Kazutaka Ota; Mitsuto Aibara; Masaya Morita; Satoshi Awata; Michio Hori; Masanori Kohda
Alternative reproductive tactics (ARTs) are found in several Lake Tanganyika shell-brooding cichlids. Field studies were conducted in the Wonzye population to examine reproductive ecology and ARTs in the Lake Tanganyika shell-brooding cichlid Neolamprologus brevis. We discovered that this fish occurred in both rocky- and sandy-bottom habitats, but in rocky habitats, brood-caring females exclusively occurred in shell-patches that another cichlid species created. All N. brevis of both sexes in ...
Full Text Available Alternative reproductive tactics (ARTs are found in several Lake Tanganyika shell-brooding cichlids. Field studies were conducted in the Wonzye population to examine reproductive ecology and ARTs in the Lake Tanganyika shell-brooding cichlid Neolamprologus brevis. We discovered that this fish occurred in both rocky- and sandy-bottom habitats, but in rocky habitats, brood-caring females exclusively occurred in shell-patches that another cichlid species created. All N. brevis of both sexes in the patches were sexually mature, whereas immature males and females with unripe eggs were found frequently in sandy-bottom habitats. Males in sandy-bottom habitats were smaller, but fed more frequently and were in better somatic condition than males in the patches. Similar tendency was found in females. This indicates that N. brevis uses different habitats depending on the stage of its life history, with migration from sandy-bottom habitats to the shell-patches for reproduction. Males in the patches exhibited different behavior patterns: floating above the patches and lying in the patches. The former was larger, more aggressive, and invested less in gonads (relative to body size than the latter. These results accord with those of other shell-brooding Lake Tanganyika cichlids with ARTs, and they therefore suggest the presence of ARTs in N. brevis.
Schürch, Roger; Rothenberger, Susan; Heg, Dik
Consistent individual differences in behavioural types may not only cause variation in life-history decisions, but may also affect the choice of social partners and sociality in general. Here, we tested whether and how behavioural type influences the establishment of social ties using the cooperatively breeding cichlid, Neolamprologus pulcher. In a habitat saturation experiment with individuals pre-tested for behavioural type, we first analysed whether behavioural type affected the likelihood...
Maan, Martine E.; Taborsky, Michael
Females of the Lake Tanganyika cichlid Lamprologus callipterus exclusively breed in empty snail shells that males collect in their territories. Male-male competition for shells is severe, leading to frequent shell stealing and territory takeover. As a consequence, males have breeding females in thei
Brawand, David; Russell, Pamela
Cichlid fishes are famous for large, diverse and replicated adaptive radiations in the Great Lakes of East Africa. To understand the molecular mechanisms underlying cichlid phenotypic diversity, we sequenced the genomes and transcriptomes of five lineages of African cichlids: the Nile tilapia (Oreochromis niloticus), an ancestral lineage with low diversity; and four members of the East African lineage: Neolamprologus brichardi/pulcher (older radiation, Lake Tanganyika), Metriaclima zebra (rec...
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
Schuetz, Dolores; Ocana, Sabine Wirtz; Maan, martine E.; Taborsky, Michael
Colonial species breed in densely aggregated territories containing no resources other than nest sites. This behaviour is usually explained by natural selection, for instance through benefits resulting from reduced predation risk. An alternative hypothesis suggests that, as in lek breeding systems,
Hirschenhauser, Katharina; Canário, Adelino V. M.; Ros, Albert F. H.; Taborsky, Michael; Oliveira, Rui Filipe
We previously investigated the androgen responsiveness of males to simulated partner and territory intrusions in five African cichlid species (Neolamprologus pulcher, Lamprologus callipterus, Tropheus moorii, Pseudosimochromis curvifrons, Oreochromis mossambicus; Hirschenhauser et al., 2004). Here we re-analysed data on 11-ketotestosterone (11-KT) levels in holding water to compare the free (presumably from the gills) and conjugated (presumably from urine and faeces) 11-KT frac...
Anderson, Caleb; Werdenig, Alexandra; Koblmüller, Stephan; Sefc, Kristina M
Mating system variability is known to exist between and within species, often due to environmental influences. An open question is whether, vice versa, similar environmental conditions entail congruent mating behavior, for example in terms of multiple paternity, in species or populations sharing largely comparable breeding modes. This study employed microsatellite markers to investigate the incidence of multiple paternity in Cyprichromis coloratus and Cyprichromis leptosoma, two sympatric, closely related, mouthbrooding Lake Tanganyika cichlids with similar ecological and behavioral characteristics including the formation of open-water schools. Mouthbrooding females of both species were collected from the same mixed-species breeding school at the same time, minimizing environmental variation during courtship and mating. In C. coloratus, four of 12 broods had more than one sire, with a mean of 1.33 reconstructed sires per brood. C. leptosoma exhibited multiple paternity in 18 of 22 broods, with a mean of 2.59 or 2.86 reconstructed sires per brood according to the programs gerud and colony, respectively. In addition, two broods were found to contain offspring transplanted from another brood. There was no significant difference in brood size between species, but mean sire number did differ significantly. Hence, substantial similarity in reproductive behavior along with shared environmental conditions during courtship and spawning did not lead to equal rates of polyandry or sneaking in the two species. PMID:26811772
Full Text Available Fish demonstrate the greatest variety of parental care strategies within the animal kingdom. Fish parents seldom provision food for offspring, with some exceptions predominantly found in substrate-brooding Central American cichlids and mouth-brooding African cichlids. Here, we provide the first evidence of food provisioning in a substrate-brooding African cichlid Neolamprologus mondabu. This fish is a maternal substrate-brooding cichlid endemic to Lake Tanganyika, and feeds on benthic animals using unique techniques-individuals typically feed on the surface of sandy substrates, but also expose prey by digging up substrates with vigorous wriggling of their body and fins. Young also feed on benthos on the substrate surface, but only using the first technique. We observed that feeding induced by digging accounted for 30% of total feeding bouts in adult females, demonstrating that digging is an important foraging tactic. However, parental females fed less frequently after digging than non-parental females, although both females stayed in pits created by digging for approximately 30 s. Instead, young gathered in the pit and fed intensively, suggesting that parental females provision food for young by means of digging. We tested this hypothesis by comparing the feeding frequency of young before and after digging that was simulated by hand, and observed that young doubled their feeding frequency after the simulated digging. This suggests that parental females engage in digging to uncover food items that are otherwise unavailable to young, and provision food for them at the expense of their own foraging. This behavior was similar to what has been observed in Central American cichlids.
Sefc, Kristina M
Cichlid fishes of Lake Tanganyika display a variety of mating and parental care behaviors, including polygamous and monogamous mouthbrooding and substrate breeding, cooperative breeding, as well as various alternative reproductive tactics such as sneaking and piracy. Moreover, reproductive behaviors sometimes vary within species both in space and in time. Here, I survey reports on mating and parenting behaviors of Lake Tanganyika cichlid species and address the evolution of mating and parenta...
Sturmbauer, Christian; Salzburger, Walter; Duftner, Nina; Schelly, Robert; Koblmüller, Stephan
Lake Tanganyika comprises a cichlid species flock with substrate-breeding and mouthbrooding lineages. While sexual selection via mate choice on male mating color is thought to boost speciation rates in mouthbrooding cichlids, this is not the case in substrate-breeding lamprologines, which mostly form stable pairs and lack sexual dichromatism. We present a comprehensive reconstruction of the evolution of the cichlid tribe Lamprologini, based upon mtDNA sequences and multilocus nuclear DNA (AFL...
Keller-Costa, Tina; Canário, Adelino V M; Hubbard, Peter C
The family Cichlidae is well-known for pair-formation, parental care, territoriality, elaborate courtship and social organization. Do cichlids use chemical communication to mediate any of these behaviours? Early studies suggest that parent cichlids can discriminate between conspecific and heterospecific wrigglers (but not eggs) using olfactory cues. Some species are able to discriminate between their own brood and other conspecific broods based on olfaction. The young recognise conspecific adults (although not necessarily their parents) through the odorants they release. In both scenarios, protection of the young from predation is the likely selective force. Some male cichlids use urinary pheromones during courtship and spawning to attract females and induce ovulation. Females--in their turn--may base their mate-choice in part on assessment of those self-same pheromones. The same pheromonal system may be involved in establishing and maintaining the social hierarchies in lek-breeding cichlids. Individual recognition is also mediated by chemical communication. Finally, there is ample behavioural evidence that cichlids--like ostariophysan fish--release alarm cues that alert conspecifics to predation danger. Although the effects of these cues may be similar (e.g., increased shelter use, tighter schooling), they are different substances which remain to be identified. Cichlids, then, use chemical communication associated with many different behaviours. However, given the diversity of cichlids, little is known about the mechanisms of chemical communication or the chemical identity of the cues involved. The aim of this mini-review is to persuade those working with cichlids to consider the involvement of chemical communication, and those working in chemical communication to consider using cichlids. PMID:25622908
Kristina M. Sefc
Full Text Available Cichlid fishes of Lake Tanganyika display a variety of mating and parental care behaviors, including polygamous and monogamous mouthbrooding and substrate breeding, cooperative breeding, as well as various alternative reproductive tactics such as sneaking and piracy. Moreover, reproductive behaviors sometimes vary within species both in space and in time. Here, I survey reports on mating and parenting behaviors of Lake Tanganyika cichlid species and address the evolution of mating and parental care patterns and sexual dimorphism. Notes on measures of sexual selection intensity and the difficulties of defining mating systems and estimating selection intensities at species level conclude the essay.
Full Text Available African cichlid fishes are an ideal system for studying explosive rates of speciation and the origin of diversity in adaptive radiation. Within the last few million years, more than 2000 species have evolved in the Great Lakes of East Africa, the largest adaptive radiation in vertebrates. These young species show spectacular diversity in their coloration, morphology and behavior. However, little is known about the genomic basis of this astonishing diversity. Recently, five African cichlid genomes were sequenced, including that of the Nile tilapia (Oreochromis niloticus, a basal and only relatively moderately diversified lineage, and the genomes of four representative endemic species of the adaptive radiations, Neolamprologus brichardi, Astatotilapia burtoni, Metriaclima zebra, and Pundamila nyererei. Using the tilapia genome as the reference genome, we generated a high-resolution genomic variation map, consisting of single nucleotide polymorphisms (SNPs, short insertions and deletions (indels, inversions and deletions. In total, around 18.8, 17.7, 17.0 and 17.0 million SNPs, 2.3, 2.2, 1.4 and 1.9 million indels, 262, 306, 162, and 154 inversions, and 3509, 2705, 2710 and 2634 deletions were inferred to have evolved in the N. brichardi, A. burtoni, P. nyererei and M. zebra respectively. Many of these variations affected the annotated gene regions in the genome. Different patterns of genetic variation were detected during the adaptive radiation of African cichlid fishes. For SNPs, the highest rate of evolution was detected in the common ancestor of N. brichardi, A. burtoni, P. nyererei and M. zebra. However, for the evolution of inversions and deletions, we found that the rates at the terminal taxa are substantially higher than the rates at the ancestral lineages. The high-resolution map provides an ideal opportunity to understand the genomic bases of the adaptive radiation of African cichlid fishes.
O'Connor, Constance M; Marsh-Rollo, Susan E; Aubin-Horth, Nadia; Balshine, Sigal
Comparative studies have revealed that vasopressin-oxytocin pathways are associated with both pair bonding and grouping behavior. However, the relationship between pair bonding and grouping behavior remains unclear. In this study, our aim was to identify whether two species that differ in grouping behavior display a corresponding difference in their pair bonds, and in the underlying vasopressin-oxytocin hormonal pathways. Using two species of cichlid fishes, the highly social Neolamprologus pulcher and the non-social Telmatochromis temporalis, we measured proximity of pairs during pair bond formation, and then measured social behaviors (proximity, aggression, submission, affiliation) and brain gene expression of isotocin and arginine vasotocin (the teleost homologues of oxytocin and vasopressin, respectively), as well as their receptors, after a temporary separation and subsequent reunion of the bonded pairs. Pairs of the social species spent more time in close proximity relative to the non-social species. Rates of aggression increased in both species following the separation and reunion treatment, relative to controls that were not separated. Overall, whole brain expression of isotocin was higher in the social species relative to the non-social species, and correlated with proximity, submission, and affiliation, but only in the social species. Our results suggest that both a social and a non-social cichlid species have similar behavioral responses to a temporary separation from a mate, and we found no difference in the brain gene expression of measured hormones and receptors based on our separation-reunion treatment. However, our results highlight the importance of isotocin in mediating submissive and affiliative behaviors in cichlid fishes, and demonstrate that isotocin has species-specific correlations with socially relevant behaviors. PMID:26519858
Full Text Available Anthropogenic (man-made noise has been shown to have a negative impact on the behaviour and physiology of a range of terrestrial and aquatic animals. However, direct assessments of fitness consequences are rare. Here we examine the effect of additional noise on early life stages in the model cichlid fish, Neolamprologus pulcher. Many fishes use and produce sounds, they are crucial elements of aquatic ecosystems, and there is mounting evidence that they are vulnerable to anthropogenic noise; adult N. pulcher have recently been shown to change key behaviours during playback of motor boat noise. Using a split-brood design to eliminate potential genetic effects, we exposed half of the eggs and fry from each clutch to four weeks of playbacks of noise originally recorded from small motor boats with the other half acting as a control (receiving no noise playback. There was no significant effect of additional noise on hatching success or fry survival, length or weight at the end of the exposure period. Although care should be taken not to generalize these findings on a single species from a laboratory study, our data suggest that moderate noise increases do not necessarily have direct negative impacts on early-life survival and growth. Further studies on a range of species in natural conditions are urgently needed to inform conservation efforts and policy decisions about the consequences of anthropogenic noise.
Full Text Available Abstract Background Cichlid fishes have been the subject of increasing scientific interest because of their rapid adaptive radiation which has led to an extensive ecological diversity and their enormous importance to tropical and subtropical aquaculture. To increase our understanding of chromosome evolution among cichlid species, karyotypes of one Asian, 22 African, and 30 South American cichlid species were investigated, and chromosomal data of the family was reviewed. Results Although there is extensive variation in the karyotypes of cichlid fishes (from 2n = 32 to 2n = 60 chromosomes, the modal chromosome number for South American species was 2n = 48 and the modal number for the African ones was 2n = 44. The only Asian species analyzed, Etroplus maculatus, was observed to have 46 chromosomes. The presence of one or two macro B chromosomes was detected in two African species. The cytogenetic mapping of 18S ribosomal RNA (18S rRNA gene revealed a variable number of clusters among species varying from two to six. Conclusions The karyotype diversification of cichlids seems to have occurred through several chromosomal rearrangements involving fissions, fusions and inversions. It was possible to identify karyotype markers for the subfamilies Pseudocrenilabrinae (African and Cichlinae (American. The karyotype analyses did not clarify the phylogenetic relationship among the Cichlinae tribes. On the other hand, the two major groups of Pseudocrenilabrinae (tilapiine and haplochromine were clearly discriminated based on the characteristics of their karyotypes. The cytogenetic mapping of 18S ribosomal RNA (18S rRNA gene did not follow the chromosome diversification in the family. The dynamic evolution of the repeated units of rRNA genes generates patterns of chromosomal distribution that do not help follows the phylogenetic relationships among taxa. The presence of B chromosomes in cichlids is of particular interest because they may not be represented in
Seehausen, Ole; Schluter, Dolph
We propose a new mechanism for diversification of male nuptial-colour patterns in the rapidly speciating cichlid fishes of Lake Victoria. Sympatric closely related species often display nuptial colours at opposite ends of the spectrum with males either blue or yellow to red. Colour polymorphisms within single populations are common too. We propose that competition between males for breeding sites promotes such colour diversification, and thereby speciation. We hypothesize that male aggression...
Masanori Kohda; Lyndon Alexander Jordan; Takashi Hotta; Naoya Kosaka; Kenji Karino; Hirokazu Tanaka; Masami Taniyama; Tomohiro Takeyama
The theoretical underpinnings of the mechanisms of sociality, e.g. territoriality, hierarchy, and reciprocity, are based on assumptions of individual recognition. While behavioural evidence suggests individual recognition is widespread, the cues that animals use to recognise individuals are established in only a handful of systems. Here, we use digital models to demonstrate that facial features are the visual cue used for individual recognition in the social fish Neolamprologus pulcher. Focal...
Natalie April van Breukelen
Full Text Available The convict cichlid (Amatitlania nigrofasciata has been extensively examined in relation to many behavioral topics, such as courtship, pair-bonding, bi-parental care, and territoriality. Recently, this model species has been utilized in studies on genetics, endocrinology, and neuroanatomy, with an ultimate goal of connecting behavior with its underlying mechanisms. The goal of this study was two-fold: (1 profile the circulating levels of plasma 11KT in the male convict cichlid at multiple points during the reproductive cycle and (2 generally compare the hormonal profiles of the widely used laboratory populations and those of a free-living population in the streams of Costa Rica. The results of the field experiment showed that male convict cichlids had higher levels of circulating 11KT during courtship and lower during the parental care and non-breeding phases. The profile of the laboratory population was similar to the profile of the free-living individuals, with significantly higher levels of 11KT occurring during courtship than during parental care, though the level of 11KT during non-breeding phase was elevated in the laboratory. The high levels of 11KT during courtship and low levels of 11KT during parental care found in both the field and the laboratory is similar to what has been reported in other species of teleosts, and may suggest an important function of 11KT in the expression of courtship behavior and the subsequent onset of parental behaviors in this model species.
Taborsky, Barbara; Arnold, Cornelia; Junker, Julian; Tschopp, Andreas
Social competence is defined as the ability of an animal to optimize the expression of social behaviour as a function of the available social information. The social environment encountered early in life can affect the expression of various social behaviours later in life. We investigated whether early social experience can affect social competence. In the cooperatively breeding cichlid Neolamprologus pulcher, we tested whether individuals reared with older brood-caring conspecifics persisten...
Full Text Available Abstract Background The cichlid fishes in general, and the exceptionally diverse East African haplochromine cichlids in particular, are famous examples of adaptive radiation and explosive speciation. Here we report the collection and annotation of more than 12,000 expressed sequence tags (ESTs generated from three different cDNA libraries obtained from the East African haplochromine cichlid species Astatotilapia burtoni and Metriaclima zebra. Results We first annotated more than 12,000 newly generated cichlid ESTs using the Gene Ontology classification system. For evolutionary analyses, we combined these ESTs with all available sequence data for haplochromine cichlids, which resulted in a total of more than 45,000 ESTs. The ESTs represent a broad range of molecular functions and biological processes. We compared the haplochromine ESTs to sequence data from those available for other fish model systems such as pufferfish (Takifugu rubripes and Tetraodon nigroviridis, trout, and zebrafish. We characterized genes that show a faster or slower rate of base substitutions in haplochromine cichlids compared to other fish species, as this is indicative of a relaxed or reinforced selection regime. Four of these genes showed the signature of positive selection as revealed by calculating Ka/Ks ratios. Conclusion About 22% of the surveyed ESTs were found to have cichlid specific rate differences suggesting that these genes might play a role in lineage specific characteristics of cichlids. We also conclude that the four genes with a Ka/Ks ratio greater than one appear as good candidate genes for further work on the genetic basis of evolutionary success of haplochromine cichlid fishes.
McGee, Matthew D; Faircloth, Brant C; Borstein, Samuel R; Zheng, Jimmy; Darrin Hulsey, C; Wainwright, Peter C; Alfaro, Michael E
Decoupling of the upper jaw bones--jaw kinesis--is a distinctive feature of the ray-finned fishes, but it is not clear how the innovation is related to the extraordinary diversity of feeding behaviours and feeding ecology in this group. We address this issue in a lineage of ray-finned fishes that is well known for its ecological and functional diversity--African rift lake cichlids. We sequenced ultraconserved elements to generate a phylogenomic tree of the Lake Tanganyika and Lake Malawi cichlid radiations. We filmed a diverse array of over 50 cichlid species capturing live prey and quantified the extent of jaw kinesis in the premaxillary and maxillary bones. Our combination of phylogenomic and kinematic data reveals a strong association between biting modes of feeding and reduced jaw kinesis, suggesting that the contrasting demands of biting and suction feeding have strongly influenced cranial evolution in both cichlid radiations. PMID:26763694
Rijssel, Jacobus Cornelis van (Jacco)
Lake Victoria cichlids show the fastest vertebrate adaptive radiation known which is why they function as a model organism to study evolution. In the past 40 years, Lake Victoria experienced severe environmental changes including the boom of the introduced, predatory Nile perch and eutrophication. Both environmental changes resulted in a decline of haplochromine cichlid species and numbers during the 1980s. However, during the 1990s and 2000s, some haplochromine species recovered. With the us...
Gonzalez-Voyer, Alejandro; Winberg, Svante; Kolm, Niclas
As with any organ, differences in brain size—after adequate control of allometry—are assumed to be a response to selection. With over 200 species and an astonishing diversity in niche preferences and social organization, Tanganyikan cichlids present an excellent opportunity to study brain evolution. We used phylogenetic comparative analyses of sexed adults from 39 Tanganyikan cichlid species in a multiple regression framework to investigate the influence of ecology, sexual selection and paren...
Barluenga, Marta; Meyer, Axel
Sympatric speciation is a contentious concept, although theoretical models as well as empirical evidence support its relevance in evolutionary biology. The Midas cichlid species complex (Amphilophus citrinellus, labiatus, zaliosus) from several crater lakes in Nicaragua fits several of the key characteristics of a sympatric speciation model. In particular, in A. citrinellus (i) strong assortative mating on the basis of colour polymorphism and (ii) ecological differentiation based on morpholog...
Malinsky, Milan; Challis, Richard J; Tyers, Alexandra M; Schiffels, Stephan; Terai, Yohey; Ngatunga, Benjamin P; Miska, Eric A; Durbin, Richard; Genner, Martin J; Turner, George F
The genomic causes and effects of divergent ecological selection during speciation are still poorly understood. Here we report the discovery and detailed characterization of early-stage adaptive divergence of two cichlid fish ecomorphs in a small (700 meters in diameter) isolated crater lake in Tanzania. The ecomorphs differ in depth preference, male breeding color, body shape, diet, and trophic morphology. With whole-genome sequences of 146 fish, we identified 98 clearly demarcated genomic "islands" of high differentiation and demonstrated the association of genotypes across these islands with divergent mate preferences. The islands contain candidate adaptive genes enriched for functions in sensory perception (including rhodopsin and other twilight-vision-associated genes), hormone signaling, and morphogenesis. Our study suggests mechanisms and genomic regions that may play a role in the closely related mega-radiation of Lake Malawi. PMID:26680190
Full Text Available BACKGROUND: The explosively radiating evolution of cichlid fishes of Lake Malawi has yielded an amazing number of haplochromine species estimated as many as 500 to 800 with a surprising degree of diversity not only in color and stripe pattern but also in the shape of jaw and body among them. As these morphological diversities have been a central subject of adaptive speciation and taxonomic classification, such high diversity could serve as a foundation for automation of species identification of cichlids. METHODOLOGY/PRINCIPAL FINDING: Here we demonstrate a method for automatic classification of the Lake Malawi cichlids based on computer vision and geometric morphometrics. For this end we developed a pipeline that integrates multiple image processing tools to automatically extract informative features of color and stripe patterns from a large set of photographic images of wild cichlids. The extracted information was evaluated by statistical classifiers Support Vector Machine and Random Forests. Both classifiers performed better when body shape information was added to the feature of color and stripe. Besides the coloration and stripe pattern, body shape variables boosted the accuracy of classification by about 10%. The programs were able to classify 594 live cichlid individuals belonging to 12 different classes (species and sexes with an average accuracy of 78%, contrasting to a mere 42% success rate by human eyes. The variables that contributed most to the accuracy were body height and the hue of the most frequent color. CONCLUSIONS: Computer vision showed a notable performance in extracting information from the color and stripe patterns of Lake Malawi cichlids although the information was not enough for errorless species identification. Our results indicate that there appears an unavoidable difficulty in automatic species identification of cichlid fishes, which may arise from short divergence times and gene flow between closely related species.
Smith, Peter F; Konings, Ad; Kornfield, Irv
The importance of species recognition to taxonomic diversity among Lake Malawi cichlids has been frequently discussed. Hybridization - the apparent breakdown of species recognition - has been observed sporadically among cichlids and has been viewed as both a constructive and a destructive force with respect to species diversity. Here we provide genetic evidence of a natural hybrid cichlid population with a unique colour phenotype and elevated levels of genetic variation. We discuss the potential evolutionary consequences of interspecific hybridization in Lake Malawi cichlids and propose that the role of hybridization in generating both genetic variability and species diversity of Lake Malawi cichlids warrants further consideration. PMID:12919487
Ready, J S; Sampaio, I; Schneider, H; Vinson, C; Dos Santos, T; Turner, G F
Laboratory mate choice experiments have confirmed species status for cichlid fish in the African Great Lakes that differ in colour and little else. Colour differences between allopatric populations of the South American cichlid genus Apistogramma are known for many species, yet the status of such populations has not been previously tested. Analysis of the genetic relationships and mate choice characteristics of populations previously described as Apistogramma caetei from eastern Amazonia indicates genetic differentiation into at least three allopatric lineages, which also show strong prezygotic isolation through female mate choice, confirming them as Biological species. If future studies confirm that this result is indicative of a general trend, the species richness of the South American cichlid fishes may presently be seriously underestimated. PMID:16780514
Full Text Available The theoretical underpinnings of the mechanisms of sociality, e.g. territoriality, hierarchy, and reciprocity, are based on assumptions of individual recognition. While behavioural evidence suggests individual recognition is widespread, the cues that animals use to recognise individuals are established in only a handful of systems. Here, we use digital models to demonstrate that facial features are the visual cue used for individual recognition in the social fish Neolamprologus pulcher. Focal fish were exposed to digital images showing four different combinations of familiar and unfamiliar face and body colorations. Focal fish attended to digital models with unfamiliar faces longer and from a further distance to the model than to models with familiar faces. These results strongly suggest that fish can distinguish individuals accurately using facial colour patterns. Our observations also suggest that fish are able to rapidly (≤ 0.5 sec discriminate between familiar and unfamiliar individuals, a speed of recognition comparable to primates including humans.
Full Text Available The cichlid fishes of the East African Great Lakes represent a model especially suited to study adaptive radiation and speciation. With several African cichlid genome projects being in progress, a promising set of closely related genomes is emerging, which is expected to serve as a valuable data base to solve questions on genotype-phenotype relations. The mitochondrial (mt genomes presented here are the first results of the assembly and annotation process for two closely related but eco-morphologically highly distinct Lake Tanganyika cichlids, Petrochromis trewavasae and Tropheus moorii. The genomic sequences comprise 16,588 bp (P. trewavasae and 16,590 bp (T. moorii, and exhibit the typical mitochondrial structure, with 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and a non-coding control region. Analyses confirmed that the two species are very closely related with an overall sequence similarity of 96%. We analyzed the newly generated sequences in the phylogenetic context of 21 published labroid fish mitochondrial genomes. Consistent with other vertebrates, the D-loop region was found to evolve faster than protein-coding genes, which in turn are followed by the rRNAs; the tRNAs vary greatly in the rate of sequence evolution, but on average evolve the slowest. Within the group of coding genes, ND6 evolves most rapidly. Codon usage is similar among examined cichlid tribes and labroid families; although a slight shift in usage patterns down the gene tree could be observed. Despite having a clearly different nucleotide composition, ND6 showed a similar codon usage. C-terminal ends of Cox1 exhibit variations, where the varying number of amino acids is related to the structure of the obtained phylogenetic tree. This variation may be of functional relevance for Cox1 synthesis.
Julia J Day
Full Text Available BACKGROUND: Understanding the causes of disparities in species diversity across taxonomic groups and regions is a fundamental aim in evolutionary biology. Addressing these questions is difficult because of the need for densely sampled phylogenies and suitable empirical systems. METHODOLOGY/PRINCIPAL FINDINGS: Here we investigate the cichlid fish radiation of Lake Tanganyika and show that per lineage diversification rates have been more than six times slower than in the species flocks of Lakes Victoria and Malawi. The result holds even at peak periods of diversification in Lake Tanganyika, ruling out the age of the lake as an explanation for slow average rates, and is robust to uncertainties over the calibration of cichlid radiations in geological time. Moreover, Lake Tanganyika lineages, irrespective of different biological characteristics (e.g. sexually dichromatic versus sexually monochromatic clades, have diversified at similar rates, falling within typical estimates across a range of plant and animal clades. For example, the mostly sexually dichromatic haplochromines, which have speciated explosively in Lakes Victoria and Malawi, have displayed modest rates in Lake Tanganyika (where they are called Tropheini. CONCLUSION/SIGNIFICANCE: Our results show that either the Lake Tanganyika environment is less conducive for cichlid speciation or the remarkable diversifying abilities of the haplochromines were inhibited by the prior occupancy of older radiations. Although the results indicate a dominant role for the environment in shaping cichlid diversification, differences in the timing of diversification among the Tanganyikan tribes indicate that biological differences were still important for the dynamics of species build-up in the lake. While we cannot resolve the timing of the radiation relative to the origin of the lake, because of the lack of robust geological date calibrations for cichlids, our results are consistent with a scenario that the
O’Quin Kelly E
Full Text Available Abstract Background Phenotypic evolution may occur through mutations that affect either the structure or expression of protein-coding genes. Although the evolution of color vision has historically been attributed to structural mutations within the opsin genes, recent research has shown that opsin regulatory mutations can also tune photoreceptor sensitivity and color vision. Visual sensitivity in African cichlid fishes varies as a result of the differential expression of seven opsin genes. We crossed cichlid species that express different opsin gene sets and scanned their genome for expression Quantitative Trait Loci (eQTL responsible for these differences. Our results shed light on the role that different structural, cis-, and trans-regulatory mutations play in the evolution of color vision. Results We identified 11 eQTL that contribute to the divergent expression of five opsin genes. On three linkage groups, several eQTL formed regulatory “hotspots” associated with the expression of multiple opsins. Importantly, however, the majority of the eQTL we identified (8/11 or 73% occur on linkage groups located trans to the opsin genes, suggesting that cichlid color vision has evolved primarily via trans-regulatory divergence. By modeling the impact of just two of these trans-regulatory eQTL, we show that opsin regulatory mutations can alter cichlid photoreceptor sensitivity and color vision at least as much as opsin structural mutations can. Conclusions Combined with previous work, we demonstrate that the evolution of cichlid color vision results from the interplay of structural, cis-, and especially trans-regulatory loci. Although there are numerous examples of structural and cis-regulatory mutations that contribute to phenotypic evolution, our results suggest that trans-regulatory mutations could contribute to phenotypic divergence more commonly than previously expected, especially in systems like color vision, where compensatory changes in the
Weiss, Juliane D.; Cotterill, Fenton P. D.; Schliewen, Ulrich K
A long history of research focused on the East Africa cichlid radiations (EAR) revealed discrepancies between mtDNA and nuclear phylogenies, suggesting that interspecific hybridisation may have been significant during the radiation of these fishes. The approximately 250 cichlid species of Lake Tanganyika have their roots in a monophyletic African cichlid assemblage, but controversies remain about the precise phylogenetic origin and placement of different lineages and consequently about L. Tan...
Koblmüller, Stephan; Elizabeth A. Odhiambo; Sinyinza, Danny; Sturmbauer, Christian; Sefc, Kristina M
The largely endemic cichlid species flocks of the East African Great Lakes are among the prime examples for explosive speciation and adaptive radiation. Speciation rates differ among cichlid lineages, and the propensity to radiate has been linked to intrinsic and extrinsic factors such as sexual selection and ecological opportunity. Remarkably, only one cichlid tribe—the Boulengerochromini—comprises just a single species, Boulengerochromis microlepis, a predominantly piscivorous endemic of La...
Machado-Schiaffino, Gonzalo; Kautt, Andreas F; Kusche, Henrik; Meyer, Axel
Background The enormous diversity found in East African cichlid fishes in terms of morphology, coloration, and behavior have made them a model for the study of speciation and adaptive evolution. In particular, haplochromine cichlids, by far the most species-rich lineage of cichlids, are a well-known textbook example for parallel evolution. Southwestern Uganda is an area of high tectonic activity, and is home to numerous crater lakes. Many Ugandan crater lakes were colonized, apparently indepe...
Verheyen, Erik; Salzburger, Walter; Snoeks, Jos; Meyer, Axel
Lake Victoria harbors a unique species-rich flock of more than 500 endemic haplochromine cichlid fishes. The origin, age, and mechanism of diversification of this extraordinary radiation are still debated. Geological evidence suggests that the lake dried out completely about 14,700 years ago.Onthe basis of phylogenetic analyses of almost 300 DNA sequences of the mitochondrial control region of East African cichlids, we find that the Lake Victoria cichlid flock is derived from the geologically...
Won, Yong-jin; Sivasundar, Arjun; Wang, Yong; Hey, Jody
The cichlid fishes of Lake Malawi are famously diverse. However, phylogenetic and population genetic studies of their history have been difficult because of the great amount of genetic variation that is shared between species. We apply a recently developed method for fitting the “isolation with migration” divergence model to a data set of specially designed compound loci to develop portraits of cichlid species divergence. Outgroup sequences from a cichlid from Lake Tanganyika permit model par...
Smith, Adam R.; Moira J. van Staaden; Carleton, Karen L.
Although the cichlids of Lake Malawi are an important model system for the study of sensory evolution and sexual selection, the evolutionary processes linking these two phenomena remain unclear. Prior works have proposed that evolutionary divergence is driven by sensory drive, particularly as it applies to the visual system. While evidence suggests that sensory drive has played a role in the speciation of Lake Victoria cichlids, the findings from several lines of research on cichlids of Lake ...
Wong, Marian; Balshine, Sigal
Social aggression is one of the most conspicuous features of animal societies, yet little is known about the causes of individual variation in aggression within social hierarchies. Recent theory suggests that when individuals form queues for breeding, variation in social aggression by non-breeding group members is related to their probability of inheriting breeding status. However, levels of aggression could also vary as a temporary response to changes in the hierarchy, with individuals becoming more aggressive as they ascend in rank, in order to re-establish dominance relationships. Using the group-living fish, Neolamprologus pulcher, we show that subordinates became more aggressive after they ascended in rank. Female ascenders exhibited more rapid increases in aggression than males, and the increased aggression was primarily directed towards group members of adjacent rather than non-adjacent rank, suggesting that social aggression was related to conflict over rank. Elevated aggression by ascenders was not sustained over time, there was no relationship between rank and aggression in stable groups, and aggression given by ascenders was not sex-biased. Together, these results suggest that the need to re-establish dominance relationships following rank ascension is an important determinant of variation in aggression in animal societies. PMID:20880857
Kirchberger, Paul C; Sefc, Kristina M; Christian Sturmbauer; Stephan Koblmüller
Hybridization among littoral cichlid species in Lake Tanganyika was inferred in several molecular phylogenetic studies. The phenomenon is generally attributed to the lake level-induced shoreline and habitat changes. These allow for allopatric divergence of geographically fragmented populations alternating with locally restricted secondary contact and introgression between incompletely isolated taxa. In contrast, the deepwater habitat is characterized by weak geographic structure and a high po...
Le Pabic, Pierre; Cooper, W. James; Schilling, Thomas F.
Background Cichlid fishes from the Rift Lakes of East Africa have undergone the most spectacular adaptive radiations in vertebrate history. Eco-morphological adaptations in lakes Victoria, Malawi and Tanganyika have resulted in a vast array of skull shapes and sizes, yet primary axes of morphological variation are conserved in all three radiations, prominently including the size of the preorbital region of the skull. This conserved pattern suggests that development may constrain the trajector...
Stefanie B. R. Penk
Full Text Available African freshwater cichlids (Cichlidae: Pseudocrenilabrinae are well known for their exceptionally great diversity and their capability of rapid speciation as well as diverse adaptations. The extant Pseudocrenilabrinae can be grouped into 27 tribes, with more than 2000 species harbored in the Great Lakes and surrounding water bodies of the East African Rift System. However, this unique diversity is not reflected in the fossil record because fossil cichlids were predominantly reported based on isolated teeth and bones. Moreover, the few articulated specimens that are known have not been analyzed sufficiently with regard to their systematic position due to lack of comparative material. Here we present a new extraordinarily well-preserved cichlid fish fossil from the Middle Miocene (c. 12.5 Ma Lagerstaette Kabchore, which was recovered during recent fieldwork in the Tugen Hills (Baringo County, Central Kenya Rift. Based on the evidence of tricuspid teeth, the Kabchore fossil can be assigned to the subclade of the Haplotilapiines within the Pseudocrenilabrinae. The multivariate analysis of a large meristic data set, derived from 1014 extant specimens (encompassing all main lineages of Haplotilapiines and usage of available osteological data suggest that this fossil is most likely related to one of the three haplotilapiine tribes Tilapiini, Haplochromini or Oreochromini. Moreover, the fossil specimen closely resembles the extinct cichlid Oreochromis martyni (Van Couvering, 1982, previously described as species of Sarotherodon from the Middle Miocene alkaline Kapkiamu Lake in the Tugen Hills. The analysis of the greatly preserved fossil fish specimen from Kabchore definitely supplements the fragmentary fossil record of Africa’s Cichlidae and will afford new insights into its evolutionary history. We also expect that this fossil will be useful as calibration point for new divergence-time estimates.
Full Text Available Lake Tanganyika is the oldest of the Great Ancient Lakes in the East Africa. This lake harbours about 250 species of cichlid fish, which are highly diverse in terms of morphology, behaviour, and ecology. Lake Tanganyika's cichlid diversity has evolved through explosive speciation and is treated as a textbook example of adaptive radiation, the rapid differentiation of a single ancestor into an array of species that differ in traits used to exploit their environments and resources. To elucidate the processes and mechanisms underlying the rapid speciation and adaptive radiation of Lake Tanganyika's cichlid species assemblage it is important to integrate evidence from several lines of research. Great efforts have been, are, and certainly will be taken to solve the mystery of how so many cichlid species evolved in so little time. In the present review, we summarize morphological studies that relate to the adaptive radiation of Lake Tanganyika's cichlids and highlight their importance for understanding the process of adaptive radiation.
Kazutaka Ota; Masanori Kohda; Tetsu Sato
When males are the larger sex, a positive allometric relationship between male and female sizes is often found across populations of a single species (i.e. Rensch’s rule). This pattern is typically explained by a sexual selection pressure on males. Here, we report that the allometric relationship was negative across populations of a shell-brooding cichlid fish Lamprologus callipterus, although males are extremely larger than females. Male L. callipterus collect and defend empty snail shells in each of which a female breeds. We found that, across six populations, male and female sizes are positively correlated with not only sexual and fecundity selection indices, but also with shell sizes. Given their different reproductive behaviours, these correlations mean that males are required to be more powerful, and thus larger, to transport larger shells, while female bodies are reduced to the shell size to enable them to enter the shells. Among the three size selections (sexual selection, fecundity selection and shell size), shell size explained the allometry, suggesting that females are more strongly subject to size selection associated with shell size availability than males. However, the allometry was violated when considering an additional population where size-selection regimes of males differed from that of other populations. Therefore, sexual size allometry will be violated by body size divergence induced by multiple selection regimes.
Salzburger, Walter; Meyer, Axel; Baric, Sanja; Verheyen, Erik; Sturmbauer, Christian
Lake Tanganyika, the oldest of the East African Great Lakes, harbors the ecologically, morphologically, and behaviorally most complex of all assemblages of cichlid Fishes, consisting of about 200 described species. The evolutionary old age of the cichlid assemblage, its extreme degree of morphological differentiation, the lack of species with intermediate morphologies, and the rapidity of lineage formation havemade evolutionary reconstruction difficult. The number and origin of seeding lineag...
Verheyen Erik; Mack Tanja; Salzburger Walter; Meyer Axel
BackgroundThe adaptive radiations of cichlid fishes in East Africa are well known for their spectacular diversity and their astonishingly fast rates of speciation. About 80% of all 2,500 cichlid species in East Africa, and virtually all cichlid species from Lakes Victoria (~500 species) and Malawi (~1,000 species) are haplochromines. Here, we present the most extensive phylogenetic and phylogeographic analysis so far that includes about 100 species and is based on about 2,000 bp of the mitoch...
Reynolds, Matthew; Langridge, Peter
Physiological breeding crosses parents with different complex but complementary traits to achieve cumulative gene action for yield, while selecting progeny using remote sensing, possibly in combination with genomic selection. Physiological approaches have already demonstrated significant genetic gains in Australia and several developing countries of the International Wheat Improvement Network. The techniques involved (see Graphical Abstract) also provide platforms for research and refinement of breeding methodologies. Recent examples of these include screening genetic resources for novel expression of Calvin cycle enzymes, identification of common genetic bases for heat and drought adaptation, and genetic dissection of trade-offs among yield components. Such information, combined with results from physiological crosses designed to test novel trait combinations, lead to more precise breeding strategies, and feed models of genotype-by-environment interaction to help build new plant types and experimental environments for future climates. PMID:27161822
Tsuboi, Masahito; Kotrschal, Alexander; Hayward, Alexander; Buechel, Severine Denise; Zidar, Josefina; Løvlie, Hanne; Kolm, Niclas
Brain size is strongly associated with body size in all vertebrates. This relationship has been hypothesized to be an important constraint on adaptive brain size evolution. The essential assumption behind this idea is that static (i.e., within species) brain-body allometry has low ability to evolve. However, recent studies have reported mixed support for this view. Here, we examine brain-body static allometry in Lake Tanganyika cichlids using a phylogenetic comparative framework. We found considerable variation in the static allometric intercept, which explained the majority of variation in absolute and relative brain size. In contrast, the slope of the brain-body static allometry had relatively low variation, which explained less variation in absolute and relative brain size compared to the intercept and body size. Further examination of the tempo and mode of evolution of static allometric parameters confirmed these observations. Moreover, the estimated evolutionary parameters indicate that the limited observed variation in the static allometric slope could be a result of strong stabilizing selection. Overall, our findings suggest that the brain-body static allometric slope may represent an evolutionary constraint in Lake Tanganyika cichlids. PMID:27241216
Paul C. Kirchberger
Full Text Available Hybridization among littoral cichlid species in Lake Tanganyika was inferred in several molecular phylogenetic studies. The phenomenon is generally attributed to the lake level-induced shoreline and habitat changes. These allow for allopatric divergence of geographically fragmented populations alternating with locally restricted secondary contact and introgression between incompletely isolated taxa. In contrast, the deepwater habitat is characterized by weak geographic structure and a high potential for gene flow, which may explain the lower species richness of deepwater than littoral lineages. For the same reason, divergent deepwater lineages should have evolved strong intrinsic reproductive isolation already in the incipient stages of diversification, and, consequently, hybridization among established lineages should have been less frequent than in littoral lineages. We test this hypothesis in the endemic Lake Tanganyika deepwater cichlid tribe Bathybatini by comparing phylogenetic trees of Hemibates and Bathybates species obtained with nuclear multilocus AFLP data with a phylogeny based on mitochondrial sequences. Consistent with our hypothesis, largely congruent tree topologies and negative tests for introgression provided no evidence for introgressive hybridization between the deepwater taxa. Together, the nuclear and mitochondrial data established a well-supported phylogeny and suggested ecological segregation during speciation.
Verheyen, Erik; Salzburger, Walter; Snoeks, Jos; Meyer, Axel
Lake Victoria harbors a unique species-rich flock of more than 500 endemic haplochromine cichlid fishes. The origin, age, and mechanism of diversification of this extraordinary radiation are still debated. Geological evidence suggests that the lake dried out completely about 14,700 years ago. On the basis of phylogenetic analyses of almost 300 DNA sequences of the mitochondrial control region of East African cichlids, we find that the Lake Victoria cichlid flock is derived from the geologically older Lake Kivu. We suggest that the two seeding lineages may have already been lake-adapted when they colonized Lake Victoria. A haplotype analysis further shows that the most recent desiccation of Lake Victoria did not lead to a complete extinction of its endemic cichlid fauna and that the major lineage diversification took place about 100,000 years ago. PMID:12649486
Vanhove, Maarten p. m.; Antoine Pariselle; Maarten Van Steenberge; Raeymaekers, Joost A. M.; Hablützel, Pascal I; Céline Gillardin; Bart Hellemans; Floris C Breman; Stephan Koblmüller; Christian Sturmbauer; Jos Snoeks; Filip A M Volckaert; Tine Huyse
The stunning diversity of cichlid fishes has greatly enhanced our understanding of speciation and radiation. Little is known about the evolution of cichlid parasites. Parasites are abundant components of biodiversity, whose diversity typically exceeds that of their hosts. In the first comprehensive phylogenetic parasitological analysis of a vertebrate radiation, we study monogenean parasites infecting tropheine cichlids from Lake Tanganyika. Monogeneans are flatworms usually infecting the bod...
Cichlid fishes in African rift lakes have undergone rapid speciation, resulting in "species flocks" with more than 300 endemic species in some of the lakes. Most researchers assume that there is little phenotypic variation in cichlid fishes. I report here extensive phenotypic plasticity in a Neotropical cichlid species. I examined the influence of diet on trophic morphology during ontogeny in Cichlasonia managuense. Two groups of full siblings were fed two different diets for eight months aft...
Meyer, Britta Silke
The East African cichlids, more precisely the cichlid fishes of Lake Tanganyika, Lake Victoria and Lake Malawi, are among the most famous textbook examples of adaptive radiations. Both hybridization and incomplete lineage sorting explain the high degree of shared gene lineages within these species-flocks. Considerable effort has been put into the understanding of the relationships between and among the main lineages as this is essential to establish the phylogenetic backbone of the East Afric...
Raeymaekers, Joost; Hablützel, Pascal István; Grégoir, Arnout; Bamps, Jolien; Roose, Anna; Vanhove, Maarten; Van SteenBerge, Maarten; Pariselle, Antoine; Huyse, Tine; Snoeks, Jos; VOLCKAERT Filip
Background: Adaptation to different ecological environments is thought to drive ecological speciation. This phenomenon culminates in the radiations of cichlid fishes in the African Great Lakes. Multiple characteristic traits of cichlids, targeted by natural or sexual selection, are considered among the driving factors of these radiations. Parasites and pathogens have been suggested to initiate or accelerate speciation by triggering both natural and sexual selection. Three prerequisites for pa...
Tetsumi Takahashi; Stephan Koblmüller
Lake Tanganyika is the oldest of the Great Ancient Lakes in the East Africa. This lake harbours about 250 species of cichlid fish, which are highly diverse in terms of morphology, behaviour, and ecology. Lake Tanganyika's cichlid diversity has evolved through explosive speciation and is treated as a textbook example of adaptive radiation, the rapid differentiation of a single ancestor into an array of species that differ in traits used to exploit their environments and resources. To elucidate...
Rüber, Lukas; Verheyen, Erik; Meyer, Axel
The current phylogenetic hypothesis for the endemic Lake Tanganyika cichlid fishes of the tribe Eretmodini is based solely on morphology and suggests that more complex trophic morphologies derived only once from a less specialized ancestral condition. A molecular phylogeny of eretmodine cichlids based on partial mitochondrial DNA cytochrome b and control-region sequences was used to reconstruct the evolutionary sequence of trophic adaptations and to test alternative models of morphological di...
Dijkstra, P. D.; Wiegertjes, G.F.; Forlenza, M.; van der Sluijs, I.; Hofmann, H. A.; Metcalfe, N. B.; Groothuis, T. G. G.
Sexual selection on male coloration has been implicated in the evolution of colourful species flocks of East African cichlid fish. During adaptive radiations, animals diverge in multiple phenotypic traits, but the role of physiology has received limited attention. Here, we report how divergence in physiology may contribute to the stable coexistence of two hybridizing incipient species of cichlid fish from Lake Victoria. Males of Pundamilia nyererei (males are red) tend to defeat those of Pund...
Schwarzer, Julia; Swartz, Ernst Roelof; Vreven, Emmanuel; Snoeks, Jos; Cotterill, Fenton Peter David; Misof, Bernhard; Schliewen, Ulrich Kurt
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 reveale...
The question of how genetic variation translates into organismal diversity has puzzled biologists for decades. Despite recent advances in evolutionary and developmental genetics, the mechanisms that underlie adaptation, diversification and evolutionary innovation remain largely unknown. The exceptionally diverse species flocks of cichlid fishes are textbook examples of adaptive radiation and explosive speciation and emerge as powerful model systems to study the genetic basis of animal diversification. East Africa's hundreds of endemic cichlid species are akin to a natural mutagenesis screen and differ greatly not only in ecologically relevant (hence naturally selected) characters such as mouth morphology and body shape, but also in sexually selected traits such as coloration. One of the most fascinating aspects of cichlid evolution is the frequent occurrence of evolutionary parallelisms, which has led to the question whether selection alone is sufficient to produce these parallel morphologies, or whether a developmental or genetic bias has influenced the direction of diversification. Here, I review fitness-relevant traits that could be responsible for the cichlids' evolutionary success and assess whether these were shaped by sexual or natural selection. I then focus on the interaction and the relative importance of sexual vs. natural selection in cichlid evolution. Finally, I discuss what is currently known about the genes underlying the morphogenesis of adaptively relevant traits and highlight the importance of the forthcoming cichlid genomes in the quest of the genetic basis of diversification in this group. PMID:18992003
Klett, Vera; Meyer, Axel
We estimated a novel phylogeny of tilapiine cichlid fish (an assemblage endemic to Africa and the Near East) within the African cichlid fishes on the basis of complete mitochondrial NADH dehydrogenase subunit 2 (ND2) gene sequences. The ND2 (1,047 bp) gene was sequenced in 39 tilapiine cichlids (38 species and 1 subspecies) and in an additional 14 nontilapiine cichlid species in order to evaluate the traditional morphologically based hypothesis of the respective monophyly of the tilapiine and...
The present paper describes the breeding program of Latxa breed in Spain. Latxacs breeding program has been on-going since 1984 and it is focused on increasing milk yield. As a consequence of its implementation, an annual genetic improvement of 3% in milk yield has obtained. Currently, new traits are being considered in the selection breeding goal.
Gómez-Laplaza, Luis M; Morgan, Elfed
The ability of the cichlid angelfish, Pterophyllum scalare, to associate time and place to locate food, provided twice a day in two different places, was tested. Food was delivered daily in one corner of the tank in the morning and in the diagonally opposite corner in the afternoon, for a 3-week period, and the distribution of the fish in the tank was noted prior to and during feeding time. The results indicate that, in a fairly uniform environment and in the absence of external time cues, angelfish can discriminate and associate time and place to obtain a food reward. It is suggested that they do so by means of an endogenous timing mechanism. PMID:16129239
Full Text Available Abstract Background Phenotypic evolution and its role in the diversification of organisms is a central topic in evolutionary biology. A neglected factor during the modern evolutionary synthesis, adaptive phenotypic plasticity, more recently attracted the attention of many evolutionary biologists and is now recognized as an important ingredient in both population persistence and diversification. The traits and directions in which an ancestral source population displays phenotypic plasticity might partly determine the trajectories in morphospace, which are accessible for an adaptive radiation, starting from the colonization of a novel environment. In the case of repeated colonizations of similar environments from the same source population this "flexible stem" hypothesis predicts similar phenotypes to arise in repeated subsequent radiations. The Midas Cichlid (Amphilophus spp. in Nicaragua has radiated in parallel in several crater-lakes seeded by populations originating from the Nicaraguan Great Lakes. Here, we tested phenotypic plasticity in the pharyngeal jaw of Midas Cichlids. The pharyngeal jaw apparatus of cichlids, a second set of jaws functionally decoupled from the oral ones, is known to mediate ecological specialization and often differs strongly between sister-species. Results We performed a common garden experiment raising three groups of Midas cichlids on food differing in hardness and calcium content. Analyzing the lower pharyngeal jaw-bones we find significant differences between diet groups qualitatively resembling the differences found between specialized species. Observed differences in pharyngeal jaw expression between groups were attributable to the diet's mechanical resistance, whereas surplus calcium in the diet was not found to be of importance. Conclusions The pharyngeal jaw apparatus of Midas Cichlids can be expressed plastically if stimulated mechanically during feeding. Since this trait is commonly differentiated - among
Patrick D. Danley
Full Text Available The cichlid fishes of the East African Great Lakes are the largest extant vertebrate radiation identified to date. These lakes and their surrounding waters support over 2,000 species of cichlid fish, many of which are descended from a single common ancestor within the past 10 Ma. The extraordinary East African cichlid diversity is intricately linked to the highly variable geologic and paleoclimatic history of this region. Greater than 10 Ma, the western arm of the East African rift system began to separate, thereby creating a series of rift basins that would come to contain several water bodies, including the extremely deep Lakes Tanganyika and Malawi. Uplifting associated with this rifting backponded many rivers and created the extremely large, but shallow Lake Victoria. Since their creation, the size, shape, and existence of these lakes have changed dramatically which has, in turn, significantly influenced the evolutionary history of the lakes' cichlids. This paper reviews the geologic history and paleoclimate of the East African Great Lakes and the impact of these forces on the region's endemic cichlid flocks.
Won, Yong-Jin; Sivasundar, Arjun; Wang, Yong; Hey, Jody
The cichlid fishes of Lake Malawi are famously diverse. However, phylogenetic and population genetic studies of their history have been difficult because of the great amount of genetic variation that is shared between species. We apply a recently developed method for fitting the "isolation with migration" divergence model to a data set of specially designed compound loci to develop portraits of cichlid species divergence. Outgroup sequences from a cichlid from Lake Tanganyika permit model parameter estimates in units of years and effective population sizes. Estimated speciation times range from 1,000 to 17,000 years for species in the genus Tropheops. These exceptionally recent dates suggest that Malawi cichlids as a group experience a very active and dynamic diversification process. Current effective population size estimates range form 2,000 to near 40,000, and to >120,000 for estimates of ancestral population sizes. It appears that very recent speciation and gene flow are among the reasons why it has been difficult to discern the phylogenetic history of Malawi cichlids. PMID:15851665
McGee, Matthew D; Borstein, Samuel R; Neches, Russell Y; Buescher, Heinz H; Seehausen, Ole; Wainwright, Peter C
Evolutionary innovations, traits that give species access to previously unoccupied niches, may promote speciation and adaptive radiation. Here, we show that such innovations can also result in competitive inferiority and extinction. We present evidence that the modified pharyngeal jaws of cichlid fishes and several marine fish lineages, a classic example of evolutionary innovation, are not universally beneficial. A large-scale analysis of dietary evolution across marine fish lineages reveals that the innovation compromises access to energy-rich predator niches. We show that this competitive inferiority shaped the adaptive radiation of cichlids in Lake Tanganyika and played a pivotal and previously unrecognized role in the mass extinction of cichlid fishes in Lake Victoria after Nile perch invasion. PMID:26612951
Boileau, Nicolas; Cortesi, Fabio; Egger, Bernd; Muschick, Moritz; Indermaur, Adrian; Theis, Anya; Büscher, Heinz H; Salzburger, Walter
Aggressive mimicry is an adaptive tactic of parasitic or predatory species that closely resemble inoffensive models in order to increase fitness via predatory gains. Although similarity of distantly related species is often intuitively implicated with mimicry, the exact mechanisms and evolutionary causes remain elusive in many cases. Here, we report a complex aggressive mimicry strategy in Plecodus straeleni, a scale-eating cichlid fish from Lake Tanganyika, which imitates two other cichlid species. Employing targeted sequencing on ingested scales, we show that P. straeleni does not preferentially parasitize its models but—contrary to prevailing assumptions—targets a variety of co-occurring dissimilar looking fish species. Combined with tests for visual resemblance and visual modelling from a prey perspective, our results suggest that complex interactions among different cichlid species are involved in this mimicry system. PMID:26399975
Arbour, Jessica Hilary; López-Fernández, Hernán
Adaptive radiations have been hypothesized to contribute broadly to the diversity of organisms. Models of adaptive radiation predict that ecological opportunity and ecological release, the availability of empty ecological niches and the response by adapting lineages to occupy them, respectively, drive patterns of phenotypic and lineage diversification. Adaptive radiations driven by 'ecological opportunity' are well established in island systems; it is less clear if ecological opportunity influences continent-wide diversification. We use Neotropical cichlid fishes to test if variation in rates of functional evolution is consistent with changing ecological opportunity. Across a functional morphological axis associated with ram-suction feeding traits, evolutionary rates declined through time as lineages diversified in South America. Evolutionary rates of ram-suction functional morphology also appear to have accelerated as cichlids colonized Central America and encountered renewed opportunity. Our results suggest that ecological opportunity may play an important role in shaping patterns of morphological diversity of even broadly distributed lineages like Neotropical cichlids. PMID:27512144
Weiss, Juliane D; Cotterill, Fenton P D; Schliewen, Ulrich K
A long history of research focused on the East Africa cichlid radiations (EAR) revealed discrepancies between mtDNA and nuclear phylogenies, suggesting that interspecific hybridisation may have been significant during the radiation of these fishes. The approximately 250 cichlid species of Lake Tanganyika have their roots in a monophyletic African cichlid assemblage, but controversies remain about the precise phylogenetic origin and placement of different lineages and consequently about L. Tanganyika colonization scenarios. 3312 AFLP loci and the mitochondrial ND2 gene were genotyped for 91 species representing almost all major lacustrine and riverine haplotilapiine east African cichlid lineages with a focus on L. Tanganyika endemics. Explicitly testing for the possibility of ancient hybridisation events, a comprehensive phylogenetic network hypothesis is proposed for the origin and diversification of L. Tanganyika cichlids. Inference of discordant phylogenetic signal strongly suggests that the genomes of two endemic L. Tanganyika tribes, Eretmodini and Tropheini, are composed of an ancient mixture of riverine and lacustrine lineages. For the first time a strong monophyly signal of all non-haplochromine mouthbrooding species endemic to L. Tanganyika ("ancient mouthbrooders") was detected. Further, in the genomes of early diverging L. Tanganyika endemics Trematocarini, Bathybatini, Hemibatini and Boulengerochromis genetic components of other lineages belonging to the East African Radiation appear to be present. In combination with recent palaeo-geological results showing that tectonic activity in the L. Tanganyika region resulted in highly dynamic and heterogeneous landscape evolution over the Neogene and Pleistocene, the novel phylogenetic data render a single lacustrine basin as the geographical cradle of the endemic L. Tanganyika cichlid lineages unlikely. Instead a scenario of a pre-rift origin of several independent L. Tanganyika precursor lineages which
Juliane D Weiss
Full Text Available A long history of research focused on the East Africa cichlid radiations (EAR revealed discrepancies between mtDNA and nuclear phylogenies, suggesting that interspecific hybridisation may have been significant during the radiation of these fishes. The approximately 250 cichlid species of Lake Tanganyika have their roots in a monophyletic African cichlid assemblage, but controversies remain about the precise phylogenetic origin and placement of different lineages and consequently about L. Tanganyika colonization scenarios. 3312 AFLP loci and the mitochondrial ND2 gene were genotyped for 91 species representing almost all major lacustrine and riverine haplotilapiine east African cichlid lineages with a focus on L. Tanganyika endemics. Explicitly testing for the possibility of ancient hybridisation events, a comprehensive phylogenetic network hypothesis is proposed for the origin and diversification of L. Tanganyika cichlids. Inference of discordant phylogenetic signal strongly suggests that the genomes of two endemic L. Tanganyika tribes, Eretmodini and Tropheini, are composed of an ancient mixture of riverine and lacustrine lineages. For the first time a strong monophyly signal of all non-haplochromine mouthbrooding species endemic to L. Tanganyika ("ancient mouthbrooders" was detected. Further, in the genomes of early diverging L. Tanganyika endemics Trematocarini, Bathybatini, Hemibatini and Boulengerochromis genetic components of other lineages belonging to the East African Radiation appear to be present. In combination with recent palaeo-geological results showing that tectonic activity in the L. Tanganyika region resulted in highly dynamic and heterogeneous landscape evolution over the Neogene and Pleistocene, the novel phylogenetic data render a single lacustrine basin as the geographical cradle of the endemic L. Tanganyika cichlid lineages unlikely. Instead a scenario of a pre-rift origin of several independent L. Tanganyika precursor
Alex O. Awiti
Full Text Available A fundamental feature of the Anthropocene is the inexorable erosion of the self-repairing capacity or adaptive renewal of natural systems because of natural perturbation, exploitation, or management failure. The concept of resilience offers a systematic framework for understanding the dynamics and variables that govern response dynamics of ecosystems. Resilience of haplochromine cichlids is assessed using limnological and biodiversity changes in Lake Victoria, the world's second largest freshwater lake, over the last five decades. The review explores the resurgence of the haplochromine cichlids using Holling's adaptive renewal cycle and attempts to illustrate how resilience-based management approaches might learn from an inadvertent management experiment. The introduction in the 1980s of the Nile perch (Lates niloticus, a fecund and voracious predator of the endemic phytoplankton feeding haplochromine cichlids, anthropogenic eutrophication, and deep water hypoxia have combined in a synergistic way to increase the vulnerability of the lake ecosystem to perturbations that were hitherto absorbed. However, the upsurge in commercial Nile perch fishing appears to be enabling the resurgence of the haplochromine cichlids. The resurgence of haplochromine cichlids is characterized by phenotypic plasticity, ecological and life history traits and demonstrates the critical role of response diversity in the maintenance of systems resilience. Resilience of the haplochromine cichlids resides in the requisite functional response diversity and habitat diversity that provide the resources for renewal and regeneration. This paper concludes that management of Nile perch fisheries and control of nutrient loading into Lake Victoria could halt or reverse eutrophication, hence offer the best promise for a diverse, productive, and resilient social-ecological system.
Aguinaga, Jefferson Yunis; Marcusso, Paulo Fernandes; Claudiano, Gustavo da Silva; Lima, Bruno Tadeu Marotta; Marotta, Bruno L; Sebastião, Fernanda de Alexandre; Fernandes, João Batista Kochenborger; de Moraes, Flávio Ruas; de Moraes, Julieta Rodini Engracia
The aim of this study was to evaluate the prevalence and seasonal distribution of the main parasite species in Amazonian ornamental cichlids that affect their trade. The study was conducted from August 2007 to September 2009. We sampled 3042 specimens from 9 different species, of which 9.47% had at least one type of external parasite. 81.25% of the cases occurred in the dry season. Crenicichla anthurus (28.57%) was the most parasitized, followed by Aequidens diadema (26.32%), Pterophyllum scalare (22.69%), Cichlasoma sp. (9.52%), Apistogramma sp. (3.88%) and Symphysodon aequifasciatus (3.66%). Monogenea was the most abundant group of parasites, occurring in 66.67% of the cases, of which 96.88% occurred in the dry season. This parasite infested 95.68% of Pterophyllum scalare, 76.67% of Apistogramma sp, 33.33% of Cichlasoma sp. and 23.81% of Symphysodon aequifasciatus cases. Ichthyophthirius multifiliis infested 100% of Aequidens diadema, 76.19% of Symphysodon aequifasciatus, 66.67% of Cichlasoma sp, 41.67% of Crenicichla anthurus and 23.33% of Apistogramma sp cases. Myxosporidia infested 58.33% of Crenicichla anthurus. Trichodina infested 4.32% of Pterophyllum scalare. The prevalence of these parasites is related to the season, preferred habitat, fish behavior, individual susceptibility and handling of animals during transportation by fishermen. PMID:25909258
Van Wassenbergh, Sam; Potes, Nuno Zavattieri; Adriaens, Dominique
Presumably as an adaptation for mouthbrooding, many cichlid fish species have evolved a prominent sexual dimorphism in the adult head. Since the head of fishes serves as a bow during locomotion, an evolutionary increase in head volume to brood more eggs can trade-off with the hydrodynamic efficiency of swimming. Here, the differences between males and females in three-dimensional shape and size of the external head surfaces and the effect thereof on drag force during locomotion was analysed for the Nile tilapia (Oreochromis niloticus), a maternal mouthbrooder. To do so, three-dimensional body surface reconstructions from laser scans and computational fluid dynamics simulations were performed. After scaling the scanned specimens to post-cranial body volume, in order to theoretically equalize propulsive power, the external volume of the head of females was 27% larger than that of males (head length + 14%; head width + 9%). These differences resulted in an approximate 15% increase in drag force. Yet, hydrodynamics imposed important constraints on the adaptation for mouthbrooding as a much more drastic drop in swimming efficiency seems avoided by mainly enlarging the head along the swimming direction. PMID:26224567
Koblmüller, Stephan; Salzburger, Walter; Sturmbauer, Christian
The cichlid species flock of Lake Tanganyika is comprised of seven seeding lineages that evolved in step with changes of the lake environment. One seeding lineage diversified into at least six lineages within a short period of time. Our study focuses on the diversification of one of these lineages, the Ectodini, comprising highly specialized, sand- and rock-dwelling species. They display two distinct breeding styles: maternal and biparental mouthbrooding. By analyzing three mtDNA gene segments in 30 species representing all 13 described genera, we show that the Ectodini rapidly diversified into four clades at the onset of their radiation. The monotypic genus Grammatotria is likely to represent the most ancestral split, followed by the almost contemporary origin of three additional clades, the first comprising the benthic genus Callochromis, the second comprising the benthic genera Asprotilapia, Xenotilapia, Enantiopus, and Microdontochromis, and the third comprising the semi-pelagic genera Ophthalmotilapia, Cardiopharynx, Cyathopharynx, Ectodus, Aulonocranus, Lestradea, and Cunningtonia. Our study confirms the benthic and sand-dwelling life-style as ancestral. Rocky habitats were colonized independently in the Xenotilapia- and Ophthalmotilapia-clade. The Xenotilapia-clade comprises both maternal and biparental mouthbrooders. Their mode of breeding appears to be highly plastic: biparental mouthbrooding either evolved once in the common ancestor of the clade, to be reverted at least three times, or evolved at least five times independently from a maternally mouthbrooding ancestor. Furthermore, the genera Xenotilapia, Microdontochromis, Lestradea, and Ophthalmotilapia appeared paraphyletic in our analyses, suggesting the need of taxonomic revision. PMID:14743316
Caroly A. Shumway
Full Text Available In this review, I explore the effects of both social organization and the physical environment, specifically habitat complexity, on the brains and behavior of highly visual African cichlid fishes, drawing on examples from primates and birds where appropriate. In closely related fishes from the monophyletic Ectodinii clade of Lake Tanganyika, both forces influence cichlid brains and behavior. Considering social influences first, visual acuity differs with respect to social organization (monogamy versus polygyny. Both the telencephalon and amygdalar homologue, area Dm, are larger in monogamous species. Monogamous species are found to have more vasotocin-immunoreactive cells in the preoptic area of the brain. Habitat complexity also influences brain and behavior in these fishes. Total brain size, telencephalic and cerebellar size are positively correlated with habitat complexity. Visual acuity and spatial memory are enhanced in cichlids living in more complex environments. However habitat complexity and social forces affect cichlid brains differently. Taken together, our field data and plasticity data suggest that some of the species-specific neural effects of habitat complexity could be the consequence of the corresponding social correlates. Environmental forces, however, exert a broader effect on brain structures than social ones do, suggesting allometric expansion of the brain structures in concert with brain size and/or co-evolution of these structures [Current Zoology 56 (1: 144–156 2010].
Maan, Martine E.; van der Spoel, Michael; Jimenez, Paloma Quesada; van Alphen, Jacques J. M.; Seehausen, Ole
Sexual selection by female choice has contributed to the rapid evolution of phenotypic diversity in the cichlid fish species flocks of East Africa. Yet, very little is known about the ecological mechanisms that drive the evolution of female mating preferences. We studied fitness correlates of male n
Sluijs, Inke van der
Mate choice by female cichlid fish from Lake Victoria plays an important role in speciation and the maintenance of species. Females are expected to select against males that are intermediate in their phenotype during the process of speciation driven by sexual selection. To test this, we hybridized t
Maan, Martine E.; Van Rooijen, Anne M. C.; Van Alphen, Jacques J. M.; Seehausen, Ole
We investigate the role of parasite-mediated sexual selection in the divergence of two species of Lake Victoria cichlids. Pundamilia pundamilia and Pundamilia nyererei represent a common pattern of male nuptial colour divergence between haplochromine sister species: metallic grey-blue in P. pundamil
Maan, ME; Haesler, MP; Seehausen, O; Van Alphen, JJM
In many haplochromine cichlid fish, male nuptial coloration is subject to female mate choice and plays a central role in the evolution of reproductive isolation between incipient species. Intraspecific variation in male coloration may serve as a target for diversifying sexual selection and provide a
Salzburger, Walter; Meyer, Axel
With more than 3,000 species, the fish family Cichlidae is one of the most species-rich families of vertebrates. Cichlids occur in southern and central America, Africa, Madagascar, and India. The hotspot of their biodiversity is East Africa, where they form adaptive radiations composed of hundreds of endemic species in several lakes of various sizes and ages. The unparalleled species richness of East African cichlids has been something of a conundrum for evolutionary biologists and ecologists, since it has been in doubt whether these hundreds of species arose by allopatric speciation or whether it is necessary to invoke somewhat less traditional models of speciation, such as micro-allopatric, peripatric, or even sympatric speciation or evolution through sexual selection mediated by female choice. Ernst Mayr's analyses of these evolutionary uniquely diverse species assemblages have contributed to a more direct approach to this problem and have led to a deeper understanding of the patterns and processes that caused the formation of these huge groups of species. We review here recent molecular data on population differentiation and phylogenetics, which have helped to unravel, to some extent, the patterns and processes that led to the formation and ecological maintenance of cichlid species flocks. It is becoming apparent that sexually selected traits do play an important role in speciation in micro-allopatric or even sympatric settings. Species richness seems to be roughly correlated with the surface area, but not the age, of the lakes. We observe that the oldest lineages of a species flock of cichlids are often less species-rich and live in the open water or deepwater habitats. While the species flocks of the Lake Malawai and the Lake Victoria areas were shown to be monophyletic, the cichlid assemblage of Lake Tanganyika seems to consist of several independent species flocks. Cichlids emerge as an evolutionary model system in which many fundamental questions in
Meyer, Britta S; Matschiner, Michael; Salzburger, Walter
The species-flocks of cichlid fishes in the East African Great Lakes Victoria, Malawi and Tanganyika constitute the most diverse extant adaptive radiations in vertebrates. Lake Tanganyika, the oldest of the lakes, harbors the morphologically and genetically most diverse assemblage of cichlids and contains the highest number of endemic cichlid genera of all African lakes. Based on morphological grounds, the Tanganyikan cichlid species have been grouped into 12-16 distinct lineages, so-called tribes. While the monophyly of most of the tribes is well established, the phylogenetic relationships among the tribes remain largely elusive. Here, we present a new tribal level phylogenetic hypothesis for the cichlid fishes of Lake Tanganyika that is based on the so far largest set of nuclear markers and a total alignment length of close to 18kb. Using next-generation amplicon sequencing with the 454 pyrosequencing technology, we compiled a dataset consisting of 42 nuclear loci in 45 East African cichlid species, which we subjected to maximum likelihood and Bayesian inference phylogenetic analyses. We analyzed the entire concatenated dataset and each marker individually, and performed a Bayesian concordance analysis and gene tree discordance tests. Overall, we find strong support for a position of the Oreochromini, Boulengerochromini, Bathybatini and Trematocarini outside of a clade combining the substrate spawning Lamprologini and the mouthbrooding tribes of the 'H-lineage', which are both strongly supported to be monophyletic. The Eretmodini are firmly placed within the 'H-lineage', as sister-group to the most species-rich tribe of cichlids, the Haplochromini. The phylogenetic relationships at the base of the 'H-lineage' received less support, which is likely due to high speciation rates in the early phase of the radiation. Discordance among gene trees and marker sets further suggests the occurrence of past hybridization and/or incomplete lineage sorting in the cichlid
Meyer, Britta S.; Indermaur, Adrian; Ehrensperger, Xenia; Egger, Bernd; Banyankimbona, Gaspard; Snoeks, Jos; Salzburger, Walter
The species flocks of cichlid fishes in the East African Great Lakes are the largest vertebrate adaptive radiations in the world and illustrious textbook examples of convergent evolution between independent species assemblages. Although recent studies suggest some degrees of genetic exchange between riverine taxa and the lake faunas, not a single cichlid species is known from Lakes Tanganyika, Malawi and Victoria that is derived from the radiation associated with another of these lakes. Here,...
Meyer, Britta S.; Matschiner, Michael; Salzburger, Walter
Highlights: • We provide a new phylogeny for Lake Tanganyika cichlids using 42 nuclear makers. • Data concatenation and a Bayesian concordance analysis lead to congruent results. • Gene tree discordance hints to past hybridization or incomplete lineage sorting. • The Lamprologini are the sister-group to the ‘H-lineage’. • The Eretmodini are nested within the ‘H-lineage’. Abstract: The species-flocks of cichlid fishes in the East African Great Lakes Victoria, Malawi and ...
Seehausen, Ole; Koetsier, Egbert; Schneider, Maria Victoria; Chapman, Lauren J.; Colin A Chapman; Knight, Mairi E.; Turner, George F.; van Alphen, Jacques J.M; Bills, Roger
Phylogenetic analyses based on mitochondrial (mt) DNA have indicated that the cichlid species flock of the Lake Victoria region is derived from a single ancestral species found in East African rivers, closely related to the ancestor of the Lake Malawi cichlid species flock. The Lake Victoria flock contains ten times less mtDNA variation than the Lake Malawi radiation, consistent with current estimates of the ages of the lakes. We present results of a phylogenetic investigation using nuclear (...
Franchini, Paolo; Xiong, Peiwen; Fruciano, Carmelo; Meyer, Axel
Cichlid fishes are an ideal model system for studying biological diversification because they provide textbook examples of rapid speciation. To date, there has been little focus on the role of gene regulation during cichlid speciation. However, in recent years, gene regulation has been recognized as a powerful force linking diversification in gene function to speciation. Here, we investigated the potential role of miRNA regulation in the diversification of six cichlid species of the Midas cichlid lineage (Amphilophus spp.) inhabiting the Nicaraguan crater lakes. Using several genomic resources, we inferred 236 Midas miRNA genes that were used to predict the miRNA target sites on 8,232 Midas 3'-UTRs. Using population genomic calculations of SNP diversity, we found the miRNA genes to be more conserved than protein coding genes. In contrast to what has been observed in other cichlid fish, but similar to what has been typically found in other groups, we observed genomic signatures of purifying selection on the miRNA targets by comparing these sites with the less conserved nontarget portion of the 3'-UTRs. However, in one species pair that has putatively speciated sympatrically in crater Lake Apoyo, we recovered a different pattern of relaxed purifying selection and high genetic divergence at miRNA targets. Our results suggest that sequence evolution at miRNA binding sites could be a critical genomic mechanism contributing to the rapid phenotypic evolution of Midas cichlids. PMID:27189980
Cacho, M S R F; Yamamoto, M E; Chellappa, S
The species, Pterophyllum scalare distinguishes itself by its breeding behavior, involving competition for territory, sexual partners, courtship and parental care. The purpose of this study was to identify the mating system adopted by this species of fish. Twenty males and twenty females were observed under semi-natural and experimental conditions to test the hypothesis of serial monogamy. Under semi-natural conditions, after the third breeding cycle, the couples changed mates. Under experimental conditions, the couples changed partners after the first breeding cycle. Under experimental conditions, mate recognition was investigated through the preference of the females, indicated by the time they spent with the males. The females were available or not for courtship from new males, depending on their aggressiveness or submission. The larger and more aggressive males obtained new mating opportunities while the submissive males were rejected by the females. The mated fish were aggressive towards intruders in the presence of the mate, protecting their pair bond. In the interval between breeding cycles, the couples did not display aggression towards intruders, confirming the hypothesis of serial monogamy. Best mate selection by the females and the opportunity of new matings for both sexes influenced the reproductive success of this species. PMID:17505764
Differently from what one could formerly imagine, that buffalo breeding activity would be solely directed to fill the so called cattle breeding gaps determined by inadequate environmental conditions for ordinary cattle breeding, it has been actually seen that in those areas where breeders could successfully organize industrial-agricultural chains, either on meat or milk and its related products production, there has been an expressive expansion .Buffalo breeding has shown to be an important a...
López-Fernández, Hernán; Honeycutt, Rodney L; Winemiller, Kirk O
Nucleotide sequences from the mitochondrial ND4 gene and the nuclear RAG2 gene were used to derive the most extensive molecular phylogeny to date for the Neotropical cichlid subfamily Geophaginae. Previous hypotheses of relationships were tested in light of these new data and a synthesis of all existing molecular information was provided. Novel phylogenetic findings included support for : (1) a 'Big Clade' containing the genera Geophagus sensu lato, Gymnogeophagus, Mikrogeophagus, Biotodoma, Crenicara, and Dicrossus; (2) a clade including the genera Satanoperca, Apistogramma, Apistogrammoides, and Taeniacara; and (3) corroboration for Kullander's clade Acarichthyini. ND4 demonstrated saturation effects at the third code position and lineage-specific rate heterogeneity, both of which influenced phylogeny reconstruction when only equal weighted parsimony was employed. Both branch lengths and internal branch tests revealed extremely short basal nodes that add support to the idea that geophagine cichlids have experienced an adaptive radiation sensu Schluter that involved ecomorphological specializations and life history diversification. PMID:15579395
The comparative osteology of the suspensorial complex in 20 species of epilithic algal feeders from Lake Tanganyika was studied as a means of obtaining fundamental data for understanding the adaptive radiation in feeding habits of cichlid fishes in the East African lakes. Six types of suspensorial complex could be recognized within the 20 species studied. For the palatine, ectopterygoid, entopterygoid, metapterygoid, quadrate, symplectic, preoperculum and hyomandibula, 5, 2, 3, 3, 5, 2, 2 and...
Sturmbauer, Christian; Meyer, Axel
Since their discovery at the turn of the century, the species assemblages of cichlid fishes in the East African Lakes Victoria, Malawi and Tanganyika have fascinated evolutionary biologists. Many models have attempted to account for the 'explosive' evolution of several hundred species within these lakes. Here we report a case of surprisingly large genetic divergence among populations of the endemic Tropheus lineage of Lake Tanganyika. This lineage of six species contains twice as much genetic...
Egger, Bernd; Obermüller, Beate; Phiri, Harris; Sturmbauer, Christian; Sefc, Kristina M
Supported by evidence for assortative mating and polygynandry, sexual selection through mate choice was suggested as the main force driving the evolution of colour diversity of haplochromine cichlids in Lakes Malawi and Victoria. The phylogenetically closely related tribe Tropheini of Lake Tanganyika includes the genus Tropheus, which comprises over 100 colour variants currently classified into six morphologically similar, polyphyletic species. To assess the potential for sexual selection in ...
Tsuboi, Masahito; González-Voyer, Alejandro; Kolm, N.
Abstract Background Phenotypic integration among different anatomical parts of the head is a common phenomenon across vertebrates. Interestingly, despite centuries of research into the factors that contribute to the existing variation in brain size among vertebrates, little is known about the role of phenotypic integration in brain size diversification. Here we used geometric morphometrics on the morphologically diverse Tanganyikan cichlids to investigate phenotypic integration across key mor...
Full Text Available The gut microbiota structure reflects both a host phylogenetic history and a signature of adaptation to the host ecological, mainly trophic niches. African cichlid fishes, with their array of closely related species that underwent a rapid dietary niche radiation, offer a particularly interesting system to explore the relative contribution of these two factors in nature. Here we surveyed the host intra- and interspecific natural variation of the gut microbiota of five cichlid species from the monophyletic tribe Perissodini of lake Tanganyika, whose members transitioned from being zooplanktivorous to feeding primarily on fish scales. The outgroup riverine species Astatotilapia burtoni, largely omnivorous, was also included in the study. Fusobacteria, Firmicutes and Proteobacteria represented the dominant components in the gut microbiota of all 30 specimens analysed according to two distinct 16S rRNA markers. All members of the Perissodini tribe showed a homogenous pattern of microbial alpha and beta diversities, with no significant qualitative differences, despite changes in diet. The recent diet shift between zooplantkon- and scale-eaters simply reflects on a significant enrichment of Clostridium taxa in scale-eaters where they might be involved in the scale metabolism. Comparison with the omnivorous species A. burtoni suggests that, with increased host phylogenetic distance and/or increasing herbivory, the gut microbiota begins differentiating also at qualitative level. The cichlids show presence of a large conserved core of taxa and a small set of core OTUs (average 13-15%, remarkably stable also in captivity, and putatively favoured by both restricted microbial transmission among related hosts (putatively enhanced by mouthbrooding behavior and common host constraints. This study sets the basis for a future large-scale investigation of the gut microbiota of cichlids and its adaptation in the process of the host adaptive radiation.
Nolan, Brian C.
Laboratory activities serve several important functions in undergraduate science education. For neuroscience majors, an important and sometimes underemphasized tool is the use of behavioral observations to help inform us about the consequences of changes that are occurring on a neuronal level. To help address this concern, the following laboratory exercise is presented. The current project tested the prediction that the most dominant fish in a tank of cichlids will have gained the most benefi...
Renn, Susan C.P.; Aubin-Horth, Nadia; Hofmann, Hans A.
Behaviour and physiology are regulated by both environment and social context. A central goal in the study of the social control of behaviour is to determine the underlying physiological, cellular and molecular mechanisms in the brain. The African cichlid fish Astatotilapia burtoni has long been used as a model system to study how social interactions regulate neural and behavioural plasticity. In this species, males are either socially dominant and reproductively active or subordinate and rep...
Raoni Rosa Rodrigues; Lucélia Nobre Carvalho; Jansen Zuanon; Kleber Del-Claro
Animal coloration has many functions, and fishes are noted among vertebrates for presenting a wide variety of color patterns. Although in marine fishes the relationship between body coloration and behavioral context is well documented, there's not much information about freshwater fishes. Here we describe color patterns displayed by the dwarf cichlid Apistogramma hippolytae and suggest that these patterns are dependent on different social and behavioral settings. Field observations were condu...
Julia Schwarzer; Bernhard Misof; Ifuta, Seraphin N.; Schliewen, Ulrich K.
Most freshwater diversity is arguably located in networks of rivers and streams, but, in contrast to lacustrine systems riverine radiations, are largely understudied. The extensive rapids of the lower Congo River is one of the few river stretches inhabited by a locally endemic cichlid species flock as well as several species pairs, for which we provide evidence that they have radiated in situ. We use more that 2,000 AFLP markers as well as multilocus sequence datasets to reconstruct their ori...
Musilová, Zuzana; Říčan, Oldřich; Janko, Karel; Novák, J.
Roč. 46, - (2008), s. 659-672. ISSN 1055-7903 R&D Projects: GA MŠk LC06073 Grant ostatní: GA UK(CZ) 182/2004/B-BIO; GA UK(CZ) 139407 Institutional research plan: CEZ:AV0Z50450515 Keywords : molecular phylogeny * Cichlids * south America Subject RIV: EG - Zoology Impact factor: 3.871, year: 2008
Recent suggestions concerning the age and origin of the flock of haplochromine cichlid fishes in Lake Victoria (East Africa) are considered. These accept as proven the suggestion that Lake Victoria dried out completely in the Late Pleistocene, was dry for several thousand years, and refilled ca. 12400 years ago. Apart from the fact that other geophysical evidence contradicts this claim, its biological implications, which do likewise, have never been considered by those who have accepted it. L...
Meyer, Axel; Kocher, Thomas D.; Basasibwaki, Pereti; Wilson, Allan C.
Lake Victoria, together with its satellite lakes, harbours roughly 200 endemic forms of cichlid fishes that are classified as 'haplo-chromines' and yet the lake system is less than a million years old. This 'flock' has attracted attention because of the possibility that it evolved within the lake from one ancestral species and that biologists are thus presented with a case of explosive evolution. Within the past decade, however, morphology has increasingly emphasized the view that the flock m...
Dijkstra, Peter Douwe
Speciation by sexual selection research has traditionally concentrated on mechanisms for divergence driven via female mate choice (intersexual selection). The pivotal role of competition between members of the same sex (intrasexual selection) has been largely overlooked. In this thesis, I describe a series of experimental studies investigating the role of intrasexual selection in sympatric divergence, using Lake Victoria haplochromine cichlid fish as a model system. Such experiments are neede...
Schaafsma, Sara M.; Groothuis, Ton G. G.
Lateralization of cerebral functions is a fundamental aspect of the organization of brain and behaviour in vertebrates. Sex differences in human lateralization have inspired researchers to postulate several hypotheses concerning the effect of prenatal testosterone on lateralization, but few experimental studies have examined these hypotheses. We investigated whether prenatal testosterone affects strength or direction of lateralization in a cichlid fish, Aequidens rivulatus. Eggs were given a ...
Maria do Socorro R.F Cacho; Sathyabama Chellappa; Maria Emília Yamamoto
The angel fish, Pterophyllum scalare is a cichlid native to the Amazon Basin of Brazil and is exported as an ornamental fish. In this study the importance of the experience and previous reproductive success of males in mate selection was investigated. In order to investigate reproductive experience, six pairs of males (experienced and inexperienced) and six females were used. Males were placed in an aquarium, where one female was released. Mate selection was verified by the time spent by a fe...
Faunce, Craig H.; Patterson, Heather M.; Lorenz, Jerome J.
Mayan cichlids (Cichlasoma urophthalmus) were collected monthly from March 1996 to October 1997 with hook-and-line gear at Taylor River, Florida, an area within the Crocodile Sanctuary of Everglades National Park, where human activities such as fishing are prohibited. Fish were aged by examining thin-sectioned otoliths, and past size-at-age information was generated by using back-calculation techniques. Marginal increment analysis showed that opaque growth zones were annuli deposited between ...
Maarten Van Steenberge
Full Text Available The unparalleled biodiversity of Lake Tanganyika (Africa has fascinated biologists for over a century; its unique cichlid communities are a preferred model for evolutionary research. Although species delineation is, in most cases, relatively straightforward, higher-order classifications were shown not to agree with monophyletic groups. Here, traditional morphological methods meet their limitations. A typical example are the tropheine cichlids currently belonging to Simochromis and Pseudosimochromis. The affiliations of these widespread and abundant cichlids are poorly understood. Molecular work suggested that genus and species boundaries should be revised. Moreover, previous morphological results indicated that intraspecific variation should be considered to delineate species in Lake Tanganyika cichlids. We review the genera Simochromis and Pseudosimochromis using an integrative approach. Besides a morphometric study and a barcoding approach, monogenean Cichlidogyrus (Platyhelminthes: Ancyrocephalidae gill parasites, often highly species-specific, are used as complementary markers. Six new species are described. Cichlidogyrus raeymaekersi sp. nov., C. muterezii sp. nov. and C. banyankimbonai sp. nov. infect S. diagramma. Cichlidogyrus georgesmertensi sp. nov. was found on S. babaulti and S. pleurospilus, C. franswittei sp. nov. on both S. marginatus and P. curvifrons and C. frankwillemsi sp. nov. only on P. curvifrons. As relatedness between Cichlidogyrus species usually reflects relatedness between hosts, we considered Simochromis monotypic because the three Cichlidogyrus species found on S. diagramma belonged to a different morphotype than those found on the other Simochromis. The transfer of S. babaulti, S. marginatus, S. pleurospilus and S. margaretae to Pseudosimochromis was justified by the similarity of their Cichlidogyrus fauna and the intermediate morphology of S. margaretae. Finally parasite data also supported the synonymy between S
Powder, Kara E; Albertson, R Craig
We have made great strides towards understanding the etiology of craniofacial disorders, especially for 'simple' Mendelian traits. However, the facial skeleton is a complex trait, and the full spectrum of genetic, developmental, and environmental factors that contribute to its final geometry remain unresolved. Forward genetic screens are constrained with respect to complex traits due to the types of genes and alleles commonly identified, developmental pleiotropy, and limited information about the impact of environmental interactions. Here, we discuss how studies in an evolutionary model - African cichlid fishes - can complement traditional approaches to understand the genetic and developmental origins of complex shape. Cichlids exhibit an unparalleled range of natural craniofacial morphologies that model normal human variation, and in certain instances mimic human facial dysmorphologies. Moreover, the evolutionary history and genomic architecture of cichlids make them an ideal system to identify the genetic basis of these phenotypes via quantitative trait loci (QTL) mapping and population genomics. Given the molecular conservation of developmental genes and pathways, insights from cichlids are applicable to human facial variation and disease. We review recent work in this system, which has identified lbh as a novel regulator of neural crest cell migration, determined the Wnt and Hedgehog pathways mediate species-specific bone morphologies, and examined how plastic responses to diet modulate adult facial shapes. These studies have not only revealed new roles for existing pathways in craniofacial development, but have identified new genes and mechanisms involved in shaping the craniofacial skeleton. In all, we suggest that combining work in traditional laboratory and evolutionary models offers significant potential to provide a more complete and comprehensive picture of the myriad factors that are involved in the development of complex traits. PMID:26719128
William G. R. Crampton
Full Text Available The discus fishes of the genus Symphysodon are popular ornamental cichlids that occur in floodplain lakes and flooded forests of the lowland Amazon Basin. These habitats are characterized by extreme seasonal fluctuations in the availability of food, shelter and dissolved oxygen, and also the densities of predators and parasites. Most aspects of discus biology are influenced by these fluctuating conditions. This paper reports an autoecological study of the western Amazonian discus S. haraldi (until recently classified as S. aequifasciatus. This species feeds predominantly on algal periphyton, fine organic detritus, plant matter, and small aquatic invertebrates. At high water it forages alone or in small groups in flooded forests. At low water it forms large aggregations in fallen tree crowns along lake margins. Breeding occurs at the beginning of the flood season, ensuring that the progeny are well grown before the next low water period. Symphysodon haraldi is an iteroparous partial spawner, reaches reproductive maturity within a year, and undertakes parental care of its eggs and larvae. The timing of spawning events, and/or the rate of brood survival, may be influenced by fluctuations in the flood level, resulting in a non-unimodal distribution of size classes for the subsequent 1+ cohort.Os acarás-disco do gênero Symphysodon são peixes ornamentais comumente encontrados em lagos e florestas alagadas das planícies inundadas da Amazônia. Estes habitats são caracterizados por uma variação sazonal extrema na disponibilidade de alimento, abrigo e oxigênio dissolvido, e também pela densidade de predadores e parasitas. A maioria dos aspectos da biologia do acará-disco são influenciados por esta variabilidade de condições sazonais. Este artigo apresenta um estudo autoecológico de S. haraldi (até recentemente classificado como S. aequifasciatus da Amazônia Ocidental. Os acarás-disco alimentam-se predominantemente de perifiton, detritos
Scott A Juntti
Full Text Available Cichlid fishes represent one of the most species-rich and rapid radiations of a vertebrate family. These ~2200 species, predominantly found in the East African Great Lakes, exhibit dramatic differences in anatomy, physiology, and behavior. However, the genetic bases for this radiation, and for the control of their divergent traits, are unknown. A flood of genomic and transcriptomic data promises to suggest mechanisms underlying the diversity, but transgenic technology will be needed to rigorously test the hypotheses generated. Here we demonstrate the successful use of the Tol2 transposon system to generate transgenic Astatotilapia burtoni, a haplochromine cichlid from Lake Tanganyika, carrying the GFP transgene under the control of the ubiquitous EF1α promoter. The transgene integrates into the genome, is successfully passed through the germline, and the widespread GFP expression pattern is stable across siblings and multiple generations. The stable inheritance and expression patterns indicate that the Tol2 system can be applied to generate A. burtoni transgenic lines. Transgenesis has proven to be a powerful technology for manipulating genes and cells in other model organisms and we anticipate that transgenic A. burtoni and other cichlids will be used to test the mechanisms underlying behavior and speciation.
Full Text Available Background: The presence of pesticide due to the huge demand for agricultural purposes is very prevalent in surface waters of Iran. These pesticides could finally accumulate in aquatic ecosystems and have been proved to have toxic effects on aquatic animals. The aim of this study was to assess the acute toxicity of Diazinon, Deltamethrin, Butachlor and Pretilachlor on Zebra Cichlid (Cryptoheros nigrofasciatus. Methods: Fish samples were exposed to different concentrations of Diazinon (60% (0, 2, 4, 8, 16 and 32 ppm, Deltamethrin (2.5% (0, 0.02, 0.04, 0.10, 0.20 and 0.40 ppm, butachlor (60% (0, 2, 4, 8, 16 and 32 ppm and pretilachlor (50% (0, 5, 10, 20, 30 and 40 ppm for 96 h within the 100 L glass aquaria and cumulative mortality of Zebra Cichlid fish was calculated in 24-h interval. Results: The very low LC50 obtained for diazinon (5.06±0.37 ppm, deltamethrin (0.15±0.39 ppm, butachlor (8.93±0.26 ppm and pretilachlor (20.72±0.58 ppm indicated that these are highly toxic chemicals. Conclusion: Our results demonstrate that deltamethrin and pretilachlor had the lowest and highest rate of mortality on the Zebra Cichlid respectively.
Ferreira, I.A.; Poletto, A.B.; Kocher, T.D.; Mota-Velasco, J.C.; Penman, D.J.; Martins, C.
Cichlid fishes have been the subject of increasing scientific interest because of their rapid adaptive radiation that has led to extensive ecological diversity and because of their enormous importance to tropical and subtropical aquaculture. To further understanding of chromosome evolution among cichlid species, we have comparatively mapped the SATA satellite DNA, the transposable element ROn-1, and repeated sequences in the bacterial artificial chromosome clone BAC-C4E09 on the chromosomes of a range of African species of Cichlidae, using fluorescence in situ hybridization. The SATA satellite DNA was mapped in almost all the centromeres of all tilapiine and haplochromine species studied. The maintenance and centromeric distribution of the SATA satellite DNA in African cichlids suggest that this sequence plays an important role in the organization and function of the centromere in these species. Furthermore, analysis of SATA element distribution clarifies that chromosome fusions occurred independently in Oreochromis and Tilapia genera, and led to the reduced chromosome number detected in O. karongae and T. mariae. The comparative chromosome mapping of the ROn-1 SINE-like element and BAC-C4E09 shows that the repeated sequences have been maintained among tilapiine, haplochromine and hemichromine fishes and has demonstrated the homology of the largest chromosomes among these groups. Furthermore, the mapping of ROn-1 suggested that different chromosomal rearrangements could have occurred in the origin of the largest chromosome pairs of tilapiines and non-tilapiines. PMID:20606399
López-Fernández, Hernán; Arbour, Jessica; Willis, Stuart; Watkins, Crystal; Honeycutt, Rodney L; Winemiller, Kirk O
Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny. PMID:24603485
Mark, Thomas; Sandøe, Peter
The aim of this paper is to discuss the potential consequences of modern dairy cattle breeding for the welfare of dairy cows. The paper focuses on so-called genomic selection, which deploys thousands of genetic markers to estimate breeding values. The discussion should help to structure the...... thoughts of breeders and other stakeholders on how to best make use of genomic breeding in the future. Intensive breeding has played a major role in securing dramatic increases in milk yield since the Second World War. Until recently, the main focus in dairy cattle breeding was on production traits, but......, unfavourable genetic trends for metabolic, reproductive, claw and leg diseases indicate that these attempts have been insufficient. Today, novel genome-wide sequencing techniques are revolutionising dairy cattle breeding; these enable genetic changes to occur at least twice as rapidly as previously. While...
Martin, Christopher H
Models predict that sympatric speciation depends on restrictive parameter ranges, such as sufficiently strong disruptive selection and assortative mating, but compelling examples in nature have rarely been used to test these predictions. I measured the strength of assortative mating within a species complex of Tilapia in Lake Ejagham, Cameroon, a celebrated example of incipient sympatric adaptive radiation. This species complex is in the earliest stages of speciation: morphological and ecological divergence are incomplete, species differ primarily in breeding coloration, and introgression is common. I captured 27 mated pairs in situ and measured the diet, color, size, and morphology of each individual. I found strong assortative mating by color, size, head depth, and dietary source of benthic or pelagic prey along two independent dimensions of assortment. Thus, Ejagham Tilapia showed strong assortative mating most conducive to sympatric speciation. Nonetheless, in contrast to a morphologically bimodal Sarotherodon cichlid species pair in the lake, Ejagham Tilapia show more limited progress toward speciation, likely due to insufficient strength of disruptive selection on morphology estimated in a previous study (γ = 0.16). This supports the predicted dependence of sympatric speciation on strong assortment and strong disruptive selection by examining a potentially stalled example in nature. PMID:23815664
Full Text Available Abstract Background After a volcano erupts, a lake may form in the cooled crater and become an isolated aquatic ecosystem. This makes fishes in crater lakes informative for understanding sympatric evolution and ecological diversification in barren environments. From a geological and limnological perspective, such research offers insight about the process of crater lake ecosystem establishment and speciation. In the present study we use genetic and coalescence approaches to infer the colonization history of Midas cichlid fishes (Amphilophus cf. citrinellus that inhabit a very young crater lake in Nicaragua-the ca. 1800 year-old Lake Apoyeque. This lake holds two sympatric, endemic morphs of Midas cichlid: one with large, hypertrophied lips (~20% of the total population and another with thin lips. Here we test the associated ecological, morphological and genetic diversification of these two morphs and their potential to represent incipient speciation. Results Gene coalescence analyses [11 microsatellite loci and mitochondrial DNA (mtDNA sequences] suggest that crater lake Apoyeque was colonized in a single event from the large neighbouring great lake Managua only about 100 years ago. This founding in historic times is also reflected in the extremely low nuclear and mitochondrial genetic diversity in Apoyeque. We found that sympatric adult thin- and thick-lipped fishes occupy distinct ecological trophic niches. Diet, body shape, head width, pharyngeal jaw size and shape and stable isotope values all differ significantly between the two lip-morphs. The eco-morphological features pharyngeal jaw shape, body shape, stomach contents and stable isotopes (δ15N all show a bimodal distribution of traits, which is compatible with the expectations of an initial stage of ecological speciation under disruptive selection. Genetic differentiation between the thin- and thick-lipped population is weak at mtDNA sequence (FST = 0.018 and absent at nuclear
Michael J. Pauers
Full Text Available For evolutionary ecologists, the holy grail of visual ecology is to establish an unambiguous link between photoreceptor sensitivity, the spectral environment, and the perception of specific visual stimuli (e.g., mates, food, predators, etc.. Due to the bright nuptial colors of the males, and the role female mate choice plays in their evolution, the haplochromine cichlid fishes of the African great lakes are favorite research subjects for such investigations. Despite this attention, current evidence is equivocal; while distinct correlations among photoreceptor sensitivity, photic environment, and male coloration exist in Lake Victorian haplochromines, attempts to find such correlations in Lake Malawian cichlids have failed. Lake Malawi haplochromines have a wide variability in their short-wavelength-sensitive photoreceptors, especially compared to their mid- and long-wavelength-sensitive photoreceptors; these cichlids also vary in the degree to which they express one of three basic color patterns (vertical bars, horizontal stripes, and solid patches of colors, each of which is likely used in a different form of communication. Thus, we hypothesize that, in these fishes, spectral sensitivity and color pattern have evolved in a correlated fashion to maximize visual communication; specifically, ultraviolet sensitivity should be found in vertically-barred species to promote ‘private’ communication, while striped species should be less likely to have ultraviolet sensitivity, since their color pattern carries ‘public’ information. Using phylogenetic independent contrasts, we found that barred species had strong sensitivity to ultraviolet wavelengths, but that striped species typically lacked sensitivity to ultraviolet light. Further, the only variable, even when environmental variables were simultaneously considered, that could predict ultraviolet sensitivity was color pattern. We also found that, using models of correlated evolution, color
Key technological problems that influence tritium breeding in fusion blankets are reviewed. The breeding potential of candidate materials is evaluated and compared to the tritium breeding requirements. The sensitivity of tritium breeding to design and nuclear data parameters is reviewed. A framework for an integrated approach to improve tritium breeding prediction is discussed with emphasis on nuclear data requirements.
Meyer, Britta S.; Indermaur, Adrian; Ehrensperger, Xenia; Egger, Bernd; Banyankimbona, Gaspard; Snoeks, Jos; Salzburger, Walter
The species flocks of cichlid fishes in the East African Great Lakes are the largest vertebrate adaptive radiations in the world and illustrious textbook examples of convergent evolution between independent species assemblages. Although recent studies suggest some degrees of genetic exchange between riverine taxa and the lake faunas, not a single cichlid species is known from Lakes Tanganyika, Malawi and Victoria that is derived from the radiation associated with another of these lakes. Here, we report the discovery of a haplochromine cichlid species in Lake Tanganyika, which belongs genetically to the species flock of haplochromines of the Lake Victoria region. The new species colonized Lake Tanganyika only recently, suggesting that faunal exchange across watersheds and, hence, between isolated ichthyofaunas, is more common than previously thought. PMID:26064619
Tritium breeding materials are essential to the operation of D-T fusion facilities. Both of the present options - solid ceramic breeding materials and liquid metal materials are reviewed with emphasis not only on their attractive features but also on critical materials issues which must be resolved
Blackberry (Rubus L. subgenus Rubus Watson) improvement has made substantial progress with over 400 cultivars named originating from wild selections to many releases from breeding efforts. Public breeding has been ongoing for over 100 years. The result of these improvements is commercial production ...
Full Text Available Differently from what one could formerly imagine, that buffalo breeding activity would be solely directed to fill the so called cattle breeding gaps determined by inadequate environmental conditions for ordinary cattle breeding, it has been actually seen that in those areas where breeders could successfully organize industrial-agricultural chains, either on meat or milk and its related products production, there has been an expressive expansion .Buffalo breeding has shown to be an important alternative not only in farms of higher technological level as also , and mainly, on small farms where it has become a key factor for increasing the average income, besides keeping labor force in country areas. This article intends to point out and examine some aspects of buffalo breeding and its potentialities in Brazil.
The achievements made in mutation breeding in Japan over the past 40 years are outlined from the viewpoint of practical breeding. Fifty-four varieties of 23 crops were obtained by direct use of induced mutants. These include 12 cereal mutant varieties, five food legumes, nine industrial crops, seven vegetables and 18 ornamentals. Ten varieties were obtained by national breeding institutes, 14 by prefectural stations and 30 by universities or private firms. The varieties produced by the national breeding programme were registered and released with Norin numbers. In most cases, ionizing radiation was used. Forty additional mutant varieties were developed through cross-breeding using induced mutants as the gene sources. Of the 33 rice varieties in this category, 21, including six national varieties, resulted from crosses involving Reimei, a semi-dwarf mutant variety. Another semi-dwarf mutant parent was used to breed two more national varieties. Three early heading mutants were also integrated into cross-breeding programmes and produced three national and two prefectural varieties. A large grain mutant produced three varieties for sake brewing. A new recessive resistant mutant allele to the soil borne virus (BaYMV) was induced in barley. One variety was bred using this mutant as a parent. Another promising disease resistant clone was induced by chronic irradiation in a gamma field in the leading Japanese pear variety Nijisseiki, which is susceptible to black spot disease caused by Alternaria alternata (Fr.) Keissler. This mutant clone maintained all the superior qualities of the original variety. The significant role of the Institute of Radiation Breeding as a core in mutation breeding is mentioned briefly. (author). 10 refs, 2 figs, 6 tabs
Lin, Susan M; Nieves-Puigdoller, Katherine; Brown, Alexandria C; McGraw, Kevin J; Clotfelter, Ethan D
Many animals use carotenoid pigments derived from their diet for coloration and immunity. The carotenoid trade-off hypothesis predicts that, under conditions of carotenoid scarcity, individuals may be forced to allocate limited carotenoids to either coloration or immunity. In polychromatic species, the pattern of allocation may differ among individuals. We tested the carotenoid trade-off hypothesis in the Midas cichlid, Amphilophus citrinellus, a species with two ontogenetic color morphs, barred and gold, the latter of which is the result of carotenoid expression. We performed a diet-supplementation experiment in which cichlids of both color morphs were assigned to one of two diet treatments that differed only in carotenoid content (beta-carotene, lutein, and zeaxanthin). We measured integument color using spectrometry, quantified carotenoid concentrations in tissue and plasma, and assessed innate immunity using lysozyme activity and alternative complement pathway assays. In both color morphs, dietary carotenoid supplementation elevated plasma carotenoid circulation but failed to affect skin coloration. Consistent with observable differences in integument coloration, we found that gold fish sequestered more carotenoids in skin tissue than barred fish, but barred fish had higher concentrations of carotenoids in plasma than gold fish. Neither measure of innate immunity differed between gold and barred fish, or as a function of dietary carotenoid supplementation. Lysozyme activity, but not complement activity, was strongly affected by body condition. Our data show that a diet low in carotenoids is sufficient to maintain both coloration and innate immunity in Midas cichlids. Our data also suggest that the developmental transition from the barred to gold morph is not accompanied by a decrease in innate immunity in this species. PMID:20151818
Taylor Martin I
Full Text Available Abstract Background Research on the evolution of reproductive isolation in African cichlid fishes has largely focussed on the role of male colours and female mate choice. Here, we tested predictions from the hypothesis that allopatric divergence in male colour is associated with corresponding divergence in preference. Methods We studied four populations of the Lake Malawi Pseudotropheus zebra complex. We predicted that more distantly-related populations that independently evolved similar colours would interbreed freely while more closely-related populations with different colours mate assortatively. We used microsatellite genotypes or mesh false-floors to assign paternity. Fisher's exact tests as well as Binomial and Wilcoxon tests were used to detect if mating departed from random expectations. Results Surprisingly, laboratory mate choice experiments revealed significant assortative mating not only between population pairs with differently coloured males, but between population pairs with similarly-coloured males too. This suggested that assortative mating could be based on non-visual cues, so we further examined the sensory basis of assortative mating between two populations with different male colour. Conducting trials under monochromatic (orange light, intended to mask the distinctive male dorsal fin hues (blue v orange of these populations, did not significantly affect the assortative mating by female P. emmiltos observed under control conditions. By contrast, assortative mating broke down when direct contact between female and male was prevented. Conclusion We suggest that non-visual cues, such as olfactory signals, may play an important role in mate choice and behavioural isolation in these and perhaps other African cichlid fish. Future speciation models aimed at explaining African cichlid radiations may therefore consider incorporating such mating cues in mate choice scenarios.
Moira J.VAN STAADEN; Adam R.SMITH
The active transmission of information from sender to recelver is a fundamental component of communication,and is therefore a primary facet in evolutionary models of sexual selection.Research in several systetms has underlined the importance of multiple sensory modalities in courtship signals.However,we still tend to think of individuals as having a relatively static signal in consecutive communicative events.While this may be true for certain traits such as body size or coloration,behaviorally modulated signals can quickly violate this assumption.In this work,we explore how intraspecific variation may be an important component of interspeclfic signal divergence using cichlid fishes from Lake Maiawi.Behavloral analyses were made using six species of Malawian cichlids from two divergent genera.while interspecific differences were found between congeners based on species-level analyses of both acoustic and audiovisual signais,intraspecific variation was of a similar magnitude.Specifically,individual fishes were found to possess highiy plastic signal repertoires.This finding was ubiquitous across all species and resulted in a great deal of overlap between heterospecific individuals,despite statistically distinct species means.These results demonstrate that some aspects of courtship in Malawian cichlids are more plastic than previously proposed,and that studies must account for signal variability within individuals.We propose here that bebavioral variability in signaling is important in determining the communication landscape on which signals are perceived.We review potential complexity deriving from multimodal signaling,discuss the sources for such lability,and suggest ways in which is issue may be approached experimentally.
Full Text Available Abstract Background The availability of a large number of recently sequenced vertebrate genomes opens new avenues to integrate cytogenetics and genomics in comparative and evolutionary studies. Cytogenetic mapping can offer alternative means to identify conserved synteny shared by distinct genomes and also to define genome regions that are still not fine characterized even after wide-ranging nucleotide sequence efforts. An efficient way to perform comparative cytogenetic mapping is based on BAC clones mapping by fluorescence in situ hybridization. In this report, to address the knowledge gap on the genome evolution in cichlid fishes, BAC clones of an Oreochromis niloticus library covering the linkage groups (LG 1, 3, 5, and 7 were mapped onto the chromosomes of 9 African cichlid species. The cytogenetic mapping data were also integrated with BAC-end sequences information of O. niloticus and comparatively analyzed against the genome of other fish species and vertebrates. Results The location of BACs from LG1, 3, 5, and 7 revealed a strong chromosomal conservation among the analyzed cichlid species genomes, which evidenced a synteny of the markers of each LG. Comparative in silico analysis also identified large genomic blocks that were conserved in distantly related fish groups and also in other vertebrates. Conclusions Although it has been suggested that fishes contain plastic genomes with high rates of chromosomal rearrangements and probably low rates of synteny conservation, our results evidence that large syntenic chromosome segments have been maintained conserved during evolution, at least for the considered markers. Additionally, our current cytogenetic mapping efforts integrated with genomic approaches conduct to a new perspective to address important questions involving chromosome evolution in fishes.
Full Text Available Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny.
Beier, M.; Hilbig, R.; Anken, R.
Inner ear otolith growth in terms of mineralisation mainly depends on the enzyme carbonic anhydrase (CAH). CAH is located in specialised, mitochondria-rich macular cells (ionocytes), which are involved in the endolymphatic ion exchange, and the enzyme is responsible for the provision of the pH-value necessary for otolithic calcium carbonate deposition. In the present study, for the first time the localisation of histochemically demonstrated CAH was analysed during the early larval development of a teleost, the cichlid fish Oreochromis mossambicus. CAH-reactivity was observed already in stage 7 animals (onset of otocyst development; staging follows Anken et al. [Anken, R., Kappel, T., Slenzka, K., Rahmann, H. The early morphogenetic development of the cichlid fish, Oreochromis mossambicus (Perciformes, Teleostei). Zool. Anz. 231, 1-10, 1993]). Neuroblasts (from which sensory and supporting cells are derived) proved to be CAH-positive. Already at stage 12 (hatch), CAH-positive regions could be attributed to ionocyte containing regions both in the so-called meshwork and patches area of the macula (i.e., clearly before ionocytes can be identified on ultrastructural level or by employing immunocytochemistry). In contrast to the circumstances observed in mammalian species, sensory hair cells stained negative for CAH in the cichlid. With the onset of stage 16 (finray primordia in dorsal fin, yolk-sac being increasingly absorbed), CAH-reactivity was observed in the vestibular nerve. This indicates the onset of myelinisation and thus commencement of operation. The localisation of CAH in the inner ear of fish (especially the differences in comparison to mammals) is discussed on the basis of its role in otolith calcification. Since the vestibular system is a detector of acceleration and thus gravity, also aspects regarding effects of altered gravity on CAH and hence on the mineralisation of otoliths in an adaptive process are addressed.
Full Text Available Abstract Background The adaptive radiations of cichlid fishes in East Africa are well known for their spectacular diversity and their astonishingly fast rates of speciation. About 80% of all 2,500 cichlid species in East Africa, and virtually all cichlid species from Lakes Victoria (~500 species and Malawi (~1,000 species are haplochromines. Here, we present the most extensive phylogenetic and phylogeographic analysis so far that includes about 100 species and is based on about 2,000 bp of the mitochondrial DNA. Results Our analyses revealed that all haplochromine lineages are ultimately derived from Lake Tanganyika endemics. We find that the three most ancestral lineages of the haplochromines sensu lato are relatively species poor, albeit widely distributed in Africa, whereas a fourth newly defined lineage – the 'modern haplochromines' – contains an unparalleled diversity that makes up more than 7% of the worlds' ~25,000 teleost species. The modern haplochromines' ancestor, most likely a riverine generalist, repeatedly gave rise to similar ecomorphs now found in several of the species flocks. Also, the Tanganyikan Tropheini are derived from that riverine ancestor suggesting that they successfully re-colonized Lake Tanganyika and speciated in parallel to an already established cichlid adaptive radiation. In contrast to most other known examples of adaptive radiations, these generalist ancestors were derived from highly diverse and specialized endemics from Lake Tanganyika. A reconstruction of life-history traits revealed that in an ancestral lineage leading to the modern haplochromines the characteristic egg-spots on anal fins of male individuals evolved. Conclusion We conclude that Lake Tanganyika is the geographic and genetic cradle of all haplochromine lineages. In the ancestors of the replicate adaptive radiations of the 'modern haplochromines', behavioral (maternal mouthbrooding, morphological (egg-spots and sexually selected (color
McLaughlin, Kirsty Elizabeth; Kunc, Hansjoerg P
Anthropogenic noise can affect behaviour across a wide range of species in both terrestrial and aquatic environments. However, behaviours might not be affected in isolation. Therefore, a more holistic approach investigating how environmental stressors, such as noise pollution, affect different behaviours in concert is necessary. Using tank-based noise exposure experiments, we tested how changes in the acoustic environment affect the behaviour of the cichlid Amatitlania nigrofasciata. We found that exposure to anthropogenic noise affected a couple of behaviours: an increase in sheltering was accompanied by a decrease in foraging. Our results highlight the multiple negative effects of an environmental stressor on an individual's behaviour. PMID:25937344
Full Text Available Abstract Background The vertebrate brain is composed of several interconnected, functionally distinct structures and much debate has surrounded the basic question of how these structures evolve. On the one hand, according to the 'mosaic evolution hypothesis', because of the elevated metabolic cost of brain tissue, selection is expected to target specific structures mediating the cognitive abilities which are being favored. On the other hand, the 'concerted evolution hypothesis' argues that developmental constraints limit such mosaic evolution and instead the size of the entire brain varies in response to selection on any of its constituent parts. To date, analyses of these hypotheses of brain evolution have been limited to mammals and birds; excluding Actinopterygii, the basal and most diverse class of vertebrates. Using a combination of recently developed phylogenetic multivariate allometry analyses and comparative methods that can identify distinct rates of evolution, even in highly correlated traits, we studied brain structure evolution in a highly variable clade of ray-finned fishes; the Tanganyikan cichlids. Results Total brain size explained 86% of the variance in brain structure volume in cichlids, a lower proportion than what has previously been reported for mammals. Brain structures showed variation in pair-wise allometry suggesting some degree of independence in evolutionary changes in size. This result is supported by variation among structures on the strength of their loadings on the principal size axis of the allometric analysis. The rate of evolution analyses generally supported the results of the multivariate allometry analyses, showing variation among several structures in their evolutionary patterns. The olfactory bulbs and hypothalamus were found to evolve faster than other structures while the dorsal medulla presented the slowest evolutionary rate. Conclusion Our results favor a mosaic model of brain evolution, as certain
Zheng, S.J.; Kamenetsky, R.; Féréol, L.; Barandiaran, X.; Rabinowitch, H.D.; Chovelon, V.; Kik, C.
This review outlines innovative methods for garlic breeding improvement and discusses the techniques used to increase variation like mutagenesis and in vitro techniques, as well as the current developments in florogenesis, sexual hybridization, genetic transformation and mass propagation. Sexual ste
California Department of Resources — This data set provides access to information gathered on annual breeding bird surveys in California using a map layer developed by the Department. This data layer...
Pinard-van der Laan, Marie-Helene
In the context of intensification and specialization of poultry production, next to welfare regulation on animal breeding, animal health issues are of increasing importance to the breeding sector because of the huge related production losses. But animal health and welfare issues are also of importance to the consumers because of potential effects on their own health and their lifestyle choices. Most effective disease control strategies should be developed in an integrated animal health manage...
University textbook Principles of Animal Breeding is intended for students of agriculture and veterinary medicine. The material is the adapted curricula of undergraduate and graduate level studies in the framework of which the modules Principles of animal breeding as well as Basics of genetics and selection of animals attended are listened. The textbook contains 14 chapters and a glossary of terms. Its concept enables combining fundamental and modern knowledge in the ...
Campbell, M L H; Sandøe, Peter
Welfare problems related to the way horses are bred, whether by coitus or by the application of artificial reproduction techniques (ARTs), have been given no discrete consideration within the academic literature. This paper reviews the existing knowledge base about welfare issues in horse breeding and identifies areas in which data is lacking. We suggest that all methods of horse breeding are associated with potential welfare problems, but also that the judicious use of ARTs can sometimes hel...
Zonabend König, Emelie
The aim of this thesis was to study potential breeding strategies for indigenous livestock in Eastern and Southern Africa under low input production systems. The thesis covered a study of the status of supportive infrastructure for use of animal genetic resources. The case of Red Maasai sheep was studied as a model for design of strategies for improvement of an indigenous breed under threat. Studies [I-II] were performed through participatory approaches by use of structured interviews, while ...
The evolution, domestication, variability and adaptation of fibre jutes in Bangladesh are described. Domestication of fibre jutes, in evolutionary terms, is recent and the spectrum of variability within them is narrow. Yield improvement by breeding has been minimal and the reasons for this are suggested. Recent germplasm collecting expeditions to the eastern hill tracts of Bangladesh have revealed wide-spectrum diversity among the vegetable jutes grown there. Variability among the vegetable types can be utilized to improve the fibre types and to this end various hybridization schemes have now been initiated by the Bangladesh Jute Research Institute. The initial breeding priority is yield per se but ideotype characteristics have been delineated. The objectives of the breeding programme are likely to become more specific as the agronomic worth of these characteristics becomes more clearly defined. The rationale for mutation breeding in jute has been the narrow-spectrum diversity within the fibre types; the wide-spectrum diversity among the hill tract vegetable jutes should, however, be exploited in imaginative hybridization programmes before resorting to large-scale mutation breeding programmes. Mutation breeding may, however, be a valuable tool for inducing changes in fibre quality characteristics when technologists identify new uses for jute and specify their requirements. At present, however, quality is assessed subjectively. (author)
Geiger, Matthias F; McCrary, Jeffrey K; Schliewen, Ulrich K
Nicaraguan Midas cichlids from crater lakes have recently attracted attention as potential model systems for speciation research, but no attempt has been made to comprehensively reconstruct phylogenetic relationships of this highly diverse and recently evolved species complex. We present a first AFLP (2793 loci) and mtDNA based phylogenetic hypothesis including all described and several undescribed species from six crater lakes (Apoyeque, Apoyo, Asososca Leon, Masaya, Tiscapa and Xiloá), the two great Lakes Managua and Nicaragua and the San Juan River. Our analyses demonstrate that the relationships between the Midas cichlid members are complex, and that phylogenetic information from different markers and methods do not always yield congruent results. Nevertheless, monophyly support for crater lake assemblages from Lakes Apoyeque, Apoyo, A. Leon is high as compared to those from L. Xiloá indicating occurrence of sympatric speciation. Further, we demonstrate that a 'three species' concept for the Midas cichlid complex is inapplicable and consequently that an individualized and voucher based approach in speciation research of the Midas cichlid complex is necessary at least as long as there is no comprehensive revision of the species complex available. PMID:20580847
Stiassny Melanie LJ
Full Text Available Abstract Background It is hypothesized that one of the mechanisms promoting diversification in cichlid fishes in the African Great Lakes has been the well-documented pattern of philopatry along shoreline habitats leading to high levels of genetic isolation among populations. However lake habitats are not the only centers of cichlid biodiversity - certain African rivers also contain large numbers of narrowly endemic species. Patterns of isolation and divergence in these systems have tended to be overlooked and are not well understood. Results We examined genetic and morphological divergence among populations of two narrowly endemic cichlid species, Teleogramma depressum and Lamprologus tigripictilis, from a 100 km stretch of the lower Congo River using both nDNA microsatellites and mtDNA markers along with coordinate-based morphological techniques. In L. tigripictilis, the strongest genetic break was concordant with measurable phenotypic divergence but no morphological disjunction was detected for T. depressum despite significant differentiation at mtDNA and nDNA microsatellite markers. Conclusions The genetic markers revealed patterns of philopatry and estimates of genetic isolation that are among the highest reported for any African cichlid species over a comparable geographic scale. We hypothesize that the high levels of philopatry observed are generated and maintained by the extreme hydrology of the lower Congo River.
Oldfield, Ronald G
Many species of fishes are aggressive when placed in small aquaria. Aggression can negatively affect the welfare of those individuals toward whom it is directed. Animals may behave aggressively in order to defend resources such as food, shelter, mates, and offspring. The decision to defend depends on the distribution of resources and on ecological factors such as number of competitors, amount of available space, and amount of habitat complexity. This study tested the effects of these factors on aggression in a common aquarium fish, the Midas cichlid (Amphilophus citrinellus). The study found that time spent behaving aggressively was not associated with small-scale differences in group size or available space. Aggression was significantly lower in a large aquarium with a complex habitat. Aquaria of sizes typically used in the companion animal (pet) hobby did not provide optimal welfare for cichlids housed with aggressive conspecifics. The public should be aware that this and similar species require larger aquaria with complex habitat, which elicit more natural behavior. PMID:21932947
Franchini, Paolo; Fruciano, Carmelo; Frickey, Tancred; Jones, Julia C; Meyer, Axel
Gut bacterial communities are now known to influence a range of fitness related aspects of organisms. But how different the microbial community is in closely related species, and if these differences can be interpreted as adaptive is still unclear. In this study we compared microbial communities in two sets of closely related sympatric crater lake cichlid fish species pairs that show similar adaptations along the limnetic-benthic axis. The gut microbial community composition differs in the species pair inhabiting the older of two crater lakes. One major difference, relative to other fish, is that in these cichlids that live in hypersaline crater lakes, the microbial community is largely made up of Oceanospirillales (52.28%) which are halotolerant or halophilic bacteria. This analysis opens up further avenues to identify candidate symbiotic or co-evolved bacteria playing a role in adaptation to similar diets and life-styles or even have a role in speciation. Future functional and phylosymbiotic analyses might help to address these issues. PMID:24733403
Hyuk Je Lee
Full Text Available Scale-eating cichlid fish, Perissodus microlepis, from Lake Tanganyika display handed (lateralized foraging behavior, where an asymmetric 'left' mouth morph preferentially feeds on the scales of the right side of its victim fish and a 'right' morph bites the scales of the left side. This species has therefore become a textbook example of the astonishing degree of ecological specialization and negative frequency-dependent selection. We investigated the strength of handedness of foraging behavior as well as its interaction with morphological mouth laterality in P. microlepis. In wild-caught adult fish we found that mouth laterality is, as expected, a strong predictor of their preferred attack orientation. Also laboratory-reared juvenile fish exhibited a strong laterality in behavioral preference to feed on scales, even at an early age, although the initial level of mouth asymmetry appeared to be small. This suggests that pronounced mouth asymmetry is not a prerequisite for handed foraging behavior in juvenile scale-eating cichlid fish and might suggest that behavioral preference to attack a particular side of the prey plays a role in facilitating morphological asymmetry of this species.
Full Text Available Behavioral lateralization has been documented in many vertebrates. The scale-eating cichlid fish Perissodus microlepis is well known for exhibiting lateral dimorphism in its mouth morphology and lateralized behavior in robbing scales from prey fish. A previous field study indicated that this mouth asymmetry closely correlates with the side on which prey is attacked, but details of this species' predation behavior have not been previously analyzed because of the rapidity of the movements. Here, we studied scale-eating behavior in cichlids in a tank through high-speed video monitoring and quantitative assessment of behavioral laterality and kinematics. The fish observed showed a clear bias toward striking on one side, which closely correlated with their asymmetric mouth morphologies. Furthermore, the maximum angular velocity and amplitude of body flexion were significantly larger during attacks on the preferred side compared to those on the nonpreferred side, permitting increased predation success. In contrast, no such lateral difference in movement elements was observed in acoustically evoked flexion during the escape response, which is similar to flexion during scale eating and suggests that they share a common motor control pathway. Thus the neuronal circuits controlling body flexion during scale eating may be functionally lateralized upstream of this common motor pathway.
Takahashi, Tetsumi; Sota, Teiji
The huge monophyletic group of the East African cichlid radiations (EAR) consists of thousands of species belonging to 12-14 tribes; the number of tribes differs among studies. Many studies have inferred phylogenies of EAR tribes using various genetic markers. However, these phylogenies partly contradict one another and can have weak statistic support. In this study, we conducted maximum-likelihood (ML) phylogenetic analyses using restriction site-associated DNA (RAD) sequences and propose a new robust phylogenetic hypothesis among Lake Tanganyika cichlid fishes, which cover most EAR tribes. Data matrices can vary in size and contents depending on the strategies used to process RAD sequences. Therefore, we prepared 23 data matrices with various processing strategies. The ML phylogenies inferred from 15 large matrices (2.0×10(6) to 1.1×10(7) base pairs) resolved every tribe as a monophyletic group with 100% bootstrap support and shared the same topology regarding relationships among the tribes. Most nodes among the tribes were supported by 100% bootstrap values, and the bootstrap support for the other node varied among the 15 ML trees from 70% to 100%. These robust ML trees differ partly in topology from those in earlier studies, and these phylogenetic relationships have important implications for the tribal classification of EAR. PMID:27068840
Bloch, A N; Estela, V J; Leese, J M; Itzkowitz, M
Many monogamous species demonstrate size-assortative mating patterns within natural populations. To better understand the role of intersexual selection in this process, we examined the effect of male preference for female body size in the convict cichlid (Amatitlania siquia). We provided males with a choice between females that differed in size, relative to each other and in relation to the focal male. Based on previous work, we expected males to prefer the largest available female mates across all treatments. Surprisingly, males spent more time near the smaller of two available females, but only when the other female was larger than the male. Additionally, males spent little time with either of two potential female mates when both females were larger than the male. We hypothesized that while males might prefer the largest of available females, female behavior might limit males from acting on this preference. To test this, males were force paired with a smaller or larger female. Pair formation only occurred when the female was smaller than the male, and females that were larger than their male counterparts showed significantly more aggression when compared to smaller females. Together, these data suggest that in the absence of intrasexual competition, male mate preference for large females in convict cichlids might be limited by female aggression. PMID:27444247
Full Text Available The approximately 700 species of cichlids found in Lake Victoria in East Africa are thought to have evolved over a short period of time, and they represent one of the largest known examples of adaptive radiation. To understand the processes that are driving this spectacular radiation, we must determine the present genetic structure of these species and elucidate how this structure relates to the ecological conditions that caused their adaptation. We analyzed the genetic structure of two pelagic and seven littoral species sampled from the southeast area of Lake Victoria using sequences from the mtDNA control region and 12 microsatellite loci as markers. Using a Bayesian model-based clustering method to analyze the microsatellite data, we separated these nine species into four groups: one group composed of pelagic species and another three groups composed mainly of rocky-shore species. Furthermore, we found significant levels of genetic variation between species within each group at both marker loci using analysis of molecular variance (AMOVA, although the nine species often shared mtDNA haplotypes. We also found significant levels of genetic variation between populations within species. These results suggest that initial groupings, some of which appear to have been related to habitat differences, as well as divergence between species within groups took place among the cichlid species of Lake Victoria.
Recent suggestions concerning the age and origin of the flock of haplochromine cichlid fishes in Lake Victoria (East Africa) are considered. These accept as proven the suggestion that Lake Victoria dried out completely in the Late Pleistocene, was dry for several thousand years, and refilled ca. 12400 years ago. Apart from the fact that other geophysical evidence contradicts this claim, its biological implications, which do likewise, have never been considered by those who have accepted it. Like those of all previous authors who have seized on the presence of the haplochromine flock of perhaps more than 600 species as evidence of extremely rapid evolution since the lake allegedly refilled, the account completely overlooks the fact that any such desiccation must have eliminated not only the haplochromine cichlids but the entire biota of the lake. Nevertheless, its present fauna not only includes the haplochromines but many other endemic organisms that would not be expected, and whose presence and history demand an explanation if the lake did indeed dry out. No such explanation has been offered, nor does such seem possible. The recent interpretation of events is questioned and rejected. PMID:11375102
Schwalbe, Margot A B; Webb, Jacqueline F
The adaptive radiations of African cichlids resulted in a diversity of feeding morphologies and strategies, but the role of sensory biology in prey detection and feeding ecology remains largely unexplored. Two endemic Lake Malawi cichlid genera, Tramitichromis and Aulonocara, feed on benthic invertebrates, but differ in lateral line morphology (narrow and widened lateral line canals, respectively) and foraging strategy. The hypothesis that they use their lateral line systems differently was tested by looking at the relative contribution of the lateral line system and vision in prey detection by Tramitichromis sp. and comparing results to those from a complementary study using Aulonocara stuartgranti (Schwalbe et al., 2012). First, behavioral trials were used to assess the ability of Tramitichromis sp. to detect live (mobile) and dead (immobile) benthic prey under light and dark conditions. Second, trials were run before, immediately after, and several weeks after chemical ablation of the lateral line system to determine its role in feeding behavior. Results show that Tramitichromis sp. is a visual predator that neither locates prey in the dark nor depends on lateral line input for prey detection and is thus distinct from A. stuartgranti, which uses its lateral line or a combination of vision and lateral line to detect prey depending on light condition. Investigating how functionally distinctive differences in sensory morphology are correlated with feeding behavior in the laboratory and determining the role of sensory systems in feeding ecology will provide insights into how sensory capabilities may contribute to trophic niche segregation. PMID:24369759
Full Text Available Background: Aquatic ecosystems are frequently subjected to contamination by toxic heavy metals and pesticides, yet very little is known about the influence of pesticides on bioaccumulation of heavy metals in aquatic organisms. Mercury is a toxic metal with no known biological benefit to organisms. Bioavailability of mercury in aquatic environments depends on biological and non-biological parameters including other pollutants. Therefore, the objectives of this research were to determine the effects of permethrin on bioaccumulation of mercury in zebra cichlid. Methods: Acute toxicity (LC50 of permethrin and mercury chloride was evaluated by estimating mortality in Probit Model in SPSS (version 19.0 IBM. In sub-lethal toxicity, zebra cichlid (Cichlasoma nigrofasciatum was exposed to various concentrations of permethrin (0.0, 0.40, 0.80, 1.20 and 1.60 µg.L-1 combined with 20 µg.L-1 mercury chloride for 15 days. At the end of the experiment, mercury concentrations were measured using ICP-OES-Perkin elmer (optima 7300-DV. Results: 96 h LC50 values of permethrin and mercury for C. nigrofasciatum were calculated to be 17.55 µg.L-1 and 140.38 µg.L-1, respectively. Our results clearly showed that the bioaccumulation of mercury in the specimens increased with increasing concentrations of permethrin to 1.20 and 1.60 µg.L-1. Conclusion: Increasing the concentration of permethrin had synergistic effects on the bioaccumulation of mercury in fish.
Full Text Available Fishes of the family Cichlidae are famous for their spectacular species flocks and therefore constitute a model system for the study of the pathways of adaptive radiation. Their radiation is connected to trophic specialization, manifested in dentition, head morphology, and body shape. Geometric morphometric methods have been established as efficient tools to quantify such differences in overall body shape or in particular morphological structures and meanwhile found wide application in evolutionary biology. As a common feature, these approaches define and analyze coordinates of anatomical landmarks, rather than traditional counts or measurements. Geometric morphometric methods have several merits compared to traditional morphometrics, particularly for the distinction and analysis of closely related entities. Cichlid evolutionary research benefits from the efficiency of data acquisition, the manifold opportunities of analyses, and the potential to visualize shape changes of those landmark-based methods. This paper briefly introduces to the concepts and methods of geometric morphometrics and presents a selection of publications where those techniques have been successfully applied to various aspects of cichlid fish diversification.
Klett, Vera; Meyer, Axel
We estimated a novel phylogeny of tilapiine cichlid fish (an assemblage endemic to Africa and the Near East) within the African cichlid fishes on the basis of complete mitochondrial NADH dehydrogenase subunit 2 (ND2) gene sequences. The ND2 (1,047 bp) gene was sequenced in 39 tilapiine cichlids (38 species and 1 subspecies) and in an additional 14 nontilapiine cichlid species in order to evaluate the traditional morphologically based hypothesis of the respective monophyly of the tilapiine and haplochromine cichlid fish assemblages. The analyses included many additional cichlid lineages, not only the so-called tilapiines, but also lineages from Lake Tanganyika, east Africa, the Neotropics and an out-group from Madagascar with a wide range of parental care and mating systems. Our results suggest, in contrast to the historical morphology-based hypotheses from Regan (1920, 1922 ), Trewavas (1983), and Stiassny (1991), that the tilapiines do not form a monophyletic group because there is strong evidence that the genus Tilapia is not monophyletic but divided into at least five distinct groups. In contrast to this finding, an allozyme analysis of Pouyaud and Agnèse (1995), largely based on the same samples as used here, found a clustering of the Tilapia species into only two groups. This discrepancy is likely caused by the difference in resolution power of the two marker systems used. Our data suggest that only type species Tilapia sparrmanii Smith (1840) should retain the genus name TILAPIA: One particular group of tilapiines (composed of genera Sarotherodon, Oreochromis, Iranocichla, and Tristramella) is more closely related to an evolutionarily highly successful lineage, the haplochromine cichlids that compose the adaptive radiations of cichlid species flocks of east Africa. It appears that the highly adaptable biology of tilapiines is the ancestral state for all African cichlids and that the more stenotypic lifestyle of the haplochromine cichlids is derived from this
Albertson R Craig; Stewart Thomas A
Abstract Background While bilaterality is a defining characteristic of triploblastic animals, several assemblages have managed to break this symmetry in order to exploit the adaptive peaks garnered through the lateralization of behaviour or morphology. One striking example of an evolved asymmetry in vertebrates comes from a group of scale-eating cichlid fishes from Lake Tanganyika. Members of the Perissodini tribe of cichlid fishes have evolved dental and craniofacial asymmetries in order to ...
Ancyrocephalidae (Monogenea) of Lake Tanganyika. III : Cichlidogyrus infecting the world's biggest cichlid and the non-endemic tribes Haplochromini, Oreochromini and Tylochromini (Teleostei, Cichlidae)
Bukinga, F. M.; Vanhove, M.P.M.; Van Steenberge, M.; Pariselle, Antoine
Lake Tanganyika is the deepest and oldest African Great Lake and of economic importance. While the diversity of its endemic cichlid radiations yielded scientific interest, a number of cichlid tribes have few representatives in the lake. Some of those, namely Oreochromini (ex-Tilapiini), Haplochromini and Tylochromini, reach higher species numbers in riverine systems. Conversely, the phylogenetic position of the monospecific and endemic Boulengerochromini is unclear. The oreochromines Oreochro...
Hata, Hiroki; Akifumi S Tanabe; Yamamoto, Satoshi; Toju, Hirokazu; Kohda, Masanori; Hori, Michio
Background Lake Tanganyika, an ancient lake in the Great Rift Valley, is famous for the adaptive radiation of cichlids. Five tribes of the Cichlidae family have acquired herbivory, with five ecomorphs: grazers, browsers, scrapers, biters and scoopers. Sixteen species of the herbivorous cichlids coexist on a rocky littoral slope in the lake. Seven of them individually defend feeding territories against intruding herbivores to establish algal farms. We collected epiphyton from these territories...
Mohamad S. Abd El-Karim
Full Text Available We assess the importance of four different food sources as dietary components of Oreochromis niloticus and Sarotherodon galilaeus in Nile sub-branches using stomach contents, fatty acids (FA and stable isotopes (SI analyses. Diatoms were the dominant food items, whereas sand and mud constitute a major part of the stomach contents of both cichlids in the northern ElBehery canal. FAs and SI were compared in cichlids and four potential food sources. Carbon isotopes excluded the fresh macrophyte Myriophyllum spicatum and its epiphytes as a potential food source, whereas FA biomarkers indicated that M. spicatum is assimilated in cichlids’ muscles as detrital materials. FA profiles of cichlids’ muscles were highly enriched by live diatom markers whereas decayed diatoms and bacterial markers were partially present. Carbon isotope signatures of cichlids were much close to that of suspended particulate organic matter (SPOM which elucidated that SPOM was the source of diatoms and bacterial detritus incorporated in cichlids muscles. Cichlids were highly enriched with nitrogen signatures which was a result of increased anthropogenic effects and incorporation of bacterial films. SI and FA analyses precisely indicated that live diatoms and bacteria, detrital macrophytes are the main sources of organic matter incorporated in cichlids muscles.
Morandini, Leonel; Ramallo, Martín Roberto; Moreira, Renata Guimarães; Höcht, Christian; Somoza, Gustavo Manuel; Silva, Ana; Pandolfi, Matías
Reared animals for edible or ornamental purposes are frequently exposed to high aggression and stressful situations. These factors generally arise from conspecifics in densely breeding conditions. In vertebrates, serotonin (5-HT) has been postulated as a key neuromodulator and neurotransmitter involved in aggression and stress. The essential amino acid L-tryptophan (trp) is crucial for the synthesis of 5-HT, and so, leaves a gateway for indirectly augmenting brain 5-HT levels by means of a trp-enriched diet. The cichlid fish Cichlasoma dimerus, locally known as chanchita, is an autochthonous, potentially ornamental species and a fruitful laboratory model which behavior and reproduction has been studied over the last 15years. It presents complex social hierarchies, and great asymmetries between subordinate and dominant animals in respect to aggression, stress, and reproductive chance. The first aim of this work was to perform a morphological description of chanchita's brain serotonergic system, in both males and females. Then, we evaluated the effects of a trp-supplemented diet, given during 4weeks, on brain serotonergic activity, stress and sexual steroid hormones, and growth in isolated specimens. Results showed that chanchita's brain serotonergic system is composed of several populations of neurons located in three main areas: pretectum, hypothalamus and raphe, with no clear differences between males and females at a morphological level. Animals fed with trp-enriched diets exhibited higher forebrain serotonergic activity and a significant reduction in their relative cortisol levels, with no effects on sexual steroid plasma levels or growth parameters. Thus, this study points to food trp enrichment as a "neurodietary'' method for elevating brain serotonergic activity and decreasing stress, without affecting growth or sex steroid hormone levels. PMID:26449161
Flint, A.P.F.; WOOLLIAMS, J. A.
We accept that we are responsible for the quality of life of animals in our care. We accept that the activities of man affect all the living things with which we share this planet. But we are slow to realize that as a result we have a duty of care for all living things. That duty extends to the breeding of animals for which we are responsible. When animals are bred by man for a purpose, the aim should be to meet certain goals: to improve the precision with which breeding outcomes can be predi...
Campbell, M.L.H.; Sandøe, Peter
Welfare problems related to the way horses are bred, whether by coitus or by the application of artificial reproduction techniques (ARTs), have been given no discrete consideration within the academic literature. This paper reviews the existing knowledge base about welfare issues in horse breeding...... and identifies areas in which data is lacking. We suggest that all methods of horse breeding are associated with potential welfare problems, but also that the judicious use of ARTs can sometimes help to address those problems. We discuss how negative welfare effects could be identified and limited and...
Weadick Cameron J
Full Text Available Abstract Background Gene duplications play an important role in the evolution of functional protein diversity. Some models of duplicate gene evolution predict complex forms of paralog divergence; orthologous proteins may diverge as well, further complicating patterns of divergence among and within gene families. Consequently, studying the link between protein sequence evolution and duplication requires the use of flexible substitution models that can accommodate multiple shifts in selection across a phylogeny. Here, we employed a variety of codon substitution models, primarily Clade models, to explore how selective constraint evolved following the duplication of a green-sensitive (RH2a visual pigment protein (opsin in African cichlids. Past studies have linked opsin divergence to ecological and sexual divergence within the African cichlid adaptive radiation. Furthermore, biochemical and regulatory differences between the RH2aα and RH2aβ paralogs have been documented. It thus seems likely that selection varies in complex ways throughout this gene family. Results Clade model analysis of African cichlid RH2a opsins revealed a large increase in the nonsynonymous-to-synonymous substitution rate ratio (ω following the duplication, as well as an even larger increase, one consistent with positive selection, for Lake Tanganyikan cichlid RH2aβ opsins. Analysis using the popular Branch-site models, by contrast, revealed no such alteration of constraint. Several amino acid sites known to influence spectral and non-spectral aspects of opsin biochemistry were found to be evolving divergently, suggesting that orthologous RH2a opsins may vary in terms of spectral sensitivity and response kinetics. Divergence appears to be occurring despite intronic gene conversion among the tandemly-arranged duplicates. Conclusions Our findings indicate that variation in selective constraint is associated with both gene duplication and divergence among orthologs in African
Mangosteen the queen of the tropical fruits is apomitic and only a cultivar is reported and it reproduces asexually. Conventional breeding is not possible and the other methods to create variabilities are through genetic engineering and mutation breeding. The former technique is still in the infantry stage in mangosteen research while the latter has been an established tool in breeding to improve cultivars. In this mutation breeding seeds of mangosteen were irradiated using gamma rays and the LD 50 for mangosteen was determined and noted to be very low at 10 Gy. After sowing in the seedbed, the seedlings were transplanted in polybags and observed in the nursery bed for about one year before planted in the field under old oil palm trees in Station MARDI, Kluang. After evaluation and screening, about 120 mutant mangosteen plants were selected and planted in Kluang. The plants were observed and some growth data taken. There were some mutant plants that have good growth vigour and more vigorous that the control plants. The trial are now in the fourth year and the plants are still in the juvenile stage. (Author)
This issue of the Mutation Breeding newsletter contains 39 articles dealing with radiation induced mutations and chemical mutagenesis techniques in plant breeding programs with the aims of improving crop productivity and disease resistance as well as exploring genetic variabilities
Muschick, Moritz; Nosil, Patrik; Roesti, Marius; Dittmann, Marie Theres; Harmon, Luke; Salzburger, Walter
Adaptive radiation (AR) is a key process in the origin of organismal diversity. However, the evolution of trait disparity in connection with ecological specialization is still poorly understood. Available models for vertebrate ARs predict that diversification occurs in the form of temporal stages driven by different selective forces. Here, we investigate the AR of cichlid fishes in East African Lake Tanganyika and use macroevolutionary model fitting to evaluate whether diversification happened in temporal stages. Six trait complexes, for which we also provide evidence of their adaptiveness, are analysed with comparative methods: body shape, pharyngeal jaw shape, gill raker traits, gut length, brain weight and body coloration. Overall, we do not find strong evidence for the 'stages model' of AR. However, our results suggest that trophic traits diversify earlier than traits implicated in macrohabitat adaptation and that sexual communication traits (i.e. coloration) diversify late in the radiation. PMID:25274371
Meyer, A; Kocher, T D; Basasibwaki, P; Wilson, A C
Lake Victoria, together with its satellite lakes, harbours roughly 200 endemic forms of cichlid fishes that are classified as 'haplochromines' and yet the lake system is less than a million years old. This 'flock' has attracted attention because of the possibility that it evolved within the lake from one ancestral species and that biologists are thus presented with a case of explosive evolution. Within the past decade, however, morphology has increasingly emphasized the view that the flock may be polyphyletic. We sequenced up to 803 base pairs of mitochondrial DNA from 14 representative Victorian species and 23 additional African species. The flock seems to be monophyletic, and is more akin to that from Lake Malawi than to species from Lake Tanganyika; in addition, it contains less genetic variation than does the human species, and there is virtually no sharing of mitochondrial DNA types among species. These results confirm that the founding event was recent. PMID:2215680
This paper deals with general rice production in Korea and the problems encountered. The history of rice growing and breeding in Korea is outlined and a description of recent advances in rice breeding is given, including a discussion of some uses of radiation treatments in the breeding programme during the last few years. (author). 2 figs, 3 tabs
Oldfield, Ronald G
Some fishes mature and function as one sex and later transform to the other sex in response to social interactions. Previous evidence suggested that a change in developmental timing may be involved in the evolution of adult sex change in fishes. The most recent support for this idea came from reports that sex in the Midas cichlid, Amphilophus citrinellus, was determined by social conditions experienced at the juvenile stage. Differentiation as a male was reported to be dependent on large body size relative to group-mates, and thought to be mediated through aggressive interactions. Here I demonstrate that socially controlled sex determination does not occur as was originally reported. Previously, I found that sex was not associated with body size in juveniles either in nature or in captivity. Similarly, I found no association between aggressive behavior and sex in juveniles. I later demonstrated that socially controlled sex determination does not typically occur in the Midas cichlid and closely related species and supported an alternative mechanism to explain large body size in adult males. Finally, in the current study I analyze gonad histology of fish from the same population used by the original authors and lay to rest the idea of socially controlled sex determination in this species. Recent observations of socially controlled sex determination in juveniles of species that typically change sex at the adult stage are examples of phenotypic plasticity, not genetic variation. Therefore, juvenile socially controlled sex determination does not support a theory that a change in developmental timing is involved in the evolution of adult sex change in fishes. PMID:21740508
Mendoza-Franco, Edgar F; Scholz, T; Rozkosná, P
During parasitological research on cichlid fish from the tributaries of the Amazon River around Iquitos, Peru, the following gill monogenoidean species were found: Tucunarella cichlae n. gen. and n. sp. from Cichla monoculus Spix and Agassiz; Gussevia alioides Kritsky, Thatcher, and Boeger, 1986 from Heros severus Heckel; Gussevia asota Kritsky, Thatcher, and Boeger, 1989 from Astronotus ocellatus (Agassiz); Gussevia disparoides Kritsky, Thatcher, and Boeger, 1986 from H. severus (all new geographical records) and Cichlasoma amazonarum Kullander (new host record); Gussevia longihaptor (Mizelle and Kritsky, 1969) Kritsky, Thatcher, and Boeger, 1986 and Gussevia undulata Kritsky, Thatcher, and Boeger, 1986 from C. monoculus ; Sciadicleithrum satanopercae Yamada, Takemoto, Bellay, and Pavanelli, 2008 from Satanoperca jurupari Heckel; and Sciadicleithrum variabilum (Mizelle and Kritsky, 1969) Kritsky, Thatcher, and Boeger, 1989 from C. amazonarum (new host and geographical records). Tucunarella n. gen. is proposed to accommodate a new species, Tucunarella cichlae , which is its type and only known species in the genus. The new genus is characterized by, besides a very large body size (about 1.5 mm vs. much less than 1 mm in other ancyrocephaline genera in Amazonia), a thickened tegument, 1 pair of eyes, overlapping gonads (testis dorsal to the germarium), nonarticulated male copulatory organ (MCO) and accessory piece, a coiled (counterclockwise) MCO, a dextral vaginal aperture, a haptor armed with 2 pairs of anchors (each with broad base and subequal roots, which are marginally folded), and dorsal and ventral bars and 14 hooks with protruding blunt thumbs and 2 different shapes (slender vs. slightly expanded shanks). Illustrations and data on morphological and biometric variability of individual species from different hosts are provided. The present data provide evidence of a relatively wide host specificity of gill monogenoideans parasitic in South American cichlids
Recknagel, Hans; Elmer, Kathryn R; Meyer, Axel
Cichlid fishes are an excellent model system for studying speciation and the formation of adaptive radiations because of their tremendous species richness and astonishing phenotypic diversity. Most research has focused on African rift lake fishes, although Neotropical cichlid species display much variability as well. Almost one dozen species of the Midas cichlid species complex (Amphilophus spp.) have been described so far and have formed repeated adaptive radiations in several Nicaraguan crater lakes. Here we apply double-digest restriction-site associated DNA sequencing to obtain a high-density linkage map of an interspecific cross between the benthic Amphilophus astorquii and the limnetic Amphilophus zaliosus, which are sympatric species endemic to Crater Lake Apoyo, Nicaragua. A total of 755 RAD markers were genotyped in 343 F(2) hybrids. The map resolved 25 linkage groups and spans a total distance of 1427 cM with an average marker spacing distance of 1.95 cM, almost matching the total number of chromosomes (n = 24) in these species. Regions of segregation distortion were identified in five linkage groups. Based on the pedigree of parents to F(2) offspring, we calculated a genome-wide mutation rate of 6.6 × 10(-8) mutations per nucleotide per generation. This genetic map will facilitate the mapping of ecomorphologically relevant adaptive traits in the repeated phenotypes that evolved within the Midas cichlid lineage and, as the first linkage map of a Neotropical cichlid, facilitate comparative genomic analyses between African cichlids, Neotropical cichlids and other teleost fishes. PMID:23316439
Yuichi Takeuchi; Michio Hori; Shinya Tada; Yoichi Oda
The scale-eating cichlid Perissodus microlepis with asymmetric mouth is an attractive model of behavioral laterality: each adult tears off scales from prey fishes' left or right flanks according to the direction in which its mouth is skewed. To investigate the development of behavioral laterality and mouth asymmetry, we analyzed stomach contents and lower jaw-bone asymmetry of various-sized P. microlepis (22 ≤ SL
Taylor, Martin I.; Rico, Ciro; Balshine, Sigal
In this study, we investigate whether apparent social monogamy (where a species forms a pair bond but may participate in copulations outside the pair bond) corresponds with genetic monogamy (where individuals participate only in copulations within a pair bond) in a biparental mouthbrooding cichlid fish, Eretmodus cyanostictus, from Lake Tanganyika, Africa. Our findings suggest that E. cyanostictus is both socially and genetically monogamous and that monogamy may result from limited opportunit...
Sturmbauer Christian; Koblmüller Stephan; Egger Bernd; Sefc Kristina M
Abstract Background Cichlid fishes are notorious for their wealth of intra- and interspecific colour pattern diversity. In Lake Tanganyika, the endemic genus Tropheus represents the most impressive example for geographic variation in the pattern and hue of integument colouration, but the taxonomy of the over 100 mostly allopatric colour morphs remains to a large degree unresolved. Previous studies of mitochondrial DNA sequence data revealed polyphyly of the six nominally described species and...
Full Text Available BACKGROUND: As in any vertebrate, heads of fishes are densely packed with functions. These functions often impose conflicting mechanical demands resulting in trade-offs in the species-specific phenotype. When phenotypical traits are linked to gender-specific parental behavior, we expect sexual differences in these trade-offs. This study aims to use mouthbrooding cichlids as an example to test hypotheses on evolutionary trade-offs between intricately linked traits that affect different aspects of fitness. We focused on the oral apparatus, which is not only equipped with features used to feed and breathe, but is also used for the incubation of eggs. We used this approach to study mouthbrooding as part of an integrated functional system with diverging performance requirements and to explore gender-specific selective environments within a species. METHODOLOGY/PRINCIPAL FINDINGS: Because cichlids are morphologically very diverse, we hypothesize that the implications of the added constraint of mouthbrooding will primarily depend on the dominant mode of feeding of the studied species. To test this, we compared the trade-off for two maternal mouthbrooding cichlid species: a "suction feeder" (Haplochromis piceatus and a "biter" (H. fischeri. The comparison of morphology and performance of both species revealed clear interspecific and intersex differences. Our observation that females have larger heads was interpreted as a possible consequence of the fact that in both the studied species mouthbrooding is done by females only. As hypothesized, the observed sexual dimorphism in head shape is inferred as being suboptimal for some aspects of the feeding performance in each of the studied species. Our comparison also demonstrated that the suction feeding species had smaller egg clutches and more elongated eggs. CONCLUSIONS/SIGNIFICANCE: Our findings support the hypothesis that there is a trade-off between mouthbrooding and feeding performance in the two
Elmer, Kathryn R; Kusche, Henrik; Lehtonen, Topi K; Meyer, Axel
The polychromatic and trophically polymorphic Midas cichlid fish species complex (Amphilophus cf. citrinellus) is an excellent model system for studying the mechanisms of speciation and patterns of phenotypic diversification in allopatry and in sympatry. Here, we first review research to date on the species complex and the geological history of its habitat. We analyse body shape variation from all currently described species in the complex, sampled from six crater lakes (maximally 1.2 23.9 ky...
Meyer Axel; Barluenga Marta
Abstract Background Elucidation of the mechanisms driving speciation requires detailed knowledge about the phylogenetic relationships and phylogeography of the incipient species within their entire ranges as well as their colonization history. The Midas cichlid species complex Amphilophus spp. has been proven to be a powerful model system for the study of ecological specialization, sexual selection and the mechanisms of sympatric speciation. Here we present a comprehensive and integrative phy...
Hodaňová,Lucie; Kalous, Lukáš; Musilová, Zuzana
Abstract A comparative cytogenetic analysis was carried out in five species of a monophyletic clade of neotropical Cichlasomatine cichlids, namely Cleithracara maronii Steindachner, 1881, Ivanacara adoketa (Kullander & Prada-Pedreros, 1993), Nannacara anomala Regan, 1905, N. aureocephalus Allgayer, 1983 and N. taenia Regan, 1912. Karyotypes and other chromosomal characteristics were revealed by CDD banding and mapped onto the phylogenetic hypothesis based on molecular analyses of four genes, ...
Full Text Available Abstract Background Elucidation of the mechanisms driving speciation requires detailed knowledge about the phylogenetic relationships and phylogeography of the incipient species within their entire ranges as well as their colonization history. The Midas cichlid species complex Amphilophus spp. has been proven to be a powerful model system for the study of ecological specialization, sexual selection and the mechanisms of sympatric speciation. Here we present a comprehensive and integrative phylogeographic analysis of the complete Midas Cichlid species complex in Nicaragua (> 2000 individuals covering the entire distributional range, using two types of molecular markers (the mitochondrial DNA control region and 15 microsatellites. We investigated the majority of known lake populations of this species complex and reconstructed their colonization history in order to distinguish between alternative speciation scenarios. Results We found that the large lakes contain older and more diverse Midas Cichlid populations, while all crater lakes hold younger and genetically less variable species assemblages. The large lakes appear to have repeatedly acted as source populations for all crater lakes, and our data indicate that faunal exchange among crater lakes is extremely unlikely. Despite their very recent (often only a few thousand years old and common origin from the two large Nicaraguan lakes, all crater lake Midas Cichlid radiations underwent independent, but parallel, evolution, and comprise distinct genetic units. Indeed several of these crater lakes contain multiple genetically distinct incipient species that most likely arose through sympatric speciation. Several crater lake radiations can be traced back to a single ancestral line, but some appear to have more than one founding lineage. The timing of the colonization(s of each crater lake differs, although most of them occurred more (probably much more recently than 20,000 years ago. Conclusion The
Rehage, Jennifer S.; Dunlop, Katherine L.; Loftus, William F.
The strong impact of non-native predators in aquatic systems is thought to relate to the evolutionary naiveté of prey. Due to isolation and limited dispersal, this naiveté may be relatively high in freshwater systems. In this study, we tested this notion by examining the antipredator response of native mosquitofish, Gambusia holbrooki, to two non-native predators found in the Everglades, the African jewelfish,Hemichromis letourneuxi, and the Mayan cichlid, Cichlasoma urophthalmus. We manipulated prey naiveté by using two mosquitofish populations that varied in their experience with the recent invader, the African jewelfish, but had similar levels of experience with the longer-established Mayan cichlid. Specifically, we tested these predictions: (1) predator hunting modes differed between the two predators, (2) predation rates would be higher by the novel jewelfish predator, (3) particularly on the naive population living where jewelfish have not invaded yet, (4) antipredator responses would be stronger to Mayan cichlids due to greater experience and weaker and/or ineffective to jewelfish, and (5) especially weakest by the naive population. We assayed prey and predator behavior, and prey mortality in lab aquaria where both predators and prey were free-ranging. Predator hunting modes and habitat domains differed, with jewelfish being more active search predators that used slightly higher parts of the water column and less of the habitat structure relative to Mayan cichlids. In disagreement with our predictions, predation rates were similar between the two predators, antipredator responses were stronger to African jewelfish (except for predator inspections), and there was no difference in response between jewelfish-savvy and jewelfish-naive populations. These results suggest that despite the novelty of introduced predators, prey may be able to respond appropriately if non-native predator archetypes are similar enough to those of native predators, if prey rely
Ota, Kazutaka; Hori, Michio; Kohda, Masanori
To determine whether the appearance of a reproductively parasitic tactic varies, and how this variation affects territorial males of the Lake Tanganyika cichlid fish Telmatochromis vittatus, we examined the reproductive ecology of territorial males in Mtondwe and compared it with that of a neighboring Wonzye population, where nest density differs from that at Mtondwe. In Wonzye, with high nest density, male tactics change with their body size from a territorial to a non-territorial parasitic ...
Hotta, Takashi; Takeyama, Tomohiro; Heg, Dik; Awata, Satoshi; Jordan, Lyndon A.; Kohda, Masanori
Theory suggests that living in large social groups with dynamic social interactions often favors the evolution of enhanced cognitive abilities. Studies of how animals assess their own contest ability commonly focus on a single cognitive task, and little is known about the diversity or co-occurrence of cognitive abilities in social species. We examined how a highly social cichlid fish Julidochromis transcriptus uses four major cognitive abilities in contest situations; direct experience, winne...
Verzijden, Machteld Nicolette
The great Lakes of East Africa are inhabited by a great number of haplochromine cichlid species, which form a diverse group in both ecology and nuptial coloration. The large number of sympatrically occuriring closely related species has raised questions about the underlying mechanism for reproductive isolation. In this thesis I describe experiments that test for the effects of early experience on their species assortative behaviour in the contexts of mate choice and male territorial interacti...
Vanhove, Maarten P M; Pariselle, Antoine; Van Steenberge, Maarten; Raeymaekers, Joost A M; Hablützel, Pascal I; Gillardin, Céline; Hellemans, Bart; Breman, Floris C; Koblmüller, Stephan; Sturmbauer, Christian; Snoeks, Jos; Volckaert, Filip A M; Huyse, Tine
The stunning diversity of cichlid fishes has greatly enhanced our understanding of speciation and radiation. Little is known about the evolution of cichlid parasites. Parasites are abundant components of biodiversity, whose diversity typically exceeds that of their hosts. In the first comprehensive phylogenetic parasitological analysis of a vertebrate radiation, we study monogenean parasites infecting tropheine cichlids from Lake Tanganyika. Monogeneans are flatworms usually infecting the body surface and gills of fishes. In contrast to many other parasites, they depend only on a single host species to complete their lifecycle. Our spatially comprehensive combined nuclear-mitochondrial DNA dataset of the parasites covering almost all tropheine host species (N = 18), reveals species-rich parasite assemblages and shows consistent host-specificity. Statistical comparisons of host and parasite phylogenies based on distance and topology-based tests demonstrate significant congruence and suggest that host-switching is rare. Molecular rate evaluation indicates that species of Cichlidogyrus probably diverged synchronically with the initial radiation of the tropheines. They further diversified through within-host speciation into an overlooked species radiation. The unique life history and specialisation of certain parasite groups has profound evolutionary consequences. Hence, evolutionary parasitology adds a new dimension to the study of biodiversity hotspots like Lake Tanganyika. PMID:26335652
Lorin, Thibault; Salzburger, Walter; Böhne, Astrid
The emergence of the steroid system is coupled to the evolution of multicellular animals. In vertebrates in particular, the steroid receptor repertoire has been shaped by genome duplications characteristic to this lineage. Here, we investigate for the first time the composition of the androgen receptor-signaling pathway in ray-finned fish genomes by focusing in particular on duplicates that emerged from the teleost-specific whole-genome duplication. We trace lineage- and species-specific duplications and gene losses for the genomic and nongenomic pathway of androgen signaling and subsequently investigate the sequence evolution of these genes. In one particular fish lineage, the cichlids, we find evidence for differing selection pressures acting on teleost-specific whole-genome duplication paralogs at a derived evolutionary stage. We then look into the expression of these duplicated genes in four cichlid species from Lake Tanganyika indicating, once more, rapid changes in expression patterns in closely related fish species. We focus on a particular case, the cichlid specific duplication of the rac1 GTPase, which shows possible signs of a neofunctionalization event. PMID:26333839
Seehausen, Ole; Koetsier, Egbert; Schneider, Maria Victoria; Chapman, Lauren J; Chapman, Colin A; Knight, Mairi E; Turner, George F; van Alphen, Jacques J M; Bills, Roger
Phylogenetic analyses based on mitochondrial (mt) DNA have indicated that the cichlid species flock of the Lake Victoria region is derived from a single ancestral species found in East African rivers, closely related to the ancestor of the Lake Malawi cichlid species flock. The Lake Victoria flock contains ten times less mtDNA variation than the Lake Malawi radiation, consistent with current estimates of the ages of the lakes. We present results of a phylogenetic investigation using nuclear (amplified fragment length polymorphism) markers and a wider coverage of riverine haplochromines. We demonstrate that the Lake Victoria-Edward flock is derived from the morphologically and ecologically diverse cichlid genus Thoracochromis from the Congo and Nile, rather than from the phenotypically conservative East African Astatotilapia. This implies that the ability to express much of the morphological diversity found in the species flock may by far pre-date the origin of the flock. Our data indicate that the nuclear diversity of the Lake Victoria-Edward species flock is similar to that of the Lake Malawi flock, indicating that the genetic diversity is considerably older than the 15 000 years that have passed since the lake began to refill. Most of this variation is manifested in trans-species polymorphisms, indicating very recent cladogenesis from a genetically very diverse founder stock. Our data do not confirm strict monophyly of either of the species flocks, but raise the possibility that these flocks have arisen from hybrid swarms. PMID:12590750
The pea as an ancient crop plant still today has wide uses and is an import source of food protein. It is also an important object for genetic studies and as such has been widely used in mutation induction experiments. However, in comparison with cereals this ancient crop plant (like several other grain legumes) has gained relatively little from advances in breeding. The review focuses on the prospects of genetic improvement of pea by induced mutations, discusses principles and gives methodological information. (author)
Full Text Available Brazil has the largest commercial beef cattle herd and is the main beef exporter in the world. Cultivated pastures arethe basis for the Brazilian beef production, and occupy an area of 101.4 million hectares. However, very few forage cultivars arecommercially available, and the majority of these are of apomictic reproduction, thus genetically homogeneous. Tropical foragebreeding is at its infancy, but much investment and efforts have been applied in the last three decades and some new cultivars havebeen released. In this paper, origin of different species, modes of reproduction, breeding programs and targets are discussed andthe resulting new cultivars released are presented.
There are several candidate concepts for tritium breeding blankets that make use of a number of special materials. These materials can be classified as Primary Blanket Materials, which have the greatest influence in determining the overall design and performance, and Secondary Blanket Materials, which have key functions in the operation of the blanket but are less important in establishing the overall design and performance. The issues associated with the blanket materials are specified and several examples of materials performance are given. Critical data needs are identified
Full Text Available This study describes the hematological parameters in Iranocichla hormuzensis, an Iranian freshwater cichlid important as ornamental and food fish. Forty fish were captured with seine net at Mehran river Hormozgan province, Iran. Blood was used to determine the total counts of red blood cells (RBC and white blood cells (WBC, hematocrit, mean corpuscular volume (MCV, mean corpuscular hemoglobin (MCH, mean corpuscular hemoglobin concentration (MCHC and morphometric data of erythrocytes. The Iranian fish showed lower RBC and WBC values than the other cichlids (Oreochromis niloticus, O. aureus, O. mossambicus, O. hybrid, Cichlasoma dimerus and Cichla monoculus. Hematocrit did not vary among the species, but MCV, MCH and MCHC in I. hormuzensis were higher than those for O. niloticus, O. aureus, O. hybrid, C. dimerus and C. monoculus. These differences may be related to different life habit of fish. This study suggests that I. hormuzensis is well acclimated to the environment being the first report for its hematology. It is also suggested high efficiency in oxygen transportation, and an efficient inflow of oxygen by the gills, indicating the welfare of fish on this environment.Este estudo descreve os parâmetros hematológicos em Iranocichla hormuzensis, ciclídeo iraniano de água doce, importante como peixe ornamental e como de consumo. Quarenta peixes foram capturados com rede no rio Mehran, província de Hormozgan, Irã. O sangue foi usado para determinar as contagens totais de eritrócitos (RBC e leucócitos (WBC, hematócrito, volume corpuscular médio (MCV, hemoglobina corpuscular média (MCH, concentração de hemoglobina corpuscular média (MCHC e dados morfométricos de eritrócitos. O peixe iraniano mostrou valores menores de RBC e WBC do que outros ciclídeos (Oreochromis niloticus, O. aureus, O. mossambicus, O. hybrid, Cichlasoma dimerus e Cichla monoculus. O hematócrito não variou entre as espécies, mas MCV, MCH e MCHC em I
This issue of the Newsletter includes articles dealing with radiation induced mutation based plant breeding research findings aimed at improving productivity, disease resistance and tolerance of stress conditions
The present position of sugar industry particularly cane sugar production in the world has been discussed. The role of African Countries which can contribute more than the present 11% to world cane sugar production is presented. The breeding methods employed in cane growing court-tries indicate the biparental crossing and selection in F1 has been the major method used to develop varieties. Due to cytogenetical peculiarities, thousands of seedlings are grown to select the desirable genotype. Mutations or sports has been a source of variation for selection in nature. Induced mutations have only enhanced the mutation rate and has enabled the plant breeders to get better variation for selection. Though many mutagens have been used gamma rays have been most effective. Induced mutations for nonflowering, spineless leaf-sheath, higher sugar content, yield md resistance to diseases like smut and downy mildew have been reported. The methods of making mutated tissues express itself have been indicated. Mutation breeding holds out promise in sugarcane in that the basic variety or genotype can be kept intact and a few characters changed as desired by the plant breeder provided proper selection methods are employed. (author)
Song, Hi Sup; Kim, Jae Sung; Kim, Jin Kyu; Shin, In Chul; Lim, Young Taek
In order to develop an advanced technical knowledge for the selection of better mutants, some of the crops were irradiated and the mutation rate, the survival rate and the method for selction of a mutant were studied. Furthermore, this study aimed to obtain basic data applicable to the development of genetic resources by evaluation and analysis the specific character for selection of the superior mutant and its plant breeding. 1. selection of the mutant with a superior resistance against environment in the principal crops 1) New varieties of mutant rices such as Wonpyeongbyeo, Wongwangbyeo, Winmibyeo, and heogseon chalbeyeo (sticky forma) were registered in the national variety list and made an application to crop variety protection right. They are under review now. 2) We also keep on studying on the number of a grain of 8 lines of excellent mutant rice for the purpose of improvement of breeding . 3) We selected 3 lines which have a resistance to pod and stem blight in large soybean, 31 lines with small grain size and higher yield, 112 lines of soybean of cooking, 7 lines of low lipoxygenase content, and 12 lines with decreased phytic acid content by 20 % compared to the previous level. 2. Selection of advanced Mugunwha (Rose of Sharon) mutant 1) Bagseul, a new variety of mutant, was developed and 30 plantlets of it are being proliferated. 2) Fifty-three lines of a mutant having a various morphologies were selected.
In order to develop an advanced technical knowledge for the selection of better mutants, some of the crops were irradiated and the mutation rate, the survival rate and the method for selction of a mutant were studied. Furthermore, this study aimed to obtain basic data applicable to the development of genetic resources by evaluation and analysis the specific character for selection of the superior mutant and its plant breeding. 1. selection of the mutant with a superior resistance against environment in the principal crops 1) New varieties of mutant rices such as Wonpyeongbyeo, Wongwangbyeo, Winmibyeo, and heogseon chalbeyeo (sticky forma) were registered in the national variety list and made an application to crop variety protection right. They are under review now. 2) We also keep on studying on the number of a grain of 8 lines of excellent mutant rice for the purpose of improvement of breeding . 3) We selected 3 lines which have a resistance to pod and stem blight in large soybean, 31 lines with small grain size and higher yield, 112 lines of soybean of cooking, 7 lines of low lipoxygenase content, and 12 lines with decreased phytic acid content by 20 % compared to the previous level. 2. Selection of advanced Mugunwha (Rose of Sharon) mutant 1) Bagseul, a new variety of mutant, was developed and 30 plantlets of it are being proliferated. 2) Fifty-three lines of a mutant having a various morphologies were selected
Hotta, Takashi; Takeyama, Tomohiro; Jordan, Lyndon Alexander; Kohda, Masanori
Animal contests are costly and tend to escalate when rivals have similar competitive abilities. Individuals that remember dominance relationships with rivals may avoid repeated agonistic interactions and hence avoid the costs of repeated escalation of contests. However, it can be difficult to experimentally disentangle the effects of memory from those of loser effects (losers behaving subordinately due to prior defeats). Here, we test whether loser effects or individual memory mediate contest behaviour in the African cichlid, Julidochromis transcriptus. We find that on days 3 and 5 after initial contests, losers display subordinate behaviour to contest winners but not to novel contestants. However, this effect disappears after 7 days, at which time losers do not display subordinate behaviour to either rival. These results show that (1) this fish can recall a previously dominant contestant for up to 5 days and (2) as no subordinate displays were shown to the novel contestant, there are no evidences for loser effects in this species. Such short-term memory of past interactions may have broad significance in social species with repeated interactions.
Full Text Available Abstract Background Cichlid fishes in Lake Tanganyika exhibit remarkable diversity in their feeding habits. Among them, seven species in the genus Perissodus are known for their unique feeding habit of scale eating with specialized feeding morphology and behaviour. Although the origin of the scale-eating habit has long been questioned, its evolutionary process is still unknown. In the present study, we conducted interspecific phylogenetic analyses for all nine known species in the tribe Perissodini (seven Perissodus and two Haplotaxodon species using amplified fragment length polymorphism (AFLP analyses of the nuclear DNA. On the basis of the resultant phylogenetic frameworks, the evolution of their feeding habits was traced using data from analyses of stomach contents, habitat depths, and observations of oral jaw tooth morphology. Results AFLP analyses resolved the phylogenetic relationships of the Perissodini, strongly supporting monophyly for each species. The character reconstruction of feeding ecology based on the AFLP tree suggested that scale eating evolved from general carnivorous feeding to highly specialized scale eating. Furthermore, scale eating is suggested to have evolved in deepwater habitats in the lake. Oral jaw tooth shape was also estimated to have diverged in step with specialization for scale eating. Conclusion The present evolutionary analyses of feeding ecology and morphology based on the obtained phylogenetic tree demonstrate for the first time the evolutionary process leading from generalised to highly specialized scale eating, with diversification in feeding morphology and behaviour among species.
Schluessel, V; Beil, O; Weber, T; Bleckmann, H
Several species have been shown to perceive symmetry as a measure of superior genetic quality, useful for assessing potential mates or mediating other visual activities such as the selection of food sources. The current study assessed whether Pseudotropheus sp. and Chiloscyllium griseum, two fish species from distantly related groups, possess symmetry perception. In alternative two choice experiments, individuals were tested for spontaneous preferences and trained to discriminate between abstract symmetrical and asymmetrical stimulus pairs. Pair discriminations were followed by extensive categorization experiments. Transfer tests elucidated whether bilaterally symmetrical and rotationally symmetrical stimuli could be distinguished. Sharks were also tested for the degree of dissimilarity between two symbols that could still be detected. While sharks showed both a spontaneous preference for symmetry as well as remarkable discrimination abilities by succeeding in all of the presented tasks, cichlids showed no spontaneous preference, had difficulties in discriminating between symbols and performed poorly in the categorization experiments. Sharks distinguished between bilaterally and rotationally symmetrical stimuli and easily differentiated between a four-armed cross (all arms 90° apart) and a cross where one of the arms was only 45° spaced from the one next to it. Performance did not decline when the separation was extended to 70°, but was significantly reduced at an 80° separation. Results indicate that the ability for symmetry perception varies across fish species and individuals, whereby some can detect even subtle differences in this respect. PMID:24794621
Aguirre-Ayala, Daniel; Vidal-Martínez, Víctor Manuel
This study aimed to determine the susceptibility of the Mayan cichlid Cichlasoma urophthalmus to infection with the fungus Aphanomyces invadans (also known as epizootic ulcerative syndrome [EUS]). A total of 27 C. urophthalmus were exposed to the original A. Invadans 2006/86/EC strain by intramuscularly injecting the fish with 25,000 zoospores/ml or exposing the fish to a suspension of 25,000 zoospores/ml in 6-L aquaria for 30 days. To assess the infectious capacity of A. invadans, 3 golden barbs (Puntius semifasciolatus) were infected intramuscularly with 200,000 zoospores/ml. A second experiment using 100 C. urophthalmus was performed for 60 days with 50 fish in each treatment group. A polymerase chain reaction (PCR)-based diagnostic method was used; muscle and gills were the target tissues. In the first experiment, none of the exposed C. urophthalmus developed skin lesions related to A. invadans infection. However, PCR analysis revealed that infection had occurred. For the intramuscular treatment, there were significant differences between the controls and the muscle samples (Fisher's exact test; P 0.05). All golden barbs became infected, as indicated by PCR, and developed skin lesions typical of A. invadans infection. We concluded that C. urophthalmus was infected with A. invadans but was an asymptomatic carrier because skin lesions did not develop. In the second experiment, all fish were negative, suggesting that the fish had cleared the infection by the end of the experiment. PMID:25742055
Suzanne M. GRAY; Laura H. McDONNELL; Fabio G. CINQUEMANI; Lauren J. CHAPMAN
Aquatic biodiversity is being lost at an unprecedented rate.One factor driving this loss is increased turbidity,an environmental stressor that can impose behavioral,morphological,and/or physiological costs on fishes.Here we describe the behavioral response of a widespread African cichlid,Pseudocrenilabrus multicolor victoriae,to turbidity.We used a split-brood rearing design to test if F1 offspring reared in turbid water,originating from river (turbid) and swamp (clear) populations,behave differently than full-sibs reared in clear water.We examined two facets of behavior:(1) behaviors of fish in full sib groups,including activity level and social dynamics collected during the rearing period; and (2) male aggressive behavior directed at potential male competitors after fish had reached maturity; this was done in an experimental set-up independent of the rearing aquaria.Regardless of population of origin,fish reared in turbid water were marginally less active and performed fewer social behaviors than those reared in clear water.On the other hand,when tested against a competitor in turbid water,males performed more aggressive behaviors,regardless of population of origin or rearing environment.Our results suggest a plastic behavioral response to turbidity that may allow P multicolor to persist over a range of turbidity levels in nature by decreasing activity and general social behaviors and intensifying reproductive behaviors to ensure reproductive success [ Current Zoology 58 (1):146-157,2012].
S. Shawn McCafferty
Full Text Available It is well appreciated that historical and ecological processes are important determinates of freshwater biogeographic assemblages. Phylogeography can potentially lend important insights into the relative contribution of historical processes in biogeography. However, the extent that phylogeography reflects historical patterns of drainage connection may depend in large part on the dispersal capability of the species. Here, we test the hypothesis that due to their relatively greater dispersal capabilities, the neotropical cichlid species Andinoacara coeruleopunctatus will display a phylogeographic pattern that differs from previously described biogeographic assemblages in this important region. Based on an analysis of 318 individuals using mtDNA ATPase 6/8 sequence and restriction fragment length polymorphism data, we found eight distinct clades that are closely associated with biogeographic patterns. The branching patterns among the clades and a Bayesian clock analysis suggest a relatively rapid colonization and diversification among drainages in the emergent Isthmus of Panama followed by the coalescing of some drainages due to historical connections. We also present evidence for extensive cross-cordillera sharing of clades in central Panama and the Canal region. Our results suggest that contemporary phylogeographic patterns and diversification in Lower Central American fishes reflect an interaction of historical drainage connections, dispersal, and demographic processes.
Ashley R. ROBART
The differential allocation hypothesis predicts individuals will increase their reproductive investment when mated to a high quality partner.In many species of fish with biparental care females prefer large males due to the males' greater ability to raise more offspring to independence.I examined the relationship between mate quality,parental care and number of offspring in a natural population of convict cichlids Amatitlania siquia.The frequency of frontal displays by females was positively correlated with male standard length.Additionally,as males increased in length relative to their mate,females increased the frequency of chases towards predators,while males decreased the number of displays towards brood predators.This trade-off in parental effort within a pair due to mate quality is a key prediction of differential allocation.The number of offspring was correlated with male,but not female,standard length.These results support the differential allocation hypothesis in that females offered more parental care to offspring of a larger male,while their mates decreased the amount of care they provided.Additionally,females benefited in terms of number of offspring by pairing with higher quality mates.Increased female investment may provide an incentive to ensure male care and maintain pair bonding,which could lead to greater reproductive success through increased offspring survival [Current Zoology 58 (1):66-72,2012].
The cichlid fish radiations in the African Great Lakes differ from all other known cases of rapid speciation in vertebrates by their spectacular trophic diversity and richness of sympatric species, comparable to the most rapid angiosperm radiations. I review factors that may have facilitated these radiations and compare these with insights from recent work on plant radiations. Work to date suggests that it was a coincidence of ecological opportunity, intrinsic ecological versatility and genomic flexibility, rapidly evolving behavioral mate choice and large amounts of standing genetic variation that permitted these spectacular fish radiations. I propose that spatially orthogonal gradients in the fit of phenotypes to the environment facilitate speciation because they allow colonization of alternative fitness peaks during clinal speciation despite local disruptive selection. Such gradients are manifold in lakes because of the interaction of water depth as an omnipresent third spatial dimension with other fitness-relevant variables. I introduce a conceptual model of adaptive radiation that integrates these elements and discuss its applicability to, and predictions for, plant radiations. PMID:25983053
Fitzpatrick, J L; Desjardins, J K; Milligan, N; Montgomerie, R; Balshine, S
Theory predicts that males experiencing elevated levels of sperm competition will invest more in gonads and produce faster-swimming sperm. Although there is ample evidence in support of the first prediction, few studies have examined sperm swimming speed in relation to sperm competition. In this study, we tested these predictions from sperm competition theory by examining sperm characteristics in Telmatochromis vittatus, a small shell-brooding cichlid fish endemic to Lake Tanganyika. Males exhibit four different reproductive tactics: pirate, territorial, satellite, and sneaker. Pirate males temporarily displace all other competing males from a shell nest, whereas sneaker males always release sperm in the presence of territorial and satellite males. Due to the fact that sneakers spawn in the presence of another male, sneakers face the highest levels of sperm competition and pirates the lowest, whereas satellites and territorials experience intermediate levels. In accordance with predictions, sperm from sneakers swam faster than sperm from males adopting the other reproductive tactics, whereas sperm from pirates was slowest. Interestingly, we were unable to detect any variation in sperm tail length among these reproductive tactics. Thus, sperm competition appears to have influenced sperm energetics in this species without having any influence on sperm size. PMID:17460159
Full Text Available Abstract Background Studies addressing the adaptive significance of female ornamentation have gained ground recently. However, the expression of female ornaments in relation to body size, known as trait allometry, still remains unexplored. Here, we investigated the allometry of a conspicuous female ornament in Pelvicachromis taeniatus, a biparental cichlid that shows mutual mate choice and ornamentation. Females feature an eye-catching pelvic fin greatly differing from that of males. Results We show that allometry of the female pelvic fin is scaled more positively in comparison to other fins. The pelvic fin exhibits isometry, whereas the other fins (except the caudal fin show negative allometry. The size of the pelvic fin might be exaggerated by male choice because males prefer female stimuli that show a larger extension of the trait. Female pelvic fin size is correlated with individual condition, suggesting that males can assess direct and indirect benefits. Conclusions The absence of positive ornament allometry might be a result of sexual selection constricted by natural selection: fins are related to locomotion and thus may be subject to viability selection. Our study provides evidence that male mate choice might scale the expression of a female sexual ornament, and therefore has implications for the understanding of the relationship of female sexual traits with body size in species with conventional sex-roles.
The outline of registered ornamental cultivars bred up by mutation breeding, the applied methods, and the radiosensitivity of air-dried seeds among ornamental plants are described. The mutation breeding of ornamental plants has not yet become a familiar means like cross breeding or line separation. But the number of the cultivars bred up by mutation breeding reached more than 270, and took a relatively large proportion of about 40 % of the agronomic cultivars bred up by mutation breeding in the world. The number of the species to which those improved cultivars belong is only 22. Considering the abundance of ornamental plant species and the successful results of mutation breeding in this field, mutation breeding techniques will be applied to many species which remain in the rudimentary stage or have never tried them. It is hoped that the information presented in this paper contributes to the promising future of ornamental plant breeding as the suggestion. Especially in ornamental plants, many spontaneously occurred novel mutants have been sought and treasured for a long time. Such mutants actually enriched the variety of flower colors, shapes and many other important characters required for being ornamentally valuable. (Kako, I.).
The Greenhouse Effect has fuzzy parameters, as do the consequences of acid rain, accidental nuclear fallout, deforestation, even the depletion of oil and natural gas reserves, and other threatening calamities. But the consequences of human over-breeding do not fall within fuzzy parameters. Reliable demographic studies predict a world population by the year 2020 of twice the present four billion or so living human beings. Some of us will see that year. But the population will again have doubled by the year 2090: sixteen billion people. The author suggests in this paper some morally permissible steps that might be taken to circumvent what otherwise is most assuredly an impending world tragedy. We have an ethical obligation to future generations. They have the moral right to a qualitatively fulfilling life, not just on allotted number of years. Some of my suggestions will not be palatable to some readers. But I urge those readers seriously to consider and if possible, hopefully, to propose alternatives
Full Text Available Maize is one of the most important economic crops and the best studied and most tractable genetic system among monocots. The development of biotechnology has led to a great increase in our knowledge of maize genetics and understanding of the structure and behaviour of maize genomes. Conventional breeding practices can now be complemented by a number of new and powerful techniques. Some of these often referred to as molecular methods, enable scientists to see the layout of the entire genome of any organism and to select plants with preferred characteristics by "reading" at the molecular level, saving precious time and resources. DNA markers have provided valuable tools in various analyses ranging from phylogenetic analysis to the positional cloning of genes. Application of molecular markers for genetic studies of maize include: assessment of genetic variability and characterization of germ plasm, identification and fingerprinting of genotypes, estimation of genetic distance, detection of monogamic and quantitative trait loci, marker assisted selection, identification of sequence of useful candidate genes, etc. The development of high-density molecular maps which has been facilitated by PCR-based markers, have made the mapping and tagging of almost any trait possible and serve as bases for marker assisted selection. Sequencing of maize genomes would help to elucidate gene function, gene regulation and their expression. Modern biotechnology also includes an array of tools for introducing or deieting a particular gene or genes to produce plants with novel traits. Development of informatics and biotechnology are resulted in bioinformatic as well as in expansion of microarrey technique. Modern biotechnologies could complement and improve the efficiency of traditional selection and breeding techniques to enhance agricultural productivity.
Patrick M Barks
Full Text Available For many animals, the ability to distinguish cues indicative of predation risk from cues unrelated to predation risk is not entirely innate, but rather is learned and improved with experience. Two pathways to such learning are possible. First, an animal could initially express antipredator behaviour toward a wide range of cues and subsequently learn which of those cues are non-threatening. Alternatively, it could initially express no antipredator behaviour toward a wide range of cues and subsequently learn which of them are threatening. While the learned recognition of threatening cues may occur either through personal interaction with a cue (asocial learning or through observation of the behaviour of social companions toward a cue (social learning, the learned recognition of non-threatening cues seems to occur exclusively through habituation, a form of asocial learning. Here, we tested whether convict cichlid fish (Amatitlaniasiquia can socially learn to recognize visual cues in their environment as either threatening or non-threatening. We exposed juvenile convict cichlids simultaneously to a novel visual cue and one of three (visual social cues: a social cue indicative of non-risk (the sight of conspecifics that had previously been habituated to the novel cue, a social cue indicative of predation risk (the sight of conspecifics trained to fear the novel cue, or a control treatment with no social cue. The subsequent response of focal fish, when presented with the novel cue alone, was not influenced by the social cue that they had previously witnessed. We therefore did not find evidence that convict cichlids in our study could use social learning to recognize novel visual cues as either threatening or non-threatening. We consider alternative explanations for our findings.
Kautt, Andreas F.; Machado-Schiaffino, Gonzalo; Meyer, Axel
The formation of species in the absence of geographic barriers (i.e. sympatric speciation) remains one of the most controversial topics in evolutionary biology. While theoretical models have shown that this most extreme case of primary divergence-with-gene-flow is possible, only a handful of accepted empirical examples exist. And even for the most convincing examples uncertainties remain; complex histories of isolation and secondary contact can make species falsely appear to have originated by sympatric speciation. This alternative scenario is notoriously difficult to rule out. Midas cichlids inhabiting small and remote crater lakes in Nicaragua are traditionally considered to be one of the best examples of sympatric speciation and lend themselves to test the different evolutionary scenarios that could lead to apparent sympatric speciation since the system is relatively small and the source populations known. Here we reconstruct the evolutionary history of two small-scale radiations of Midas cichlids inhabiting crater lakes Apoyo and Xiloá through a comprehensive genomic data set. We find no signs of differential admixture of any of the sympatric species in the respective radiations. Together with coalescent simulations of different demographic models our results support a scenario of speciation that was initiated in sympatry and does not result from secondary contact of already partly diverged populations. Furthermore, several species seem to have diverged simultaneously, making Midas cichlids an empirical example of multispecies outcomes of sympatric speciation. Importantly, however, the demographic models strongly support an admixture event from the source population into both crater lakes shortly before the onset of the radiations within the lakes. This opens the possibility that the formation of reproductive barriers involved in sympatric speciation was facilitated by genetic variants that evolved in a period of isolation between the initial founding
The objective of this article is to highlight some successful approaches to organic plant breeding and to encourage the organic movement to engage in an increasing number of organic breeding and organic breeding research projects.
Chickpea is an important food legume in Turkey. Turkey is one of the most important gene centers in the world for legumes. The most widely known characteristic of chickpea is that it is an important vegetable protein source used in human and animal nutrition. However, the dry grains of chickpea, has 2-3 times more protein than our traditional food of wheat. In addition, cheakpea is also energy source because of its high carbohydrate content. It is very rich in some vitamin and mineral basis. In the plant breeding, mutation induction has become an effective way of supplementing existing germplasm and improving cultivars. Many successful examples of mutation induction have proved that mutation breeding is an effective and important approach to food legume improvement. The induced mutation technique in chickpea has proved successful and good results have been attained. Realizing the potential of induced mutations, a mutation breeding programme was initiated at the Nuclear Agriculture Section of the Saraykoey Nuclear Research and Training Center in 1994. The purpose of the study was to obtain high yielding chickpea mutants with large seeds, good cooking quality and high protein content. Beside this some characters such as higher adaptation ability, tolerant to cold and drought, increased machinery harvest type, higher yield, resistant to diseases especially to antracnose and pest were investigated too. Parents varieties were ILC-482, AK-7114 and AKCIN-91 (9 % seed moisture content and germination percentage 98 %) in these experiments. The irradiation doses were 0 (control), 50, 100, 150, 200, 250, 300, 350, 400, 500 ve 600 Gy for greenhouse experiments and 0 (control), 50, 100, 150, 200, 250, 300, 350 ve 400 Gy for field experiments, respectively. One thousand seeds for per treatment were sown in the field for the M1. At maturity, 3500 single plants were harvested and 20 seeds were taken from each M1 plant and planted in the following season. During plant growth
Groenewoud, Frank; Frommen, Joachim Gerhard; Josi, Dario; Tanaka, Hirokazu; Jungwirth, Arne; Taborsky, Michael
Predation risk is a major ecological factor selecting for group living. It is largely ignored, however, as an evolutionary driver of social complexity and cooperative breeding, which is attributed mainly to a combination of habitat saturation and enhanced relatedness levels. Social cichlids neither suffer from habitat saturation, nor are their groups composed primarily of relatives. This demands alternative ecological explanations for the evolution of advanced social organization. To address this question, we compared the ecology of eight populations of Neolamprologus pulcher, a cichlid fish arguably representing the pinnacle of social evolution in poikilothermic vertebrates. Results show that variation in social organization and behavior of these fish is primarily explained by predation risk and related ecological factors. Remarkably, ecology affects group structure more strongly than group size, with predation inversely affecting small and large group members. High predation and shelter limitation leads to groups containing few small but many large members, which is an effect enhanced at low population densities. Apparently, enhanced safety from predators by cooperative defense and shelter construction are the primary benefits of sociality. This finding suggests that predation risk can be fundamental for the transition toward complex social organization, which is generally undervalued. PMID:27035973
M. Egas; Seehausen, O.; Mrosso, H D J; D. A. Joyce; Konijnendijk, N.
We examined genetic structure among five species of Lake Victoria haplochromine cichlids in four island communities, using a full factorial sampling design that compared genetic differentiation between pairs of species and populations of varying morphological similarity and geographical proximity. We found that allopatric conspecific populations were on average significantly more strongly differentiated than sympatric heterospecific populations of morphologically similar species. Allopatric h...
Grant E. BROWN, Christopher D. JACKSON, Patrick H. MALKA,Élisa JACQUES, Marc-Andre COUTURIER
Full Text Available Freshwater vertebrate and invertebrate prey species commonly rely on chemosensory information, including non-injury released disturbance cues, to assess local predation threats. We conducted laboratory studies to (1 determine if urea can function as a disturbance cue in juvenile convict cichlids and rainbow trout and (2 determine if the background level of urea influences the behavioral response to a subsequent pulse of urea (‘background noise’ hypothesis. In the first series of trials, juvenile cichlids and trout were exposed to urea at varying concentrations (0 to 0.5 mg L-1 for cichlids and 0 to 1.0 mg L-1 for trout. Our results suggest that both cichilds and trout exhibited functionally similar responses to urea and conspecific disturbance cues and that increasing the concentration of urea results in an increase intensity of antipredator behaviour. In the second series of trials, we pre-exposed cichlids or trout to intermediate or high concentrations of urea (or a distilled water control and then tested for the response to a second pulse of urea at at intermediate or high concentrations (versus a distilled water control. Our results demonstrate that pre-exposure to urea reduces or eliminates the response to a second pulse of urea, supporting the background noise hypothesis. Together, our results suggest that pulses of urea, released by disturbed or stressed individuals, may function as an early warning signal in freshwater prey species [Current Zoology 58 (2: 250–259 , 2012].
Yu, Zengliang; Deng, Jianguo; He, Jianjun; Huo, Yuping; Wu, Yuejin; Wang, Xuedong; Lui, Guifu
Ion implantation as a new mutagenic method has been used in the rice breeding program since 1986, and for mutation breeding of other crops later. It has been shown, in principle and in practice, that this method has many outstanding advantages: lower damage rate; higher mutation rate and wider mutational spectrum. Many new lines of rice with higher yield rate; broader disease resistance; shorter growing period but higher quality have been bred from ion beam induced mutants. Some of these lines have been utilized for the intersubspecies hybridization. Several new lines of cotton, wheat and other crops are now in breeding. Some biophysical effects of ion implantation for crop seeds have been studied.
A review of genetic studies related to the breeding of improved cultivars of safflower (Carthamus tinctorius L.) indicated that it was possible to modify the following over a wide range: duration of the rosette stage, stem length, branching habit, degree of spininess, head number, head size, flower morphology, mating system, seed size, hull thickness and thereby oil and protein contents, and fatty acid composition of the oil. Safflower breeders have concentrated most of their efforts on identifying and evaluating the great range of variability in cultivated safflower and its closely related wild species, and not on exploring means to increase variability. Limited experiments with gamma rays and ethyl methanesulphonate indicated that additional variability could be induced. Mutagenic agents should be used to obtain the following: resistance to foliar diseases where resistant germplasm is not available, increased levels of resistance to Phytophthora root rot, resistance to dodder and orobanche, resistance to insect pests, earlier maturity, and additional modifications in the fatty acid composition of the oil. (author)
Chickpea is an important food legume in Turkey. Turkey is one of the most important gene centers in the world for legumes. Realizing the potential of induced mutations, a mutation breeding programme was initiated at the Nuclear Agriculture Section of the Saraykoy Nuclear Research and Training Center in 1994. The purpose of the study was to obtain high yielding chickpea mutants with large seeds, good cooking quality and high protein content. Beside this some characters such as higher adaptation ability, tolerant to cold and drought, increased machinery harvest type, higher yield, resistant to diseases especially to antracnose and pest were investigated too. Parent varieties were ILC-482, AK-7114 and AKCIN-91 had been used in these experiments. The irradiation doses were 0 (control), 50, 100, 150, 200, 250, 300, 350 and 400 Gy for field experiments, respectively. As a result of these experiments, two promising mutant lines were chosen and given to the Seed Registration and Certification Center for official registration These two promising mutants were tested at five different locations of Turkey, in 2004 and 2005 years. After 2 years of registration experiments one of outstanding mutants was officially released as mutant chickpea variety under the name TAEK-SAGEL, in 2006. Some basic characteristics of this mutant are; earliness (95-100 day), high yield capacity (180-220 kg/da), high seed protein (22-25 %), first pot height (20-25 cm), 100 seeds weight (42-48 g), cooking time (35-40 min) and resistance to Ascochyta blight.
Raoni Rosa Rodrigues
Full Text Available Animal coloration has many functions, and fishes are noted among vertebrates for presenting a wide variety of color patterns. Although in marine fishes the relationship between body coloration and behavioral context is well documented, there's not much information about freshwater fishes. Here we describe color patterns displayed by the dwarf cichlid Apistogramma hippolytae and suggest that these patterns are dependent on different social and behavioral settings. Field observations were conducted underwater in a pond in Central Amazonia, Brazil. We recorded six body coloration patterns related to seven different kinds of behavioral activities: foraging, resting, reproductive and agonistic displays, aggression (attacking and fleeing and parental care. Changes in coloration occur rapidly and take only a few seconds. Females on parental care exhibited a unique pattern that are more persistent and probably manifests more slowly. In the shallow and clear waters of the natural environment of this dwarf cichlid, color communication seems to constitute an efficient way to display information about individual mood, social status and reproductive readiness, contributing to minimize loss of energy in unnecessary interactions.Coloração animal tem diferentes funções, e os peixes se destacam entre os vertebrados por apresentarem uma grande diversidade de padrões de cores. Embora se conheça relativamente bem a relação entre coloração e contexto comportamental para peixes marinhos, pouco se sabe para os peixes de água doce. Nós descrevemos os padrões de coloração de um ciclídeo amazônico, Apistogramma hippolytae, e sugerimos como esses padrões são dependentes das características sociais e comportamentais. Realizamos observações subaquáticas utilizando mergulho livre em campo durante o dia em uma lagoa na Amazônia Central. Nós caracterizamos seis padrões de coloração associados a sete comportamentos diferentes: alimentação, repouso
Melgen A. García-Lizárraga
Full Text Available The population structure and reproductive condition of the Sinaloa cichlid Cichlasoma beani from samples obtained from June 2000 to July 2001 were determined. Samples in the first week each month from the largest trader of tilapia in the Aguamilpa Reservoir in Mexico and were caught in gillnets (9.6 and 11.4 cm stretch-mesh size. Of 596 specimens, there were 427 males and 169 females; monthly sex ratio, frequency of lengths by the multinomial distribution, timing of reproduction, condition index, and size at first maturity was determined. Differences in the sex ratio and monthly totals were significant, favoring males, except for September 2000 and March 2001. From one (August 2000 to three modal groups (July 2000 and June 2001 were identified by size. There were no significant differences in standard length weight relationships by sex, which indicated that a shared model for both genders is appropriate, and isometric growth was detected. Based on the proportion of mature and partially matures fish, the main reproductive period was April through June; size at first maturity was 18.9 cm. Water temperature was not significantly related to the percentage of mature and partially matures Sinaloa cichlids or spawning. These findings provide information for regulating the Cichlasoma beani fishery in this region such minimum legal size and non-fishing period.Se determinó la estructura poblacional y condición reproductiva del cíclido de Sinaloa Cichlasoma beani desde junio de 2000 a julio de 2001. Las muestras se obtuvieron de la captura comercial de tilapia en el embalse de Aguamilpa, México durante la primera semana de cada mes. Los especímenes se capturaron con redes de enmalle (9,6 y 11,4 cm de tamaño de malla. De los 596 organismos recolectados, 427 fueron machos y 169 hembras. Se determinó la proporción de sexos mensual, grupos modales de tallas a través de una distribución multinomial, época reproductiva, índice de condición y talla
Full Text Available Background: There is much evidence indicating that natural substances from edible and medicinal plants possess powerful antioxidant and hepatoprotective activities. The objective of the present study was to investigate the potential hepatoprotective effect of silymarin in fish exposed to malathion. Methods: Zebra cichlid fish were allocated into five groups of which one group received normal feed and served as control. Fish from group 2 were treated with 0.1 mg.L-1 malathion. Fish from group 3 and 4 were fed with enriched diet with 1400 mg and 2100 mg silymarin per 1 kg feed, respectively. While fish from group 5 and 6 were fed with enriched diet with 1400 mg and 2100 mg silymarin per 1 kg feed, respectively and simultaneously were treated with 0.1 mg.L-1 malathion for 15 days. Activities of hepatic enzymes including alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase were evaluated. Oxidative stress was ascertained by measuring malondialdehyde as marker of lipid peroxidation and total cellular antioxidant capacity. Results: Exposure to malathion caused a significant increase in MDA levels and altered AST, ALT, ALP and LDH activities in liver tissues (p<0.05. The hepatic antioxidant capacity was significantly lowered in malathion treated fish as compared to the control group (p<0.05. Treatment with silymarin significantly ameliorated these changes in the malathion-treated groups. Conclusion: These finding demonstrated that silymarin have protective effects against the toxic influence of malathion on the examined biochemical parameters in liver tissue of fish.
Hesse, Saskia; Thünken, Timo
Living in groups is a widespread phenomenon in many animal taxa. The reduction of predation risk is thought to be an important cause for the formation of groups. Consequently, grouping behavior is particularly pronounced during vulnerable life stages, i.e., as juveniles. However, group living does not only provide benefits but also imposes costs on group members, e.g., increased competition for food. Thus, benefits of grouping behavior might not be evident when predation risk is absent. The adaptive significance of living and also developing in a group independent from predation risk has received relatively little attention although this might have important implications on the evolution and maintenance of group living. The first aim of the present study was to examine whether the social environment affects juvenile performance in the cichlid fish Pelvicachromis taeniatus and, secondly, whether kinship affects social behavior. Kin selection theory predicts benefits from grouping with kin. Here, we demonstrate that juveniles reared in a group grow on average faster compared to juveniles reared in isolation under standardized laboratory conditions without predation risk. Furthermore, we found significant differences in social behavior between juveniles reared in a group and reared in isolation. Fish reared in isolation were significantly more aggressive and less willing to shoal than group-reared fish. As expected, genetic relatedness influenced social behavior in group-reared fish as well: dyads of juveniles consisting of kin showed increased group cohesiveness compared to non-kin dyads. We discuss the potential benefits of group living in general and living with kin in particular.
Alcazar, Rosa M; Becker, Lisa; Hilliard, Austin T; Kent, Kai R; Fernald, Russell D
Male African cichlid fish, Astatotilapia burtoni, have been classified as dominant or subordinate, each with unique behavioral and endocrine profiles. Here we characterize two distinct subclasses of dominant males based on types of aggressive behavior: (1) males that display escalating levels of aggression and court females while they establish a territory, and (2) males that display a stable level of aggression and delay courting females until they have established a territory. To profile differences in their approach to a challenge, we used an intruder assay. In every case, there was a male-male confrontation between the resident dominant male and the intruder, with the intruder quickly taking a subordinate role. However, we found that dominant males with escalating aggression spent measurably more time attacking subordinates than did dominant males with stable aggression that instead increased their attention toward the females in their tank. There was no difference in the behavior of intruders exposed to either type of dominant male, suggesting that escalating aggression is an intrinsic characteristic of some dominant males and is not elicited by the behavior of their challengers. Male behavior during the first 15 min of establishing a territory predicts their aggressive class. These two types of dominant males also showed distinctive physiological characteristics. After the intruder assay, males with escalating aggression had elevated levels of 11-ketotestosterone (11-KT), testosterone, estradiol, and cortisol, while those with stable aggression did not. These observations show that the same stimulus can elicit different behavioral and endocrine responses among A. burtoni dominant males that characterize them as either escalating or stable aggressive types. Our ability to identify which individuals within a population have escalating levels of aggressive responses versus those which have stable levels of aggressive responses when exposed to the same stimulus
We used a field survey and a laboratory rearing experiment to (a) examine response (size and survival) to life-long hypoxia in offspring of the African maternal mouth-brooding cichlid Pseudocrenilabrus multicolor victoriae (Seegers) and (b) explore the degree to which developmental response can be environmentally-induced.Embryo size metrics were quantified in 9 field populations across a range of dissolved oxygen (DO) concentrations.In the laboratory,first generation (F1) broods of low-DO origin were reared under high or low DO.Brooding period was quantified for the mothers; and egg size,egg metabolic rate and juvenile size-at-release were quantified in their (F2) offspring.The F2 offspring were split and grown for 3 months post-release under high or low DO,and juvenile size and survival were quantified.In the field survey,across stages,embryos from low-DO field populations were shorter and weighed less than embryos from high-DO populations.In the laboratory experiment,F2 eggs and juveniles-at-release from mother's mouth did not differ in mass,length,survival regardless of development DO environment.However,juveniles diverged in size after leaving mother's mouth,exhibiting smaller size when grown under low DO.Size differences in embryo size across field populations and divergence in embryo size after release from the mother's mouthsupport predictions for smaller body size under hypoxia.There was no evidence for negative effects on survival of juveniles after 3 months.Brooding period was 16％ shorter in females reared under low DO suggesting that hypoxia may accelerate embryo development.This work provides insights into how bearer fishes respond to hypoxic stress relative to fishes with no post-spawning parental care; a shorter brooding interval and smaller body size may provide an optimal solution to parent and embryo survival under hypoxia in brooding fishes.
Husemann, Martin; Nguyen, Rachel; Ding, Baoqing; Danley, Patrick D
We estimated the effective population sizes (Ne ) and tested for short-term temporal demographic stability of populations of two Lake Malawi cichlids: Maylandia benetos, a micro-endemic, and Maylandia zebra, a widespread species found across the lake. We sampled a total of 351 individuals, genotyped them at 13 microsatellite loci and sequenced their mitochondrial D-loop to estimate genetic diversity, population structure, demographic history and effective population sizes. At the microsatellite loci, genetic diversity was high in all populations. Yet, genetic diversity was relatively low for the sequence data. Microsatellites yielded mean Ne estimates of 481 individuals (±99 SD) for M. benetos and between 597 (±106.3 SD) and 1524 (±483.9 SD) individuals for local populations of M. zebra. The microsatellite data indicated no deviations from mutation-drift equilibrium. Maylandia zebra was further found to be in migration-drift equilibrium. Temporal fluctuations in allele frequencies were limited across the sampling period for both species. Bayesian Skyline analyses suggested a recent expansion of M. zebra populations in line with lake-level fluctuations, whereas the demographic history of M. benetos could only be estimated for the very recent past. Divergence time estimates placed the origin of M. benetos within the last 100 ka after the refilling of the lake and suggested that it split off the sympatric M. zebra population. Overall, our data indicate that micro-endemics and populations in less favourable habitats have smaller Ne , indicating that drift may play an important role driving their divergence. Yet, despite small population sizes, high genetic variation can be maintained. PMID:25891855
Full Text Available Otolithic end organs in fishes function as accelerometers and are involved in the senses of balance and hearing (e.g. Popper et al. 2005. Otolith mass and shape are likely decisive factors influencing otolith motion, but while it is largely unknown how different shapes affect otolith movement relative to the sensory epithelium (Popper et al. 2005, greater otolith mass is predicted to result in enhanced stimulation of sensory hair cells and improved hearing (Lychakov and Rebane 2005. What few studies exist on this topic, however, yielded contradicting results in that they did or did not find a correlation between increased otolith mass and enhanced hearing (see Kéver et al. 2014. We investigated the relationship between otolith morphology (including 3D-models of otoliths based on high-resolution microCT imaging and otolith weight and hearing abilities in cichlids while comparing three species (Etroplus maculatus, Hemichromis guttatus, Steatocranus tinanti with different swimbladder morphology and hearing abilities (Schulz-Mirbach et al. 2014. We predicted Etroplus maculatus—the species that displays the best hearing sensitivities—to possess larger/heavier otoliths. As swimbladder extensions in this species are connected to the lagena, we further predicted to find heavier lagenar otoliths. Compared to H. guttatus and S. tinanti, E. maculatus showed the heaviest saccular otoliths, while lagenar otoliths were significantly thinner and lighter than in the former two species, apparently contradicting the hypothesis that the lagena and its otolith are primarily involved in improved hearing abilities. Our results support the idea that there is no ‘simple’ relationship between otolith weight, ancilliary auditory structures and hearing abilities. 3D-models of inner ears and otoliths may be ideally suited for future studies modeling complex otolith motion and thus, may provide a better understanding of how otolith morphology contributes to inner
Da Cuña, Rodrigo H; Rey Vázquez, Graciela; Dorelle, Luciana; Rodríguez, Enrique M; Guimarães Moreira, Renata; Lo Nostro, Fabiana L
The organochlorine pesticide endosulfan (ES) is used in several countries as a wide spectrum insecticide on crops with high commercial value. Due to its high toxicity to non-target animals, its persistence in the environment and its ability to act as an endocrine disrupting compound in fish, ES use is currently banned or restricted in many other countries. Previous studies on the cichlid fish Cichlasoma dimerus have shown that waterborne exposure to ES can lead to both decreased pituitary FSH content and histological alterations of testes. As gonadotropin-stimulated sex steroids release from gonads was inhibited by ES in vitro, the aim of the present study was to elucidate possible mechanisms of disruption of ES on gonadal steroidogenesis in C. dimerus, as well as compare the action of the active ingredient (AI) with that of currently used commercial formulations (CF). Testis and ovary fragments were incubated with ES (AI or CF) and/or steroidogenesis activators or precursors. Testosterone and estradiol levels were measured in the incubation media. By itself, ES did not affect hormone levels. Co-incubation with LH and the adenylate cyclase activator forskolin caused a decrease of the stimulated sex steroids release. When co-incubated with precursors dehydroandrostenedione and 17αhydroxyprogesterone, ES did not affect the increase caused by their addition alone. No differences were observed between the AI and CFs, suggesting that the effect on steroidogenesis disruption is mainly caused by the AI. Results indicate that action of ES takes place downstream of LH-receptor activation and upstream of the studied steroidogenic enzymes. PMID:27235598
Michael J.PAUERS; Jeffrey S.MCKINNON
Sexual selection is widely viewed as playing a central role in hapiochromine cichlid speciation.Hypothetically,once divergent mate preferences evolve among populations of these fishes,reproductive isolation follows and the populations begin to behave as different species.Various studies have examined patterns of assortative mating among species and sometimes populations,but few have examined variation in directional preferences,especially among populations of the same species.We investigated mate choice behavior in two populations of Labeotropheus fuelleborni,a Lake Malawi endemic.We test whether mating.preferences between populations are based on the same traits and in the same direction as preferences within populations.We examine the potential contributions of two classes of trait,color patterns and behaviors,to reproductive isolation.When females chose between either two males of their own population,or two from another,female preferences were generally similar (for the female population) across the two contexts.Mate choice patterns differed between (female) populations for a measure of color,but only modestly for male behavior.In a separate experiment we simultaneously offered females a male of their own population and a male from a different population.In these trials,females consistently preferred males from their own population,which were also the males that displayed more frequently than their opponents,but not necessarily those with color traits suggested to be most attractive in the previous experiment.Thus directional preferences for chroma and related aspects of color may be important when females are presented with males of otherwise similar phenotypes,but may play little role in mediating assortative mating among populations with substantially different color patterns.A preference for male behavior could play some role in speciation if males preferentially court same-population females,as we have observed for the populations studied herein.
Schönleber, J.; Anken, R. H.
Previous investigations revealed that the growth of fish inner ear otoliths depends on the amplitude and the direction of gravity, thus suggesting the existence of a (negative) feedback mechanism. In the course of these experiments, it was shown that altered gravity both affected otolith size (and thus the provision of the proteinacious matrix) as well as the incorporation of calcium. It is hitherto unknown, as of whether sensory hair cells are involved either in the regulation of otolith growth or in the provision of otolithic material (such as protein or inorganic components) or even both. The ototoxic aminoglycoside gentamicin (GM) damages hair cells in many vertebrates (and is therefore used for the treatment of Meniere's disease in humans). The present study was thus designed to determine as of whether vestibular sensory cells are needed for otolith growth by applying GM in order to induce a (functionally relevant) loss of these cells. Developing cichlid fish Oreochromis mossambicus were therefore immersed in 120 mg/l GM for 10 or 21 days. At the beginning and at the end of the experimental periods, the fish were incubated in the calcium-tracer alizarin complexone (AC). After the experiment, otoliths were dissected and the area grown during GM-exposure (i.e., the area enclosed by the two AC labellings) was determined planimetrically. The results showed that incubating the animals in a GM-solution had no effect on otolith growth, but the development of otolith asymmetry was affected. Ultrastructural examinations of the sensory hair cells revealed that they had obviously not been affected by GM-treatment (no degenerative morphological features observed). Overall, the present results suggest that hair cells are not affected by GM concerning their possible role in (general) otolith growth, but that these cells indeed might have transitionally been impaired by GM resulting in a decreased capacity of regulating otolith symmetry.
Dwyer, James Fitzgerald
Like many species, Floridaâ s population of Northern Crested Caracaras (Caracara cheriway, hereafter â caracaraâ ) is likely declining due to loss of breeding habitat. Consequently, management-oriented restrictions on landscape modification are applied where breeding occurs, but management rarely is extended beyond breeding areas. Focusing management on breeding areas can be effective if all caracaras occupy breeding areas, all breeding areas are detected, and no intermittent breeding oc...
Godiksen, Helene; Jessen, Flemming
the enzyme or its membrane lipid environment is still a matter of discussion. In this study we compared the temperature dependence and Ca2+-dependence of SR Ca2+-ATPase in haddock (Melanogrammus aeglefinus), salmon (Salmo, salar), rainbow trout (Oncorhynchus mykiss) and zebra cichlid (Cichlasoma...... nigrofasciatum). The Arrhenius plot of zebra cichlid showed a break point at 20 degreesC, and the haddock Arrhenius plot was non-linear with pronounced changes in slope in the. temperature area, 6-14 degreesC. In Arrhenius plot from both salmon and rainbow trout a plateau exists with an almost constant SR Ca2......+- ATPase activity. The temperature range of the plateau was 14-21 and 18-25 degreesC in salmon and rainbow trout, respectively. Ca2+-dependence in the four different fish species investigated was very similar with half maximal activation (K-0.5) between 0.2 and 0.6 muM and half maximal inhibition (I-0...
Wilson, Laura A B; Colombo, Marco; Sánchez-Villagra, Marcelo R; Salzburger, Walter
Phenotype-environment correlations and the evolution of trait interactions in adaptive radiations have been widely studied to gain insight into the dynamics underpinning rapid species diversification. In this study we explore the phenotype-environment correlation and evolution of operculum shape in cichlid fishes using an outline-based geometric morphometric approach combined with stable isotope indicators of macrohabitat and trophic niche. We then apply our method to a sample of extinct saurichthyid fishes, a highly diverse and near globally distributed group of actinopterygians occurring throughout the Triassic, to assess the utility of extant data to inform our understanding of ecomorphological evolution in extinct species flocks. A series of comparative methods were used to analyze shape data for 54 extant species of cichlids (N = 416), and 6 extinct species of saurichthyids (N = 44). Results provide evidence for a relationship between operculum shape and feeding ecology, a concentration in shape evolution towards present along with evidence for convergence in form, and significant correlation between the major axes of shape change and measures of gut length and body elongation. The operculum is one of few features that can be compared in extant and extinct groups, enabling reconstruction of phenotype-environment interactions and modes of evolutionary diversification in deep time. PMID:26584885
Michael R Kidd
Full Text Available The factors promoting the evolution of parental care strategies have been extensively studied in experiment and theory. However, most attempts to examine parental care in an evolutionary context have evaluated broad taxonomic categories. The explosive and recent diversifications of East African cichlid fishes offer exceptional opportunities to study the evolution of various life history traits based on species-level phylogenies. The Xenotilapia lineage within the endemic Lake Tanganyika cichlid tribe Ectodini comprises species that display either biparental or maternal only brood care and hence offers a unique opportunity to study the evolution of distinct parental care strategies in a phylogenetic framework. In order to reconstruct the evolutionary relationships among 16 species of this lineage we scored 2,478 Amplified Fragment Length Polymorphisms (AFLPs across the genome. We find that the Ectodini genus Enantiopus is embedded within the genus Xenotilapia and that during 2.5 to 3 million years of evolution within the Xenotilapia clade there have been 3-5 transitions from maternal only to biparental care. While most previous models suggest that uniparental care (maternal or paternal arose from biparental care, we conclude from our species-level analysis that the evolution of parental care strategies is not only remarkably fast, but much more labile than previously expected.
Kevin J. Parsons
Full Text Available The African cichlids of the East-African rift-lakes provide one of the most dramatic examples of adaptive radiation known. It has long been thought that functional decoupling of the oral and pharyngeal jaws in cichlids has facilitated their explosive evolution. Recent research has also shown that craniofacial evolution from radiations in lakes Victoria, Malawi, and Tanganyika has occurred along a shared primary axis of shape divergence, whereby the preorbital region of the skull changes in a manner that is, relatively independent from other head regions. We predicted that the preorbital region would comprise a variational module and used an extensive dataset from each lake that allowed us to test this prediction using a model selection approach. Our findings supported the presence of a preorbital module across all lakes, within each lake, and for Malawi, within sand and rock-dwelling clades. However, while a preorbital module was consistently present, notable differences were also observed among groups. Of particular interest, a negative association between patterns of variational modularity was observed between the sand and rock-dwelling clades, a patter consistent with character displacement. These findings provide the basis for further experimental research involving the determination of the developmental and genetic bases of these patterns of modularity.
The induction of cytochrome P4501A-mediated activity (e.g. ethoxyresorufin-O-deethylation, EROD) has been used as a biomarker for monitoring fish exposure to AhR-receptor ligands such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and polychlorinated dibenzo-dioxins/furans (PCDD/Fs). In this study we found that hepatic EROD is induced in fish ('Nile tilapia', Oreochromis niloticus and 'acara', Geophagus brasiliensis) from the Guandu River (7-17-fold) and Jacarepagua Lake (7-fold), Rio de Janeiro, Brazil. Since both cichlid fish are consumed by the local population and the Guandu River is the main source of the drinking water supply for the greater Rio de Janeiro metropolitan area, pollution by cytochrome P4501A-inducing chemicals is a cause for concern and should be further investigated in sediments, water and biota. We additionally showed that EROD activity in the fish liver post-mitochondrial supernatant-simpler, cheaper and less time consuming to prepare than the microsomal fraction-is sufficiently sensitive for monitoring purposes. - Increased EROD activity in the liver of cichlid fishes indicated that Guandu River, the source of drinking water supply for Rio de Janeiro is polluted by CYP1A-inducing chemicals
Parente, Thiago E.M.; Oliveira, Ana C.A.X. de [Laboratorio de Toxicologia Ambiental, Escola Nacional de Saude Publica - FIOCRUZ, Av Brasil 4036, Predio de Expansao do Campus, Rio de Janeiro, RJ 21041-361 (Brazil); Paumgartten, Francisco J.R. [Laboratorio de Toxicologia Ambiental, Escola Nacional de Saude Publica - FIOCRUZ, Av Brasil 4036, Predio de Expansao do Campus, Rio de Janeiro, RJ 21041-361 (Brazil)], E-mail: firstname.lastname@example.org
The induction of cytochrome P4501A-mediated activity (e.g. ethoxyresorufin-O-deethylation, EROD) has been used as a biomarker for monitoring fish exposure to AhR-receptor ligands such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and polychlorinated dibenzo-dioxins/furans (PCDD/Fs). In this study we found that hepatic EROD is induced in fish ('Nile tilapia', Oreochromis niloticus and 'acara', Geophagus brasiliensis) from the Guandu River (7-17-fold) and Jacarepagua Lake (7-fold), Rio de Janeiro, Brazil. Since both cichlid fish are consumed by the local population and the Guandu River is the main source of the drinking water supply for the greater Rio de Janeiro metropolitan area, pollution by cytochrome P4501A-inducing chemicals is a cause for concern and should be further investigated in sediments, water and biota. We additionally showed that EROD activity in the fish liver post-mitochondrial supernatant-simpler, cheaper and less time consuming to prepare than the microsomal fraction-is sufficiently sensitive for monitoring purposes. - Increased EROD activity in the liver of cichlid fishes indicated that Guandu River, the source of drinking water supply for Rio de Janeiro is polluted by CYP1A-inducing chemicals.
This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants
A comprehensive programme on experimental mutagenesis was started in 1956 for both genetic research and mutation breed ing at the Nuclear Center. Remarkable efforts were produced on durum wheat over the past 20 years and a lot of knowledge was gained on several aspects of this crop: radiobiology, mutagenesis, cytology and cytogenetics, genetics and breeding. This review concern: radiogenetical studies, isolation of useful mutations, agronomic evaluation of mutant lines and use of mutations in hybridization programs. Details are given on the genetic contribution of mutagenesis to the evolution of new cultivars in durums and on the economic evaluation of the cultivars obtained by mutation breeding. An economic return on mutation breeding of durum wheat is attempted. (author)
US Fish and Wildlife Service, Department of the Interior — This report summarizes the 2000 breeding season for grassland birds in Illinois. The report begins by summarizing weather conditions throughout the season and...
This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants
This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants
This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants
This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants
This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants
This issue of the Newsletter presents reports and research abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants