pure wild relative and fixation of more vigorous genome segments originating from crops, stabilizing plant traits at elevated levels. Such information can be used to indentify segments which are less likely to introgress into wild relative populations as a target for transgene insertion. © ISBR, EDP Sciences, 2010.

  5. Morphological identification of Lucilia sericata, Lucilia cuprina and their hybrids (Diptera, Calliphoridae)

    Science.gov (United States)

    Williams, Kirstin A.; Villet, Martin H.

    2014-01-01

    Abstract Hybrids of Lucilia sericata and Lucilia cuprina have been shown to exist in previous studies using molecular methods, but no study has shown explicitly that these hybrids can be identified morphologically. Published morphological characters used to identify L. sericata and L. cuprina were reviewed, and then scored and tested using specimens of both species and known hybrids. Ordination by multi-dimensional scaling indicated that the species were separable, and that hybrids resembled L. cuprina, whatever their origin. Discriminant function analysis of the characters successfully separated the specimens into three unambiguous groups – L. sericata, L. cuprina and hybrids. The hybrids were morphologically similar irrespective of whether they were from an ancient introgressed lineage or more modern. This is the first evidence that hybrids of these two species can be identified from their morphology. The usefulness of the morphological characters is also discussed and photographs of several characters are included to facilitate their assessment. PMID:25061373

  6. Chromosome rearrangements, recombination suppression, and limited segregation distortion in hybrids between Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) and rainbow trout (O. mykiss)

    Science.gov (United States)

    2013-01-01

    Background Introgressive hybridization is an important evolutionary process that can lead to the creation of novel genome structures and thus potentially new genetic variation for selection to act upon. On the other hand, hybridization with introduced species can threaten native species, such as cutthroat trout (Oncorhynchus clarkii) following the introduction of rainbow trout (O. mykiss). Neither the evolutionary consequences nor conservation implications of rainbow trout introgression in cutthroat trout is well understood. Therefore, we generated a genetic linkage map for rainbow-Yellowstone cutthroat trout (O. clarkii bouvieri) hybrids to evaluate genome processes that may help explain how introgression affects hybrid genome evolution. Results The hybrid map closely aligned with the rainbow trout map (a cutthroat trout map does not exist), sharing all but one linkage group. This linkage group (RYHyb20) represented a fusion between an acrocentric (Omy28) and a metacentric chromosome (Omy20) in rainbow trout. Additional mapping in Yellowstone cutthroat trout indicated the two rainbow trout homologues were fused in the Yellowstone genome. Variation in the number of hybrid linkage groups (28 or 29) likely depended on a Robertsonian rearrangement polymorphism within the rainbow trout stock. Comparison between the female-merged F1 map and a female consensus rainbow trout map revealed that introgression suppressed recombination across large genomic regions in 5 hybrid linkage groups. Two of these linkage groups (RYHyb20 and RYHyb25_29) contained confirmed chromosome rearrangements between rainbow and Yellowstone cutthroat trout indicating that rearrangements may suppress recombination. The frequency of allelic and genotypic segregation distortion varied among parents and families, suggesting few incompatibilities exist between rainbow and Yellowstone cutthroat trout genomes. Conclusions Chromosome rearrangements suppressed recombination in the hybrids. This result

  7. Hybridization rapidly reduces fitness of a native trout in the wild

    Science.gov (United States)

    Muhlfeld, C.C.; Kalinowski, S.T.; McMahon, T.E.; Taper, M.L.; Painter, S.; Leary, R.F.; Allendorf, F.W.

    2009-01-01

    Human-mediated hybridization is a leading cause of biodiversity loss worldwide. How hybridization affects fitness and what level of hybridization is permissible pose difficult conservation questions with little empirical information to guide policy and management decisions. This is particularly true for salmonids, where widespread introgression among non-native and native taxa has often created hybrid swarms over extensive geographical areas resulting in genomic extinction. Here, we used parentage analysis with multilocus microsatellite markers to measure how varying levels of genetic introgression with non-native rainbow trout (Oncorhynchus mykiss) affect reproductive success (number of offspring per adult) of native westslope cutthroat trout (Oncorhynchus clarkii lewisi) in the wild. Small amounts of hybridization markedly reduced fitness of male and female trout, with reproductive success sharply declining by approximately 50 per cent, with only 20 per cent admixture. Despite apparent fitness costs, our data suggest that hybridization may spread due to relatively high reproductive success of first-generation hybrids and high reproductive success of a few males with high levels of admixture. This outbreeding depression suggests that even low levels of admixture may have negative effects on fitness in the wild and that policies protecting hybridized populations may need reconsideration. ?? 2009 The Royal Society.

  8. Some rare Indo-Pacific coral species are probable hybrids.

    Directory of Open Access Journals (Sweden)

    Zoe T Richards

    Full Text Available BACKGROUND: Coral reefs worldwide face a variety of threats and many coral species are increasingly endangered. It is often assumed that rare coral species face higher risks of extinction because they have very small effective population sizes, a predicted consequence of which is decreased genetic diversity and adaptive potential. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that some Indo-Pacific members of the coral genus Acropora have very small global population sizes and are likely to be unidirectional hybrids. Whether this reflects hybrid origins or secondary hybridization following speciation is unclear. CONCLUSIONS/SIGNIFICANCE: The interspecific gene flow demonstrated here implies increased genetic diversity and adaptive potential in these coral species. Rare Acropora species may therefore be less vulnerable to extinction than has often been assumed because of their propensity for hybridization and introgression, which may increase their adaptive potential.

  9. Hybridization among three native North American Canis species in a region of natural sympatry.

    Directory of Open Access Journals (Sweden)

    Frank Hailer

    2008-10-01

    Full Text Available Population densities of many species throughout the world are changing due to direct persecution as well as anthropogenic habitat modification. These changes may induce or increase the frequency of hybridization among taxa. If extensive, hybridization can threaten the genetic integrity or survival of endangered species. Three native species of the genus Canis, coyote (C. latrans, Mexican wolf (C. lupus baileyi and red wolf (C. rufus, were historically sympatric in Texas, United States. Human impacts caused the latter two to go extinct in the wild, although they survived in captive breeding programs. Morphological data demonstrate historic reproductive isolation between all three taxa. While the red wolf population was impacted by introgressive hybridization with coyotes as it went extinct in the wild, the impact of hybridization on the Texas populations of the other species is not clear.We surveyed variation at maternally and paternally inherited genetic markers (mitochondrial control region sequence and Y chromosome microsatellites in coyotes from Texas, Mexican wolves and red wolves from the captive breeding programs, and a reference population of coyotes from outside the historic red wolf range. Levels of variation and phylogenetic analyses suggest that hybridization has occasionally taken place between all three species, but that the impact on the coyote population is very small.Our results demonstrate that the factors driving introgressive hybridization in sympatric Texan Canis are multiple and complex. Hybridization is not solely determined by body size or sex, and density-dependent effects do not fully explain the observed pattern either. No evidence of hybridization was identified in the Mexican wolf captive breeding program, but introgression appears to have had a greater impact on the captive red wolves.

  10. Characterization of new allele influencing flowering time in bread wheat introgressed from Triticum militinae.

    Science.gov (United States)

    Ivaničová, Zuzana; Jakobson, Irena; Reis, Diana; Šafář, Jan; Milec, Zbyněk; Abrouk, Michael; Doležel, Jaroslav; Järve, Kadri; Valárik, Miroslav

    2016-09-25

    Flowering time variation was identified within a mapping population of doubled haploid lines developed from a cross between the introgressive line 8.1 and spring bread wheat cv. Tähti. The line 8.1 carried introgressions from tetraploid Triticum militinae in the cv. Tähti genetic background on chromosomes 1A, 2A, 4A, 5A, 7A, 1B and 5B. The most significant QTL for the flowering time variation was identified within the introgressed region on chromosome 5A and its largest effect was associated with the VRN-A1 locus, accounting for up to 70% of phenotypic variance. The allele of T. militinae origin was designated as VRN-A1f-like. The effect of the VRN-A1f-like allele was verified in two other mapping populations. QTL analysis identified that in cv. Tähti and cv. Mooni genetic background, VRN-A1f-like allele incurred a delay of 1.9-18.6 days in flowering time, depending on growing conditions. Sequence comparison of the VRN-A1f-like and VRN-A1a alleles from the parental lines of the mapping populations revealed major mutations in the promoter region as well as in the first intron, including insertion of a MITE element and a large deletion. The sequence variation allowed construction of specific diagnostic PCR markers for VRN-A1f-like allele determination. Identification and quantification of the effect of the VRN-A1f-like allele offers a useful tool for wheat breeding and for studying fine-scale regulation of flowering pathways in wheat. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Introgression of physiological traits for a comprehensive improvement of drought adaptation in crop plants

    Science.gov (United States)

    Sreeman, Sheshshayee M.; Vijayaraghavareddy, Preethi; Sreevathsa, Rohini; Rajendrareddy, Sowmya; Arakesh, Smitharani; Bharti, Pooja; Dharmappa, Prathibha; Soolanayakanahally, Raju

    2018-04-01

    Burgeoning population growth, industrial demand and the predicted global climate change resulting in erratic monsoon rains are expected to severely limit fresh water availability for agriculture both in irrigated and rainfed ecosystems. In order to remain food and nutrient secure, agriculture research needs to focus on devising strategies to save water in irrigated conditions and to develop superior cultivars with improved water productivity to sustain yield under rainfed conditions. Recent opinions accruing in the scientific literature strongly favour the adoption of a “trait based” approach for increasing water productivity especially the traits associated with maintenance of positive tissue turgor and maintenance of increased carbon assimilation as the most relevant traits to improve crop growth rates under water limiting conditions and to enhance water productivity. The advent of several water saving agronomic practices notwithstanding, a genetic enhancement strategy of introgressing distinct physiological, morphological and cellular mechanisms on to a single elite genetic background is essential for achieving a comprehensive improvement in drought adaptation in crop plants. The significant progress made in genomics, though would provide the necessary impetus, a clear understanding of the “traits” to be introgressed is the most essential need of the hour. Water uptake by a better root architecture, water conservation by preventing unproductive transpiration is crucial for maintaining positive tissue water relations. Improved carbon assimilation associated with carboxylation capacity and mesophyll conductance is equally important in sustaining crop growth rates under water limited conditions. Besides these major traits, we summarized the available information in literature on classifying various drought adaptive traits. We provide evidences that water-use efficiency when introgressed with moderately higher transpiration, would significantly enhance

  12. Sequence-Based Introgression Mapping Identifies Candidate White Mold Tolerance Genes in Common Bean

    Directory of Open Access Journals (Sweden)

    Sujan Mamidi

    2016-07-01

    Full Text Available White mold, caused by the necrotrophic fungus (Lib. de Bary, is a major disease of common bean ( L.. WM7.1 and WM8.3 are two quantitative trait loci (QTL with major effects on tolerance to the pathogen. Advanced backcross populations segregating individually for either of the two QTL, and a recombinant inbred (RI population segregating for both QTL were used to fine map and confirm the genetic location of the QTL. The QTL intervals were physically mapped using the reference common bean genome sequence, and the physical intervals for each QTL were further confirmed by sequence-based introgression mapping. Using whole-genome sequence data from susceptible and tolerant DNA pools, introgressed regions were identified as those with significantly higher numbers of single-nucleotide polymorphisms (SNPs relative to the whole genome. By combining the QTL and SNP data, WM7.1 was located to a 660-kb region that contained 41 gene models on the proximal end of chromosome Pv07, while the WM8.3 introgression was narrowed to a 1.36-Mb region containing 70 gene models. The most polymorphic candidate gene in the WM7.1 region encodes a BEACH-domain protein associated with apoptosis. Within the WM8.3 interval, a receptor-like protein with the potential to recognize pathogen effectors was the most polymorphic gene. The use of gene and sequence-based mapping identified two candidate genes whose putative functions are consistent with the current model of pathogenicity.

  13. Rapid and targeted introgression of genes into popular wheat cultivars using marker-assisted background selection.

    Directory of Open Access Journals (Sweden)

    Harpinder S Randhawa

    Full Text Available A marker-assisted background selection (MABS-based gene introgression approach in wheat (Triticum aestivum L. was optimized, where 97% or more of a recurrent parent genome (RPG can be recovered in just two backcross (BC generations. A four-step MABS method was developed based on 'Plabsim' computer simulations and wheat genome structure information. During empirical optimization of this method, double recombinants around the target gene were selected in a step-wise fashion during the two BC cycles followed by selection for recurrent parent genotype on non-carrier chromosomes. The average spacing between carrier chromosome markers was <4 cM. For non-carrier chromosome markers that flanked each of the 48 wheat gene-rich regions, this distance was approximately 12 cM. Employed to introgress seedling stripe rust (Puccinia striiformis f. sp. tritici resistance gene Yr15 into the spring wheat cultivar 'Zak', marker analysis of 2,187 backcross-derived progeny resulted in the recovery of a BC(2F(2ratio3 plant with 97% of the recurrent parent genome. In contrast, only 82% of the recurrent parent genome was recovered in phenotypically selected BC(4F(7 plants developed without MABS. Field evaluation results from 17 locations indicated that the MABS-derived line was either equal or superior to the recurrent parent for the tested agronomic characteristics. Based on these results, MABS is recommended as a strategy for rapidly introgressing a targeted gene into a wheat genotype in just two backcross generations while recovering 97% or more of the recurrent parent genotype.

  14. Introgression of a Rare Haplotype from Southeastern Africa to Breed California Blackeyes with Larger Seeds

    Directory of Open Access Journals (Sweden)

    Mitchell R Lucas

    2015-03-01

    Full Text Available Seed size distinguishes most crops from their wild relatives and is an important quality trait for the grain legume cowpea. In order to breed cowpea varieties with larger seeds we introgressed a rare haplotype associated with large seeds at the Css-1 locus from an African buff seed type cultivar, IT82E-18 (18.5g/100 seeds, into a blackeye seed type cultivar, CB27 (22g/100 seed. Four RILs derived from these two parents were chosen for marker-assisted breeding based on SNP genotyping with a goal of stacking large seed haplotypes into a CB27 background. Foreground and background selection were performed during two cycles of backcrossing based on genome-wide SNP markers. The average seed size of introgression lines homozygous for haplotypes associated with large seeds was 28.7g/100 seed and 24.8g/100 seed for cycles 1 and 2, respectively. One cycle 1 introgression line with desirable seed quality was selfed for two generations to make families with very large seeds (28-35g/100 seeds. Field-based performance trials helped identify breeding lines that not only have large seeds but are also desirable in terms of yield, maturity, and plant architecture when compared to industry standards. A principal component analysis was used to explore the relationships between the parents relative to a core set of landraces and improved varieties based on high-density SNP data. The geographic distribution of haplotypes at the Css-1 locus suggest the haplotype associated with large seeds is unique to accessions collected from Southeastern Africa. Therefore this QTL has a strong potential to develop larger seeded varieties for other growing regions which is demonstrated in this work using a California pedigree.

  15. Introgression of Physiological Traits for a Comprehensive Improvement of Drought Adaptation in Crop Plants

    Directory of Open Access Journals (Sweden)

    Sheshshayee M. Sreeman

    2018-04-01

    Full Text Available Burgeoning population growth, industrial demand, and the predicted global climate change resulting in erratic monsoon rains are expected to severely limit fresh water availability for agriculture both in irrigated and rainfed ecosystems. In order to remain food and nutrient secure, agriculture research needs to focus on devising strategies to save water in irrigated conditions and to develop superior cultivars with improved water productivity to sustain yield under rainfed conditions. Recent opinions accruing in the scientific literature strongly favor the adoption of a “trait based” crop improvement approach for increasing water productivity. Traits associated with maintenance of positive tissue turgor and maintenance of increased carbon assimilation are regarded as most relevant to improve crop growth rates under water limiting conditions and to enhance water productivity. The advent of several water saving agronomic practices notwithstanding, a genetic enhancement strategy of introgressing distinct physiological, morphological, and cellular mechanisms on to a single elite genetic background is essential for achieving a comprehensive improvement in drought adaptation in crop plants. The significant progress made in genomics, though would provide the necessary impetus, a clear understanding of the “traits” to be introgressed is the most essential need of the hour. Water uptake by a better root architecture, water conservation by preventing unproductive transpiration are crucial for maintaining positive tissue water relations. Improved carbon assimilation associated with carboxylation capacity and mesophyll conductance is important in sustaining crop growth rates under water limited conditions. Besides these major traits, we summarize the available information in literature on classifying various drought adaptive traits. We provide evidences that Water-Use Efficiency when introgressed with moderately higher transpiration, would

  16. Bucking the trend in wolf-dog hybridization: first evidence from europe of hybridization between female dogs and male wolves.

    Science.gov (United States)

    Hindrikson, Maris; Männil, Peep; Ozolins, Janis; Krzywinski, Andrzej; Saarma, Urmas

    2012-01-01

    Studies on hybridization have proved critical for understanding key evolutionary processes such as speciation and adaptation. However, from the perspective of conservation, hybridization poses a concern, as it can threaten the integrity and fitness of many wild species, including canids. As a result of habitat fragmentation and extensive hunting pressure, gray wolf (Canis lupus) populations have declined dramatically in Europe and elsewhere during recent centuries. Small and fragmented populations have persisted, but often only in the presence of large numbers of dogs, which increase the potential for hybridization and introgression to deleteriously affect wolf populations. Here, we demonstrate hybridization between wolf and dog populations in Estonia and Latvia, and the role of both genders in the hybridization process, using combined analysis of maternal, paternal and biparental genetic markers. Eight animals exhibiting unusual external characteristics for wolves - six from Estonia and two from Latvia - proved to be wolf-dog hybrids. However, one of the hybridization events was extraordinary. Previous field observations and genetic studies have indicated that mating between wolves and dogs is sexually asymmetrical, occurring predominantly between female wolves and male dogs. While this was also the case among the Estonian hybrids, our data revealed the existence of dog mitochondrial genomes in the Latvian hybrids and, together with Y chromosome and autosomal microsatellite data, thus provided the first evidence from Europe of mating between male wolves and female dogs. We discuss patterns of sexual asymmetry in wolf-dog hybridization.

  17. Historical and current introgression in a Mesoamerican hummingbird species complex: a biogeographic perspective

    Directory of Open Access Journals (Sweden)

    Rosa Alicia Jiménez

    2016-01-01

    Full Text Available The influence of geologic and Pleistocene glacial cycles might result in morphological and genetic complex scenarios in the biota of the Mesoamerican region. We tested whether berylline, blue-tailed and steely-blue hummingbirds, Amazilia beryllina, Amazilia cyanura and Amazilia saucerottei, show evidence of historical or current introgression as their plumage colour variation might suggest. We also analysed the role of past and present climatic events in promoting genetic introgression and species diversification. We collected mitochondrial DNA (mtDNA sequence data and microsatellite loci scores for populations throughout the range of the three Amazilia species, as well as morphological and ecological data. Haplotype network, Bayesian phylogenetic and divergence time inference, historical demography, palaeodistribution modelling, and niche divergence tests were used to reconstruct the evolutionary history of this Amazilia species complex. An isolation-with-migration coalescent model and Bayesian assignment analysis were assessed to determine historical introgression and current genetic admixture. mtDNA haplotypes were geographically unstructured, with haplotypes from disparate areas interdispersed on a shallow tree and an unresolved haplotype network. Assignment analysis of the nuclear genome (nuDNA supported three genetic groups with signs of genetic admixture, corresponding to: (1 A. beryllina populations located west of the Isthmus of Tehuantepec; (2 A. cyanura populations between the Isthmus of Tehuantepec and the Nicaraguan Depression (Nuclear Central America; and (3 A. saucerottei populations southeast of the Nicaraguan Depression. Gene flow and divergence time estimates, and demographic and palaeodistribution patterns suggest an evolutionary history of introgression mediated by Quaternary climatic fluctuations. High levels of gene flow were indicated by mtDNA and asymmetrical isolation-with-migration, whereas the microsatellite analyses

  18. The in silico identification and characterization of a bread wheat/Triticum militinae introgression line

    Czech Academy of Sciences Publication Activity Database

    Abrouk, Michael; Balcárková, Barbora; Šimková, Hana; Komínková, Eva; Martis, M.M.; Jakobson, I.; Timofejeva, L.; Rey, Elodie; Vrána, Jan; Kilian, A.; Jarve, K.; Doležel, Jaroslav; Valárik, Miroslav

    2017-01-01

    Roč. 15, č. 2 (2017), s. 249-256 ISSN 1467-7644 R&D Projects: GA MŠk(CZ) LO1204; GA ČR(CZ) GA14-07164S Institutional support: RVO:61389030 Keywords : crop improvement * powdery mildew * common wheat * chromosomes * genome * resistance * plant * recombination * evolution * barley * GenomeZipper * alien introgression * comparative analysis * chromosome rearrangement * chromosome translocation * linkage drag Subject RIV: EB - Gene tics ; Molecular Biology OBOR OECD: Plant sciences, botany Impact factor: 7.443, year: 2016

  19. Historical and current introgression in a Mesoamerican hummingbird species complex: a biogeographic perspective

    Science.gov (United States)

    Jiménez, Rosa Alicia

    2016-01-01

    The influence of geologic and Pleistocene glacial cycles might result in morphological and genetic complex scenarios in the biota of the Mesoamerican region. We tested whether berylline, blue-tailed and steely-blue hummingbirds, Amazilia beryllina, Amazilia cyanura and Amazilia saucerottei, show evidence of historical or current introgression as their plumage colour variation might suggest. We also analysed the role of past and present climatic events in promoting genetic introgression and species diversification. We collected mitochondrial DNA (mtDNA) sequence data and microsatellite loci scores for populations throughout the range of the three Amazilia species, as well as morphological and ecological data. Haplotype network, Bayesian phylogenetic and divergence time inference, historical demography, palaeodistribution modelling, and niche divergence tests were used to reconstruct the evolutionary history of this Amazilia species complex. An isolation-with-migration coalescent model and Bayesian assignment analysis were assessed to determine historical introgression and current genetic admixture. mtDNA haplotypes were geographically unstructured, with haplotypes from disparate areas interdispersed on a shallow tree and an unresolved haplotype network. Assignment analysis of the nuclear genome (nuDNA) supported three genetic groups with signs of genetic admixture, corresponding to: (1) A. beryllina populations located west of the Isthmus of Tehuantepec; (2) A. cyanura populations between the Isthmus of Tehuantepec and the Nicaraguan Depression (Nuclear Central America); and (3) A. saucerottei populations southeast of the Nicaraguan Depression. Gene flow and divergence time estimates, and demographic and palaeodistribution patterns suggest an evolutionary history of introgression mediated by Quaternary climatic fluctuations. High levels of gene flow were indicated by mtDNA and asymmetrical isolation-with-migration, whereas the microsatellite analyses found evidence

  20. Genetic basis of hybrid male sterility among three closely related species of Drosophila.

    Science.gov (United States)

    Mishra, Paras Kumar; Singh, B N

    2005-05-01

    The genetic basis of hybrid male sterility among three closely related species, Drosophila bipectinata, D. parabipectinata and D. malerkotliana has been investigated by using backcross analysis methods. The role of Y chromosome, major hybrid sterility (MHS) genes (genetic factors) and cytoplasm (non-genetic factor) have been studied in the hybrids of these three species. In the species pair, bipectinata--parabipectinata, Y chromosome introgression of parabipectinata in the genomic background of bipectinata and the reciprocal Y chromosome introgression were unsuccessful as all males in second backcross generation were sterile. Neither MHS genes nor cytoplasm was found important for sterility. This suggests the involvement of X-Y, X-autosomes or polygenic interactions in hybrid male sterility. In bipectinata--malerkotliana and parabipectinata--malerkotliana species pairs, Y chromosome substitution in reciprocal crosses did not affect male fertility. Backcross analyses also show no involvement of MHS genes or cytoplasm in hybrid male sterility in these two species pairs. Therefore, X- autosome interaction or polygenic interaction is supposed to be involved in hybrid male sterility in these two species pairs. These findings also provide evidence that even in closely related species, genetic interactions underlying hybrid male sterility may vary.

  1. Hybridization of an invasive shrub affects tolerance and resistance to defoliation by a biological control agent

    Science.gov (United States)

    Williams, Wyatt I.; Friedman, Jonathan M.; Gaskin, John F.; Norton, Andrew P.

    2014-01-01

    Evolution has contributed to the successful invasion of exotic plant species in their introduced ranges, but how evolution affects particular control strategies is still under evaluation. For instance, classical biological control, a common strategy involving the utilization of highly specific natural enemies to control exotic pests, may be negatively affected by host hybridization because of shifts in plant traits, such as root allocation or chemical constituents. We investigated introgression between two parent species of the invasive shrub tamarisk (Tamarix spp.) in the western United States, and how differences in plant traits affect interactions with a biological control agent. Introgression varied strongly with latitude of origin and was highly correlated with plant performance. Increased levels of T. ramosissima introgression resulted in both higher investment in roots and tolerance to defoliation and less resistance to insect attack. Because tamarisk hybridization occurs predictably on the western U.S. landscape, managers may be able to exploit this information to maximize control efforts. Genetic differentiation in plant traits in this system underpins the importance of plant hybridization and may explain why some biological control releases are more successful than others.

  2. Sequence-based SSR marker development and their application in defining the Introgressions of LA0716 (Solanum pennellii in the background of cv. M82 (Solanum lycopersicum.

    Directory of Open Access Journals (Sweden)

    Wenbo Long

    Full Text Available The introgression lines (ILs from cv. M82 (Solanum lycopersicum × LA0716 (S. pennellii have been proven to be exceptionally useful for genetic analysis and gene cloning. The introgressions were originally defined by RFLP markers at their development. The objectives of this study are to develop polymorphic SSR markers, and to re-define the DNA introgression from LA0716 in the ILs. Tomato sequence data was scanned by software to generate SSR markers. In total, 829 SSRs, which could be robustly amplified by PCR, were developed. Among them, 658 SSRs were dinucleotide repeats, 162 were trinucleotide repeats, and nine were tetranucleotide repeats. The 829 SSRs together with 96 published RFLPs were integrated into the physical linkage map of S. lycopersicum. Introgressions of DNA fragments from LA0716 were re-defined among the 75 ILs using the newly developed SSRs. A specific introgression of DNA fragment from LA0716 was identified in 72 ILs as described previously by RFLP, whereas the specific DNA introgression described previously were not detected in the ILs LA4035, LA4059 and LA4091. The physical location of each investigated DNA introgression was finely determined by SSR mapping. Among the 72 ILs, eight ILs showed a shorter and three ILs (IL3-2, IL12-3 and IL12-3-1 revealed a longer DNA introgression than that framed by RFLPs. Furthermore, 54 previously undefined segments were found in 21 ILs, ranging from 1 to 11 DNA introgressions per IL. Generally, the newly developed SSRs provide additional markers for genetic studies of tomatoes, and the fine definition of DNA introgressions from LA0716 would facilitate the use of the ILs for genetic analysis and gene cloning.

  3. Molecular identification of vectors of Leishmania in Colombia: mitochondrial introgression in the Lutzomyia townsendi series.

    Science.gov (United States)

    Testa, J M; Montoya-Lerma, J; Cadena, H; Oviedo, M; Ready, P D

    2002-12-01

    The identity of the sandfly vectors of Leishmania braziliensis in Valle del Cauca Department, Colombia, was originally given as Lutzomyia townsendi, but then changed to L. youngi, another member of the L. townsendi series (Verrucarum group) with isomorphic females. To identify members of this series in Valle del Cauca, we analyzed the nuclear gene elongation factor-alpha (EF-alpha) and the mitochondrial gene cytochrome b (Cyt b). DNA sequences from the L. verrucarum series (L. columbiana, L. evansi and L. ovallesi) were used as outgroups. Flies from two locations on the western cordillera of the Andes were identified as L. townsendi s.s., according to male morphology and distinctive gene lineages. In the third location, on the central cordillera of the Andes, most specimens were identified as belonging to a geographical population of L. youngi, according to male morphology, an EF-alpha lineage shared with L. youngi from the Venezuelan-type locality, and a distinctive Cyt b sub-lineage. All other specimens were identified as L. youngi with the introgressed Cyt b sequences of L. townsendi. Such interspecific introgression implies that vectorial traits and ecological associations may no longer be viewed as fixed properties of different morphospecies.

  4. Are both sympatric species Ilex perado and Ilex canariensis secretly hybridizing? Indication from nuclear markers collected in Tenerife

    Directory of Open Access Journals (Sweden)

    Manen Jean-François

    2004-11-01

    Full Text Available Abstract Background Intra-specific and intra-individual polymorphism is frequently observed in nuclear markers of Ilex (Aquifoliaceae and discrepancy between plastid and nuclear phylogenies is the rule in this genus. These observations suggest that inter-specific plastid or/and nuclear introgression played an important role in the process of evolution of Ilex. With the aim of a precise understanding of the evolution of this genus, two distantly related sympatric species collected in Tenerife (Canary Islands, I. perado and I. canariensis, were studied in detail. Introgression between these two species was previously never reported. One plastid marker (the atpB-rbcL spacer and two nuclear markers, the ribosomal internal transcribed spacer (ITS and the nuclear encoded plastid glutamine synthetase (nepGS were analyzed for 13 and 27 individuals of I. perado and I. canariensis, respectively. Results The plastid marker is intra-specifically constant and correlated with species identity. On the other hand, whereas the nuclear markers are conserved in I. perado, they are highly polymorphic in I. canariensis. The presence of pseudogenes and recombination in ITS sequences of I. canariensis explain this polymorphism. Ancestral sequence polymorphism with incomplete lineage sorting, or past or recent hybridization with an unknown species could explain this polymorphism, not resolved by concerted evolution. However, as already reported for many other plants, past or recent introgression of an alien genotype seem the most probable explanation for such a tremendous polymorphism. Conclusions Data do not allow the determination with certitude of the putative species introgressing I. canariensis, but I. perado is suspected. The introgression would be unilateral, with I. perado as the male donor, and the paternal sequences would be rapidly converted in highly divergent and consequently unidentifiable pseudogenes. At least, this study allows the establishment of

  5. The Evolution of Polymorphic Hybrid Incompatibilities in House Mice.

    Science.gov (United States)

    Larson, Erica L; Vanderpool, Dan; Sarver, Brice A J; Callahan, Colin; Keeble, Sara; Provencio, Lorraine P; Kessler, Michael D; Stewart, Vanessa; Nordquist, Erin; Dean, Matthew D; Good, Jeffrey M

    2018-04-24

    Resolving the mechanistic and genetic bases of reproductive barriers between species is essential to understanding the evolutionary forces that shape speciation. Intrinsic hybrid incompatibilities are often treated as fixed between species, yet there can be considerable variation in the strength of reproductive isolation between populations. The extent and causes of this variation remain poorly understood in most systems. We investigated the genetic basis of variable hybrid male sterility (HMS) between two recently diverged subspecies of house mice, Mus musculus domesticus and M. m. musculus We found that polymorphic HMS has a surprisingly complex genetic basis, with contributions from at least five autosomal loci segregating between two closely related wild-derived strains of M. m. musculus One of the HMS-linked regions on Chromosome 4 also showed extensive introgression among inbred laboratory strains and transmission ratio distortion (TRD) in hybrid crosses. Using additional crosses and whole genome sequencing of sperm pools, we showed that TRD was limited to hybrid crosses and was not due to differences in sperm motility between M. m. musculus strains. Based on these results, we argue that TRD likely reflects additional incompatibilities that reduce hybrid embryonic viability. In some common inbred strains of mice, selection against deleterious interactions appears to have unexpectedly driven introgression at loci involved in epistatic hybrid incompatibilities. The highly variable genetic basis to F1 hybrid incompatibilities between closely related mouse lineages argues that a thorough dissection of reproductive isolation will require much more extensive sampling of natural variation than has been commonly utilized in mice and other model systems. Copyright © 2018, Genetics.

  6. The complex biogeography of the plant pathogen Xylella fastidiosa: genetic evidence of introductions and Subspecific introgression in Central America.

    Science.gov (United States)

    Nunney, Leonard; Ortiz, Beatriz; Russell, Stephanie A; Ruiz Sánchez, Rebeca; Stouthamer, Richard

    2014-01-01

    The bacterium Xylella fastidiosa is a plant pathogen with a history of economically damaging introductions of subspecies to regions where its other subspecies are native. Genetic evidence is presented demonstrating the introduction of two new taxa into Central America and their introgression into the native subspecies, X. fastidiosa subsp. fastidiosa. The data are from 10 genetic outliers detected by multilocus sequence typing (MLST) of isolates from Costa Rica. Six (five from oleander, one from coffee) defined a new sequence type (ST53) that carried alleles at six of the eight loci sequenced (five of the seven MLST loci) diagnostic of the South American subspecies Xylella fastidiosa subsp. pauca which causes two economically damaging plant diseases, citrus variegated chlorosis and coffee leaf scorch. The two remaining loci of ST53 carried alleles from what appears to be a new South American form of X. fastidiosa. Four isolates, classified as X. fastidiosa subsp. fastidiosa, showed a low level of introgression of non-native DNA. One grapevine isolate showed introgression of an allele from X. fastidiosa subsp. pauca while the other three (from citrus and coffee) showed introgression of an allele with similar ancestry to the alleles of unknown origin in ST53. The presence of X. fastidiosa subsp. pauca in Central America is troubling given its disease potential, and establishes another route for the introduction of this economically damaging subspecies into the US or elsewhere, a threat potentially compounded by the presence of a previously unknown form of X. fastidiosa.

  7. The complex biogeography of the plant pathogen Xylella fastidiosa: genetic evidence of introductions and Subspecific introgression in Central America.

    Directory of Open Access Journals (Sweden)

    Leonard Nunney

    Full Text Available The bacterium Xylella fastidiosa is a plant pathogen with a history of economically damaging introductions of subspecies to regions where its other subspecies are native. Genetic evidence is presented demonstrating the introduction of two new taxa into Central America and their introgression into the native subspecies, X. fastidiosa subsp. fastidiosa. The data are from 10 genetic outliers detected by multilocus sequence typing (MLST of isolates from Costa Rica. Six (five from oleander, one from coffee defined a new sequence type (ST53 that carried alleles at six of the eight loci sequenced (five of the seven MLST loci diagnostic of the South American subspecies Xylella fastidiosa subsp. pauca which causes two economically damaging plant diseases, citrus variegated chlorosis and coffee leaf scorch. The two remaining loci of ST53 carried alleles from what appears to be a new South American form of X. fastidiosa. Four isolates, classified as X. fastidiosa subsp. fastidiosa, showed a low level of introgression of non-native DNA. One grapevine isolate showed introgression of an allele from X. fastidiosa subsp. pauca while the other three (from citrus and coffee showed introgression of an allele with similar ancestry to the alleles of unknown origin in ST53. The presence of X. fastidiosa subsp. pauca in Central America is troubling given its disease potential, and establishes another route for the introduction of this economically damaging subspecies into the US or elsewhere, a threat potentially compounded by the presence of a previously unknown form of X. fastidiosa.

  8. Identification of a Rice stripe necrosis virus resistance locus and yield component QTLs using Oryza sativa × O. glaberrima introgression lines

    Directory of Open Access Journals (Sweden)

    Prado Gustavo

    2010-01-01

    Full Text Available Abstract Background Developing new population types based on interspecific introgressions has been suggested by several authors to facilitate the discovery of novel allelic sources for traits of agronomic importance. Chromosome segment substitution lines from interspecific crosses represent a powerful and useful genetic resource for QTL detection and breeding programs. Results We built a set of 64 chromosome segment substitution lines carrying contiguous chromosomal segments of African rice Oryza glaberrima MG12 (acc. IRGC103544 in the genetic background of Oryza sativa ssp. tropical japonica (cv. Caiapó. Well-distributed simple-sequence repeats markers were used to characterize the introgression events. Average size of the substituted chromosomal segments in the substitution lines was about 10 cM and covered the whole donor genome, except for small regions on chromosome 2 and 4. Proportions of recurrent and donor genome in the substitution lines were 87.59% and 7.64%, respectively. The remaining 4.78% corresponded to heterozygotes and missing data. Strong segregation distortion was found on chromosomes 3 and 6, indicating the presence of interspecific sterility genes. To illustrate the advantages and the power of quantitative trait loci (QTL detection using substitution lines, a QTL detection was performed for scored traits. Transgressive segregation was observed for several traits measured in the population. Fourteen QTLs for plant height, tiller number per plant, panicle length, sterility percentage, 1000-grain weight and grain yield were located on chromosomes 1, 3, 4, 6 and 9. Furthermore, a highly significant QTL controlling resistance to the Rice stripe necrosis virus was located between SSR markers RM202-RM26406 (44.5-44.8 cM on chromosome 11. Conclusions Development and phenotyping of CSSL libraries with entire genome coverage represents a useful strategy for QTL discovery. Mapping of the RSNV locus represents the first identification

  9. Pm55, a developmental-stage and tissue-specific powdery mildew resistance gene introgressed from Dasypyrum villosum into common wheat.

    Science.gov (United States)

    Zhang, Ruiqi; Sun, Bingxiao; Chen, Juan; Cao, Aizhong; Xing, Liping; Feng, Yigao; Lan, Caixia; Chen, Peidu

    2016-10-01

    Powdery mildew resistance gene Pm55 was physically mapped to chromosome arm 5VS FL 0.60-0.80 of Dasypyrum villosum . Pm55 is present in T5VS·5AL and T5VS·5DL translocations, which should be valuable resources for wheat improvement. Powdery mildew caused by Blumeria graminis f. sp. tritici is a major wheat disease worldwide. Exploiting novel genes effective against powdery mildew from wild relatives of wheat is a promising strategy for controlling this disease. To identify novel resistance genes for powdery mildew from Dasypyrum villosum, a wild wheat relative, we evaluated a set of Chinese Spring-D. villosum disomic addition and whole-arm translocation lines for reactions to powdery mildew. Based on the evaluation data, we concluded that the D. villosum chromosome 5V controls post-seedling resistance to powdery mildew. Subsequently, three introgression lines were developed and confirmed by molecular and cytogenetic analysis following ionizing radiation of the pollen of a Chinese Spring-D. villosum 5V disomic addition line. A homozygous T5VS·5AL translocation line (NAU421) with good plant vigor and full fertility was further characterized using sequential genomic in situ hybridization, C-banding, and EST-STS marker analysis. A dominant gene permanently named Pm55 was located in chromosome bin 5VS 0.60-0.80 based on the responses to powdery mildew of all wheat-D. villosum 5V introgression lines evaluated at both seeding and adult stages. This study demonstrated that Pm55 conferred growth-stage and tissue-specific dependent resistance; therefore, it provides a novel resistance type for powdery mildew. The T5VS·5AL translocation line with additional softness loci Dina/Dinb of D. villosum provides a possibility of extending the range of grain textures to a super-soft category. Accordingly, this stock is a new source of resistance to powdery mildew and may be useful in both resistance mechanism studies and soft wheat improvement.

  10. Dispersal and selection mediate hybridization between a native and invasive species

    Science.gov (United States)

    Kovach, Ryan P.; Muhlfeld, Clint C.; Boyer, Matthew C.; Lowe, Winsor H.; Allendorf, Fred W.; Luikart, Gordon

    2015-01-01

    Hybridization between native and non-native species has serious biological consequences, but our understanding of how dispersal and selection interact to influence invasive hybridization is limited. Here, we document the spread of genetic introgression between a native (Oncorhynchus clarkii) and invasive (Oncorhynchus mykiss) trout, and identify the mechanisms influencing genetic admixture. In two populations inhabiting contrasting environments, non-native admixture increased rapidly from 1984 to 2007 and was driven by surprisingly consistent processes. Individual admixture was related to two phenotypic traits associated with fitness: size at spawning and age of juvenile emigration. Fish with higher non-native admixture were larger and tended to emigrate at a younger age—relationships that are expected to confer fitness advantages to hybrid individuals. However, strong selection against non-native admixture was evident across streams and cohorts (mean selection coefficient against genotypes with non-native alleles (s) ¼ 0.60; s.e. ¼ 0.10). Nevertheless, hybridization was promoted in both streams by the continuous immigration of individuals with high levels of non-native admixture from other hybrid source populations. Thus, antagonistic relationships between dispersal and selection are mediating invasive hybridization between these fish, emphasizing that data on dispersal and natural selection are needed to fully understand the dynamics of introgression between native and non-native species. .

  11. Study on the introgression of beef breeds in Canchim cattle using single nucleotide polymorphism markers.

    Directory of Open Access Journals (Sweden)

    Marcos Eli Buzanskas

    Full Text Available The aim of this study was to evaluate the level of introgression of breeds in the Canchim (CA: 62.5% Charolais-37.5% Zebu and MA genetic group (MA: 65.6% Charolais-34.4% Zebu cattle using genomic information on Charolais (CH, Nelore (NE, and Indubrasil (IB breeds. The number of animals used was 395 (CA and MA, 763 (NE, 338 (CH, and 37 (IB. The Bovine50SNP BeadChip from Illumina panel was used to estimate the levels of introgression of breeds considering the Maximum likelihood, Bayesian, and Single Regression method. After genotype quality control, 32,308 SNPs were considered in the analysis. Furthermore, three thresholds to prune out SNPs in linkage disequilibrium higher than 0.10, 0.05, and 0.01 were considered, resulting in 15,286, 7,652, and 1,582 SNPs, respectively. For k = 2, the proportion of taurine and indicine varied from the expected proportion based on pedigree for all methods studied. For k = 3, the Regression method was able to differentiate the animals in three main clusters assigned to each purebred breed, showing more reasonable according to its biological viewpoint. Analyzing the data considering k = 2 seems to be more appropriate for Canchim-MA animals due to its biological interpretation. The usage of 32,308 SNPs in the analyses resulted in similar findings between the estimated and expected breed proportions. Using the Regression approach, a contribution of Indubrasil was observed in Canchim-MA when k = 3 was considered. Genetic parameter estimation could account for this breed composition information as a source of variation in order to improve the accuracy of genetic models. Our findings may help assemble appropriate reference populations for genomic prediction for Canchim-MA in order to improve prediction accuracy. Using the information on the level of introgression in each individual could also be useful in breeding or crossing design to improve individual heterosis in crossbred cattle.

  12. Genomic Analysis Reveals Hypoxia Adaptation in the Tibetan Mastiff by Introgression of the Gray Wolf from the Tibetan Plateau.

    Science.gov (United States)

    Miao, Benpeng; Wang, Zhen; Li, Yixue

    2017-03-01

    The Tibetan Mastiff (TM), a native of the Tibetan Plateau, has quickly adapted to the extreme highland environment. Recently, the impact of positive selection on the TM genome was studied and potential hypoxia-adaptive genes were identified. However, the origin of the adaptive variants remains unknown. In this study, we investigated the signature of genetic introgression in the adaptation of TMs with dog and wolf genomic data from different altitudes in close geographic proximity. On a genome-wide scale, the TM was much more closely related to other dogs than wolves. However, using the 'ABBA/BABA' test, we identified genomic regions from the TM that possibly introgressed from Tibetan gray wolf. Several of the regions, including the EPAS1 and HBB loci, also showed the dominant signature of selective sweeps in the TM genome. We validated the introgression of the two loci by excluding the possibility of convergent evolution and ancestral polymorphisms and examined the haplotypes of all available canid genomes. The estimated time of introgression based on a non-coding region of the EPAS1 locus mostly overlapped with the Paleolithic era. Our results demonstrated that the introgression of hypoxia adaptive genes in wolves from the highland played an important role for dogs living in hypoxic environments, which indicated that domestic animals could acquire local adaptation quickly by secondary contact with their wild relatives. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Risk and efficacy of human-enabled interspecific hybridization for climate-change adaptation: Response to Hamilton and Miller (2016)

    Science.gov (United States)

    Kovach, Ryan P.; Luikart, Gordon; Lowe, Winsor H.; Boyer, Matthew C.; Muhlfeld, Clint C.

    2016-01-01

    Hamilton and Miller (2016) provide an interesting and provocative discussion of how hybridization and introgression can promote evolutionary potential in the face of climate change. They argue that hybridization—mating between individuals from genetically distinct populations—can alleviate inbreeding depression and promote adaptive introgression and evolutionary rescue. We agree that deliberate intraspecific hybridization (mating between individuals of the same species) is an underused management tool for increasing fitness in inbred populations (i.e., genetic rescue; Frankham 2015; Whiteley et al. 2015). The potential risks and benefits of assisted gene flow have been discussed in the literature, and an emerging consensus suggests that mating between populations isolated for approximately 50–100 generations can benefit fitness, often with a minor risk of outbreeding depression (Frankham et al. 2011; Aitken & Whitlock 2013; Allendorf et al. 2013).

  14. SNP data in the detection of hybridization levels between wild boar and domestic pig in Europe

    DEFF Research Database (Denmark)

    Iacolina, Laura; Bakan, Jana; Cubric-Curik, Vlatka

    , a better understanding of hybridization patterns in Europe might have important implications for conservation and management of both wild populations and local breeds, as well as for the contingency of infectious diseases. Here we present the results for the analysis of 235 wild boars (WB; from 22 areas......, additionally, highlights the presence of several individuals, of both ancestries, with intermediate positions. This result was confirmed by Admixture analysis that detected the presence of hybrid individuals in both WB and local domestic pig breeds. The introgression level varies considerably among populations...

  15. Introgression of the callipyge mutation into the Assaf fat tail breed

    International Nuclear Information System (INIS)

    Gootwine, E.; Rosov, A.; Bor, A.; Yossafi, S.; Zenue, A.

    2003-01-01

    Introgression of the callipyge (CLPG) mutation into the fat-tail Assaf breed was initiated by inseminating Assaf ewes with Dorset-Hampshire semen from a ram that was heterozygous for the callipyge mutation. Presence of the mutation in the F1 generation and the first backcross generation (BC1) was validated using molecular markers linked to the CLPG locus. Carcasses of callipyge BC1-CN lambs had significantly (P less than 0.01) better conformation than carcasses of normal BC1-NN lambs and straightbred Assaf lambs. Computerized tomography analysis of live BC1 and Assaf lambs showed that carrying the callipyge mutation increased Longissimus dorsi and Quadriceps femoris muscles by about 30

  16. Hybrids between cultivated and wild carrots in natural populations in Denmark

    DEFF Research Database (Denmark)

    Magnussen, L.S.; Hauser, Thure Pavlo

    2007-01-01

    Many cultivated plant species are able to hybridize with related wild plants. However, it is not clear whether their hybrids are able to survive and reproduce outside managed fields, and if cultivar genes introgress into wild populations. In areas where wild carrots co-occur with carrot root......-crops, pollen and seeds may flow from two different sources in the fields to the surrounding wild populations: from pure cultivar plants that occasionally flower, and from flowering 'bolters' that originate from hybridizations between wild (male) and cultivated carrots (female) in seed production fields...... by AFLP. Four hybrids were identified among the 71 plants analysed, and these were most likely F(2) or backcross individuals, sired by pollen from hybrid bolters. Wild populations close to fields were genetically somewhat more similar to cultivars than wild populations far from fields, suggesting...

  17. Africanization in the United States: Replacement of Feral European Honeybees (Apis mellifera L.) by an African Hybrid Swarm

    OpenAIRE

    Pinto, M. Alice; Rubink, William L.; Patton, John C.; Coulson, Robert N.; Johnston, J. Spencer

    2005-01-01

    The expansion of Africanized honeybees from South America to the southwestern United States in 50 years is considered one of the most spectacular biological invasions yet documented. In the American tropics, it has been shown that during their expansion Africanized honeybees have low levels of introgressed alleles from resident European populations. In the United States, it has been speculated, but not shown, that Africanized honeybees would hybridize extensively with European ho...

  18. Quantifying rooting at depth in a wheat doubled haploid population with introgression from wild emmer.

    Science.gov (United States)

    Clarke, Christina K; Gregory, Peter J; Lukac, Martin; Burridge, Amanda J; Allen, Alexandra M; Edwards, Keith J; Gooding, Mike J

    2017-09-01

    The genetic basis of increased rooting below the plough layer, post-anthesis in the field, of an elite wheat line (Triticum aestivum 'Shamrock') with recent introgression from wild emmer (T. dicoccoides), is investigated. Shamrock has a non-glaucous canopy phenotype mapped to the short arm of chromosome 2B (2BS), derived from the wild emmer. A secondary aim was to determine whether genetic effects found in the field could have been predicted by other assessment methods. Roots of doubled haploid (DH) lines from a winter wheat ('Shamrock' × 'Shango') population were assessed using a seedling screen in moist paper rolls, in rhizotrons to the end of tillering, and in the field post-anthesis. A linkage map was produced using single nucleotide polymorphism markers to identify quantitative trait loci (QTLs) for rooting traits. Shamrock had greater root length density (RLD) at depth than Shango, in the field and within the rhizotrons. The DH population exhibited diversity for rooting traits within the three environments studied. QTLs were identified on chromosomes 5D, 6B and 7B, explaining variation in RLD post-anthesis in the field. Effects associated with the non-glaucous trait on RLD interacted significantly with depth in the field, and some of this interaction mapped to 2BS. The effect of genotype was strongly influenced by the method of root assessment, e.g. glaucousness expressed in the field was negatively associated with root length in the rhizotrons, but positively associated with length in the seedling screen. To our knowledge, this is the first study to identify QTLs for rooting at depth in field-grown wheat at mature growth stages. Within the population studied here, our results are consistent with the hypothesis that some of the variation in rooting is associated with recent introgression from wild emmer. The expression of genetic effects differed between the methods of root assessment. © The Author 2017. Published by Oxford University Press on behalf of the

  19. The rise and fall of the mountain hare (Lepus timidus) during Pleistocene glaciations: expansion and retreat with hybridization in the Iberian Peninsula.

    Science.gov (United States)

    Melo-Ferreira, J; Boursot, P; Randi, E; Kryukov, A; Suchentrunk, F; Ferrand, N; Alves, P C

    2007-02-01

    The climatic fluctuations during glaciations have affected differently arctic and temperate species. In the northern hemisphere, cooling periods induced the expansion of many arctic species to the south, while temperate species were forced to retract in southern refugia. Consequently, in some areas the alternation of these species set the conditions for competition and eventually hybridization. Hares in the Iberian Peninsula appear to illustrate this phenomenon. Populations of Iberian hare (Lepus granatensis), brown hare (Lepus europaeus) and broom hare (Lepus castroviejoi) in Northern Iberia harbour mitochondrial haplotypes from the mountain hare (Lepus timidus), a mainly boreal and arctic species presently absent from the peninsula. To understand the history of this past introgression we analysed sequence variation and geographical distribution of mitochondrial control region and cytochrome b haplotypes of L. timidus origin found in 378 specimens of these four species. Among 124 L. timidus from the Northern Palaearctic and the Alps we found substantial nucleotide diversity (2.3%) but little differentiation between populations. Based on the mismatch distribution of the L. timidus sequences, this could result from an expansion at a time of temperature decrease favourable to this arctic species. The nucleotide diversity of L. timidus mtDNA found in Iberian L. granatensis, L. europaeus and L. castroviejoi (183, 70 and 1 specimens, respectively) was of the same order as that in L. timidus over its range (1.9%), suggesting repeated introgression of multiple lineages. The structure of the coalescent of L. granatensis sequences indicates that hybridization with L. timidus was followed by expansion of the introgressed haplotypes, as expected during a replacement with competition, and occurred when temperatures started to rise, favouring the temperate species. Whether a similar scenario explains the introgression into Iberian L. europaeus remains unclear but it is possible

  20. Origin, radiation, dispersion and allopatric hybridization in the chub Leuciscus cephalus.

    Science.gov (United States)

    Durand, J D; Unlü, E; Doadrio, I; Pipoyan, S; Templeton, A R

    2000-08-22

    The phylogenetic relationships of 492 chub (Leuciscus cephalus) belonging to 89 populations across the species' range were assessed using 600 base pairs of cytochrome b. Furthermore, nine species belonging to the L. cephalus complex were also analysed (over the whole cytochrome b) in order to test potential allopatric hybridization with L. cephalus sensu stricto (i.e. the chub). Our results show that the chub includes four highly divergent lineages descending from a quick radiation that took place three million years ago. The geographical distribution of these lineages and results of the nested clade analysis indicated that the chub may have originated from Mesopotamia. Chub radiation probably occurred during an important vicariant event such as the isolation of numerous Turkish river systems, a consequence of the uplift of the Anatolian Plateau (formerly covered by a broad inland lake). Dispersion of these lineages arose from the changes in the European hydrographic network and, thus, the chub and endemic species of the L. cephalus complex met by secondary contacts. Our results show several patterns of introgression, from Leuciscus lepidus fully introgressed by chub mitochondrial DNA to Leuciscus borysthenicus where no introgression at all was detected. We assume that these hybridization events might constitute an important evolutionary process for the settlement of the chub in new environments in the Mediterranean area.

  1. Experimental Crossing of Two Distinct Species of Leopard Geckos, Eublepharis angramainyu and E. macularius: Viability, Fertility and Phenotypic Variation of the Hybrids.

    Science.gov (United States)

    Jančúchová-Lásková, Jitka; Landová, Eva; Frynta, Daniel

    2015-01-01

    Hybridization between distinct species of animals and subsequent genetic introgression plays a considerable role in the speciation process and the emergence of adaptive characters. Fitness of between-species hybrids usually sharply decreases with the divergence time of the concerned species and the divergence depth, which still allows for a successful crossing differs among principal clades of vertebrates. Recently, a review of hybridization events among distinct lizard species revealed that lizards belong to vertebrates with a highly developed ability to hybridize. In spite of this, reliable reports of experimental hybridizations between genetically fairly divergent species are only exceptional. Here, we show the results of the crossing of two distinct allopatric species of eyelid geckos possessing temperature sex determination and lacking sex chromosomes: Eublepharis macularius distributed in Pakistan/Afghanistan area and E. angramainyu, which inhabits Mesopotamia and adjacent areas. We demonstrated that F1 hybrids were viable and fertile, and the introgression of E. angramainyu genes into the E. macularius genome can be enabled via a backcrossing. The examined hybrids (except those of the F2 generation) displayed neither malformations nor a reduced survival. Analyses of morphometric and coloration traits confirmed phenotypic distinctness of both parental species and their F1 hybrids. These findings contrast with long-term geographic and an evolutionary separation of the studied species. Thus, the occurrence of fertile hybrids of comparably divergent species, such as E. angramainyu and E. macularius, may also be expected in other taxa of squamates. This would violate the current estimates of species diversity in lizards.

  2. Genetic interactions underlying hybrid male sterility in the Drosophila bipectinata species complex.

    Science.gov (United States)

    Mishra, Paras Kumar; Singh, Bashisth Narayan

    2006-06-01

    Understanding genetic mechanisms underlying hybrid male sterility is one of the most challenging problems in evolutionary biology especially speciation. By using the interspecific hybridization method roles of Y chromosome, Major Hybrid Sterility (MHS) genes and cytoplasm in sterility of hybrid males have been investigated in a promising group, the Drosophila bipectinata species complex that consists of four closely related species: D. pseudoananassae, D. bipectinata, D. parabipectinata and D. malerkotliana. The interspecific introgression analyses show that neither cytoplasm nor MHS genes are involved but X-Y interactions may be playing major role in hybrid male sterility between D. pseudoananassae and the other three species. The results of interspecific introgression analyses also show considerable decrease in the number of males in the backcross offspring and all males have atrophied testes. There is a significant positive correlation between sex - ratio distortion and severity of sterility in backcross males. These findings provide evidence that D. pseudoananassae is remotely related with other three species of the D. bipectinata species complex.

  3. Continuous Morphological Variation Correlated with Genome Size Indicates Frequent Introgressive Hybridization among Diphasiastrum Species (Lycopodiaceae) in Central Europe

    Czech Academy of Sciences Publication Activity Database

    Hanušová, K.; Ekrt, L.; Vít, Petr; Kolář, Filip; Urfus, Tomáš

    2014-01-01

    Roč. 9, č. 6 (2014), no.-e99552 E-ISSN 1932-6203 R&D Projects: GA ČR GB14-36079G Institutional support: RVO:67985939 Keywords : genome size * merphometrics * Diphasiastrum Subject RIV: EF - Botanics Impact factor: 3.234, year: 2014

  4. Development of novel ash hybrids to introgress resistance to emerald ash borer into north American ash species

    Science.gov (United States)

    Jennifer L. Koch; David W. Carey; Mary E. Mason

    2008-01-01

    Currently, there is no evidence that any of the native North American ash species have any resistance to the emerald ash borer (EAB). This means that the entire ash resource of the eastern United States and Canada is at risk of loss due to EAB. In contrast, outbreaks of EAB in Asian ash species are rare and appear to be isolated responses to stress (Bauer et al. 2005,...

  5. The genetic basis of Haldane's rule and the nature of asymmetric hybrid male sterility among Drosophila simulans, Drosophila mauritiana and Drosophila sechellia.

    Science.gov (United States)

    Zeng, L W; Singh, R S

    1993-05-01

    Haldane's rule (i.e., the preferential hybrid sterility and inviability of heterogametic sex) has been known for 70 years, but its genetic basis, which is crucial to the understanding of the process of species formation, remains unclear. In the present study, we have investigated the genetic basis of hybrid male sterility using Drosophila simulans, Drosophila mauritiana and Drosophila sechellia. An introgression of D. sechellia Y chromosome into a fairly homogenous background of D. simulans did not show any effect of the introgressed Y on male sterility. The substitution of D. simulans Y chromosome into D. sechellia, and both reciprocal Y chromosome substitutions between D. simulans and D. mauritiana were unsuccessful. Introgressions of cytoplasm between D. simulans and D. mauritiana (or D. sechellia) also did not have any effect on hybrid male sterility. These results rule out the X-Y interaction hypothesis as a general explanation of Haldane's rule in this species group and indicate an involvement of an X-autosome interaction. Models of symmetrical and asymmetrical X-autosome interaction have been developed which explain the Y chromosome substitution results and suggest that evolution of interactions between different genetic elements in the early stages of speciation is more likely to be of an asymmetrical nature. The model of asymmetrical X-autosome interaction also predicts that different sets of interacting genes may be involved in different pairs of related species and can account for the observation that hybrid male sterility in many partially isolated species is often nonreciprocal or unidirectional.

  6. Sorting through the chaff, nDNA gene trees for phylogenetic inference and hybrid identification of annual sunflowers (Helianthus sect. Helianthus).

    Science.gov (United States)

    Moody, Michael L; Rieseberg, Loren H

    2012-07-01

    The annual sunflowers (Helianthus sect. Helianthus) present a formidable challenge for phylogenetic inference because of ancient hybrid speciation, recent introgression, and suspected issues with deep coalescence. Here we analyze sequence data from 11 nuclear DNA (nDNA) genes for multiple genotypes of species within the section to (1) reconstruct the phylogeny of this group, (2) explore the utility of nDNA gene trees for detecting hybrid speciation and introgression; and (3) test an empirical method of hybrid identification based on the phylogenetic congruence of nDNA gene trees from tightly linked genes. We uncovered considerable topological heterogeneity among gene trees with or without three previously identified hybrid species included in the analyses, as well as a general lack of reciprocal monophyly of species. Nonetheless, partitioned Bayesian analyses provided strong support for the reciprocal monophyly of all species except H. annuus (0.89 PP), the most widespread and abundant annual sunflower. Previous hypotheses of relationships among taxa were generally strongly supported (1.0 PP), except among taxa typically associated with H. annuus, apparently due to the paraphyly of the latter in all gene trees. While the individual nDNA gene trees provided a useful means for detecting recent hybridization, identification of ancient hybridization was problematic for all ancient hybrid species, even when linkage was considered. We discuss biological factors that affect the efficacy of phylogenetic methods for hybrid identification.

  7. Cultivar-Based Introgression Mapping Reveals Wild Species-Derived Pm-0, the Major Powdery Mildew Resistance Locus in Squash

    Science.gov (United States)

    Holdsworth, William L.; LaPlant, Kyle E.; Bell, Duane C.; Jahn, Molly M.; Mazourek, Michael

    2016-01-01

    Powdery mildew is a major fungal disease on squash and pumpkin (Cucurbita spp.) in the US and throughout the world. Genetic resistance to the disease is not known to occur naturally within Cucurbita pepo and only infrequently in Cucurbita moschata, but has been achieved in both species through the introgression of a major resistance gene from the wild species Cucurbita okeechobeensis subsp. martinezii. At present, this gene, Pm-0, is used extensively in breeding, and is found in nearly all powdery mildew-resistant C. pepo and C. moschata commercial cultivars. In this study, we mapped C. okeechobeensis subsp. martinezii-derived single nucleotide polymorphism (SNP) alleles in a set of taxonomically and morphologically diverse and resistant C. pepo and C. moschata cultivars bred at Cornell University that, by common possession of Pm-0, form a shared-trait introgression panel. High marker density was achieved using genotyping-by-sequencing, which yielded over 50,000 de novo SNP markers in each of the three Cucurbita species genotyped. A single 516.4 kb wild-derived introgression was present in all of the resistant cultivars and absent in a diverse set of heirlooms that predated the Pm-0 introgression. The contribution of this interval to powdery mildew resistance was confirmed by association mapping in a C. pepo cultivar panel that included the Cornell lines, heirlooms, and 68 additional C. pepo cultivars and with an independent F2 population derived from C. okeechobeensis subsp. martinezii x C. moschata. The interval was refined to a final candidate interval of 76.4 kb and CAPS markers were developed inside this interval to facilitate marker-assisted selection. PMID:27936008

  8. Introgression evidence and phylogenetic relationships among three (ParaMisgurnus species as revealed by mitochondrial and nuclear DNA markers

    Directory of Open Access Journals (Sweden)

    Jakovlić I.

    2013-01-01

    Full Text Available The taxonomy of (ParaMisgurnus genera is still debated. We therefore used mitochondrial and nuclear DNA markers to analyze the phylogenetic relationships among Misgurnus anguillicaudatus, Paramisgurnus dabryanus and Misgurnus fossilis. Differing phylogenetic signals from mitochondrial and nuclear marker data suggest an introgression event in the history of M. anguillicaudatus and M. mohoity. No substantial genetic evidence was found that Paramisgurnus dabryanus should be classified as a separate genus.

  9. Cultivar-Based Introgression Mapping Reveals Wild Species-Derived Pm-0, the Major Powdery Mildew Resistance Locus in Squash.

    Science.gov (United States)

    Holdsworth, William L; LaPlant, Kyle E; Bell, Duane C; Jahn, Molly M; Mazourek, Michael

    2016-01-01

    Powdery mildew is a major fungal disease on squash and pumpkin (Cucurbita spp.) in the US and throughout the world. Genetic resistance to the disease is not known to occur naturally within Cucurbita pepo and only infrequently in Cucurbita moschata, but has been achieved in both species through the introgression of a major resistance gene from the wild species Cucurbita okeechobeensis subsp. martinezii. At present, this gene, Pm-0, is used extensively in breeding, and is found in nearly all powdery mildew-resistant C. pepo and C. moschata commercial cultivars. In this study, we mapped C. okeechobeensis subsp. martinezii-derived single nucleotide polymorphism (SNP) alleles in a set of taxonomically and morphologically diverse and resistant C. pepo and C. moschata cultivars bred at Cornell University that, by common possession of Pm-0, form a shared-trait introgression panel. High marker density was achieved using genotyping-by-sequencing, which yielded over 50,000 de novo SNP markers in each of the three Cucurbita species genotyped. A single 516.4 kb wild-derived introgression was present in all of the resistant cultivars and absent in a diverse set of heirlooms that predated the Pm-0 introgression. The contribution of this interval to powdery mildew resistance was confirmed by association mapping in a C. pepo cultivar panel that included the Cornell lines, heirlooms, and 68 additional C. pepo cultivars and with an independent F2 population derived from C. okeechobeensis subsp. martinezii x C. moschata. The interval was refined to a final candidate interval of 76.4 kb and CAPS markers were developed inside this interval to facilitate marker-assisted selection.

  10. Efficient anchoring of alien chromosome segments introgressed into bread wheat by new Leymus racemosus genome-based markers.

    Science.gov (United States)

    Edet, Offiong Ukpong; Kim, June-Sik; Okamoto, Masanori; Hanada, Kousuke; Takeda, Tomoyuki; Kishii, Masahiro; Gorafi, Yasir Serag Alnor; Tsujimoto, Hisashi

    2018-03-27

    The tertiary gene pool of bread wheat, to which Leymus racemosus belongs, has remained underutilized due to the current limited genomic resources of the species that constitute it. Continuous enrichment of public databases with useful information regarding these species is, therefore, needed to provide insights on their genome structures and aid successful utilization of their genes to develop improved wheat cultivars for effective management of environmental stresses. We generated de novo DNA and mRNA sequence information of L. racemosus and developed 110 polymorphic PCR-based markers from the data, and to complement the PCR markers, DArT-seq genotyping was applied to develop additional 9990 SNP markers. Approximately 52% of all the markers enabled us to clearly genotype 22 wheat-L. racemosus chromosome introgression lines, and L. racemosus chromosome-specific markers were highly efficient in detailed characterization of the translocation and recombination lines analyzed. A further analysis revealed remarkable transferability of the PCR markers to three other important Triticeae perennial species: L. mollis, Psathyrostachys huashanica and Elymus ciliaris, indicating their suitability for characterizing wheat-alien chromosome introgressions carrying chromosomes of these genomes. The efficiency of the markers in characterizing wheat-L. racemosus chromosome introgression lines proves their reliability, and their high transferability further broadens their scope of application. This is the first report on sequencing and development of markers from L. racemosus genome and the application of DArT-seq to develop markers from a perennial wild relative of wheat, marking a paradigm shift from the seeming concentration of the technology on cultivated species. Integration of these markers with appropriate cytogenetic methods would accelerate development and characterization of wheat-alien chromosome introgression lines.

  11. Hybridization, transgressive segregation and evolution of new ...

    Indian Academy of Sciences (India)

    Unknown

    This paper is dedicated to the memory of our teacher, Prof. N. B. ... of genetic variations wherein favourably interacting gene complexes are determined ... speciation. Hybrid-zone studies can yield information ... tic systems and in speciation, using an artificial hybrid ...... process of the development of reproductive isolation in.

  12. Sound Zones

    DEFF Research Database (Denmark)

    Møller, Martin Bo; Olsen, Martin

    2017-01-01

    Sound zones, i.e. spatially confined regions of individual audio content, can be created by appropriate filtering of the desired audio signals reproduced by an array of loudspeakers. The challenge of designing filters for sound zones is twofold: First, the filtered responses should generate...... an acoustic separation between the control regions. Secondly, the pre- and post-ringing as well as spectral deterioration introduced by the filters should be minimized. The tradeoff between acoustic separation and filter ringing is the focus of this paper. A weighted L2-norm penalty is introduced in the sound...

  13. Cytogenetics of Festulolium (Festuca x Lolium hybrids).

    Science.gov (United States)

    Kopecký, D; Lukaszewski, A J; Dolezel, J

    2008-01-01

    Grasses are the most important and widely cultivated crops. Among them, ryegrasses (Lolium spp.) and fescues (Festuca spp.) provide high quality fodder for livestock, are used for turf and amenity purposes, and play a fundamental role in environment protection. Species from the two genera display complementary agronomic characteristics and are often grown in mixtures. Breeding efforts to combine desired features in single entities culminated with the production of Festuca x Lolium hybrids. The so called Festuloliums enjoy a considerable commercial success with numerous cultivars registered all over the world. They are also very intriguing from a strictly cytogenetic point of view as the parental chromosomes recombine freely in hybrids. Until a decade ago this phenomenon was only known in general quantitative terms. The introduction of molecular cytogenetic tools such as FISH and GISH permitted detailed studies of intergeneric chromosome recombination and karyotyping of Festulolium cultivars. These tools were also invaluable in revealing the origin of polyploid fescues, and facilitated the development of chromosome substitution and introgression lines and physical mapping of traits of interest. Further progress in this area will require the development of a larger set of cytogenetic markers and high-resolution cytogenetic maps. It is expected that the Lolium-Festuca complex will continue providing opportunities for breeding superior grass cultivars and the complex will remain an attractive platform for fundamental research of the early steps of hybrid speciation and interaction of parental genomes, as well as the processes of chromosome pairing, elimination and recombination. 2008 S. Karger AG, Basel

  14. Crop to wild introgression in lettuce: following the fate of crop genome segments in backcross populations

    NARCIS (Netherlands)

    Uwimana, B.; Smulders, M.J.M.; Hooftman, D.A.P.; Hartman, Y.; van Tienderen, P.H.; Jansen, J.; McHale, L.K.; Michelmore, R.W.; Visser, R.G.F.; van de Wiel, C.C.M.

    2012-01-01

    Background: After crop-wild hybridization, some of the crop genomic segments may become established in wild populations through selfing of the hybrids or through backcrosses to the wild parent. This constitutes a possible route through which crop (trans)genes could become established in natural

  15. Crop to wild introgression in lettuce: following the fate of crop genome segments in backcross populations

    NARCIS (Netherlands)

    Uwimana, B.; Smulders, M.J.M.; Hooftman, D.A.P.; Hartman, Y.; Tienderen, van P.H.; Jansen, J.; McHale, L.K.; Michelmore, R.; Visser, R.G.F.; Wiel, van de C.C.M.

    2012-01-01

    After crop-wild hybridization, some of the crop genomic segments may become established in wild populations through selfing of the hybrids or through backcrosses to the wild parent. This constitutes a possible route through which crop (trans)genes could become established in natural populations. The

  16. Hybrid fitness, adaptation and evolutionary diversification: lessons learned from Louisiana Irises.

    Science.gov (United States)

    Arnold, M L; Ballerini, E S; Brothers, A N

    2012-03-01

    Estimates of hybrid fitness have been used as either a platform for testing the potential role of natural hybridization in the evolution of species and species complexes or, alternatively, as a rationale for dismissing hybridization events as being of any evolutionary significance. From the time of Darwin's publication of The Origin, through the neo-Darwinian synthesis, to the present day, the observation of variability in hybrid fitness has remained a challenge for some models of speciation. Yet, Darwin and others have reported the elevated fitness of hybrid genotypes under certain environmental conditions. In modern scientific terminology, this observation reflects the fact that hybrid genotypes can demonstrate genotype × environment interactions. In the current review, we illustrate the development of one plant species complex, namely the Louisiana Irises, into a 'model system' for investigating hybrid fitness and the role of genetic exchange in adaptive evolution and diversification. In particular, we will argue that a multitude of approaches, involving both experimental and natural environments, and incorporating both manipulative analyses and surveys of natural populations, are necessary to adequately test for the evolutionary significance of introgressive hybridization. An appreciation of the variability of hybrid fitness leads to the conclusion that certain genetic signatures reflect adaptive evolution. Furthermore, tests of the frequency of allopatric versus sympatric/parapatric divergence (that is, divergence with ongoing gene flow) support hybrid genotypes as a mechanism of evolutionary diversification in numerous species complexes.

  17. IDENTIFICATION AND MAPPING OF A GENE FOR RICE SLENDER KERNEL USING Oryza glumaepatula INTROGRESSION LINES

    Directory of Open Access Journals (Sweden)

    Sobrizal Sobrizal

    2016-10-01

    Full Text Available World demand for superior rice grain quality tends to increase. One of the  criteria of appearance quality of rice grain is grain shape. Rice consumers  exhibit wide preferences for grain shape, but most Indonesian rice consumers prefer long and slender grain. The objectives of this study were to identify and map a gene for rice slender kernel trait using Oryza  glumaepatula introgression lines with O. sativa cv. Taichung 65 genetic background. A segregation analysis of BC4F2 population derived from backcrosses of a donor parent O. glumaepatula into a recurrent parent Taichung 65 showed that the slender kernel was controlled by a single recessive gene. This new identified gene was designated as sk1 (slender kernel 1. Moreover, based on the RFLP analyses using 14 RFLP markers located on chromosomes 2, 8, 9, and 10 in which the O. glumaepatula chromosomal segments were retained in BC4F2 population, the sk1 was located between RFLP markers C679 and C560 on the long arm of chromosome 2, with map distances of 2.8 and 1.5 cM, respectively. The wild rice O. glumaepatula carried a recessive allele for slender kernel. This allele may be useful in breeding of rice with slender kernel types. In addition, the development of plant materials and RFLP map associated with slender kernel in this study is the preliminary works in the effort to isolate this important grain shape gene.

  18. Targeted introgression of cotton fibre quality quantitative trait loci using molecular markers

    International Nuclear Information System (INIS)

    Lacape, J.M.; Trung-Bieu Nguyen; Hau, B.; Giband, M.

    2007-01-01

    Within the framework of a cotton breeding programme, molecular markers are used to improve the efficiency of the introgression of fibre quality traits of Gossypium barbadense into G. hirsutum. A saturated genetic map was developed based on genotyping data obtained from the BC 1 (75 plants) and BC 2 (200 plants) generations. Phenotypic measurements conducted over three generations (BC 1 , BC 2 and BC 2 S 1 ) allowed 80 quantitative trait loci (QTL) to be detected for fibre length, uniformity, strength, elongation, fineness and colour. Positive QTL, i.e. those for which favourable alleles came from the G. barbadense parent, were harboured by 19 QTL-rich regions on 15 'carrier' chromosomes. In subsequent generations (BC 3 and BC 4 ), markers framing the QTL-rich regions were used to select about 10 percent of over 400 plants analysed in each generation. Although BC plants selected through the marker-assisted selection (MAS) process show promising fibre quality, only their full field evaluation will allow validation of the procedure. (author)

  19. The Birth of a Black Rice Gene and Its Local Spread by Introgression.

    Science.gov (United States)

    Oikawa, Tetsuo; Maeda, Hiroaki; Oguchi, Taichi; Yamaguchi, Takuya; Tanabe, Noriko; Ebana, Kaworu; Yano, Masahiro; Ebitani, Takeshi; Izawa, Takeshi

    2015-09-01

    The origin and spread of novel agronomic traits during crop domestication are complex events in plant evolution. Wild rice (Oryza rufipogon) has red grains due to the accumulation of proanthocyanidins, whereas most cultivated rice (Oryza sativa) varieties have white grains induced by a defective allele in the Rc basic helix-loop-helix (bHLH) gene. Although the events surrounding the origin and spread of black rice traits remain unknown, varieties with black grains due to anthocyanin accumulation are distributed in various locations throughout Asia. Here, we show that the black grain trait originated from ectopic expression of the Kala4 bHLH gene due to rearrangement in the promoter region. Both the Rc and Kala4 genes activate upstream flavonol biosynthesis genes, such as chalcone synthase and dihydroflavonol-4-reductase, and downstream genes, such as leucoanthocyanidin reductase and leucoanthocyanidin dioxygenase, to produce the respective specific pigments. Genome analysis of 21 black rice varieties as well as red- and white-grained landraces demonstrated that black rice arose in tropical japonica and its subsequent spread to the indica subspecies can be attributed to the causal alleles of Kala4. The relatively small size of genomic fragments of tropical japonica origin in some indica varieties indicates that refined introgression must have occurred by natural crossbreeding in the course of evolution of the black trait in rice. © 2015 American Society of Plant Biologists. All rights reserved.

  20. Introgression of novel traits from a wild wheat relative improves drought adaptation in wheat.

    Science.gov (United States)

    Placido, Dante F; Campbell, Malachy T; Folsom, Jing J; Cui, Xinping; Kruger, Greg R; Baenziger, P Stephen; Walia, Harkamal

    2013-04-01

    Root architecture traits are an important component for improving water stress adaptation. However, selection for aboveground traits under favorable environments in modern cultivars may have led to an inadvertent loss of genes and novel alleles beneficial for adapting to environments with limited water. In this study, we elucidate the physiological and molecular consequences of introgressing an alien chromosome segment (7DL) from a wild wheat relative species (Agropyron elongatum) into cultivated wheat (Triticum aestivum). The wheat translocation line had improved water stress adaptation and higher root and shoot biomass compared with the control genotypes, which showed significant drops in root and shoot biomass during stress. Enhanced access to water due to higher root biomass enabled the translocation line to maintain more favorable gas-exchange and carbon assimilation levels relative to the wild-type wheat genotypes during water stress. Transcriptome analysis identified candidate genes associated with root development. Two of these candidate genes mapped to the site of translocation on chromosome 7DL based on single-feature polymorphism analysis. A brassinosteroid signaling pathway was predicted to be involved in the novel root responses observed in the A. elongatum translocation line, based on the coexpression-based gene network generated by seeding the network with the candidate genes. We present an effective and highly integrated approach that combines root phenotyping, whole-plant physiology, and functional genomics to discover novel root traits and the underlying genes from a wild related species to improve drought adaptation in cultivated wheat.

  1. Genetic Analysis of Kernel Traits in Maize-Teosinte Introgression Populations

    Directory of Open Access Journals (Sweden)

    Zhengbin Liu

    2016-08-01

    Full Text Available Seed traits have been targeted by human selection during the domestication of crop species as a way to increase the caloric and nutritional content of food during the transition from hunter-gather to early farming societies. The primary seed trait under selection was likely seed size/weight as it is most directly related to overall grain yield. Additional seed traits involved in seed shape may have also contributed to larger grain. Maize (Zea mays ssp. mays kernel weight has increased more than 10-fold in the 9000 years since domestication from its wild ancestor, teosinte (Z. mays ssp. parviglumis. In order to study how size and shape affect kernel weight, we analyzed kernel morphometric traits in a set of 10 maize-teosinte introgression populations using digital imaging software. We identified quantitative trait loci (QTL for kernel area and length with moderate allelic effects that colocalize with kernel weight QTL. Several genomic regions with strong effects during maize domestication were detected, and a genetic framework for kernel traits was characterized by complex pleiotropic interactions. Our results both confirm prior reports of kernel domestication loci and identify previously uncharacterized QTL with a range of allelic effects, enabling future research into the genetic basis of these traits.

  2. Transcriptome alteration in a rice introgression line with enhanced alkali tolerance.

    Science.gov (United States)

    Zhang, Yunhong; Lin, Xiuyun; Ou, Xiufang; Hu, Lanjuan; Wang, Jinming; Yang, Chunwu; Wang, Shucai; Liu, Bao

    2013-07-01

    Alkali stress inhibits plant growth and development and thus limits crop productivity. To investigate the possible genetic basis of alkali tolerance in rice, we generated an introgressed rice line (K83) with significantly enhanced tolerance to alkali stress compared to its recipient parental cultivar (Jijing88). By using microarray analysis, we examined the global gene expression profiles of K83 and Jijing88, and found that more than 1200 genes were constitutively and differentially expressed in K83 in comparison to Jijing88 with 572 genes up- and 654 down-regulated. Upon alkali treatment, a total of 347 genes were found up- and 156 down-regulated in K83 compared to 591 and 187, respectively, in Jijing88. Among the up-regulated genes in both K83 and Jijing88, only 34 were constitutively up-regulated in K83, suggesting that both the constitutive differentially expressed genes in K83 and those induced by alkali treatment are most likely responsible for enhanced alkali tolerance. A gene ontology analysis based on all annotated, differentially expressed genes revealed that genes with expression alterations were enriched in pathways involved in metabolic processes, catalytic activity, and transport and transcription factor activities, suggesting that these pathways are associated with alkali stress tolerance in rice. Our results illuminated the novel genetic aspects of alkali tolerance in rice and established a repertory of potential target genes for biotechnological manipulations that can be used to generate alkali-tolerant rice cultivars. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  3. Coastal zone

    International Nuclear Information System (INIS)

    2002-01-01

    The report entitled Climate Change Impacts and Adaptation : A Canadian Perspective, presents a summary of research regarding the impacts of climate change on key sectors over the past five years as it relates to Canada. This chapter on the coastal zone focuses on the impact of climate change on Canada's marine and Great Lakes coasts with tips on how to deal with the impacts associated with climate change in sensitive environments. This report is aimed at the sectors that will be most affected by adaptation decisions in the coastal zone, including fisheries, tourism, transportation and water resources. The impact of climate change in the coastal zone may include changes in water levels, wave patterns, storm surges, and thickness of seasonal ice cover. The Intergovernmental Panel on Climate Change projects global average sea level will rise between 9 and 88 centimetres between 1990 to 2100, but not all areas of Canada will experience the same rate of future sea level change. The main physical impact would be shoreline change that could result in a range of biophysical and socio-economic impacts, some beneficial, some negative. The report focuses on issues related to infrastructure and communities in coastal regions. It is noted that appropriate human adaptation will play a vital role in reducing the extent of potential impacts by decreasing the vulnerability of average zone to climate change. The 3 main trends in coastal adaptation include: (1) increase in soft protection, retreat and accommodation, (2) reliance on technology such as geographic information systems to manage information, and (3) awareness of the need for coastal adaptation that is appropriate for local conditions. 61 refs., 7 figs

  4. Molecular Characterization of Natural Hybrids Formed between Five Related Indigenous Clade 6 Phytophthora Species

    Science.gov (United States)

    Burgess, Treena I.

    2015-01-01

    Most Phytophthora hybrids characterized to date have emerged from nurseries and managed landscapes, most likely generated as a consequence of biological invasions associated with the movement of living plants and germplasm for ornamental, horticultural and agricultural purposes. Presented here is evidence for natural hybridization among a group of five closely related indigenous clade 6 Phytophthora species isolated from waterways and riparian ecosystems in Western Australia. Molecular characterization of hybrids consisted of cloning and sequencing two nuclear genes (ITS and ASF), sequencing of two further nuclear loci (BT and HSP) and of two mitochondrial loci (COI and NADH). Additionally, phenotypic traits including morphology of sporangia and optima and maxima temperatures for growth were also determined. In most cases the nuclear genes were biparentally and in all cases the mtDNA were uniparentally inherited, indicating hybrid formation through sexual crosses. Some isolates bear the molecular signature of three parents suggesting additional hybrid events, although it cannot be determined from the data if these were sequential or simultaneous. These species and their hybrids co-exist in riparian ecosystems and waterways where their ability for rapid asexual proliferation would enable them to rapidly colonize green plant litter. The apparent ease of hybridization could eventually lead to the merging of species through introgression. However, at this point in time, species integrity has been maintained and a more likely scenario is that the hybrids are not stable evolutionary lineages, but rather transient hybrid clones. PMID:26248187

  5. Hybridization rates between lettuce (Lactuca sativa) and its wild relative (L. serriola) under field conditions.

    Science.gov (United States)

    D'Andrea, Luigi; Felber, François; Guadagnuolo, Roberto

    2008-01-01

    Hybridization and introgression between crops and wild relatives may have important evolutionary and ecological consequences such as gene swamping or increased invasiveness. In the present study, we investigated hybridization under field conditions between crop lettuce (Lactuca sativa) and its wild relative prickly lettuce (L. serriola), two cross-compatible, predominantly autogamous and insect pollinated species. In 2003 and 2004, we estimated the rates of hybridization between L. sativa and L. serriola in close-to-reality field experiments carried out in two locations of Northern Switzerland. Seeds set by the experimental wild plants were collected and sown (44 352 in 2003 and 252 345 in 2004). Progeny was screened morphologically for detecting natural hybrids. Prior to the experiment, specific RAPD markers were used to confirm that morphological characters were reliable for hybrid identification. Hybridization occurred up to the maximal distance tested (40 m), and hybridization rates varied between 0 to 26%, decreasing with distance. More than 80% of the wild plants produced at least one hybrid (incidence of hybridization, IH) at 0 m and 1 m. It equaled 4 to 5% at 40 m. In sympatric crop-wild populations, cross-pollination between cultivated lettuce and its wild relative has to be seen as the rule rather than the exception for short distances.

  6. The maintenance of hybrids by parasitism in a freshwater snail.

    Science.gov (United States)

    Guttel, Yonathan; Ben-Ami, Frida

    2014-11-01

    Hybrids have often been labelled evolutionary dead-ends due to their lower fertility and viability. However, there is growing awareness that hybridisation between different species may play a constructive role in animal evolution as a means to create variability. Thus, hybridisation and introgression may contribute to adaptive evolution, for example with regards to natural antagonists (parasites, predators, competitors) and adaptation to local environmental conditions. Here we investigated whether parasite intensity contributes to the continuous recreation of hybrids in 74 natural populations of Melanopsis, a complex of freshwater snails with three species. We also examined, under laboratory conditions, whether hybrids and their parental taxa differ in their tolerance of low and high temperatures and salinity levels. Infections were consistently less prevalent in males than in females, and lower in snails from deeper habitats. Infection prevalence in hybrids was significantly lower than in the parental taxa. Low hybrid infection rates could not be explained by sediment type, snail density or geographic distribution of the sampling sites. Interestingly, infected hybrid snails did not show signs of parasite-induced gigantism, whereas all parental taxa did. We found that hybrids mostly coped with extreme temperatures and salinity levels as well as their parental taxa did. Taken together, our results suggest that Melanopsis hybrids perform better in the presence of parasites and environmental stress. This may explain the widespread and long-term occurrence of Melanopsis hybrids as evidenced by paleontological and biogeographic data. Hybridisation may be an adaptive host strategy, reducing infection rates and resisting gigantism. Copyright © 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

  7. On the complexity of the Saccharomyces bayanus taxon: hybridization and potential hybrid speciation.

    Directory of Open Access Journals (Sweden)

    Laura Pérez-Través

    Full Text Available Although the genus Saccharomyces has been thoroughly studied, some species in the genus has not yet been accurately resolved; an example is S. bayanus, a taxon that includes genetically diverse lineages of pure and hybrid strains. This diversity makes the assignation and classification of strains belonging to this species unclear and controversial. They have been subdivided by some authors into two varieties (bayanus and uvarum, which have been raised to the species level by others. In this work, we evaluate the complexity of 46 different strains included in the S. bayanus taxon by means of PCR-RFLP analysis and by sequencing of 34 gene regions and one mitochondrial gene. Using the sequence data, and based on the S. bayanus var. bayanus reference strain NBRC 1948, a hypothetical pure S. bayanus was reconstructed for these genes that showed alleles with similarity values lower than 97% with the S. bayanus var. uvarum strain CBS 7001, and of 99-100% with the non S. cerevisiae portion in S. pastorianus Weihenstephan 34/70 and with the new species S. eubayanus. Among the S. bayanus strains under study, different levels of homozygosity, hybridization and introgression were found; however, no pure S. bayanus var. bayanus strain was identified. These S. bayanus hybrids can be classified into two types: homozygous (type I and heterozygous hybrids (type II, indicating that they have been originated by different hybridization processes. Therefore, a putative evolutionary scenario involving two different hybridization events between a S. bayanus var. uvarum and unknown European S. eubayanus-like strains can be postulated to explain the genomic diversity observed in our S. bayanus var. bayanus strains.

  8. Detection of nitrogen deficiency QTL in juvenile wild barley introgression lines growing in a hydroponic system

    Directory of Open Access Journals (Sweden)

    Hoffmann Astrid

    2012-10-01

    Full Text Available Abstract Background In this report we studied the genetic regulation of juvenile development of wild barley introgression lines (S42ILs under two contrasting hydroponic nitrogen (N supplies. Ten shoot and root related traits were examined among 42 S42ILs and the recurrent parent ‘Scarlett’. The traits included tiller number, leaf number, plant height, leaf and root length, leaf to root length ratio, shoots and root dry weight, shoot to root weight ratio, and chlorophyll content. Our aims were (1 to test the suitability of a hydroponic system for early detection of favourable S42ILs, (2 to locate quantitative trait loci (QTL that control the examined traits, (3 to identify favourable wild barley alleles that improve trait performances in regard to N treatment and, finally, (4 to validate the identified QTL through comparison with previously reported QTL originating from the same parental cross. Results The phenotypic data were analysed in a mixed model association study to detect QTL. The post-hoc Dunnett test identified 28 S42ILs that revealed significant (P Hsp effects for tiller number, leaf number, leaf length, plant height and leaf to root ratio on the long arm of chromosome 7H. These QTL correspond to QTL for ears per plant and plant height that were previously detected in field trials conducted with the same S42ILs or with the S42 population. Conclusion Our results suggest that the QTL we identified under hydroponic N cultivation partly correspond to QTL detected in field experiments. Due to this finding, screening of plants in early developmental stages grown in a hydroponic system may be a fast and cost effective method for early QTL detection and marker-assisted allelic selection, potentially speeding up elite barley breeding programs.

  9. Variability and performance evaluation of introgressed Nigerian dura x Deli dura oil palm progenies.

    Science.gov (United States)

    Noh, A; Rafii, M Y; Mohd Din, A; Kushairi, A; Norziha, A; Rajanaidu, N; Latif, M A; Malek, M A

    2014-04-03

    Twelve introgressed oil palm (Elaeis guineensis) progenies of Nigerian dura x Deli dura were evaluated for bunch yield, yield attributes, bunch quality components and vegetative characters at the Malaysian Palm Oil Board Research Station, in Keratong, Pahang, Malaysia. Analysis of variance revealed significant to highly significant genotypic differences, indicating sufficient genetic variability among the progenies for bunch yield and its attributes, vegetative characters and bunch quality components, except fruit to bunch ratio. Fresh fruit bunch yield ranged from 167 kg·palm(-1)·year(-1) in PK1330 to 212 kg·palm(-1)·year(-1) in PK1351, with a mean yield of 192 kg·palm(-1)·year(-1). Among the progeny, PK1313 had the highest oil to bunch ratio (19.36%), due to its high mesocarp to fruit ratio, fruit to bunch ratio and low shell to fruit ratio. Among the progenies, PK1313 produced the highest oil yield of 31.4 kg·palm(-1)·year(-1), due to a high mesocarp to fruit ratio (61.2%) and a low shell to fruit ratio (30.7%), coupled with high fruit to bunch ratio (65.6%). PK1330 was found promising for selection, as it had desirable vegetative characters, including smaller petiole cross section (27.15 cm2), short rachis length (4.83 m), short palm height (1.85 m), and the lowest leaf number (164.6), as these vegetative characters are prerequisites for selecting palms for high density planting and high yield per hectare. The genetic variability among the progenies was found to be high, indicating ample scope for further breeding, followed by selection.

  10. Introgression of ivermectin resistance genes into a susceptible Haemonchus contortus strain by multiple backcrossing.

    Directory of Open Access Journals (Sweden)

    Elizabeth Redman

    2012-02-01

    Full Text Available Anthelmintic drug resistance in livestock parasites is already widespread and in recent years there has been an increasing level of anthelmintic drug selection pressure applied to parasitic nematode populations in humans leading to concerns regarding the emergence of resistance. However, most parasitic nematodes, particularly those of humans, are difficult experimental subjects making mechanistic studies of drug resistance extremely difficult. The small ruminant parasitic nematode Haemonchus contortus is a more amenable model system to study many aspects of parasite biology and investigate the basic mechanisms and genetics of anthelmintic drug resistance. Here we report the successful introgression of ivermectin resistance genes from two independent ivermectin resistant strains, MHco4(WRS and MHco10(CAVR, into the susceptible genome reference strain MHco3(ISE using a backcrossing approach. A panel of microsatellite markers were used to monitor the procedure. We demonstrated that after four rounds of backcrossing, worms that were phenotypically resistant to ivermectin had a similar genetic background to the susceptible reference strain based on the bulk genotyping with 18 microsatellite loci and individual genotyping with a sub-panel of 9 microsatellite loci. In addition, a single marker, Hcms8a20, showed evidence of genetic linkage to an ivermectin resistance-conferring locus providing a starting point for more detailed studies of this genomic region to identify the causal mutation(s. This work presents a novel genetic approach to study anthelmintic resistance and provides a "proof-of-concept" of the use of forward genetics in an important model strongylid parasite of relevance to human hookworms. The resulting strains provide valuable resources for candidate gene studies, whole genome approaches and for further genetic analysis to identify ivermectin resistance loci.

  11. Detection of nitrogen deficiency QTL in juvenile wild barley introgression lines growing in a hydroponic system.

    Science.gov (United States)

    Hoffmann, Astrid; Maurer, Andreas; Pillen, Klaus

    2012-10-20

    In this report we studied the genetic regulation of juvenile development of wild barley introgression lines (S42ILs) under two contrasting hydroponic nitrogen (N) supplies. Ten shoot and root related traits were examined among 42 S42ILs and the recurrent parent 'Scarlett'. The traits included tiller number, leaf number, plant height, leaf and root length, leaf to root length ratio, shoots and root dry weight, shoot to root weight ratio, and chlorophyll content. Our aims were (1) to test the suitability of a hydroponic system for early detection of favourable S42ILs, (2) to locate quantitative trait loci (QTL) that control the examined traits, (3) to identify favourable wild barley alleles that improve trait performances in regard to N treatment and, finally, (4) to validate the identified QTL through comparison with previously reported QTL originating from the same parental cross. The phenotypic data were analysed in a mixed model association study to detect QTL. The post-hoc Dunnett test identified 28 S42ILs that revealed significant (P hydroponic N study corresponded to QTL that were also detected in field trials with adult plants of a similar S42IL set or of the original S42 population. For instance, S42IL-135, -136 and -137, revealed increasing Hsp effects for tiller number, leaf number, leaf length, plant height and leaf to root ratio on the long arm of chromosome 7H. These QTL correspond to QTL for ears per plant and plant height that were previously detected in field trials conducted with the same S42ILs or with the S42 population. Our results suggest that the QTL we identified under hydroponic N cultivation partly correspond to QTL detected in field experiments. Due to this finding, screening of plants in early developmental stages grown in a hydroponic system may be a fast and cost effective method for early QTL detection and marker-assisted allelic selection, potentially speeding up elite barley breeding programs.

  12. Reduced SNP panels for genetic identification and introgression analysis in the dark honey bee (Apis mellifera mellifera.

    Directory of Open Access Journals (Sweden)

    Irene Muñoz

    Full Text Available Beekeeping activities, especially queen trading, have shaped the distribution of honey bee (Apis mellifera subspecies in Europe, and have resulted in extensive introductions of two eastern European C-lineage subspecies (A. m. ligustica and A. m. carnica into the native range of the M-lineage A. m. mellifera subspecies in Western Europe. As a consequence, replacement and gene flow between native and commercial populations have occurred at varying levels across western European populations. Genetic identification and introgression analysis using molecular markers is an important tool for management and conservation of honey bee subspecies. Previous studies have monitored introgression by using microsatellite, PCR-RFLP markers and most recently, high density assays using single nucleotide polymorphism (SNP markers. While the latter are almost prohibitively expensive, the information gained to date can be exploited to create a reduced panel containing the most ancestry-informative markers (AIMs for those purposes with very little loss of information. The objective of this study was to design reduced panels of AIMs to verify the origin of A. m. mellifera individuals and to provide accurate estimates of the level of C-lineage introgression into their genome. The discriminant power of the SNPs using a variety of metrics and approaches including the Weir & Cockerham's FST, an FST-based outlier test, Delta, informativeness (In, and PCA was evaluated. This study shows that reduced AIMs panels assign individuals to the correct origin and calculates the admixture level with a high degree of accuracy. These panels provide an essential tool in Europe for genetic stock identification and estimation of admixture levels which can assist management strategies and monitor honey bee conservation programs.

  13. Hybrid reactors

    International Nuclear Information System (INIS)

    Moir, R.W.

    1980-01-01

    The rationale for hybrid fusion-fission reactors is the production of fissile fuel for fission reactors. A new class of reactor, the fission-suppressed hybrid promises unusually good safety features as well as the ability to support 25 light-water reactors of the same nuclear power rating, or even more high-conversion-ratio reactors such as the heavy-water type. One 4000-MW nuclear hybrid can produce 7200 kg of 233 U per year. To obtain good economics, injector efficiency times plasma gain (eta/sub i/Q) should be greater than 2, the wall load should be greater than 1 MW.m -2 , and the hybrid should cost less than 6 times the cost of a light-water reactor. Introduction rates for the fission-suppressed hybrid are usually rapid

  14. Conservation of the Red Kite Milvus milvus (Aves: Accipitriformes) is not affected by the establishment of a broad hybrid zone with the Black Kite Milvus migrans migrans in central Europe

    Czech Academy of Sciences Publication Activity Database

    Heneberg, P.; Dolinay, Matej; Matušík, H.; Pfeiffer, T.; Nachtigall, W.; Bizos, J.; Šimčíková, D.; Literák, I.

    2016-01-01

    Roč. 11, č. 7 (2016), č. článku 159202. E-ISSN 1932-6203 Institutional support: RVO:68081766 Keywords : Old-World vultures * mitochondrial DNA * harriers circus * bird * gene * sterility * Eagles * hybridization * phylogeny Subject RIV: EG - Zoology Impact factor: 2.806, year: 2016

  15. Unidirectional hybridization at a species' range boundary: implications for habitat tracking

    DEFF Research Database (Denmark)

    Beatty, Gemma, E.; Philipp, Marianne; Provan, Jim

    2010-01-01

    hybridization may lead to the extinction of peripheral populations of P. minor where the two species grow sympatrically. Extinction could occur as a result of genetic assimilation where F1s are fertile, or via the removal of unidirectionally pollinated sterile F1s, or by a combination of these processes......Aim Introgressive hybridization between a locally rare species and a more abundant congener can drive population extinction via genetic assimilation, or the replacement of the rare species gene pool with that of the common species. To date, however, few studies have assessed the effects...... of such processes at the limits of species' distribution ranges. In this study, we have examined the potential for hybridization between range-edge populations of the wintergreen Pyrola minor and sympatric populations of Pyrola grandiflora. Location Qeqertarsuaq, Greenland and Churchill, Manitoba, Canada. Methods...

  16. Transfer of bacterial blight resistance from Oryza meyeriana to O.Sativa L.by asymmetric somatic hybridization

    Institute of Scientific and Technical Information of China (English)

    ZHU Yongsheng; CHEN Baotang; YU Shunwu; ZHANG Duanpin; ZHANG Xueqin; YAN Qiusheng

    2004-01-01

    Asymmetric somatic hybrid plants were produced between cultivated rice (Oryza sativa L.) and wild species [O. Meyeriana (Zoll. etMor, exSteud.)] with high resistance to rice bacterial blight. X-ray-irradiated protoplasts of the wild species were used as donor and chemically fused with iodoacetamide-inactivated protoplasts of rice cv. 02428to produce hybrids. Seventy-two plants were regenerated from 623 calli based on metabolic complementation. The morphological characters of the plants closely resembled that of the rice. Simple sequence repeats were employed to identify their hybridity. Cytological analysis of root-tips revealed that their chromosome number varied in the range of 27-38. The somatic hybrids were inoculated with strains of Xanthamonas oryzae pv. Oryzae at adult growth stage and demonstrated the resistance to bacterial blight introgression from the O. Meyeriana.

  17. Hybridization dynamics between Colorado's native cutthroat trout and introduced rainbow trout.

    Science.gov (United States)

    Metcalf, Jessica L; Siegle, Matthew R; Martin, Andrew P

    2008-01-01

    Newly formed hybrid populations provide an opportunity to examine the initial consequences of secondary contact between species and identify genetic patterns that may be important early in the evolution of hybrid inviability. Widespread introductions of rainbow trout (Oncorhynchus mykiss) into watersheds with native cutthroat trout (Oncorhynchus clarkii) have resulted in hybridization. These introductions have contributed to the decline of native cutthroat trout populations. Here, we examine the pattern of hybridization between introduced rainbow trout and 2 populations of cutthroat trout native to Colorado. For this study, we utilized 7 diagnostic, codominant nuclear markers and a diagnostic mitochondrial marker to investigate hybridization in a population of greenback cutthroat trout (Oncorhynchus clarkii stomias) and a population of Colorado River cutthroat trout (Oncorhynchus clarkii pleuriticus). We infer that cutthroat-rainbow trout hybrid swarms have formed in both populations. Although a mixture of hybrid genotypes was present, not all genotype combinations were detected at expected frequencies. We found evidence that mitochondrial DNA introgression in hybrids is asymmetric and more likely from rainbow trout than from cutthroat trout. A difference in spawning time of the 2 species or differences in the fitness between the reciprocal crosses may explain the asymmetry. Additionally, the presence of intraspecific cytonuclear associations found in both populations is concordant with current hypotheses regarding coevolution of mitochondrial and nuclear genomes.

  18. Shoal bass hybridization in the Chattahoochee River Basin near Atlanta, Georgia

    Science.gov (United States)

    Taylor, Andrew T.; Tringali, Michael D.; O'Rourke, Patrick M.; Long, James M.

    2018-01-01

    The shoal bass (Micropterus cataractae) is a sportfish endemic to the Apalachicola-Chattahoochee-Flint Basin of the southeastern United States. Introgression with several non-native congeners poses a pertinent threat to shoal bass conservation, particularly in the altered habitats of the Chattahoochee River. Our primary objective was to characterize hybridization in shoal bass populations near Atlanta, Georgia, including a population inhabiting Big Creek and another in the main stem Chattahoochee River below Morgan Falls Dam (MFD). A secondary objective was to examine the accuracy of phenotypic identifications below MFD based on a simplified suite of characters examined in the field. Fish were genotyped with 16 microsatellite DNA markers, and results demonstrated that at least four black bass species were involved in introgressive hybridization. Of 62 fish genotyped from Big Creek, 27% were pure shoal bass and 65% represented either F1 hybrids of shoal bass x smallmouth bass (M. dolomieu) or unidirectional backcrosses towards shoal bass. Of 29 fish genotyped below MFD and downstream at Cochran Shoals, 45% were pure shoal bass. Six hybrid shoal bass included both F1 hybrids and backcrosses with non-natives including Alabama bass (M. henshalli), spotted bass (M. punctulatus), and smallmouth bass. Shoal bass alleles comprised only 21% of the overall genomic composition in Big Creek and 31% below MFD (when combined with Cochran Shoals). Phenotypic identification below MFD resulted in an overall correct classification rate of 86% when discerning pure shoal bass from all other non-natives and hybrids. Results suggest that although these two shoal bass populations feature some of the highest introgression rates documented, only a fleeting opportunity may exist to conserve pure shoal bass in both populations. Continued supplemental stocking of pure shoal bass below MFD appears warranted to thwart increased admixture among multiple black bass taxa, and a similar stocking

  19. Heritability and genetic advance studies for biochemical traits in F2-3 introgressed families of Brassica

    International Nuclear Information System (INIS)

    Farhatullah, N.K.; Khalil, I.H.; Nahed, H.

    2015-01-01

    Higher heritability estimates along with high genetic advance values are effective in envisaging gain under selection in developing genotypes. The objective of the present study was to evaluate variability, heritability and genetic advance in 10 interspecific F2-3 families of Brassica species (B. napus * B. juncea, B. napus * B. rapa). These families were studied for heterospecific introgression of biochemical traits. Low to high heritability estimates were recorded for seed quality traits. Considerable variations within F2-3 families were observed for biochemical traits. Most of the F2-3 families for oil content and erucic showed moderate to high heritability indicating the slightest influence of environment thus modification of trait by selection would be more effective. Among F2-3 introgressed families Bn-510 x Bj-109 produced high oil i.e., 49.5% while Bn-532 x Br-118 (24.4%), Bn-533 x Bj-109 (24.1%) and high protein percentage in terms of mean performance. In the present research, individual segregating progenies of interspecific cross populations i.e., which possessed combination of desirable traits, were identified which could be incorporated in the future Breeding programs and it may facilitate varietal development. (author)

  20. Hybrid composites

    CSIR Research Space (South Africa)

    Jacob John, Maya

    2009-04-01

    Full Text Available mixed short sisal/glass hybrid fibre reinforced low density polyethylene composites was investigated by Kalaprasad et al [25].Chemical surface modifications such as alkali, acetic anhydride, stearic acid, permanganate, maleic anhydride, silane...

  1. Hybrid intermediaries

    OpenAIRE

    Cetorelli, Nicola

    2014-01-01

    I introduce the concept of hybrid intermediaries: financial conglomerates that control a multiplicity of entity types active in the "assembly line" process of modern financial intermediation, a system that has become known as shadow banking. The complex bank holding companies of today are the best example of hybrid intermediaries, but I argue that financial firms from the "nonbank" space can just as easily evolve into conglomerates with similar organizational structure, thus acquiring the cap...

  2. Marker-assisted introgression of opaque2 allele for rapid conversion ...

    Indian Academy of Sciences (India)

    Running title: ... develop diverse QPM varieties across different maturity groups and ..... (c) Morphological characteristics of MAS-derived inbreds: .... Kaul J., Dass S., Sekhar J.C. and Bhardwaj J.C. 2009 Maize hybrid and .... Figure captions: ..... blade; CL: cob length; CG: cob girth; NR: No. of rows; NKR: No. of kernel per row; ...

  3. Prospects for introgressing tomato chromosomes into the potato genome: An assessment through GISH analysis

    NARCIS (Netherlands)

    Garriga Calderé, F.; Huigen, D.J.; Jacobsen, E.; Ramanna, M.S.

    1999-01-01

    With a view to assess the possibility of homoeologous pairing and crossing-over between the chromosomes of potato (Solanum tuberosum) and tomato (Lycopersicon esculentum), a somatic fusion hybrid and two monosomic alien tomato addition genotypes were investigated through genomic in situ

  4. Genetic dissection of hybrid incompatibilities between Drosophila simulans and D. mauritiana. II. Mapping hybrid male sterility loci on the third chromosome.

    Science.gov (United States)

    Tao, Yun; Zeng, Zhao-Bang; Li, Jian; Hartl, Daniel L; Laurie, Cathy C

    2003-08-01

    Hybrid male sterility (HMS) is a rapidly evolving mechanism of reproductive isolation in Drosophila. Here we report a genetic analysis of HMS in third-chromosome segments of Drosophila mauritiana that were introgressed into a D. simulans background. Qualitative genetic mapping was used to localize 10 loci on 3R and a quantitative trait locus (QTL) procedure (multiple-interval mapping) was used to identify 19 loci on the entire chromosome. These genetic incompatibilities often show dominance and complex patterns of epistasis. Most of the HMS loci have relatively small effects and generally at least two or three of them are required to produce complete sterility. Only one small region of the third chromosome of D. mauritiana by itself causes a high level of infertility when introgressed into D. simulans. By comparison with previous studies of the X chromosome, we infer that HMS loci are only approximately 40% as dense on this autosome as they are on the X chromosome. These results are consistent with the gradual evolution of hybrid incompatibilities as a by-product of genetic divergence in allopatric populations.

  5. Comparing two approaches for introgression of germplasm from Aegilops tauschii into common wheat

    Directory of Open Access Journals (Sweden)

    Thomas S. Cox

    2017-10-01

    Full Text Available Allelic diversity in the wild grass Aegilops tauschii is vastly greater than that in the D genome of common wheat (Triticum aestivum, of which Ae. tauschii is the source. Since the 1980s, there have been numerous efforts to harness a much larger share of Ae. tauschii's extensive and highly variable gene pool for wheat improvement. Those efforts have followed two distinct approaches: production of amphiploids, known as “synthetic hexaploids,” between T. turgidum and Ae. tauschii, and direct hybridization between T. aestivum and Ae. tauschii; both approaches then involve backcrossing to T. aestivum. Both synthetic hexaploid production and direct hybridization have led to the transfer of numerous new genes into common wheat that confer improvements in many traits. This work has led to release of improved cultivars in China, the United States, and many other countries. Each approach to D-genome improvement has advantages and disadvantages. For example, production of synthetic hexaploids can incorporate useful germplasm from both T. turgidum and Ae. tauschii, thereby enhancing the A, B, and D genomes; on the other hand, direct hybridization rapidly restores the recurrent parent's A and B genomes and avoids incorporation of genes with adverse effects on threshability, hybrid necrosis, vernalization response, milling and baking quality, and other traits, which are often transferred when T. turgidum is used as a parent. Choice of method will depend in part on the type of wheat being developed and the target environment. However, more extensive use of the so-far underexploited direct hybridization approach is especially warranted.

  6. Rangewide genetic analysis of Lesser Prairie-Chicken reveals population structure, range expansion, and possible introgression

    Science.gov (United States)

    Oyler-McCance, Sara J.; DeYoung, Randall W; Fike, Jennifer; Hagen, Christian A.; Johnson, Jeff A.; Larsson, Lena C.; Patten, Michael

    2016-01-01

    The distribution of the Lesser Prairie-Chicken (Tympanuchus pallidicinctus) has been markedly reduced due to loss and fragmentation of habitat. Portions of the historical range, however, have been recolonized and even expanded due to planting of conservation reserve program (CRP) fields that provide favorable vegetation structure for Lesser Prairie-Chickens. The source population(s) feeding the range expansion is unknown, yet has resulted in overlap between Lesser and Greater Prairie-Chickens (T. cupido) increasing the potential for hybridization. Our objectives were to characterize connectivity and genetic diversity among populations, identify source population(s) of recent range expansion, and examine hybridization with the Greater Prairie-Chicken. We analyzed 640 samples from across the range using 13 microsatellites. We identified three to four populations corresponding largely to ecoregions. The Shinnery Oak Prairie and Sand Sagebrush Prairie represented genetically distinct populations (F ST > 0.034 and F ST > 0.023 respectively). The Shortgrass/CRP Mosaic and Mixed Grass ecoregions appeared admixed (F ST = 0.009). Genetic diversity was similar among ecoregions and N e ranged from 142 (95 % CI 99–236) for the Shortgrass/CRP Mosaic to 296 (95 % CI 233–396) in the Mixed Grass Prairie. No recent migration was detected among ecoregions, except asymmetric dispersal from both the Mixed Grass Prairie and to a lesser extent the Sand Sagebrush Prairie north into adjacent Shortgrass/CRP Mosaic (m = 0.207, 95 % CI 0.116–0.298, m = 0.097, 95 % CI 0.010–0.183, respectively). Indices investigating potential hybridization in the Shortgrass/CRP Mosaic revealed that six of the 13 individuals with hybrid phenotypes were significantly admixed suggesting hybridization. Continued monitoring of diversity within and among ecoregions is warranted as are actions promoting genetic connectivity and range expansion.

  7. Isoenzymatic variability in progeny of Pinus mugo Turra x Pinus sylvestris L. hybrids from Bór na Czerwonem, in experimental culture

    Directory of Open Access Journals (Sweden)

    Maria A. Bobowicz

    2014-01-01

    Full Text Available The article describes the genetic structure of 12-year old seedlings. They were grown in an experimental culture representing the progeny of natural hybrids of Pinus mugo Turra and Pinus sylvestris L. from the peatbog Bór na Czerwonem. The studies were carried out on seedlings, employing electrophoresis of enzymatic proteins from winter buds. Parallel isoenzymatic analyses were also conducted for trees of P. mugo Turra from Tatra Mountains and for P. sylvestris L. trees from Białowieża in order to determine similarities of the hybrids to the 'pure' species, thought to represent parental forms, and for natural hybrids from Bór na Czerwonem. The obtained electrophoretic patterns made the determination of genetic structure of the population possible, namely of the observed heterozygosity, expected heterozygosity, Wright's fixation index and coefficients of similarity according to Nei and Hedrick. Genetic distances between the populations were also estimated. The variability of 11 enzymatic loci demonstrated the highest level of variability in the population of hybrids. Coefficients of genetic differentiation (GST and of gene flow, (Nm suggested a close relationship of the hybrids to P. mugo which may indicate an introgressive type of the hybrid swarm, from which the studied trees originated. The analysis of genetic similarity coefficients, according to Nei and Hedrick, demonstrated also an extensive similarity of the two hybrid groups to P. mugo. However, upon analysis of individual enzymatic loci, some of them highly resembled P. mugo while others were similar to P. sylvestris. The closest genetic similarity was demonstrated for the group of hybrids from the peatbog and the respective of hybrides group from culture. The variable gene expression as well as asymmetric inheritance of isoenzymes provided additional evidence of the introgressive character of the studied trees from the hybrid population.

  8. Genetic structure of Miscanthus sinensis and M. sacchariflorus in Japan indicates a gradient of bidirectional but asymmetric introgression

    DEFF Research Database (Denmark)

    Clark, Lindsay V; Stewart, J Ryan; Nishiwaki, Aya

    2015-01-01

    Unilateral introgression from diploids to tetraploids has been hypothesized to be an important evolutionary mechanism in plants. However, few examples have been definitively identified, perhaps because data of sufficient depth and breadth were difficult to obtain before the advent of affordable...

  9. Identification, introgression, and molecular marker genetic analysis and selection of a highly effective novel oat crown rust resistance from diploid oat, Avena strigosa

    Science.gov (United States)

    A new highly effective resistance to oat crown rust (Puccinia coronata f. sp. avenae) was identified in the diploid oat Avena strigosa PI 258731 and introgressed into hexaploid cultivated oat. Young plants with this resistance show moderate susceptibility, whereas older plant tissues and adult plant...

  10. Introgression of heat shock protein (Hsp70 and sHsp) genes into the Malaysian elite chilli variety Kulai (Capsicum annuum L.) through the application of marker-assisted backcrossing (MAB).

    Science.gov (United States)

    Usman, Magaji G; Rafii, Mohd Y; Martini, Mohammad Y; Yusuff, Oladosu A; Ismail, Mohd R; Miah, Gous

    2018-03-01

    Backcrossing together with simple sequence repeat marker strategy was adopted to improve popular Malaysian chilli Kulai (Capsicum annuum L.) for heat tolerance. The use of molecular markers in backcross breeding and selection contributes significantly to overcoming the main drawbacks such as increase linkage drag and time consumption, in the ancient manual breeding approach (conventional), and speeds up the genome recovery of the recurrent parent. The strategy was adopted to introgress heat shock protein gene(s) from AVPP0702 (C. annuum L.), which are heat-tolerant, into the genetic profile of Kulai, a popular high-yielding chilli but which is heat sensitive. The parents were grown on seed trays, and parental screening was carried out with 252 simple sequence repeat markers. The selected parents were crossed and backcrossed to generate F 1 hybrids and backcross generations. Sixty-eight markers appeared to be polymorphic and were used to assess the backcross generation; BC 1 F 1 , BC 2 F 1 and BC 3 F 1 . The average recipient allele of the selected four BC 1 F 1 plants was 80.75% which were used to produce the BC 2 F 1 generation. BC 1 -P 7 was the best BC 1 F 1 plant because it had the highest recovery at 83.40% and was positive to Hsp-linked markers (Hsp70-u2 and AGi42). After three successive generations of backcrossing, the average genome recovery of the recurrent parent in the selected plants in BC 3 F 1 was 95.37%. Hsp gene expression analysis was carried out on BC 1 F 1 , BC 2 F 1 and BC 3 F 1 selected lines. The Hsp genes were found to be up-regulated when exposed to heat treatment. The pattern of Hsp expression in the backcross generations was similar to that of the donor parent. This confirms the successful introgression of a stress-responsive gene (Hsp) into a Kulai chilli pepper variety. Furthermore, the yield performance viz. plant height, number of fruits, fruit length and weight and total yield of the improved plant were similar with the recurrent

  11. Genetics of reproductive isolation in the Drosophila simulans clade: complex epistasis underlying hybrid male sterility.

    Science.gov (United States)

    Cabot, E L; Davis, A W; Johnson, N A; Wu, C I

    1994-05-01

    We have analyzed the sterility associated with introgressions of the distal one-fourth of the X chromosome from either Drosophila mauritiana or Drosophila sechellia into the genome of Drosophila simulans using a series of visible and DNA markers. Because in Drosophila hybrids, male sterility is usually complete and is often tightly linked with each of several markers used in crosses, a simple genetic basis has generally been assumed. In our low resolution mapping experiment, we were not able to reject the null hypothesis that a single gene, introgressed from either D. mauritiana or D. sechellia, is the cause of male sterility. High resolution mapping, however, reveals a much more complex picture. At least three distinct factors from D. mauritiana, or two from D. sechellia, were identified that need to be jointly present to confer full sterility. Each individual factor by itself is relatively ineffective in causing sterility, or even a partial spermatogenic defect. Moreover, there appear to be more sterility factors on comparable introgressions from D. mauritiana than from D. sechellia. On the basis of these observations, we propose a model which suggests that multilocus weak allele interactions are a very common cause of reproductive incompatibility between closely related species. We also present theoretical argument and empirical evidence against extrapolating the results of within-species analysis to interpret the genetic basis of species differences. The implications of this model on the theories of evolution of species differences and the attempt to understand the mechanisms of hybrid sterility/inviability at the molecular level are discussed.

  12. Species delineation and hybrid identification using diagnostic nuclear markers for Plectropomus leopardus and Plectropomus maculatus

    KAUST Repository

    He, Song

    2018-06-01

    Diagnostic molecular markers are an essential tool in the study of species’ ecology and evolution, particularly in closely related and sympatric species. Furthermore, the increasing awareness of wild-hybrids has led to a renewed interest in rapid diagnostic assays. Here, we test the ability of two mitochondrial (Cytb and COI) and two nuclear markers (ETS2 and TMO-4c4) to confidently discriminate purebred P. leopardus and P. maculatus and their first-generation hybrids. A sample of 48 purebred individuals and 91 interspecific hybrids were used in this study and their delineation confirmed using a set of microsatellite markers. Our results indicate mitochondrial markers could not distinguish even between species but both nuclear markers confidently identified species and first-generation hybrids. However, later-generation hybrids could not always be confidently identified due to on-going introgression between species. Our findings provide a robust tool to distinguish purebred individuals and interspecific hybrids in a pair of species with an unexpectedly high incidence of hybridization. The quick species discrimination abilities provided by these diagnostic markers are important for stock assessment and recruitment studies of these important fishery species.

  13. Occurrence of metaxenia and false hybrids in Brassica juncea L. cv. Kikarashina × B. napus

    Science.gov (United States)

    Tsuda, Mai; Konagaya, Ken-ichi; Okuzaki, Ayako; Kaneko, Yukio; Tabei, Yutaka

    2011-01-01

    Imported genetically modified (GM) canola (Brassica napus) is approved by Japanese law. Some GM canola varieties have been found around importation sites, and there is public concern that these may have any harmful effects on related species such as reduction of wild relatives. Because B. juncea is distributed throughout Japan and is known to be high crossability with B. napus, it is assumed to be a recipient of B. napus. However, there are few reports for introgression of cross-combination in B. juncea × B. napus. To assess crossability, we artificially pollinated B. juncea with B. napus. After harvesting a large number of progeny seeds, we observed false hybrids and metaxenia of seed coats. Seed coat color was classified into four categories and false hybrids were confirmed by morphological characteristics and random amplified polymorphic DNA (RAPD) markers. Furthermore, the occurrence of false hybrids was affected by varietal differences in B. napus, whereas that of metaxenia was related to hybridity. Therefore, we suggest that metaxenia can be used as a marker for hybrid identification in B. juncea L. cv. Kikarashina × B. napus. Our results suggest that hybrid productivity in B. juncea × B. napus should not be evaluated by only seed productivity, crossability ought to be assessed the detection of true hybrids. PMID:23136472

  14. Species delineation and hybrid identification using diagnostic nuclear markers for Plectropomus leopardus and Plectropomus maculatus

    KAUST Repository

    He, Song; Harrison, Hugo B.; Berumen, Michael L.

    2018-01-01

    Diagnostic molecular markers are an essential tool in the study of species’ ecology and evolution, particularly in closely related and sympatric species. Furthermore, the increasing awareness of wild-hybrids has led to a renewed interest in rapid diagnostic assays. Here, we test the ability of two mitochondrial (Cytb and COI) and two nuclear markers (ETS2 and TMO-4c4) to confidently discriminate purebred P. leopardus and P. maculatus and their first-generation hybrids. A sample of 48 purebred individuals and 91 interspecific hybrids were used in this study and their delineation confirmed using a set of microsatellite markers. Our results indicate mitochondrial markers could not distinguish even between species but both nuclear markers confidently identified species and first-generation hybrids. However, later-generation hybrids could not always be confidently identified due to on-going introgression between species. Our findings provide a robust tool to distinguish purebred individuals and interspecific hybrids in a pair of species with an unexpectedly high incidence of hybridization. The quick species discrimination abilities provided by these diagnostic markers are important for stock assessment and recruitment studies of these important fishery species.

  15. Hybridization of two major termite invaders as a consequence of human activity.

    Science.gov (United States)

    Chouvenc, Thomas; Helmick, Ericka E; Su, Nan-Yao

    2015-01-01

    While hybridization of an invasive species with a native species is a common occurrence, hybridization between two invasive species is rare. Formosan subterranean termites (Coptotermes formosanus) and Asian subterranean termites (C. gestroi) are both ecologically successful and are the two most economically important termite pests in the world. Both species have spread throughout many areas of the world due to human activity; however, their distributions overlap in only three narrow areas because of distinct ecological requirements. In south Florida, where C. formosanus and C. gestroi are both invasive, the dispersal flight seasons of both species overlapped for the first time on record in 2013 and 2014. Pairings of heterospecific individuals were readily observed in the field and C. gestroi males preferentially engaged in mating behavior with C. formosanus females rather than females from their own species. In the laboratory, heterospecific and conspecific pairings had an equal colony establishment rate, but heterospecific incipient colonies had twice the growth rate of conspecific incipient colonies, suggesting a potential case of hybrid vigor. As all pre-zygotic barriers were lifted between the two species in the field, the apparent absence of post-zygotic barriers in the laboratory raises the possibility for introgressive hybridization in south Florida. While laboratory observations remain to be confirmed in the field, and the alate hybrid fertility is currently unknown, our results raise a tangible concern about the hybridization of two major destructive pest species. Such hybridization would likely be associated with a new economic impact.

  16. Hybridization of two major termite invaders as a consequence of human activity.

    Directory of Open Access Journals (Sweden)

    Thomas Chouvenc

    Full Text Available While hybridization of an invasive species with a native species is a common occurrence, hybridization between two invasive species is rare. Formosan subterranean termites (Coptotermes formosanus and Asian subterranean termites (C. gestroi are both ecologically successful and are the two most economically important termite pests in the world. Both species have spread throughout many areas of the world due to human activity; however, their distributions overlap in only three narrow areas because of distinct ecological requirements. In south Florida, where C. formosanus and C. gestroi are both invasive, the dispersal flight seasons of both species overlapped for the first time on record in 2013 and 2014. Pairings of heterospecific individuals were readily observed in the field and C. gestroi males preferentially engaged in mating behavior with C. formosanus females rather than females from their own species. In the laboratory, heterospecific and conspecific pairings had an equal colony establishment rate, but heterospecific incipient colonies had twice the growth rate of conspecific incipient colonies, suggesting a potential case of hybrid vigor. As all pre-zygotic barriers were lifted between the two species in the field, the apparent absence of post-zygotic barriers in the laboratory raises the possibility for introgressive hybridization in south Florida. While laboratory observations remain to be confirmed in the field, and the alate hybrid fertility is currently unknown, our results raise a tangible concern about the hybridization of two major destructive pest species. Such hybridization would likely be associated with a new economic impact.

  17. Molecular mapping of the novel powdery mildew resistance gene Pm36 introgressed from Triticum turgidum var. dicoccoides in durum wheat.

    Science.gov (United States)

    Blanco, Antonio; Gadaleta, A; Cenci, A; Carluccio, A V; Abdelbacki, A M M; Simeone, R

    2008-06-01

    Powdery mildew, caused by Blumeria graminis f.sp. tritici, is one of the most important wheat diseases in many regions of the world. Triticum turgidum var. dicoccoides (2n=4x=AABB), the progenitor of cultivated wheats, shows particular promises as a donor of useful genetic variation for several traits, including disease resistances. The wild emmer accession MG29896, resistant to powdery mildew, was backcrossed to the susceptible durum wheat cultivar Latino, and a set of backcross inbred lines (BC(5)F(5)) was produced. Genetic analysis of F(3) populations from two resistant introgression lines (5BIL-29 x Latino and 5BIL-42 x Latino) indicated that the powdery mildew resistance is controlled by a single dominant gene. Molecular markers and the bulked segregant analysis were used to characterize and map the powdery mildew resistance. Five AFLP markers (XP43M32((250)), XP46M31((410)), XP41M37((100)), XP41M39((250)), XP39M32((120))), three genomic SSR markers (Xcfd07, Xwmc75, Xgwm408) and one EST-derived SSR marker (BJ261635) were found to be linked to the resistance gene in 5BIL-29 and only the BJ261635 marker in 5BIL-42. By means of Chinese Spring nullisomic-tetrasomic, ditelosomic and deletion lines, the polymorphic markers and the resistance gene were assigned to chromosome bin 5BL6-0.29-0.76. These results indicated that the two lines had the same resistance gene and that the introgressed dicoccoides chromosome segment was longer (35.5 cM) in 5BIL-29 than that introgressed in 5BIL-42 (less than 1.5 cM). As no powdery mildew resistance gene has been reported on chromosome arm 5BL, the novel resistance gene derived from var. dicoccoides was designated Pm36. The 244 bp allele of BJ261635 in 5BIL-42 can be used for marker-assisted selection during the wheat resistance breeding process for facilitating gene pyramiding.

  18. Introgression and pyramiding into common bean market class fabada of genes conferring resistance to anthracnose and potyvirus.

    Science.gov (United States)

    Ferreira, Juan José; Campa, Ana; Pérez-Vega, Elena; Rodríguez-Suárez, Cristina; Giraldez, Ramón

    2012-03-01

    Anthracnose and bean common mosaic (BCM) are considered major diseases in common bean crop causing severe yield losses worldwide. This work describes the introgression and pyramiding of genes conferring genetic resistance to BCM and anthracnose local races into line A25, a bean genotype classified as market class fabada. Resistant plants were selected using resistance tests or combining resistance tests and marker-assisted selection. Lines A252, A321, A493, Sanilac BC6-Are, and BRB130 were used as resistance sources. Resistance genes to anthracnose (Co-2 ( C ), Co-2 ( A252 ) and Co-3/9) and/or BCM (I and bc-3) were introgressed in line A25 through six parallel backcrossing programs, and six breeding lines showing a fabada seed phenotype were obtained after six backcross generations: line A1258 from A252; A1231 from A321; A1220 from A493; A1183 and A1878 from Sanilac BC6-Are; and line A2418 from BRB130. Pyramiding of different genes were developed using the pedigree method from a single cross between lines obtained in the introgression step: line A1699 (derived from cross A1258 × A1220), A2438 (A1220 × A1183), A2806 (A1878 × A2418), and A3308 (A1699 × A2806). A characterization based on eight morpho-agronomic traits revealed a limited differentiation among the obtained breeding lines and the recurrent line A25. However, using a set of seven molecular markers linked to the loci used in the breeding programs it was possible to differentiate the 11 fabada lines. Considering the genetic control of the resistance in resistant donor lines, the observed segregations in the last backcrossing generation, the reaction against the pathogens, and the expression of the molecular markers it was also possible to infer the genotype conferring resistance in the ten fabada breeding lines obtained. As a result of these breeding programs, genetic resistance to three anthracnose races controlled by genes included in clusters Co-2 and Co-3/9, and genetic resistance to BCM controlled

  19. Feasible introgression of an anti-pathogen transgene into an urban mosquito population without using gene-drive.

    Directory of Open Access Journals (Sweden)

    Kenichi W Okamoto

    2014-07-01

    Full Text Available Introgressing anti-pathogen constructs into wild vector populations could reduce disease transmission. It is generally assumed that such introgression would require linking an anti-pathogen gene with a selfish genetic element or similar technologies. Yet none of the proposed transgenic anti-pathogen gene-drive mechanisms are likely to be implemented as public health measures in the near future. Thus, much attention now focuses instead on transgenic strategies aimed at mosquito population suppression, an approach generally perceived to be practical. By contrast, aiming to replace vector competent mosquito populations with vector incompetent populations by releasing mosquitoes carrying a single anti-pathogen gene without a gene-drive mechanism is widely considered impractical.Here we use Skeeter Buster, a previously published stochastic, spatially explicit model of Aedes aegypti to investigate whether a number of approaches for releasing mosquitoes with only an anti-pathogen construct would be efficient and effective in the tropical city of Iquitos, Peru. To assess the performance of such releases using realistic release numbers, we compare the transient and long-term effects of this strategy with two other genetic control strategies that have been developed in Ae. aegypti: release of a strain with female-specific lethality, and a strain with both female-specific lethality and an anti-pathogen gene. We find that releasing mosquitoes carrying only an anti-pathogen construct can substantially decrease vector competence of a natural population, even at release ratios well below that required for the two currently feasible alternatives that rely on population reduction. Finally, although current genetic control strategies based on population reduction are compromised by immigration of wild-type mosquitoes, releasing mosquitoes carrying only an anti-pathogen gene is considerably more robust to such immigration.Contrary to the widely held view that

  20. Generation of a multi-locus chicken introgression line to study the effects of genetic interactions on metabolic phenotypes in chickens

    Directory of Open Access Journals (Sweden)

    Weronica eEk

    2012-03-01

    Full Text Available Most biological traits are regulated by a complex interplay between genetic and environmental factors. By intercrossing divergent lines, it is possible to identify individual and interacting QTL involved in the genetic architecture of these traits. When the loci have been mapped, alternative strategies are needed for fine-mapping and studying the individual and interactive effects of the QTL in detail. We have previously identified, replicated and fine-mapped a four-locus QTL network that determines nearly half of the eight-fold difference in body-weight at 56 days of age between two divergently selected chicken lines. Here, we describe, to our knowledge, the first generation of a three-locus QTL introgression line in chickens to further study the effect of three of the interacting loci in this network on metabolic phenotypes. Recurrent marker assisted backcrossing was used to simultaneously transfer QTL alleles from the low-weight selected line into the high-weight selected line. Three generations of backcrossing and one generation of intercrossing resulted in an introgression line where all three introgressed QTL and several unlinked and linked control-loci were segregating at nearly expected allele frequencies. We show that marker-based sexing is an efficient method for sexing breeding populations and how intensive selection can be applied using artificial insemination to generate large half-sib families. Based on our empirical observations, we provide recommendations for future introgression-line breeding experiments. In the future, use of this confirmed introgression line will facilitate detailed studies of the effects of genetic interactions on complex traits.

  1. Mapping of stripe rust resistance gene in an Aegilops caudate introgression line in wheat and its genetic association with leaf rust resistance.

    Science.gov (United States)

    Toor, Puneet Inder; Kaur, Satinder; Bansal, Mitaly; Yadav, Bharat; Chhuneja, Parveen

    2016-12-01

    A pair of stripe rust and leaf rust resistance genes was introgressed from Aegilops caudata, a nonprogenitor diploid species with the CC genome, to cultivated wheat. Inheritance and genetic mapping of stripe rust resistance gene in backcrossrecombinant inbred line (BC-RIL) population derived from the cross of a wheat-Ae. caudata introgression line (IL) T291- 2(pau16060) with wheat cv. PBW343 is reported here. Segregation of BC-RILs for stripe rust resistance depicted a single major gene conditioning adult plant resistance (APR) with stripe rust reaction varying from TR-20MS in resistant RILs signifying the presence of some minor genes as well. Genetic association with leaf rust resistance revealed that two genes are located at a recombination distance of 13%. IL T291-2 had earlier been reported to carry introgressions on wheat chromosomes 2D, 3D, 4D, 5D, 6D and 7D. Genetic mapping indicated the introgression of stripe rust resistance gene on wheat chromosome 5DS in the region carrying leaf rust resistance gene LrAc, but as an independent introgression. Simple sequence repeat (SSR) and sequence-tagged site (STS) markers designed from the survey sequence data of 5DS enriched the target region harbouring stripe and leaf rust resistance genes. Stripe rust resistance locus, temporarily designated as YrAc, mapped at the distal most end of 5DS linked with a group of four colocated SSRs and two resistance gene analogue (RGA)-STS markers at a distance of 5.3 cM. LrAc mapped at a distance of 9.0 cM from the YrAc and at 2.8 cM from RGA-STS marker Ta5DS_2737450, YrAc and LrAc appear to be the candidate genes for marker-assisted enrichment of the wheat gene pool for rust resistance.

  2. Hybridization relics complicate barcode-based identification of species in earthworms.

    Science.gov (United States)

    Dupont, L; Porco, D; Symondson, W O C; Roy, V

    2016-07-01

    Introgressive hybridization results in mito-nuclear discordance which could obscure the delimitation of closely related taxa. Although such events are increasingly reported, they have been poorly studied in earthworms. Here, we propose a method for investigating the degree of introgressive hybridization between three taxa of the Allolobophora chlorotica aggregate within two field populations (N = 67 and N = 105) using a reference data set including published DNA barcoding and microsatellite data of all known A. chlorotica lineages (N = 85). For this, we used both molecular phylogenetic and population genetic approaches. The test of correspondence between mitochondrial cytochrome c oxidase I (COI) lineages and clusters of nuclear microsatellite genotypes allowed individuals to be sorted in three categories (matching, admixed and nonmatching) and additional markers (mitochondrial NADH dehydrogenase subunit 1, nuclear Histone 3 and Internal transcribed Spacer Region 2) were used for phylogenetic reconstructions in order to check assignments. Although 15 admixed individuals were observed, no early-generation hybrids were detected within the two populations. Interestingly, 14 nonmatching individuals (i.e. with a mtDNA haplotype that did not correspond to their nuclear cluster) were detected, a pattern that would result after multiple generations of unidirectional hybridization of female from one taxon to male of the other taxon. Because earthworms are simultaneous hermaphrodites, these events of unidirectional hybridization suggest sterility of the male function in several crosses and highlight that some individuals can be misidentified if reliance is placed on COI barcodes alone. These findings could improve the use of these barcodes in earthworms for species delineation. © 2016 John Wiley & Sons Ltd.

  3. Zone separator for multiple zone vessels

    Science.gov (United States)

    Jones, John B.

    1983-02-01

    A solids-gas contact vessel, having two vertically disposed distinct reaction zones, includes a dynamic seal passing solids from an upper to a lower zone and maintaining a gas seal against the transfer of the separate treating gases from one zone to the other, and including a stream of sealing fluid at the seal.

  4. Repeated trans-watershed hybridization among haplochromine cichlids (Cichlidae) was triggered by Neogene landscape evolution.

    Science.gov (United States)

    Schwarzer, Julia; Swartz, Ernst Roelof; Vreven, Emmanuel; Snoeks, Jos; Cotterill, Fenton Peter David; Misof, Bernhard; Schliewen, Ulrich Kurt

    2012-11-07

    The megadiverse haplochromine cichlid radiations of the East African lakes, famous examples of explosive speciation and adaptive radiation, are according to recent studies, introgressed by different riverine lineages. This study is based on the first comprehensive mitochondrial and nuclear DNA dataset from extensive sampling of riverine haplochromine cichlids. It includes species from the lower River Congo and Angolan (River Kwanza) drainages. Reconstruction of phylogenetic hypotheses revealed the paradox of clearly discordant phylogenetic signals. Closely related mtDNA haplotypes are distributed thousands of kilometres apart and across major African watersheds, whereas some neighbouring species carry drastically divergent mtDNA haplotypes. At shallow and deep phylogenetic layers, strong signals of hybridization are attributed to the complex Late Miocene/Early Pliocene palaeohistory of African rivers. Hybridization of multiple lineages across changing watersheds shaped each of the major haplochromine radiations in lakes Tanganyika, Victoria, Malawi and the Kalahari Palaeolakes, as well as a miniature species flock in the Congo basin (River Fwa). On the basis of our results, introgression occurred not only on a spatially restricted scale, but massively over almost the whole range of the haplochromine distribution. This provides an alternative view on the origin and exceptional high diversity of this enigmatic vertebrate group.

  5. Experimental Crossing of Two Distinct Species of Leopard Geckos, Eublepharis angramainyu and E. macularius: Viability, Fertility and Phenotypic Variation of the Hybrids.

    Directory of Open Access Journals (Sweden)

    Jitka Jančúchová-Lásková

    Full Text Available Hybridization between distinct species of animals and subsequent genetic introgression plays a considerable role in the speciation process and the emergence of adaptive characters. Fitness of between-species hybrids usually sharply decreases with the divergence time of the concerned species and the divergence depth, which still allows for a successful crossing differs among principal clades of vertebrates. Recently, a review of hybridization events among distinct lizard species revealed that lizards belong to vertebrates with a highly developed ability to hybridize. In spite of this, reliable reports of experimental hybridizations between genetically fairly divergent species are only exceptional. Here, we show the results of the crossing of two distinct allopatric species of eyelid geckos possessing temperature sex determination and lacking sex chromosomes: Eublepharis macularius distributed in Pakistan/Afghanistan area and E. angramainyu, which inhabits Mesopotamia and adjacent areas. We demonstrated that F1 hybrids were viable and fertile, and the introgression of E. angramainyu genes into the E. macularius genome can be enabled via a backcrossing. The examined hybrids (except those of the F2 generation displayed neither malformations nor a reduced survival. Analyses of morphometric and coloration traits confirmed phenotypic distinctness of both parental species and their F1 hybrids. These findings contrast with long-term geographic and an evolutionary separation of the studied species. Thus, the occurrence of fertile hybrids of comparably divergent species, such as E. angramainyu and E. macularius, may also be expected in other taxa of squamates. This would violate the current estimates of species diversity in lizards.

  6. The existence of fertile hybrids of closely related model earthworm species, Eisenia andrei and E. fetida.

    Directory of Open Access Journals (Sweden)

    Barbara Plytycz

    Full Text Available Lumbricid earthworms Eisenia andrei (Ea and E. fetida (Ef are simultaneous hermaphrodites with reciprocal insemination capable of self-fertilization while the existence of hybridization of these two species was still debatable. During the present investigation fertile hybrids of Ea and Ef were detected. Virgin specimens of Ea and Ef were laboratory crossed (Ea+Ef and their progeny was doubly identified. 1 -identified by species-specific maternally derived haploid mitochondrial DNA sequences of the COI gene being either 'a' for worms hatched from Ea ova or 'f' for worms hatched from Ef ova. 2 -identified by the diploid maternal/paternal nuclear DNA sequences of 28s rRNA gene being either 'AA' for Ea, 'FF' for Ef, or AF/FA for their hybrids derived either from the 'aA' or 'fF' ova, respectively. Among offspring of Ea+Ef pairs in F1 generation there were mainly aAA and fFF earthworms resulted from the facilitated self-fertilization and some aAF hybrids from aA ova but none fFA hybrids from fF ova. In F2 generation resulting from aAF hybrids mated with aAA a new generations of aAA and aAF hybrids were noticed, while aAF hybrids mated with fFF gave fFF and both aAF and fFA hybrids. Hybrids intercrossed together produced plenty of cocoons but no hatchlings independently whether aAF+aAF or aAF+fFA were mated. These results indicated that Ea and Ef species, easy to maintain in laboratory and commonly used as convenient models in biomedicine and ecotoxicology, may also serve in studies on molecular basis of interspecific barriers and mechanisms of introgression and speciation. Hypothetically, their asymmetrical hybridization can be modified by some external factors.

  7. Mechanisms of Transmission Ratio Distortion at Hybrid Sterility Loci Within and Between Mimulus Species

    Directory of Open Access Journals (Sweden)

    Rachel E. Kerwin

    2017-11-01

    Full Text Available Hybrid incompatibilities are a common correlate of genomic divergence and a potentially important contributor to reproductive isolation. However, we do not yet have a detailed understanding of how hybrid incompatibility loci function and evolve within their native species, or why they are dysfunctional in hybrids. Here, we explore these issues for a well-studied, two-locus hybrid incompatibility between hybrid male sterility 1 (hms1 and hybrid male sterility 2 (hms2 in the closely related yellow monkeyflower species Mimulus guttatus and M. nasutus. By performing reciprocal backcrosses with introgression lines (ILs, we find evidence for gametic expression of the hms1-hms2 incompatibility. Surprisingly, however, hybrid transmission ratios at hms1 do not reflect this incompatibility, suggesting that additional mechanisms counteract the effects of gametic sterility. Indeed, our backcross experiment shows hybrid transmission bias toward M. guttatus through both pollen and ovules, an effect that is particularly strong when hms2 is homozygous for M. nasutus alleles. In contrast, we find little evidence for hms1 transmission bias in crosses within M. guttatus, providing no indication of selfish evolution at this locus. Although we do not yet have sufficient genetic resolution to determine if hybrid sterility and transmission ratio distortion (TRD map to the same loci, our preliminary fine-mapping uncovers a genetically independent hybrid lethality system involving at least two loci linked to hms1. This fine-scale dissection of TRD at hms1 and hms2 provides insight into genomic differentiation between closely related Mimulus species and reveals multiple mechanisms of hybrid dysfunction.

  8. Mechanisms of Transmission Ratio Distortion at Hybrid Sterility Loci Within and Between Mimulus Species.

    Science.gov (United States)

    Kerwin, Rachel E; Sweigart, Andrea L

    2017-11-06

    Hybrid incompatibilities are a common correlate of genomic divergence and a potentially important contributor to reproductive isolation. However, we do not yet have a detailed understanding of how hybrid incompatibility loci function and evolve within their native species, or why they are dysfunctional in hybrids. Here, we explore these issues for a well-studied, two-locus hybrid incompatibility between hybrid male sterility 1 ( hms1 ) and hybrid male sterility 2 ( hms2 ) in the closely related yellow monkeyflower species Mimulus guttatus and M. nasutus By performing reciprocal backcrosses with introgression lines (ILs), we find evidence for gametic expression of the hms1-hms2 incompatibility. Surprisingly, however, hybrid transmission ratios at hms1 do not reflect this incompatibility, suggesting that additional mechanisms counteract the effects of gametic sterility. Indeed, our backcross experiment shows hybrid transmission bias toward M. guttatus through both pollen and ovules, an effect that is particularly strong when hms2 is homozygous for M. nasutus alleles. In contrast, we find little evidence for hms1 transmission bias in crosses within M. guttatus , providing no indication of selfish evolution at this locus. Although we do not yet have sufficient genetic resolution to determine if hybrid sterility and transmission ratio distortion (TRD) map to the same loci, our preliminary fine-mapping uncovers a genetically independent hybrid lethality system involving at least two loci linked to hms1 This fine-scale dissection of TRD at hms1 and hms2 provides insight into genomic differentiation between closely related Mimulus species and reveals multiple mechanisms of hybrid dysfunction. Copyright © 2017 Kerwin and Sweigart.

  9. Genotype × environment interactions of yield traits in backcross introgression lines derived from Oryza sativa cv. Swarna /Oryza nivara

    Directory of Open Access Journals (Sweden)

    Divya Balakrishnan

    2016-10-01

    Full Text Available Advanced backcross introgression lines (BILs developed from crosses of Oryza sativa var. Swarna/O. nivara accessions were grown and evaluated for yield and related traits. Trials were conducted for consecutive three seasons in field conditions in a randomized complete block design with three replications. Data on yield traits under irrigated conditions were analyzed using the Additive Main Effect and Multiplicative Interaction (AMMI, Genotype and Genotype × Environment Interaction (GGE and modified rank-sum statistic (YSi for yield stability. BILs viz., G3 (14S and G6 (166S showed yield stability across the seasons along with high mean yield performance. G3 is early in flowering with high yield and has good grain quality and medium height, hence could be recommended for most of the irrigated locations. G6 is a late duration genotype, with strong culm strength, high grain number and panicle weight. G6 has higher yield and stability than Swarna but has Swarna grain type. Among the varieties tested DRRDhan 40 and recurrent parent Swarna showed stability for yield traits across the seasons. The component traits thousand grain weight, panicle weight, panicle length, grain number and plant height explained highest genotypic percentage over environment and interaction factors and can be prioritized to dissect stable QTLs/ genes. These lines were genotyped using microsatellite markers covering the entire rice genome and also using a set of markers linked to previously reported yield QTLs. It was observed that wild derived lines with more than 70% of recurrent parent genome were stable and showed enhanced yield levels compared to genotypes with higher donor genome introgressions.

  10. The high-quality genome of Brassica napus cultivar 'ZS11' reveals the introgression history in semi-winter morphotype.

    Science.gov (United States)

    Sun, Fengming; Fan, Guangyi; Hu, Qiong; Zhou, Yongming; Guan, Mei; Tong, Chaobo; Li, Jiana; Du, Dezhi; Qi, Cunkou; Jiang, Liangcai; Liu, Weiqing; Huang, Shunmou; Chen, Wenbin; Yu, Jingyin; Mei, Desheng; Meng, Jinling; Zeng, Peng; Shi, Jiaqin; Liu, Kede; Wang, Xi; Wang, Xinfa; Long, Yan; Liang, Xinming; Hu, Zhiyong; Huang, Guodong; Dong, Caihua; Zhang, He; Li, Jun; Zhang, Yaolei; Li, Liangwei; Shi, Chengcheng; Wang, Jiahao; Lee, Simon Ming-Yuen; Guan, Chunyun; Xu, Xun; Liu, Shengyi; Liu, Xin; Chalhoub, Boulos; Hua, Wei; Wang, Hanzhong

    2017-11-01

    Allotetraploid oilseed rape (Brassica napus L.) is an agriculturally important crop. Cultivation and breeding of B. napus by humans has resulted in numerous genetically diverse morphotypes with optimized agronomic traits and ecophysiological adaptation. To further understand the genetic basis of diversification and adaptation, we report a draft genome of an Asian semi-winter oilseed rape cultivar 'ZS11' and its comprehensive genomic comparison with the genomes of the winter-type cultivar 'Darmor-bzh' as well as two progenitors. The integrated BAC-to-BAC and whole-genome shotgun sequencing strategies were effective in the assembly of repetitive regions (especially young long terminal repeats) and resulted in a high-quality genome assembly of B. napus 'ZS11'. Within a short evolutionary period (~6700 years ago), semi-winter-type 'ZS11' and the winter-type 'Darmor-bzh' maintained highly genomic collinearity. Even so, certain genetic differences were also detected in two morphotypes. Relative to 'Darmor-bzh', both two subgenomes of 'ZS11' are closely related to its progenitors, and the 'ZS11' genome harbored several specific segmental homoeologous exchanges (HEs). Furthermore, the semi-winter-type 'ZS11' underwent potential genomic introgressions with B. rapa (A r ). Some of these genetic differences were associated with key agronomic traits. A key gene of A03.FLC3 regulating vernalization-responsive flowering time in 'ZS11' was first experienced HE, and then underwent genomic introgression event with A r , which potentially has led to genetic differences in controlling vernalization in the semi-winter types. Our observations improved our understanding of the genetic diversity of different B. napus morphotypes and the cultivation history of semi-winter oilseed rape in Asia. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  11. Historical introgression of the downy mildew resistance gene Rpv12 from the Asian species Vitis amurensis into grapevine varieties.

    Directory of Open Access Journals (Sweden)

    Silvia Venuti

    Full Text Available The Amur grape (Vitis amurensis Rupr. thrives naturally in cool climates of Northeast Asia. Resistance against the introduced pathogen Plasmopara viticola is common among wild ecotypes that were propagated from Manchuria into Chinese vineyards or collected by Soviet botanists in Siberia, and used for the introgression of resistance into wine grapes (Vitis vinifera L.. A QTL analysis revealed a dominant gene Rpv12 that explained 79% of the phenotypic variance for downy mildew resistance and was inherited independently of other resistance genes. A Mendelian component of resistance-a hypersensitive response in leaves challenged with P. viticola-was mapped in an interval of 0.2 cM containing an array of coiled-coil NB-LRR genes on chromosome 14. We sequenced 10-kb genic regions in the Rpv12(+ haplotype and identified polymorphisms in 12 varieties of V. vinifera using next-generation sequencing. The combination of two SNPs in single-copy genes flanking the NB-LRR cluster distinguished the resistant haplotype from all others found in 200 accessions of V. vinifera, V. amurensis, and V. amurensis x V. vinifera crosses. The Rpv12(+ haplotype is shared by 15 varieties, the most ancestral of which are the century-old 'Zarja severa' and 'Michurinets'. Before this knowledge, the chromosome segment around Rpv12(+ became introgressed, shortened, and pyramided with another downy mildew resistance gene from North American grapevines (Rpv3 only by phenotypic selection. Rpv12(+ has an additive effect with Rpv3(+ to protect vines against natural infections, and confers foliar resistance to strains that are virulent on Rpv3(+ plants.

  12. Hybrid stars

    Indian Academy of Sciences (India)

    Hybrid stars. AsHOK GOYAL. Department of Physics and Astrophysics, University of Delhi, Delhi 110 007, India. Abstract. Recently there have been important developments in the determination of neutron ... number and the electric charge. ... available to the system to rearrange concentration of charges for a given fraction of.

  13. Introgression of mountain hare (Lepus timidus) mitochondrial DNA into wild brown hares (Lepus europaeus) in Denmark

    DEFF Research Database (Denmark)

    Fredsted, Tina; Jensen, Trine-Lee Wincentz; Villesen, Palle

    2006-01-01

    Background In Europe the mountain hare (Lepus timidus) exists in Great Britain, Norway, Sweden, Finland, parts of the Alps and in Eastern Europe, but not in Denmark. Interspecific hybridization has been demonstrated between native Swedish mountain hares and introduced brown hares (Lepus europaeus......). During the data collection in a study concerning Danish brown hares we identified 16 hares with a single very divergent haplotype. Results Phylogenetic analysis shows that the divergent Danish haplotype is most closely related to the Swedish mountain hare. The frequency of Lepus timidus mtDNA haplotype...

  14. Reconstruction of the Evolutionary History of Saccharomyces cerevisiae x S. kudriavzevii Hybrids Based on Multilocus Sequence Analysis

    Science.gov (United States)

    Peris, David; Lopes, Christian A.; Arias, Armando; Barrio, Eladio

    2012-01-01

    In recent years, interspecific hybridization and introgression are increasingly recognized as significant events in the evolution of Saccharomyces yeasts. These mechanisms have probably been involved in the origin of novel yeast genotypes and phenotypes, which in due course were to colonize and predominate in the new fermentative environments created by human manipulation. The particular conditions in which hybrids arose are still unknown, as well as the number of possible hybridization events that generated the whole set of natural hybrids described in the literature during recent years. In this study, we could infer at least six different hybridization events that originated a set of 26 S. cerevisiae x S. kudriavzevii hybrids isolated from both fermentative and non-fermentative environments. Different wine S. cerevisiae strains and European S. kudriavzevii strains were probably involved in the hybridization events according to gene sequence information, as well as from previous data on their genome composition and ploidy. Finally, we postulate that these hybrids may have originated after the introduction of vine growing and winemaking practices by the Romans to the present Northern vine-growing limits and spread during the expansion of improved viticulture and enology practices that occurred during the Late Middle Ages. PMID:23049811

  15. Reconstruction of the evolutionary history of Saccharomyces cerevisiae x S. kudriavzevii hybrids based on multilocus sequence analysis.

    Directory of Open Access Journals (Sweden)

    David Peris

    Full Text Available In recent years, interspecific hybridization and introgression are increasingly recognized as significant events in the evolution of Saccharomyces yeasts. These mechanisms have probably been involved in the origin of novel yeast genotypes and phenotypes, which in due course were to colonize and predominate in the new fermentative environments created by human manipulation. The particular conditions in which hybrids arose are still unknown, as well as the number of possible hybridization events that generated the whole set of natural hybrids described in the literature during recent years. In this study, we could infer at least six different hybridization events that originated a set of 26 S. cerevisiae x S. kudriavzevii hybrids isolated from both fermentative and non-fermentative environments. Different wine S. cerevisiae strains and European S. kudriavzevii strains were probably involved in the hybridization events according to gene sequence information, as well as from previous data on their genome composition and ploidy. Finally, we postulate that these hybrids may have originated after the introduction of vine growing and winemaking practices by the Romans to the present Northern vine-growing limits and spread during the expansion of improved viticulture and enology practices that occurred during the Late Middle Ages.

  16. Radiation protection zoning

    International Nuclear Information System (INIS)

    2015-01-01

    Radiation being not visible, the zoning of an area containing radioactive sources is important in terms of safety. Concerning radiation protection, 2 work zones are defined by regulations: the monitored zone and the controlled zone. The ministerial order of 15 may 2006 settles the frontier between the 2 zones in terms of radiation dose rates, the rules for access and the safety standards in both zones. Radioprotection rules and the name of the person responsible for radiation protection must be displayed. The frontier between the 2 zones must be materialized and marked with adequate equipment (specific danger signs and tapes). Both zones are submitted to selective entrance, the access for the controlled zone is limited because of the radiation risk and of the necessity of confining radioactive contamination while the limitation of the access to the monitored zone is due to radiation risk only. (A.C.)

  17. Rural Productivity Zones (RPZs) for microenterprises

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, R.D.

    1997-12-01

    In this paper the authors discuss the concept of rural productivity zones (RPZs) which are defined as a business incubator to foster income-producing opportunities for the rural poor. The essential ingredients of such a program include: electric power; business development assistance; office services; and quality work space. The electric power source must be a good quality system, consisting of a diesel/wind/photovoltaic hybrid type system, providing reliable service, with a local maintenance program and a functional load management program.

  18. Water deficit affects primary metabolism differently in two Lolium multiflorum/Festuca arundinacea introgression forms with a distinct capacity for photosynthesis and membrane regeneration.

    Directory of Open Access Journals (Sweden)

    Dawid Perlikowski

    2016-07-01

    Full Text Available Understanding how plants respond to drought at different levels of cell metabolism is an important aspect of research on the mechanisms involved in stress tolerance. Furthermore, a dissection of drought tolerance into its crucial components by the use of plant introgression forms facilitates to analyze this trait more deeply. The important components of plant drought tolerance are the capacity for photosynthesis under drought conditions, and the ability of cellular membrane regeneration after stress cessation. Two closely related introgression forms of Lolium multiflorum/Festuca arundinacea, differing in the level of photosynthetic capacity during stress, and in the ability to regenerate their cellular membranes after stress cessation, were used as forage grass models in a primary metabolome profiling and in an evaluation of chloroplast 1,6-bisphosphate aldolase accumulation level and activity, during 11 days of water deficit, followed by 10 days of rehydration. It was revealed here that the introgression form, characterized by the ability to regenerate membranes after rehydration, contained higher amounts of proline, melibiose, galactaric acid, myo-inositol and myo-inositol-1-phosphate involved in osmoprotection and stress signaling under drought. Moreover, during the rehydration period, this form also maintained elevated accumulation levels of most the primary metabolites, analyzed here. The other introgression form, characterized by the higher capacity for photosynthesis, revealed a higher accumulation level and activity of chloroplast aldolase under drought conditions, and higher accumulation levels of most photosynthetic products during control and drought periods. The potential impact of the observed metabolic alterations on cellular membrane recovery after stress cessation, and on a photosynthetic capacity under drought conditions in grasses, are discussed.

  19. Introgression of lineage c honey bees into black honey bee populations: a genome-wide estimation using single nucleotide polymorphisms (SNPS)

    OpenAIRE

    Henriques, Dora; Chavez-Galarza, Julio; Kryger, Per; Johnston, J. Spencer; De la Rúa, Pilar; Rufino, José; Dall'Olio, Raffaele; Garnery, Lionel; Pinto, M. Alice

    2012-01-01

    The black honey bee, Apis mellifera mellifera L., is probably the honey bee subspecies more threatened by introgression from foreign subspecies, specially lineage C A. m. carnica and A. m. ligustica. In fact, in some areas of its distributional range, intensive beekeeping with foreign subspecies has driven A. m. mellifera populations to nearly replacement. While massive and repeated introductions may lead to loss of native genetic patrimony, a low level of gene flow can also be detrimental be...

  20. A maize introgression library reveals ample genetic variability for root architecture, water use efficiency and grain yield under different water regimes

    OpenAIRE

    Salvi, S.; Giuliani, S.; Cané, M.; Sciara, G.; Bovina, R.; Welcker, Claude; Cabrera Bosquet, Llorenç; Grau, Antonin; Tardieu, Francois; Meriggi, P.

    2015-01-01

    The genetic dissection of root system architecture (RSA) provides valuable opportunities towards a better understanding of its role in determining yield under different water regimes. To this end, a maize introgression library comprised of 75 BC5 lines derived from the cross between Gaspé Flint (an early line; donor parent) and B73 (an elite line; recurrent parent) were evaluated in two experiments conducted under well-watered and water-deficit conditions (WW and WD, respectively) in order to...

  1. Do competitive conditions affect introgression of transgenes from oilseed rape (Brassica napus) to weedy Brassica rapa? AS case study with special reference to transplastomic oilseed rape

    DEFF Research Database (Denmark)

    Johannessen, Marina

    In species where chloroplast inheritance is exclusively or predominantly maternal, pollen-mediated flow of transgenes is reduced if transgenes are inserted in chloroplast DNA instead of nuclear DNA. However, transmission of chloroplast-encoded transgeneswill still occur if transgenic individuals ...... affected the thousand-kernel weight significantly. It was concluded that further introgression of transgenes from transplastomic oilseed rape to B. rapa is mostlikely at current field densities of B. napus and when B. rapa is an abundant weed....

  2. Molecular Evidence for the Hybrid Origin of Ilex dabieshanensis (Aquifoliaceae.

    Directory of Open Access Journals (Sweden)

    Lin Shi

    Full Text Available Ilex, the largest genus of dioecious woody plants, is a good study system to assess the role of hybridization in speciation and evolution. Ilex dabieshanensis, a tree endemic to Dabieshan Mountains region, was initially described as a new species. Based on morphological intermediacy and sympatric distribution with its putative parental species, I. cornuta and I. latifolia, we proposed it as a natural hybrid between them. In this study, we sequenced one chloroplast intergenic spacer (trnH-psbA and two nuclear genes (gapC and nepGS in I. dabieshanensis and its putative parental species to test the hybrid origin hypothesis. Our results showed that there were one to two differentially fixed sequence differences between I. cornuta and I. latifolia at the two nuclear genes. Twelve of the 14 individuals of I. dabieshanensis exhibited additivity in chromatograms on these differentially fixed sites at both nuclear genes, and the remaining two exhibited additivity in chromatograms on the fixed site at only the nepGS gene. Except one haplotype of I. cornuta at the nepGS gene, all of the haplotypes of I. cornuta at the two nuclear genes were well separated from those of I. latifolia, and most haplotypes of I. dabieshanensis were shared with those of I. cornuta and I. latifolia. Phylogenetic analysis of these haplotypes was largely consistent with haplotype network analysis. I. cornuta and I. latifolia differed by two nucleotide substitutions in the chloroplast intergenic spacer, and 12 individuals of I. dabieshanensis had the same sequences as I. latifolia, while the remaining two were identical with I. cornuta. The molecular data provide convincing evidence for the hybrid origin of I. dabieshanensis and asymmetrical direction of hybridization. One haplotype of I. cornuta at the nepGS gene was nested with those of I. latifolia, indicating introgression to I. cornuta.

  3. Development and Genetic Characterization of Advanced Backcross Materials and An Introgression Line Population of Solanum incanum in a S. melongena Background

    Directory of Open Access Journals (Sweden)

    Pietro Gramazio

    2017-08-01

    Full Text Available Advanced backcrosses (ABs and introgression lines (ILs of eggplant (Solanum melongena can speed up genetics and genomics studies and breeding in this crop. We have developed the first full set of ABs and ILs in eggplant using Solanum incanum, a wild eggplant that has a relatively high tolerance to drought, as a donor parent. The development of these ABs and IL eggplant populations had a low efficiency in the early stages, because of the lack of molecular markers and genomic tools. However, this dramatically improved after performing genotyping-by-sequencing in the first round of selfing, followed by high-resolution-melting single nucleotide polymorphism genotyping in subsequent selection steps. A set of 73 selected ABs covered 99% of the S. incanum genome, while 25 fixed immortal ILs, each carrying a single introgressed fragment in homozygosis, altogether spanned 61.7% of the S. incanum genome. The introgressed size fragment in the ILs contained between 0.1 and 10.9% of the S. incanum genome, with a mean value of 4.3%. Sixty-eight candidate genes involved in drought tolerance were identified in the set of ILs. This first set of ABs and ILs of eggplant will be extremely useful for the genetic dissection of traits of interest for eggplant, and represents an elite material for introduction into the breeding pipelines for developing new eggplant cultivars adapted to the challenges posed by the climate-change scenario.

  4. SNPs selected by information content outperform randomly selected microsatellite loci for delineating genetic identification and introgression in the endangered dark European honeybee (Apis mellifera mellifera).

    Science.gov (United States)

    Muñoz, Irene; Henriques, Dora; Jara, Laura; Johnston, J Spencer; Chávez-Galarza, Julio; De La Rúa, Pilar; Pinto, M Alice

    2017-07-01

    The honeybee (Apis mellifera) has been threatened by multiple factors including pests and pathogens, pesticides and loss of locally adapted gene complexes due to replacement and introgression. In western Europe, the genetic integrity of the native A. m. mellifera (M-lineage) is endangered due to trading and intensive queen breeding with commercial subspecies of eastern European ancestry (C-lineage). Effective conservation actions require reliable molecular tools to identify pure-bred A. m. mellifera colonies. Microsatellites have been preferred for identification of A. m. mellifera stocks across conservation centres. However, owing to high throughput, easy transferability between laboratories and low genotyping error, SNPs promise to become popular. Here, we compared the resolving power of a widely utilized microsatellite set to detect structure and introgression with that of different sets that combine a variable number of SNPs selected for their information content and genomic proximity to the microsatellite loci. Contrary to every SNP data set, microsatellites did not discriminate between the two lineages in the PCA space. Mean introgression proportions were identical across the two marker types, although at the individual level, microsatellites' performance was relatively poor at the upper range of Q-values, a result reflected by their lower precision. Our results suggest that SNPs are more accurate and powerful than microsatellites for identification of A. m. mellifera colonies, especially when they are selected by information content. © 2016 John Wiley & Sons Ltd.

  5. Development and validation of cross-transferable and polymorphic DNA markers for detecting alien genome introgression in Oryza sativa from Oryza brachyantha.

    Science.gov (United States)

    Ray, Soham; Bose, Lotan K; Ray, Joshitha; Ngangkham, Umakanta; Katara, Jawahar L; Samantaray, Sanghamitra; Behera, Lambodar; Anumalla, Mahender; Singh, Onkar N; Chen, Meingsheng; Wing, Rod A; Mohapatra, Trilochan

    2016-08-01

    African wild rice Oryza brachyantha (FF), a distant relative of cultivated rice Oryza sativa (AA), carries genes for pests and disease resistance. Molecular marker assisted alien gene introgression from this wild species to its domesticated counterpart is largely impeded due to the scarce availability of cross-transferable and polymorphic molecular markers that can clearly distinguish these two species. Availability of the whole genome sequence (WGS) of both the species provides a unique opportunity to develop markers, which are cross-transferable. We observed poor cross-transferability (~0.75 %) of O. sativa specific sequence tagged microsatellite (STMS) markers to O. brachyantha. By utilizing the genome sequence information, we developed a set of 45 low cost PCR based co-dominant polymorphic markers (STS and CAPS). These markers were found cross-transferrable (84.78 %) between the two species and could distinguish them from each other and thus allowed tracing alien genome introgression. Finally, we validated a Monosomic Alien Addition Line (MAAL) carrying chromosome 1 of O. brachyantha in O. sativa background using these markers, as a proof of concept. Hence, in this study, we have identified a set molecular marker (comprising of STMS, STS and CAPS) that are capable of detecting alien genome introgression from O. brachyantha to O. sativa.

  6. Hybrid male sterility between the fresh- and brackish-water types of ninespine stickleback Pungitius pungitius (Pisces, Gasterosteidae).

    Science.gov (United States)

    Takahashi, Hiroshi; Nagai, Terumi; Goto, Akira

    2005-01-01

    Two ecologically distinct forms, fresh- and brackish-water types, of ninespine stickleback co-exist in several freshwater systems on the coast of eastern Hokkaido. Recent genetic analyses of 13 allozyme loci revealed genetic separation between the two types even though their spawning grounds were in close proximity. On the other hand, there is only a small difference in mitochondrial DNA (mtDNA) sequence between the two types suggesting that they diverged quite recently or that mtDNA introgression occurred between them. To test for postzygotic reproductive isolating mechanisms and hybrid mediated gene flow, we examined the viability and reproductive performance of reciprocal F1 hybrids. The hybrids grew to the adult size normally and both sexes expressed secondary sexual characters in the reciprocal crosses. The female hybrids were reciprocally fertile, while the male hybrids were reciprocally sterile. Histological and flow-cytometric analyses of the hybrid testis revealed that the sterility pattern was classified as 'gametic sterility,' with gonads of normal size but abnormal spermatogenesis. To our knowledge, the present finding is a novel example of one sex hybrid sterility in the stickleback family (Gasterosteidae).

  7. Correction to: An Arabidopsis introgression zone studied at high spatio-temporal resolution: interglacial and multiple genetic contact exemplified using whole nuclear and plastid genomes.

    Science.gov (United States)

    Hohmann, Nora; Koch, Marcus A

    2018-04-11

    ᅟ: Upon publication of the original article [1], the authors had flagged that there was an error in Fig. 1c, as the key in this figure was displaying incorrectly. The colours had not displayed in the key in the final published article, and instead appear as plain white.

  8. Hybrid Qualifications

    DEFF Research Database (Denmark)

    Against the background of increasing qualification needs there is a growing awareness of the challenge to widen participation in processes of skill formation and competence development. At the same time, the issue of permeability between vocational education and training (VET) and general education...... has turned out as a major focus of European education and training policies and certainly is a crucial principle underlying the European Qualifications Framework (EQF). In this context, «hybrid qualifications» (HQ) may be seen as an interesting approach to tackle these challenges as they serve «two...

  9. Hybrid Gear

    Science.gov (United States)

    Handschuh, Robert F. (Inventor); Roberts, Gary D. (Inventor)

    2016-01-01

    A hybrid gear consisting of metallic outer rim with gear teeth and metallic hub in combination with a composite lay up between the shaft interface (hub) and gear tooth rim is described. The composite lay-up lightens the gear member while having similar torque carrying capability and it attenuates the impact loading driven noise/vibration that is typical in gear systems. The gear has the same operational capability with respect to shaft speed, torque, and temperature as an all-metallic gear as used in aerospace gear design.

  10. X chromosome control of meiotic chromosome synapsis in mouse inter-subspecific hybrids.

    Directory of Open Access Journals (Sweden)

    Tanmoy Bhattacharyya

    2014-02-01

    Full Text Available Hybrid sterility (HS belongs to reproductive isolation barriers that safeguard the integrity of species in statu nascendi. Although hybrid sterility occurs almost universally among animal and plant species, most of our current knowledge comes from the classical genetic studies on Drosophila interspecific crosses or introgressions. With the house mouse subspecies Mus m. musculus and Mus m. domesticus as a model, new research tools have become available for studies of the molecular mechanisms and genetic networks underlying HS. Here we used QTL analysis and intersubspecific chromosome substitution strains to identify a 4.7 Mb critical region on Chromosome X (Chr X harboring the Hstx2 HS locus, which causes asymmetrical spermatogenic arrest in reciprocal intersubspecific F1 hybrids. Subsequently, we mapped autosomal loci on Chrs 3, 9 and 13 that can abolish this asymmetry. Combination of immunofluorescent visualization of the proteins of synaptonemal complexes with whole-chromosome DNA FISH on pachytene spreads revealed that heterosubspecific, unlike consubspecific, homologous chromosomes are predisposed to asynapsis in F1 hybrid male and female meiosis. The asynapsis is under the trans- control of Hstx2 and Hst1/Prdm9 hybrid sterility genes in pachynemas of male but not female hybrids. The finding concurred with the fertility of intersubpecific F1 hybrid females homozygous for the Hstx2(Mmm allele and resolved the apparent conflict with the dominance theory of Haldane's rule. We propose that meiotic asynapsis in intersubspecific hybrids is a consequence of cis-acting mismatch between homologous chromosomes modulated by the trans-acting Hstx2 and Prdm9 hybrid male sterility genes.

  11. X chromosome control of meiotic chromosome synapsis in mouse inter-subspecific hybrids.

    Science.gov (United States)

    Bhattacharyya, Tanmoy; Reifova, Radka; Gregorova, Sona; Simecek, Petr; Gergelits, Vaclav; Mistrik, Martin; Martincova, Iva; Pialek, Jaroslav; Forejt, Jiri

    2014-02-01

    Hybrid sterility (HS) belongs to reproductive isolation barriers that safeguard the integrity of species in statu nascendi. Although hybrid sterility occurs almost universally among animal and plant species, most of our current knowledge comes from the classical genetic studies on Drosophila interspecific crosses or introgressions. With the house mouse subspecies Mus m. musculus and Mus m. domesticus as a model, new research tools have become available for studies of the molecular mechanisms and genetic networks underlying HS. Here we used QTL analysis and intersubspecific chromosome substitution strains to identify a 4.7 Mb critical region on Chromosome X (Chr X) harboring the Hstx2 HS locus, which causes asymmetrical spermatogenic arrest in reciprocal intersubspecific F1 hybrids. Subsequently, we mapped autosomal loci on Chrs 3, 9 and 13 that can abolish this asymmetry. Combination of immunofluorescent visualization of the proteins of synaptonemal complexes with whole-chromosome DNA FISH on pachytene spreads revealed that heterosubspecific, unlike consubspecific, homologous chromosomes are predisposed to asynapsis in F1 hybrid male and female meiosis. The asynapsis is under the trans- control of Hstx2 and Hst1/Prdm9 hybrid sterility genes in pachynemas of male but not female hybrids. The finding concurred with the fertility of intersubpecific F1 hybrid females homozygous for the Hstx2(Mmm) allele and resolved the apparent conflict with the dominance theory of Haldane's rule. We propose that meiotic asynapsis in intersubspecific hybrids is a consequence of cis-acting mismatch between homologous chromosomes modulated by the trans-acting Hstx2 and Prdm9 hybrid male sterility genes.

  12. X Chromosome Control of Meiotic Chromosome Synapsis in Mouse Inter-Subspecific Hybrids

    Science.gov (United States)

    Bhattacharyya, Tanmoy; Reifova, Radka; Gregorova, Sona; Simecek, Petr; Gergelits, Vaclav; Mistrik, Martin; Martincova, Iva; Pialek, Jaroslav; Forejt, Jiri

    2014-01-01

    Hybrid sterility (HS) belongs to reproductive isolation barriers that safeguard the integrity of species in statu nascendi. Although hybrid sterility occurs almost universally among animal and plant species, most of our current knowledge comes from the classical genetic studies on Drosophila interspecific crosses or introgressions. With the house mouse subspecies Mus m. musculus and Mus m. domesticus as a model, new research tools have become available for studies of the molecular mechanisms and genetic networks underlying HS. Here we used QTL analysis and intersubspecific chromosome substitution strains to identify a 4.7 Mb critical region on Chromosome X (Chr X) harboring the Hstx2 HS locus, which causes asymmetrical spermatogenic arrest in reciprocal intersubspecific F1 hybrids. Subsequently, we mapped autosomal loci on Chrs 3, 9 and 13 that can abolish this asymmetry. Combination of immunofluorescent visualization of the proteins of synaptonemal complexes with whole-chromosome DNA FISH on pachytene spreads revealed that heterosubspecific, unlike consubspecific, homologous chromosomes are predisposed to asynapsis in F1 hybrid male and female meiosis. The asynapsis is under the trans- control of Hstx2 and Hst1/Prdm9 hybrid sterility genes in pachynemas of male but not female hybrids. The finding concurred with the fertility of intersubpecific F1 hybrid females homozygous for the Hstx2Mmm allele and resolved the apparent conflict with the dominance theory of Haldane's rule. We propose that meiotic asynapsis in intersubspecific hybrids is a consequence of cis-acting mismatch between homologous chromosomes modulated by the trans-acting Hstx2 and Prdm9 hybrid male sterility genes. PMID:24516397

  13. Patterns of contemporary hybridization inferred from paternity analysis in a four-oak-species forest

    Directory of Open Access Journals (Sweden)

    Gailing Oliver

    2009-12-01

    Full Text Available Abstract Background Few studies address the issue of hybridization in a more than two-species context. The species-rich Quercus complex is one of the systems which can offer such an opportunity. To investigate the contemporary pattern of hybridization we sampled and genotyped 320 offspring from a natural mixed forest comprising four species of the European white oak complex: Quercus robur, Q. petraea, Q. pubescens, and Q. frainetto. Results A total of 165 offspring were assigned unambiguously to one of the pollen donors within the study plot. The minimum amount of effective pollen originating from outside the plot varied markedly among the seed parents, ranging from 0.18 to 0.87. The majority of the successful matings (64.1% occurred between conspecific individuals indicating the existence of reproductive barriers between oak species. However, the isolation was not complete since we found strong evidence for both first-generation (8.4% and later-generation hybrids (27.5%. Only two out of eight seed parents, belonging to Q. petraea and Q. robur, showed a high propensity to hybridize with Q. pubescens and Q. petraea, respectively. Significant structure of the effective pollen pools (Φpt = 0.069, P = 0.01 was detected in our sample. However, no support was found for the isolation by distance hypothesis. The proportion of hybrids was much higher (79% in the seed generation when compared to the adult tree generation. Conclusion First-generation hybrids were observed only between three out of six possible species combinations. Hybrids between one pair of species preferred to mate with one of their parental species. The observation of first and later-generation hybrids in higher frequency in acorns than in adults might be explained by selection against hybrid genotypes, the history of this uneven-aged forest or past introgression between species.

  14. Strong spatial segregation between wildcats and domestic cats may explain low hybridization rates on the Iberian Peninsula.

    Science.gov (United States)

    Gil-Sánchez, J M; Jaramillo, J; Barea-Azcón, J M

    2015-12-01

    The European wildcat (Felis silvestris silvestris) is an endangered felid impacted by genetic introgression with the domestic cat (Felis silvestris catus). The problem of hybridization has had different effects in different areas. In non-Mediterranean regions pure forms of wildcats became almost extinct, while in Mediterranean regions genetic introgression is a rare phenomenon. The study of the potential factors that prevent the gene flow in areas of lower hybridization may be key to wildcat conservation. We studied the population size and spatial segregation of wildcats and domestic cats in a typical Mediterranean area of ancient sympatry, where no evidence of hybridization had been detected by genetic studies. Camera trapping of wild-living cats and walking surveys of stray cats in villages were used for capture-recapture estimations of abundance and spatial segregation. Results showed (i) a low density of wildcats and no apparent presence of putative hybrids; (ii) a very low abundance of feral cats in spite of the widespread and large population sources of domestic cats inhabiting villages; (iii) strong spatial segregation between wildcats and domestic/feral cats; and (iv) no relationship between the size of the potential population sources and the abundance of feral cats. Hence, domestic cats were limited in their ability to become integrated into the local habitat of wildcats. Ecological barriers (habitat preferences, food limitations, intra-specific and intra-guild competition, predation) may explain the severe divergences of hybridization impact observed at a biogeographic level. This has a direct effect on key conservation strategies for wildcats (i.e., control of domestic cats). Copyright © 2015 Elsevier GmbH. All rights reserved.

  15. Genome-wide dissection of hybrid sterility in Drosophila confirms a polygenic threshold architecture.

    Science.gov (United States)

    Morán, Tomás; Fontdevila, Antonio

    2014-01-01

    To date, different studies about the genetic basis of hybrid male sterility (HMS), a postzygotic reproductive barrier thoroughly investigated using Drosophila species, have demonstrated that no single major gene can produce hybrid sterility without the cooperation of several genetic factors. Early work using hybrids between Drosophila koepferae (Dk) and Drosophila buzzatii (Db) was consistent with the idea that HMS requires the cooperation of several genetic factors, supporting a polygenic threshold (PT) model. Here we present a genome-wide mapping strategy to test the PT model, analyzing serially backcrossed fertile and sterile males in which the Dk genome was introgressed into the Db background. We identified 32 Dk-specific markers significantly associated with hybrid sterility. Our results demonstrate 1) a strong correlation between the number of segregated sterility markers and males' degree of sterility, 2) the exchangeability among markers, 3) their tendency to cluster into low-recombining chromosomal regions, and 4) the requirement for a minimum number (threshold) of markers to elicit sterility. Although our findings do not contradict a role for occasional major hybrid-sterility genes, they conform more to the view that HMS primarily evolves by the cumulative action of many interacting genes of minor effect in a complex PT architecture.

  16. Intuitionistic hybrid logic

    DEFF Research Database (Denmark)

    Braüner, Torben

    2011-01-01

    Intuitionistic hybrid logic is hybrid modal logic over an intuitionistic logic basis instead of a classical logical basis. In this short paper we introduce intuitionistic hybrid logic and we give a survey of work in the area.......Intuitionistic hybrid logic is hybrid modal logic over an intuitionistic logic basis instead of a classical logical basis. In this short paper we introduce intuitionistic hybrid logic and we give a survey of work in the area....

  17. Multi-locus phylogeny reveals instances of mitochondrial introgression and unrecognized diversity in Kenyan barbs (Cyprininae: Smiliogastrini).

    Science.gov (United States)

    Schmidt, Ray C; Bart, Henry L; Nyingi, Wanja Dorothy

    2017-06-01

    The phylogenetics and taxonomic status of small African barbs (Cyprininae: Smiliogastrini) remains unresolved despite the recent decision to elevate the genus name Enteromius for the group. The main barrier to understanding the origin of African small barbs and evolutionary relationships within the group is the poor resolution of phylogenies published to date. These phylogenies usually rely on mitochondrial markers and have limited taxon sampling. Here we investigate the phylogenetic relationships of small barbs of Kenya utilizing cytochrome b, Growth Hormone (GH) intron 2, and RAG1 markers from multiple populations of many species in the region. This multi-locus study produced well-supported phylogenies and revealed additional issues that complicate understanding the relationships among East African barbs. We observed widespread mtDNA introgression within the Kenyan barbs, highlighting the need to include nuclear markers in phylogenetic studies of the group. The GH intron 2 resolved heterospecific individuals and aided in inferring the species level phylogeny. The study reveals unrecognized diversity within the group, including within species reported to occur throughout East Africa, and it provides the groundwork for future taxonomic work in the region and across Africa. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Identification of tomato introgression lines with enhanced susceptibility or resistance to infection by parasitic giant dodder (Cuscuta reflexa).

    Science.gov (United States)

    Krause, Kirsten; Johnsen, Hanne R; Pielach, Anna; Lund, Leidulf; Fischer, Karsten; Rose, Jocelyn K C

    2018-02-01

    The parasitic flowering plant genus Cuscuta (dodder) is a parasitic weed that infects many important crops. Once it winds around the shoots of potential host plants and initiates the development of penetration organs, called haustoria, only a few plant species have been shown to deploy effective defense mechanisms to ward off Cuscuta parasitization. However, a notable exception is Solanum lycopersicum (tomato), which exhibits a local hypersensitive reaction when attacked by giant dodder (Cuscuta reflexa). Interestingly, the closely related wild desert tomato, Solanum pennellii, is unable to stop the penetration of its tissue by the C. reflexa haustoria. In this study, we observed that grafting a S. pennellii scion onto the rootstock of the resistant S. lycopersicum did not change the susceptibility phenotype of S. pennellii. This suggests that hormones, or other mobile substances, produced by S. lycopersicum do not induce a defense reaction in the susceptible tissue. Screening of a population of introgression lines harboring chromosome fragments from S. pennellii in the genome of the recurrent parent S. lycopersicum, revealed that most lines exhibit the same defense reaction as shown by the S. lycopersicum parental line. However, several lines showed different responses and exhibited either susceptibility, or cell death that extended considerably beyond the infection site. These lines will be valuable for the future identification of key loci involved in the perception of, and resistance to, C. reflexa and for developing strategies to enhance resistance to infection in crop species. © 2017 Scandinavian Plant Physiology Society.

  19. Introgression of wild alleles into the tetraploid peanut crop to improve water use efficiency, earliness and yield.

    Directory of Open Access Journals (Sweden)

    Wellison F Dutra

    Full Text Available The introduction of genes from wild species is a practice little adopted by breeders for the improvement of commercial crops, although it represents an excellent opportunity to enrich the genetic basis and create new cultivars. In peanut, this practice is being increasingly adopted. In this study we present results of introgression of wild alleles from the wild species Arachis duranensis and A. batizocoi improving photosynthetic traits and yield in a set of lines derived from the cross of an induced allotetraploid and cultivated peanut with selection under water stress. The assays were carried out in greenhouse and field focusing on physiological and agronomic traits. A multivariate model (UPGMA was adopted in order to classify drought tolerant lines. Several lines showed improved levels of tolerance, with values similar to or greater than the tolerant control. Two BC1F6 lines (53 P4 and 96 P9 were highlighted for good drought-related traits, earliness and pod yield, having better phenotypic profile to the drought tolerant elite commercial cultivar BR1. These lines are good candidates for the creation of peanut cultivars suitable for production in semiarid environments.

  20. Marker-assisted introgression of broad-spectrum blast resistance genes into the cultivated MR219 rice variety.

    Science.gov (United States)

    Miah, Gous; Rafii, Mohd Y; Ismail, Mohd R; Puteh, Adam B; Rahim, Harun A; Latif, Mohammad A

    2017-07-01

    The rice cultivar MR219 is famous for its better yield and long and fine grain quality; however, it is susceptible to blast disease. The main objective of this study was to introgress blast resistance genes into MR219 through marker-assisted selection (MAS). The rice cultivar MR219 was used as the recurrent parent, and Pongsu Seribu 1 was used as the donor. Marker-assisted foreground selection was performed using RM6836 and RM8225 to identify plants possessing blast resistance genes. Seventy microsatellite markers were used to estimate recurrent parent genome (RPG) recovery. Our analysis led to the development of 13 improved blast resistant lines with Piz, Pi2 and Pi9 broad-spectrum blast resistance genes and an MR219 genetic background. The RPG recovery of the selected improved lines was up to 97.70% with an average value of 95.98%. Selected improved lines showed a resistance response against the most virulent blast pathogen pathotype, P7.2. The selected improved lines did not express any negative effect on agronomic traits in comparison with MR219. The research findings of this study will be a conducive approach for the application of different molecular techniques that may result in accelerating the development of new disease-resistant rice varieties, which in turn will match rising demand and food security worldwide. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  1. A complex genetic basis to X-linked hybrid male sterility between two species of house mice.

    Science.gov (United States)

    Good, Jeffrey M; Dean, Matthew D; Nachman, Michael W

    2008-08-01

    The X chromosome plays a central role in the evolution of reproductive isolation, but few studies have examined the genetic basis of X-linked incompatibilities during the early stages of speciation. We report the results of a large experiment focused on the reciprocal introgression of the X chromosome between two species of house mice, Mus musculus and M. domesticus. Introgression of the M. musculus X chromosome into a wild-derived M. domesticus genetic background produced male-limited sterility, qualitatively consistent with previous experiments using classic inbred strains to represent M. domesticus. The genetic basis of sterility involved a minimum of four X-linked factors. The phenotypic effects of major sterility QTL were largely additive and resulted in complete sterility when combined. No sterility factors were uncovered on the M. domesticus X chromosome. Overall, these results revealed a complex and asymmetric genetic basis to X-linked hybrid male sterility during the early stages of speciation in mice. Combined with data from previous studies, we identify one relatively narrow interval on the M. musculus X chromosome involved in hybrid male sterility. Only a handful of spermatogenic genes are within this region, including one of the most rapidly evolving genes on the mouse X chromosome.

  2. Zoning Districts - Volusia County HUB Zones

    Data.gov (United States)

    NSGIC Local Govt | GIS Inventory — Historically Underutilized Business (HUB) Zones in Volusia County. Go to http://www.sba.gov/hubzone or contact the Department of Economic Development (386) 248-8048...

  3. Hybridized Tetraquarks

    CERN Document Server

    Esposito, A.; Polosa, A.D.

    2016-01-01

    We propose a new interpretation of the neutral and charged X, Z exotic hadron resonances. Hybridized-tetraquarks are neither purely compact tetraquark states nor bound or loosely bound molecules. The latter would require a negative or zero binding energy whose counterpart in h-tetraquarks is a positive quantity. The formation mechanism of this new class of hadrons is inspired by that of Feshbach metastable states in atomic physics. The recent claim of an exotic resonance in the Bs pi+- channel by the D0 collaboration and the negative result presented subsequently by the LHCb collaboration are understood in this scheme, together with a considerable portion of available data on X, Z particles. Considerations on a state with the same quantum numbers as the X(5568) are also made.

  4. Neurospora tetrasperma crosses heterozygous for hybrid ...

    Indian Academy of Sciences (India)

    2017-02-10

    nucleus stage that follows meiosis and a post-meiotic mitosis, and the ascospores that form in eight-spored asci are usually homokaryotic. We had previously created novel TNt strains by introgressing four Neurospora crassa ...

  5. Neurospora tetrasperma crosses heterozygous for hybrid

    Indian Academy of Sciences (India)

    nucleus stage that follows meiosis and apost-meiotic mitosis, and the ascospores that form in eight-spored asci are usually homokaryotic. We had previouslycreated novel TNt strains by introgressing four Neurospora crassa insertional ...

  6. Hybridization and genome evolution I: The role of contingency during hybrid speciation

    Directory of Open Access Journals (Sweden)

    Fabrice EROUKHMANOFF, Richard I. BAILEY, Glenn-Peter SæTRE

    2013-10-01

    Full Text Available Homoploid hybrid speciation (HHS involves the recombination of two differentiated genomes into a novel, functional one without a change in chromosome number. Theoretically, there are numerous ways for two parental genomes to recombine. Hence, chance may play a large role in the formation of a hybrid species. If these genome combinations can evolve rapidly following hybridization and sympatric situations are numerous, recurrent homoploid hybrid speciation is a possibility. We argue that three different, but not mutually exclusive, types of contingencies could influence this process. First, many of these “hopeful monsters” of recombinant parent genotypes would likely have low fitness. Only specific combinations of parental genomic contributions may produce viable, intra-fertile hybrid species able to accommodate potential constraints arising from intragenomic conflict. Second, ecological conditions (competition, geography of the contact zones or the initial frequency of both parent species might favor different outcomes ranging from sympatric coexistence to the formation of hybrid swarms and ultimately hybrid speciation. Finally, history may also play an important role in promoting or constraining recurrent HHS if multiple hybridization events occur sequentially and parental divergence or isolation differs along this continuum. We discuss under which conditions HHS may occur multiple times in parallel and to what extent recombination and selection may fuse the parent genomes in the same or different ways. We conclude by examining different approaches that might help to solve this intriguing evolutionary puzzle [Current Zoology 59 (5: 667-674, 2013]. 

  7. Continuity controlled Hybrid Automata

    NARCIS (Netherlands)

    Bergstra, J.A.; Middelburg, C.A.

    We investigate the connections between the process algebra for hybrid systems of Bergstra and Middelburg and the formalism of hybrid automata of Henzinger et al. We give interpretations of hybrid automata in the process algebra for hybrid systems and compare them with the standard interpretation

  8. Continuity Controlled Hybrid Automata

    NARCIS (Netherlands)

    Bergstra, J.A.; Middelburg, C.A.

    2004-01-01

    We investigate the connections between the process algebra for hybrid systems of Bergstra and Middelburg and the formalism of hybrid automata of Henzinger et al. We give interpretations of hybrid automata in the process algebra for hybrid systems and compare them with the standard interpretation of

  9. Continuity controlled hybrid automata

    NARCIS (Netherlands)

    Bergstra, J.A.; Middelburg, C.A.

    2004-01-01

    We investigate the connections between the process algebra for hybrid systems of Bergstra and Middelburg and the formalism of hybrid automata of Henzinger et al. We give interpretations of hybrid automata in the process algebra for hybrid systems and compare them with the standard interpretation of

  10. Continuity controlled hybrid automata

    NARCIS (Netherlands)

    Bergstra, J.A.; Middelburg, C.A.

    2006-01-01

    We investigate the connections between the process algebra for hybrid systems of Bergstra and Middelburg and the formalism of hybrid automata of Henzinger et al. We give interpretations of hybrid automata in the process algebra for hybrid systems and compare them with the standard interpretation of

  11. Development and Characterization of Somatic Hybrids of Ulva reticulata Forsskål (× Monostroma oxyspermum (Kutz.Doty

    Directory of Open Access Journals (Sweden)

    Vishal eGupta

    2015-01-01

    Full Text Available Ulvophycean species with diverse trait characteristics provide an opportunity to create novel allelic recombinant variants. The present study reports the development of seaweed variants with improved agronomic traits through protoplast fusion between Monostroma oxyspermum (Kutz. Doty and Ulva reticulata Forsskål. A total of 12 putative hybrids were screened based on the variations in morphology and total DNA content over the fusion partners. DNA-fingerprinting by inter simple sequence repeat (ISSR and amplified fragment length polymorphism (AFLP analysis confirmed genomic introgression in the hybrids. The DNA fingerprint revealed sharing of parental alleles in regenerated hybrids and a few alleles that were unique to hybrids. The epigenetic variations in hybrids estimated in terms of DNA methylation polymorphism also revealed sharing of methylation loci with both the fusion partners. The functional trait analysis for growth showed a hybrid with heterotic trait (DGR%= 36.7±1.55% over the fusion partners U. reticulata (33.2±2.6% and M. oxyspermum (17.8±1.77%, while others were superior to the mid-parental value (25.2±2.2% (p<0.05. The fatty acid (FA analysis of hybrids showed notable variations over fusion partners. Most hybrids showed increased polyunsaturated FAs (PUFAs compared to saturated FAs (SFAs and mainly includes the nutritionally important linoleic acid, α-linolenic acid, oleic acid, stearidonic acid, and docosahexaenoic acid. The other differences observed include superior cellulose content and antioxidative potential in hybrids over fusion partners. The hybrid varieties with superior traits developed in this study unequivocally demonstrate the significance of protoplast fusion technique in developing improved varients of macroalgae.

  12. Development and Characterization of Somatic Hybrids of Ulva reticulata Forsskål (×) Monostroma oxyspermum (Kutz.)Doty

    Science.gov (United States)

    Gupta, Vishal; Kumari, Puja; Reddy, CRK

    2015-01-01

    Ulvophycean species with diverse trait characteristics provide an opportunity to create novel allelic recombinant variants. The present study reports the development of seaweed variants with improved agronomic traits through protoplast fusion between Monostroma oxyspermum (Kutz.) Doty and Ulva reticulata Forsskål. A total of 12 putative hybrids were screened based on the variations in morphology and total DNA content over the fusion partners. DNA-fingerprinting by inter simple sequence repeat (ISSR) and amplified fragment length polymorphism (AFLP) analysis confirmed genomic introgression in the hybrids. The DNA fingerprint revealed sharing of parental alleles in regenerated hybrids and a few alleles that were unique to hybrids. The epigenetic variations in hybrids estimated in terms of DNA methylation polymorphism also revealed sharing of methylation loci with both the fusion partners. The functional trait analysis for growth showed a hybrid with heterotic trait (DGR% = 36.7 ± 1.55%) over the fusion partners U. reticulata (33.2 ± 2.6%) and M. oxyspermum (17.8 ± 1.77%), while others were superior to the mid-parental value (25.2 ± 2.2%) (p < 0.05). The fatty acid (FA) analysis of hybrids showed notable variations over fusion partners. Most hybrids showed increased polyunsaturated FAs (PUFAs) compared to saturated FAs (SFAs) and mainly includes the nutritionally important linoleic acid, α-linolenic acid, oleic acid, stearidonic acid, and docosahexaenoic acid. The other differences observed include superior cellulose content and antioxidative potential in hybrids over fusion partners. The hybrid varieties with superior traits developed in this study unequivocally demonstrate the significance of protoplast fusion technique in developing improved varients of macroalgae. PMID:25688248

  13. North African hybrid sparrows (Passer domesticus, P. hispaniolensis) back from oblivion – ecological segregation and asymmetric mitochondrial introgression between parental species

    Czech Academy of Sciences Publication Activity Database

    Belkacem, A. A.; Gast, Oliver; Stuckas, H.; Canal, D.; LoValvo, M.; Giacalone, G.; Päckert, M.

    2016-01-01

    Roč. 6, č. 15 (2016), s. 5190-5206 ISSN 2045-7758 Institutional support: RVO:68081766 Keywords : Agricultural landscape mosaic * Algeria * breeding phenology * NADH dehydrogenase * nest site choice Subject RIV: EG - Zoology Impact factor: 2.440, year: 2016

  14. Distinguishing between Incomplete Lineage Sorting and Genomic Introgressions: Complete Fixation of Allospecific Mitochondrial DNA in a Sexually Reproducing Fish (Cobitis; Teleostei), despite Clonal Reproduction of Hybrids

    Czech Academy of Sciences Publication Activity Database

    Choleva, Lukáš; Musilová, Zuzana; Kohoutová-Šedivá, Alena; Pačes, Jan; Ráb, Petr; Janko, Karel

    2014-01-01

    Roč. 9, č. 6 (2014), e80641-e80641 E-ISSN 1932-6203 R&D Projects: GA ČR GAP506/10/1155; GA ČR GPP506/12/P857 Institutional support: RVO:67985904 Keywords : Cobitis * gene flow * coalescence * incomplete lineage sorting * asexual * gynogenesis Subject RIV: EG - Zoology Impact factor: 3.234, year: 2014 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0080641

  15. Towards stacked zone plates

    International Nuclear Information System (INIS)

    Werner, S; Rehbein, S; Guttman, P; Heim, S; Schneider, G

    2009-01-01

    Fresnel zone plates are the key optical elements for soft and hard x-ray microscopy. For short exposure times and minimum radiation load of the specimen the diffraction efficiency of the zone plate objectives has to be maximized. As the efficiency strongly depends on the height of the diffracting zone structures the achievable aspect ratio of the nanostructures determines these limits. To reach aspect ratios ≥ 20:1 for high efficient optics we propose to superimpose zone plates on top of each other. With this multiplication approach the final aspect ratio is only limited by the number of stacked zone plate layers. For the stack process several nanostructuring process steps have to be developed and/or improved. Our results show for the first time two layers of zone plates stacked on top of each other.

  16. Corporate Hybrid Bonds

    OpenAIRE

    Ahlberg, Johan; Jansson, Anton

    2016-01-01

    Hybrid securities do not constitute a new phenomenon in the Swedish capital markets. Most commonly, hybrids issued by Swedish real estate companies in recent years are preference shares. Corporate hybrid bonds on the other hand may be considered as somewhat of a new-born child in the family of hybrid instruments. These do, as all other hybrid securities, share some equity-like and some debt-like characteristics. Nevertheless, since 2013 the interest for the instrument has grown rapidly and ha...

  17. Flooding tolerance in interspecific introgression lines containing chromosome segments from teosinte (Zea nicaraguensis) in maize (Zea mays subsp. mays)

    Science.gov (United States)

    Mano, Y.; Omori, F.

    2013-01-01

    Background and Aims Nicaraguan teosinte (Zea nicaraguensis), a species found in frequently flooded areas, provides useful germplasm for breeding flooding-tolerant maize (Z. mays subsp. mays). The objective of this study was to select flooding-tolerant lines using a library of introgression lines (ILs), each containing a chromosome segment from Z. nicaraguensis in the maize inbred line Mi29. Methods To produce the ILs, a single F1 plant derived from a cross between maize Mi29 and Z. nicaraguensis was backcrossed to Mi29 three times, self-pollinated four times and genotyped using simple sequence repeat markers. Flooding tolerance was evaluated at the seedling stage under reducing soil conditions. Key Results By backcrossing and selfing, a series of 45 ILs were developed covering nearly the entire maize genome. Five flooding-tolerant lines were identified from among the ILs by evaluating leaf injury. Among these, line IL#18, containing a Z. nicaraguensis chromosome segment on the long arm of chromosome 4, showed the greatest tolerance to flooding, suggesting the presence of a major quantitative trait locus (QTL) in that region. The presence of the QTL was verified by examining flooding tolerance in a population segregating for the candidate region of chromosome 4. There was no significant relationship between the capacity to form constitutive aerenchyma and flooding tolerance in the ILs, indicating the presence of other factors related to flooding tolerance under reducing soil conditions. Conclusions A flooding-tolerant genotype, IL#18, was identified; this genotype should be useful for maize breeding. In addition, because the chromosome segments of Z. nicaraguensis in the ILs cover nearly the entire genome and Z. nicaraguensis possesses several unique traits related to flooding tolerance, the ILs should be valuable material for additional QTL detection and the development of flooding-tolerant maize lines. PMID:23877074

  18. Characterization of QTL for unique agronomic traits of new-plant-type rice varieties using introgression lines of IR64

    Directory of Open Access Journals (Sweden)

    Analiza G. Tagle

    2016-02-01

    Full Text Available To enhance the yield potential of an elite indica rice cultivar, an introgression (BC3-derived line of IR64, YTH288, was developed using a new-plant-type cultivar, IR66215-44-2-3, as a donor parent. YTH288 has agronomically valuable characteristics such as large panicles, few unproductive tillers, and large leaves inherited from NPT. To identify the genetic basis of these traits, we used 167 F2 plants derived from a cross between IR64 and YTH288 to conduct QTL analysis for five agronomic traits: days to heading (DTH, culm length (CL, flag leaf length (FLL, flag leaf width (FLW, and filled spikelet number per panicle (FSN. Six putative QTL were detected: four on chromosome 4 (for CL, FLL, FLW, and FSN and two on chromosome 2 (for DTH and FLL. All QTL with the IR66215-44-2-3 allele, except that for FLL on chromosome 2, had positive effects on each trait. To confirm the effects of these putative QTL, we developed NILs with the IR64 genetic background by marker-assisted selection. We observed significant differences in several agronomic traits between IR64 and NILs that carried these QTL on chromosomes 2 and 4. Additionally, four IR64-NILs carrying chromosomal segments derived from different NPT varieties on the long arm of chromosome 4 exhibited similar pleiotropic effects for unique agronomic traits. These NILs can be used as research materials for studying each trait and as breeding materials for yield improvement of indica rice cultivars.

  19. Transcriptomic analysis of fiber strength in upland cotton chromosome introgression lines carrying different Gossypium barbadense chromosomal segments.

    Directory of Open Access Journals (Sweden)

    Lei Fang

    Full Text Available Fiber strength is the key trait that determines fiber quality in cotton, and it is closely related to secondary cell wall synthesis. To understand the mechanism underlying fiber strength, we compared fiber transcriptomes from different G. barbadense chromosome introgression lines (CSILs that had higher fiber strengths than their recipient, G. hirsutum acc. TM-1. A total of 18,288 differentially expressed genes (DEGs were detected between CSIL-35431 and CSIL-31010, two CSILs with stronger fiber and TM-1 during secondary cell wall synthesis. Functional classification and enrichment analysis revealed that these DEGs were enriched for secondary cell wall biogenesis, glucuronoxylan biosynthesis, cellulose biosynthesis, sugar-mediated signaling pathways, and fatty acid biosynthesis. Pathway analysis showed that these DEGs participated in starch and sucrose metabolism (328 genes, glycolysis/gluconeogenesis (122 genes, phenylpropanoid biosynthesis (101 genes, and oxidative phosphorylation (87 genes, etc. Moreover, the expression of MYB- and NAC-type transcription factor genes were also dramatically different between the CSILs and TM-1. Being different to those of CSIL-31134, CSIL-35431 and CSIL-31010, there were many genes for fatty acid degradation and biosynthesis, and also for carbohydrate metabolism that were down-regulated in CSIL-35368. Metabolic pathway analysis in the CSILs showed that different pathways were changed, and some changes at the same developmental stage in some pathways. Our results extended our understanding that carbonhydrate metabolic pathway and secondary cell wall biosynthesis can affect the fiber strength and suggested more genes and/or pathways be related to complex fiber strength formation process.

  20. Mapping of powdery mildew resistance gene Pm53 introgressed from Aegilops speltoides into soft red winter wheat.

    Science.gov (United States)

    Petersen, Stine; Lyerly, Jeanette H; Worthington, Margaret L; Parks, Wesley R; Cowger, Christina; Marshall, David S; Brown-Guedira, Gina; Murphy, J Paul

    2015-02-01

    A powdery mildew resistance gene was introgressed from Aegilops speltoides into winter wheat and mapped to chromosome 5BL. Closely linked markers will permit marker-assisted selection for the resistance gene. Powdery mildew of wheat (Triticum aestivum L.) is a major fungal disease in many areas of the world, caused by Blumeria graminis f. sp. tritici (Bgt). Host plant resistance is the preferred form of disease prevention because it is both economical and environmentally sound. Identification of new resistance sources and closely linked markers enable breeders to utilize these new sources in marker-assisted selection as well as in gene pyramiding. Aegilops speltoides (2n = 2x = 14, genome SS), has been a valuable disease resistance donor. The powdery mildew resistant wheat germplasm line NC09BGTS16 (NC-S16) was developed by backcrossing an Ae. speltoides accession, TAU829, to the susceptible soft red winter wheat cultivar 'Saluda'. NC-S16 was crossed to the susceptible cultivar 'Coker 68-15' to develop F2:3 families for gene mapping. Greenhouse and field evaluations of these F2:3 families indicated that a single gene, designated Pm53, conferred resistance to powdery mildew. Bulked segregant analysis showed that multiple simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers specific to chromosome 5BL segregated with the resistance gene. The gene was flanked by markers Xgwm499, Xwmc759, IWA6024 (0.7 cM proximal) and IWA2454 (1.8 cM distal). Pm36, derived from a different wild wheat relative (T. turgidum var. dicoccoides), had previously been mapped to chromosome 5BL in a durum wheat line. Detached leaf tests revealed that NC-S16 and a genotype carrying Pm36 differed in their responses to each of three Bgt isolates. Pm53 therefore appears to be a new source of powdery mildew resistance.