It is important to know the degree and direction of heterosis for its commercial exploitation. Heterosis and in-breeding depression were estimated in 8x8 half diallel crosses of rice. The planted materials consisted ofeight parental inbred lines, their F1 hybrids and F2 populations using randomized complete block design with ...
Full Text Available Combining ability, heterosis and inbreeding depression were estimated in grain amaranths for ten characters. Non-additive genetic variance was predominant for majority of characters in both F1 and F2 generations. The parent AG-21 was good general combiner for yield/plant also showed high GCA effects for panicles/plant and harvest index in both F1 and F2 generations. Seven characters, the best F2s on the basis of SCA involves one parent with high GCA effect and the other with poor or average GCA effects. The hybrids which exhibited highest heterosis also showed high inbreeding depression. Heterosis over better parent was highest for economic grain yield (145.047%, followed by panicles/plant (113.675%, panicle length (33.656% and grain weight/panicle (23.566%.
DEPRESIÓN EN VIGOR POR ENDOGAMIA Y HETEROSIS PARA EL RENDIMIENTO Y SUS COMPONENTES EN ZAPALLO Cucurbita moschata Duch. Ex Poir INBREEDING DEPRESSION AND HETEROSIS FOR YIELD AND ITS COMPONENTS IN PUMPKIN Cucurbita moschata Duch. Ex Poir
Miguel Mariano Espitia Camacho
Full Text Available El estudio tuvo como objetivos estimar la depresión por endogamia (DE y cuatro tipos de heterosis: promedio general (HP, promedio de progenitores (HM, heterobeltiosis (HB y útil (HU, en dos dialélos [uno entre cinco variedades (V y el otro entre cinco líneas endogamicas S1 (LS1, derivadas de éstas], para el rendimiento por planta (PFP, número de frutos por planta (NFP y peso promedio de fruto (PPF. Los 30 genotipos se evaluaron en el municipio de Candelaria (Valle del Cauca, Colombia, en un diseño de bloques completos al azar con cinco repeticiones. Se presentaron diferencias significativas (p 40 % y HU (>60 % en PFP.With the goal of estimating inbreeding depression (DE and the four types of heterosis: general average (HP, mean (HM, heterobeltiosis (HB and standard (HU, in two diallelic [one among five cross pollinated varieties (VAR and the other among five self-pollinated lines S1(LS1, derived from these], for yield/plant (PFP, number of fruits/plant (NFP and weight/fruit (PPF. The 30 genotypes were evaluated using a complete randomized design with five replicates in Candelaria (Valle del Cauca, Colombia . Significant differences (p 40 % and HU (>60 % in PFP.
Brzeski, Kristin E; Rabon, David R; Chamberlain, Michael J; Waits, Lisette P; Taylor, Sabrina S
In natural populations, the expression and severity of inbreeding depression can vary widely across taxa. Describing processes that influence the extent of inbreeding and inbreeding depression aid in our understanding of the evolutionary history of mating systems such as cooperative breeding and nonrandom mate selection. Such findings also help shape wildlife conservation theory because inbreeding depression reduces the viability of small populations. We evaluated the extent of inbreeding and inbreeding depression in a small, re-introduced population of red wolves (Canis rufus) in North Carolina. Since red wolves were first re-introduced in 1987, pedigree inbreeding coefficients (f) increased considerably and almost every wild born wolf was inbred (average f = 0.154 and max f = 0.383). The large inbreeding coefficients were due to both background relatedness associated with few founders and numerous close relative matings. Inbreeding depression was most evident for adult body size and generally absent for direct fitness measures such as reproductive success and survival; no lethal equivalents (LE = 0.00) were detected in juvenile survival. The lack of strong inbreeding depression in direct measures of fitness could be due to a founder effect or because there were no outbred individuals for comparison. Our results highlight the variable expression of inbreeding depression across traits and the need to measure a number of different traits when evaluating inbreeding depression in a wild population. © 2014 John Wiley & Sons Ltd.
Schou, M F; Loeschcke, V; Kristensen, T N
Many natural populations experience inbreeding and genetic drift as a consequence of nonrandom mating or low population size. Furthermore, they face environmental challenges that may interact synergistically with deleterious consequences of increased homozygosity and further decrease fitness. Most studies on inbreeding-environment (I-E) interactions use one or two stress levels, whereby the resolution of the possible stress and inbreeding depression interaction is low. Here we produced Drosophila melanogaster replicate populations, maintained at three different population sizes (10, 50 and a control size of 500) for 25 generations. A nutritional stress gradient was imposed on the replicate populations by exposing them to 11 different concentrations of yeast in the developmental medium. We assessed the consequences of nutritional stress by scoring egg-to-adult viability and body mass of emerged flies. We found: (1) unequivocal evidence for I-E interactions in egg-to-adult viability and to a lesser extent in dry body mass, with inbreeding depression being more severe under higher levels of nutritional stress; (2) a steeper increase in inbreeding depression for replicate populations of size 10 with increasing nutritional stress than for replicate populations of size 50; (3) a nonlinear norm of reaction between inbreeding depression and nutritional stress; and (4) a faster increase in number of lethal equivalents in replicate populations of size 10 compared with replicate populations of size 50 with increasing nutritional stress levels. Our data provide novel and strong evidence that deleterious fitness consequences of I-E interactions are more pronounced at higher nutritional stress and at higher inbreeding levels.
W. J. Libby; B. G. McCutchan; C. I. Millar
Given the polyploid chromosome constitution of Sequoia sempervirens, there was reason to question whether it would exhibit inbreeding depression. Preliminary results from studies of self and related outcross families are reported as a guide to the selection of trees for redwood seed orchards and breeding-orchards. The data indicate that, compared to...
Ana M Tortajada
Full Text Available Inbreeding depression is an important evolutionary factor, particularly when new habitats are colonized by few individuals. Then, inbreeding depression by drift could favour the establishment of later immigrants because their hybrid offspring would enjoy higher fitness. Rotifers are the only major zooplanktonic group where information on inbreeding depression is still critically scarce, despite the fact that in cyclical parthenogenetic rotifers males are haploid and could purge deleterious recessive alleles, thereby decreasing inbreeding depression.We studied the effects of inbreeding in two populations of the cyclical parthenogenetic rotifer Brachionus plicatilis. For each population, we compared both the parental fertilization proportion and F1 fitness components from intraclonal (selfed and interclonal (outcrossed crosses. The parental fertilization proportion was similar for both types of crosses, suggesting that there is no mechanism to avoid selfing. In the F1 generation of both populations, we found evidence of inbreeding depression for the fitness components associated with asexual reproduction; whereas inbreeding depression was only found for one of the two sexual reproduction fitness components measured.Our results show that rotifers, like other major zooplanktonic groups, can be affected by inbreeding depression in different stages of their life cycle. These results suggest that haplodiploidy does not purge efficiently deleterious recessive alleles. The inbreeding depression detected here has important implications when a rotifer population is founded and intraclonal crossing is likely to occur. Thus, during the foundation of new populations inbreeding depression may provide opportunities for new immigrants, increasing gene flow between populations, and affecting genetic differentiation.
The explanation for heterosis phenomenon is based on ideas: (i) every trait of an organism depends on many genes. (ii) Inbreeding depression and heterosis are related to individual genetic diversity. To assess individual genetic diversity ofan organism, I suggest the term number of genetic properties. Assessing the ...
Abstract. The explanation for heterosis phenomenon is based on ideas: (i) every trait of an organism depends on many genes. (ii) Inbreeding depression and heterosis are related to individual genetic diversity. To assess individual genetic diversity of an organism, I suggest the term number of genetic properties. Assessing ...
Full Text Available ABSTRACT Inbreeding depression, reduction in performance of quantitative traits, including reproduction and survival, caused by inbreeding, is a well-known phenomenon observed in almost all experimental, domesticated, and natural populations. In spite of its importance to the fate of a small population and numerous research performed in the last century, the genetic basis of inbreeding depression is still unclear. Recent fast development of molecular techniques has enabled estimation of a genomic inbreeding coefficient (FROH, which reflects realized autozygosity and can be further partitioned to chromosomes and chromosomal segments. In this review, we first describe classical approach used in the estimation of inbreeding in livestock populations, followed by early concepts of replacing pedigree inbreeding coefficient by individual heterozygosity. Then, we explain runs of homozygosity as key approach in estimating realized autozygosity. Furthermore, we present two different concepts of analysing regions that substantially contribute to the inbreeding depression. Thus, we describe how to identify or map mutations that result in the reduction of performance and, in terms of quantitative genetics, how to analyse the architecture of inbreeding depression. At the end, we discuss future perspectives in eliminating deleterious mutations from livestock populations.
The objective of this study was to investigate the effect of inbreeding depression on functional herd life in the South African Jersey population based on individual level and rate of inbreeding. A pedigree file of the South African Jersey breed (n = 912 638) was obtained from the Integrated Registration and Genetic ...
Full Text Available Stature is a classical and highly heritable complex trait, with 80%-90% of variation explained by genetic factors. In recent years, genome-wide association studies (GWAS have successfully identified many common additive variants influencing human height; however, little attention has been given to the potential role of recessive genetic effects. Here, we investigated genome-wide recessive effects by an analysis of inbreeding depression on adult height in over 35,000 people from 21 different population samples. We found a highly significant inverse association between height and genome-wide homozygosity, equivalent to a height reduction of up to 3 cm in the offspring of first cousins compared with the offspring of unrelated individuals, an effect which remained after controlling for the effects of socio-economic status, an important confounder (χ(2 = 83.89, df = 1; p = 5.2 × 10(-20. There was, however, a high degree of heterogeneity among populations: whereas the direction of the effect was consistent across most population samples, the effect size differed significantly among populations. It is likely that this reflects true biological heterogeneity: whether or not an effect can be observed will depend on both the variance in homozygosity in the population and the chance inheritance of individual recessive genotypes. These results predict that multiple, rare, recessive variants influence human height. Although this exploratory work focuses on height alone, the methodology developed is generally applicable to heritable quantitative traits (QT, paving the way for an investigation into inbreeding effects, and therefore genetic architecture, on a range of QT of biomedical importance.
de Boer, Raïssa A; Eens, Marcel; Fransen, Erik; Müller, Wendt
Understanding how the intensity of inbreeding depression is influenced by stressful environmental conditions is an important area of enquiry in various fields of biology. In birds, environmental stress during early development is often related to hatching asynchrony; differences in age, and thus size, impose a gradient in conditions ranging from benign (first hatched chick) to harsh (last hatched chick). Here, we compared the effect of hatching order on growth rate in inbred (parents are full siblings) and outbred (parents are unrelated) canary chicks (Serinus canaria). We found that inbreeding depression was more severe under more stressful conditions, being most evident in later hatched chicks. Thus, consideration of inbreeding-environment interactions is of vital importance for our understanding of the biological significance of inbreeding depression and hatching asynchrony. The latter is particularly relevant given that hatching asynchrony is a widespread phenomenon, occurring in many bird species. The exact causes of the observed inbreeding-environment interaction are as yet unknown, but may be related to a decrease in maternal investment in egg contents with laying position (i.e. prehatching environment), or to performance of the chicks during sibling competition and/or their resilience to food shortage (i.e. posthatching environment). © 2015 The Author(s).
Janicke Tim; Vellnow Nikolas; Lamy Thomas; Chapuis Elodie; David Patrice
Inbreeding is expected to impair male and female reproductive performance, but little is known on how inbreeding depression varies between sexes and different levels of competition. We studied inbreeding depression in mating behavior and its reproductive consequences in a hermaphroditic freshwater snail and demonstrate that inbreeding depresses mating success in both sex functions. However, the magnitude of inbreeding depression does not differ between sex functions and is not affected by the...
Inbreeding depression is caused by increased homozygosity in the genome and merges two genetic mechanisms, a higher impact from recessive mutations and the waste of overdominance contributions. It is of major concern for the conservation of endangered populations of plants and animals, as major abnormalities are more frequent in inbred families than in outcrosses. Nevertheless, we lack appropriate analytical methods to estimate the hidden inbreeding depression load (IDL) in the genome of each individual. Here, a new mixed linear model approach has been developed to account for the inbreeding depression-related background of each individual in the pedigree. Within this context, inbred descendants contributed relevant information to predict the IDL contained in the genome of a given ancestor; moreover, known relationships spread these predictions to the remaining individuals in the pedigree, even if not contributing inbred offspring. Results obtained from the analysis of weaning weight in the MARET rabbit population demonstrated that the genetic background of inbreeding depression distributed heterogeneously across individuals and inherited generation by generation. Moreover, this approach was clearly preferred in terms of model fit and complexity when compared with classical approaches to inbreeding depression. This methodology must be viewed as a new tool for a better understanding of inbreeding in domestic and wild populations. © 2017 Blackwell Verlag GmbH.
Full Text Available The purpose of this study was to investigate inbreeding depression (DE in castor bean. From a population derived from the Guarani cultivar, 60 mother plants were sampled. Three types of progenies were obtained from each one: from self-pollination (AU, from crosses (CR and from open pollination (PL. Grain yield of the progenies was evaluated in two locations. There was a strong interaction of progenies x locations, which led to obtaining estimates within each location. Broad variation was observed in inbreeding depression, with mean values of 6.7% and 13.4%, comparing AU progenies with PL progenies. It was observed that the population has high potential for selecting promising inbred lines. The frequency of mother plants generating progenies with simultaneous high general combination capacity and low inbreeding depression was low. Recurrent selection will increase the occurrence of parent plants associating these two properties, which is necessary for obtaining superior synthetic varieties.
Memon, S.; Baloch, M.J.; Baloch, G.M.
genetically diverse female lines of sunflower were crossed with male testers to get heterotic hybrids. studies were carried-out during 2008-2010 at experiment filed of agriculture research institute, tandojam, sindh, pakistan. six female lines like t-4-0319, pac-0505, ho-i, hysun-33, peshawar-93 and cms-03 and three testers i.e., pac-0306, pac-64-a and sf-187 were crossed in a line * tester mating design, thus 18 f1 and f2 hybrids were developed for evaluation of heterosis and inbreeding depression for days to initial flowering, days to maturity, leaves/plant, plant height (cm), head diameter (cm), 1000-achene weight (g), seed yield kg/ha and oil yield kg/ha. the experiment was conducted in a randomised completeb lock design with four replications. the analysis of variance revealed significant differences among parents, f1s and f2 hybrids for all the traits studied. the existence of significant genetic variability among the plant traits is particularly useful because variations in these traits would allow further improvement in sunflower seed yield and oil traits. the f1 hybrids ho-i * pac-0306 and ho-i pa * c-64-a exhibited desirable negative mid and better parent heterosis for days to initial flowering, days to maturity and plant height. these hybrids also manifested desirable positive heterotic effects for leaves/plant, head diameter, 1000-achene.s weight, seed yield and oil yield. inbreeding depression for phenological, seed yield and oil traits showed that desirable high inbreeding depression was observed in hybrids ho-i * p*ac-64-a, ho-i * pac-0306 and ho-i * sf-187 for days to initial flowering, similarly t-4-0319 * pac-0306, pac-0505 ± sf-187 and ho-i * pac-64-a explicated maximum but rewarding inbreeding depression for days to maturity. the f2 hybrids hysun-33 * sf-187 and peshawer-93 * pac-64-a may be the most desirable ones in the sense that they recorded comparatively moderate inbreeding depression with enough number of leaves to be productive if f2
To study the genetic potential, heterotic effects and inbreeding depression, 8 X 8 F/sub 2/diallel populations with parental lines of upland cotton were grown during crop season 2010 in a randomized complete block design at Khyber Pakhtunkhwa Agricultural University Peshawar, Pakistan. Highly significant ( p = 0.01 ) variations were noticed among parental lines and F/sub 2/ populations for all the traits. According to genotypes mean performance for various traits, plant height varied from 101.60 to 126.30 cm and 98.60 to 140.60 cm, bolls plant/sup -1/ (12.87 to 19.53; 12.13 to 22.60), boll weight (3.80 to 5.01 g; 3.04 to 5.38 g) and seed cotton yield plant/sup -1/ varied from 55.74 to 85.47 g and 45.57 to 96.05 g in parental cultivars and their F/sub 2/ populations, respectively. However, 12 and 7 F/sub 2/ populations manifested significant heterosis over mid and better parents for plant height, 7 and 3 for bolls plant/sup -1/, 13 and 9 for boll weight and 13 and 5 F/sub 2/ populations for seed cotton yield plant/sup -1/, respectively. F/sub 2/ populations i.e. CIM-554 X CIM-473, CIM-554 X CIM-499, CIM-496 X SLH-284, CIM-473 X CIM-446 and CIM-554 X SLH-284 with low mean values for plant height performed better and manifested highly significant heterotic values over mid and better parents for bolls per plant, boll weight and seed cotton yield. By comparing F/sub 2/ mean values with F/sub 1/s, inbreeding depression was observed for plant height (0.66 to 23. 99%), bolls per plant (5.00 to 63.16%), boll weight (0.20 to 23.24%) and seed cotton yield (0.44 to 75.52%). However, 62% of F/sub 2/ populations revealed negative values for inbreeding depression, 14% for bolls per plant, 77% for boll weight and 21% for yield, revealed that these F/sub 2/ populations were more stable and performed better than F/sub 1/s even after segregation. Although, F/sub 2/ populations may display less heterosis as compared to F/sub 1/, but still better than high parents and can be used as
Cleso Antônio Patto Pacheco
Full Text Available The study of inbreeding depression is important for breeding strategies such as use of inbred progenies or extraction of inbreed lines. A diallel of 28 maize open-pollinated varieties was evaluated in 10 environments in the early 1990s. At the same time, S1 populations for each of the 28 varieties were evaluated in the same 10 experiments (environments. Yield reductions of the populations from S0 to S1 (mean of the 10 environments, varied from 34.6% (CMS-01 to 59.2% (CMS-30, with an average of 49.1%. Inbreeding depression was greater in populations with a wider genetic base, which had never been exposed to inbreeding (CMS-30, BR-107, PH4, Cunha, Saracura, Nitrodent, and Nitroflint. Inbred lines with greater yield means should be obtained from the BR-105, BR-111, CMS-01, CMS-03, BR-106, CMS-14c, and CMS-28 populations. The use of parameter estimates generated by analysis of inbreeding depression, allow to make inferences about frequencies of deleterious alleles in the population. The frequencies of favorable alleles in the parents can be obtained by diallel analysis. The association of these two types of information, can provide a better interpretation of the genetic parameters and also can improve the process of selection of parents for either an intra- or an inter-populational breeding program.
Henrique José Camargo Senhorinho
Full Text Available The objective of this study was to evaluate the combining ability and inbreeding depression of commercial maize hybrids for agricultural traits. Twenty-two commercial maize hybrids, 96 F1 crosses from a partial diallel scheme, 22 S1 populations and 4 controls were evaluated in a 12x12 simples square lattice experimental setup, totaling 144 treatments, in the municipality of Sabáudia (PR, Brazil, for harvests from 2011/2012 and 2012/2013. Three traits were evaluated: grain yield, plant height and ear height. The Griffing method (1956 was applied for the evaluation of the general combining ability (GCA and specific combining ability (SCA. The 30B39, 30K64 and 30B30 hybrids showed increased yield, 30F53 and P1630 showed reduced plant height and AG9040 and AG7010 showed reduced ear height. These hybrids can be recommended for the extraction of inbred lines and formation of composites followed by intrapopulation selection. The combinations 30B39 x AG8088, 30B39 x AG9045 and P1630 x AG8021 showed desirable SCA effects for grain yield, plant height and ear height and are recommended for use in reciprocal recurrent selection programs. High magnitudes of inbreeding depression were verified for yield and lower values for inbreeding depression for plant and ear heights. Thus, strategies are recommended for interpopulation breeding accompanied by inbred lines extraction.
Rokouei, M; Torshizi, R Vaez; Shahrbabak, M Moradi
reproductive traits, the observed undesirable effect of inbreeding was not significant, except for the calving interval (0.53 d per 1% increase in inbreeding) in the third parity and age at first calving (0.45 d per 1% increase in inbreeding). Calving ease in heifers and cows was significantly influenced...... scores than animals with low inbreeding coefficients. For type traits, the influence of inbreeding was significant only for stature, chest width, body depth, size, rear udder height, suspensory ligament, udder depth, and front and rear teat placement. Cows with high levels of inbreeding coefficient were...
Losdat, Sylvain; Germain, Ryan R; Nietlisbach, Pirmin; Arcese, Peter; Reid, Jane M
Inbreeding is widely hypothesized to shape mating systems and population persistence, but such effects will depend on which traits show inbreeding depression. Population and evolutionary consequences could be substantial if inbreeding decreases sperm performance and hence decreases male fertilization success and female fertility. However, the magnitude of inbreeding depression in sperm performance traits has rarely been estimated in wild populations experiencing natural variation in inbreeding. Further, the hypothesis that inbreeding could increase within-ejaculate variation in sperm traits and thereby further affect male fertilization success has not been explicitly tested. We used a wild pedigreed song sparrow ( Melospiza melodia ) population, where frequent extrapair copulations likely create strong postcopulatory competition for fertilization success, to quantify effects of male coefficient of inbreeding ( f ) on key sperm performance traits. We found no evidence of inbreeding depression in sperm motility, longevity, or velocity, and the within-ejaculate variance in sperm velocity did not increase with male f . Contrary to inferences from highly inbred captive and experimental populations, our results imply that moderate inbreeding will not necessarily constrain sperm performance in wild populations. Consequently, the widely observed individual-level and population-level inbreeding depression in male and female fitness may not stem from reduced sperm performance in inbred males.
Keller, Lukas F; Grant, Peter R; Grant, B Rosemary; Petren, Kenneth
Understanding the fitness consequences of inbreeding (inbreeding depression) is of importance to evolutionary and conservation biology. There is ample evidence for inbreeding depression in captivity, and data from wild populations are accumulating. However, we still lack a good quantitative understanding of inbreeding depression and what influences its magnitude in natural populations. Specifically, the relationship between the magnitude of inbreeding depression and environmental severity is unclear. We quantified inbreeding depression in survival and reproduction in populations of cactus finches (Geospiza scandens) and medium ground finches (Geospiza fortis) living on Isla Daphne Major in the Galápagos Archipelago. Our analyses showed that inbreeding strongly reduced the recruitment probability (probability of breeding given that an adult is alive) in both species. Additionally, in G. scandens, first-year survival of an offspring with f = 0.25 was reduced by 21% and adults with f = 0.25 experienced a 45% reduction in their annual probability of survival. The magnitude of inbreeding depression in both adult and juvenile survival of this species was strongly modified by two environmental conditions, food availability and number of competitors. In juveniles, inbreeding depression was only present in years with low food availability, and in adults inbreeding depression was five times more severe in years with low food availability and large population sizes. The combination of relatively severe inbreeding depression in survival and the reduced recruitment probability led to the fact that very few inbred G. scandens ever succeeded in breeding. Other than recruitment probability, no other trait showed evidence of inbreeding depression in G. fortis, probably for two reasons: a relatively high rate of extrapair paternity (20%), which may lead to an underestimate of the apparent inbreeding depression, and low sample sizes of highly inbred G. fortis, which leads to low
Escobar, J.S.; Auld, J.R.; Correa, A.C.; Alonso, J.M.; Bony, Y.K.; Coutellec, M.-A.; Koene, J.M.; Pointier, J.-P.; Jarne, P.; David, P.
In hermaphrodites, traits that influence the selfing rate can coevolve with inbreeding depression, leading to the emergence of evolutionary syndromes. Theory predicts a negative correlation between inbreeding depression and selfing rate across species. This prediction has only been examined and
Vermeulen, Cornelius J.; Bijlsma, R.; Loeschcke, Volker
Background: The study of inbreeding depression has major relevance for many disciplines, including conservation genetics and evolutionary biology. Still, the molecular genetic basis of this phenomenon remains poorly characterised, as knowledge on the mechanistic causes of inbreeding depression and
Angeloni, F.; Vergeer, P.; Wagemaker, C.A.M.; Ouborg, N.J.
Inbreeding depression plays a central role within the conservation genetics paradigm. Until now inbreeding depression is incorporated into models of population viability as a mean value (e.g. number of lethal equivalents) for all traits in a population. In this study of the locally threatened
Bechsgaard, Jesper Smærup; Hoffmann, Ary A; Sgró, Carla
in 5 widespread and 5 tropical restricted species of Drosophila with aim of testing whether the two species groups suffered differently from inbreeding depression. The traits investigated wwere egg-to-adult viability, develpmental time and resistance to heat, vold and desiccation. Our results showed...... that levels of inbreeding depression were species and trait specific and did not differ between the species groups for stress resistance traits. However, for the life history traits developmental time and egg-to-adult viability, more inbreeding depression was observed in the tropical species. The results...... reported suggest that for life history traits tropical species of Drosophila will suffer more from inbreeding depression than widespread species in case of increases in the rate of inbreeding e.g. due to declines in population sizes....
in Spanish dairy cattle. From the results of a study with Spanish horses, Gómez et al. (2009) recommended the use of the individual increase in inbreeding coefficient (∆Fi) instead of the individual inbreeding coefficient (Fi) owing to the better fit with data and the special property whereby individual inbreeding coefficients are ...
Pedersen, Kamilla Sofie; Pedersen, Louise Dybdahl; Sorensen, Anders Christian; Nielsen, Anna Busch; Kristensen, Torsten Nygaard
Mating between closely related individuals often causes reduced fitness, which is termed "inbreeding depression". Inbreeding is, therefore, a threat towards the persistence of animal and plant populations. Here we present methods and results from a practical for high-school and first-year university students and discuss learning outcomes…
Keser Lidewij H
Full Text Available Abstract Background Solanum carolinense (horsenettle is a highly successful weed with a gametophytic self-incompatibility (SI system. Previous studies reveal that the strength of SI in S. carolinense is a plastic trait, associated with particular S-alleles. The importance of this variation in self-fertility on the ability of horsenettle to found and establish new populations will depend, to a large extent, on the magnitude of inbreeding depression. We performed a series of greenhouse and field experiments to determine the magnitude of inbreeding depression in S. carolinense, whether inbreeding depression varies by family, and whether the estimates of inbreeding depression vary under field and greenhouse conditions. We performed a series of controlled self- and cross-pollinations on 16 genets collected from a large population in Pennsylvania to obtain progeny with different levels of inbreeding. We grew the selfed and outcrossed progeny in the greenhouse and under field conditions and recorded various measures of growth and reproductive output. Results In the greenhouse study we found (1 a reduction in flower, fruit and seed production per fruit in inbred (selfed progeny when compared to outbred (outcrossed progeny; (2 a reduction in growth of resprouts obtained from rhizome cuttings of selfed progeny; and (3 an increase in the ability to self-fertilize in the selfed progeny. In the field, we found that (1 outcrossed progeny produced more leaves than their selfed siblings; (2 herbivory seems to add little to inbreeding depression; and (3 outcrossed plants grew faster and were able to set more fruits than selfed plants. Conclusion Solanum carolinense experiences low levels of inbreeding depression under greenhouse conditions and slightly more inbreeding depression under our field conditions. The combined effects of low levels of inbreeding depression and plasticity in the strength of SI suggest that the production of selfed progeny may play an
Full Text Available Inbreeding depression occurs when the offspring produced as a result of matings between relatives show reduced fitness, and is generally understood as a consequence of the elevated expression of deleterious recessive alleles. How inbreeding depression varies across environments is of importance for the evolution of inbreeding avoidance behaviour, and for understanding extinction risks in small populations. However, inbreeding-by-environment (IxE interactions have rarely been investigated in wild populations.We analysed 41 years of breeding events from a wild great tit (Parus major population and used 11 measures of the environment to categorise environments as relatively good or poor, testing whether these measures influenced inbreeding depression. Although inbreeding always, and environmental quality often, significantly affected reproductive success, there was little evidence for statistically significant I x E interactions at the level of individual analyses. However, point estimates of the effect of the environment on inbreeding depression were sometimes considerable, and we show that variation in the magnitude of the I x E interaction across environments is consistent with the expectation that this interaction is more marked across environmental axes with a closer link to overall fitness, with the environmental dependence of inbreeding depression being elevated under such conditions. Hence, our analyses provide evidence for an environmental dependence of the inbreeding x environment interaction: effectively an I x E x E.Overall, our analyses suggest that I x E interactions may be substantial in wild populations, when measured across relevant environmental contrasts, although their detection for single traits may require very large samples, or high rates of inbreeding.
Michalczyk, Łukasz; Martin, Oliver Y.; Millard, Anna L.; Emerson, Brent C.; Gage, Matthew J. G.
As populations decline to levels where reproduction among close genetic relatives becomes more probable, subsequent increases in homozygous recessive deleterious expression and/or loss of heterozygote advantage can lead to inbreeding depression. Here, we measure how inbreeding across replicate lines of the flour beetle Tribolium castaneum impacts on male reproductive fitness in the absence or presence of male–male competition. Effects on male evolution from mating pattern were removed by enforcing monogamous mating throughout. After inbreeding across eight generations, we found that male fertility in the absence of competition was unaffected. However, we found significant inbreeding depression of sperm competitiveness: non-inbred males won 57 per cent of fertilizations in competition, while inbred equivalents only sired 42 per cent. We also found that the P2 ‘offence’ role in sperm competition was significantly more depressed under inbreeding than sperm ‘defence’ (P1). Mating behaviour did not explain these differences, and there was no difference in the viability of offspring sired by inbred or non-inbred males. Sperm length variation was significantly greater in the ejaculates of inbred males. Our results show that male ability to achieve normal fertilization success was not depressed under strong inbreeding, but that inbreeding depression in these traits occurred when conditions of sperm competition were generated. PMID:20554548
Mc Parland Sinéad
Full Text Available Abstract The objective of this study was to investigate whether inbreeding depression in milk production or fertility performance has been partially purged due to selection within the Irish Holstein-Friesian population. Classical, ancestral (i.e., the inbreeding of an individual's ancestors according to two different formulae and new inbreeding coefficients (i.e., part of the classical inbreeding coefficient that is not accounted for by ancestral inbreeding were computed for all animals. The effect of each coefficient on 305-day milk, fat and protein yield as well as calving interval, age at first calving and survival to second lactation was investigated. Ancestral inbreeding accounting for all common ancestors in the pedigree had a positive effect on 305-day milk and protein yield, increasing yields by 4.85 kg and 0.12 kg, respectively. However, ancestral inbreeding accounting only for those common ancestors, which contribute to the classical inbreeding coefficient had a negative effect on all milk production traits decreasing 305-day milk, fat and protein yields by -8.85 kg, -0.53 kg and -0.33 kg, respectively. Classical, ancestral and new inbreeding generally had a detrimental effect on fertility and survival traits. From this study, it appears that Irish Holstein-Friesians have purged some of their genetic load for milk production through many years of selection based on production alone, while fertility, which has been less intensely selected for in the population demonstrates no evidence of purging.
Ahmad, M.; Khan, S.; Ahmad, F.; Shah, N.H.; Akhtar, N.
The research was conducted to evaluate the performance of S1 lines for inbreeding depression regarding different parameters, using maize variety Azam. The maize variety was self-pollinated for one generation in spring season and in the next sowing season 99 S1 lines obtained from selfing was sown with a parental line. Days to silking, pollen-shedding, plant height , ear-height, ear-length, ear-diameter, number of ears/row, kernel rows/ear and 100 kernel weight showed inbreeding depression with varying degrees while yield kg/ha showed severe inbreeding depression with an average of 362.08 kg/ha. Average value of inbreeding depression for days to silking and pollen-shedding was calculated as 2.02 and 2.21 days, respectively. Average values of inbreeding depression for plant height and ear-height were recorded as 21.50 cm and 4.87 cm, respectively. While, for earlength, ear-diameter, number of ears/row, kernel rows/ear and 100 grain weight, the average value of inbreeding depression was recorded as 1.80 cm, 0.2 cm, 2.5, 2.11 and 3.89 g, respectively. Grain yield was positively and significantly correlated with plant height, ear height and yield components. Maturity traits were positively and significantly linked with each other. It is concluded that by subjecting the maize to self-pollination nearly all the lines were affected; however, some lines were affected severely and others tolerated inbreeding to some extent. The lines showing tolerance against inbreeding depression was selected for further maize breeding. (author)
Deoclecio Domingos Garbuglio
Full Text Available Inbreeding can potentially be used for the development of inbred lines containing alleles of interest, but the genetic causes that control inbreeding depression are not completely known, and there are few studies found in the literature. The present study aimed to obtain estimates of inbreeding depression for eight traits in seven tropical maize populations, analyze the effects of inbreeding over generations and environments, and predict the behavior of inbred lines in future generation S? through linear regression methods. It was found that regardless of the base population used, prediction values could vary when the model was based on only 2 generations of inbreeding due to the environmental component. The influence of the environment in this type of study could be reduced when considering 3 generations of inbreeding, allowing greater precision in predicting the phenotypes of inbred lines. The use of linear regression was effective for inbred line prediction for the different agronomic traits evaluated. The use of 3 levels of inbreeding minimizes the effects of the environmental component in inbred line prediction for grain yield. GO-S was the most promising population for inbred line extraction.
Full Text Available Avoidance of mating between related individuals is usually considered adaptive because it decreases the probability of inbreeding depression in offspring. However, mating between related partners can be adaptive if outbreeding depression is stronger than inbreeding depression or if females gain inclusive fitness benefits by mating with close kin. In the present study, we used microsatellite data to infer the parentage of juveniles born in a French colony of feral pigeons, which allowed us to deduce parent pairs. Despite detectable inbreeding depression, we found that pairwise relatedness between mates was significantly higher than between nonmates, with a mean coefficient of relatedness between mates of 0.065, approximately half the theoretical value for first cousins. This higher relatedness between mates cannot be explained by spatial genetic structure in this colonial bird; it therefore probably results from an active choice. As inbreeding but not outbreeding depression is observed in the study population, this finding accords with the idea that mating with genetically similar mates can confer a benefit in terms of inclusive fitness. Our results and published evidence suggest that preference for related individuals as mates might be relatively frequent in birds.
Costa e Silva, J; Hardner, C; Tilyard, P; Potts, B M
Inbreeding adversely affects fitness traits in many plant and animal species, and the magnitude, stability and genetic basis of inbreeding depression (ID) will have short- and long-term evolutionary consequences. The effects of four degrees of inbreeding (selfing, f=50% full- and half-sib matings, f=25 and 12.5% and unrelated outcrosses, f=0%) on survival and growth of an island population of Eucalyptus globulus were studied at two sites for over 14 years. For selfs, ID in survival increased over time, reaching a maximum of 49% by age 14 years. However, their inbreeding depression for stem diameter remained relatively stable with age, and ranged from 28 to 36% across years and sites. ID for survival was markedly greater on the more productive site, possibly due to greater and earlier onset of inter-tree competition, but was similar on both sites for the diameter of survivors. The deleterious trait response to increasing inbreeding coefficients was linear for survival and diameter. Non-significant quadratic effects suggested that epistasis did not contribute considerably to the observed ID at the population level. Among- and within-family coefficients of variation for diameter increased with inbreeding degree, and the variance among the outcrossed families was significant only on the more productive site. The performance of self-families for diameter was highly stable between sites. This suggests that, for species with mixed mating systems, environmentally stable inbreeding effects in open-pollinated progenies may tend to mask the additive genotype-by-environment interaction for fitness traits and the adaptive response to the environment. PMID:21224873
Thiele, Jan; Hansen, Thomas Møller; Siegismund, Hans Redlef
The magnitude and variation of inbreeding depression (ID) within populations is important for the evolution and maintenance of mixed mating systems. We studied ID and its genetic variation in a range of floral and fitness traits in a small and large population of the perennial herb Silene nutans,...
Yun, Li; Agrawal, Aneil F
In what types of environments should we expect to find strong inbreeding depression? Previous studies indicate that inbreeding depression, δ, is positively correlated with the stressfulness of the environment in which it is measured. However, it remains unclear why stress, per se, should increase δ. To our knowledge, only "competitive stress" has a logical connection to δ. Through competition for resources, better quality (outbred) individuals make the environment worse for lower quality (inbred) individuals, accentuating the differences between them. For this reason, we expect inbreeding depression to be stronger in environments where the fitness of individuals is more sensitive to the presence of conspecifics (i.e., where fitness is more density dependent). Indeed, some studies suggest a role for competition within environments, but this idea has not been tested in the context of understanding variation in δ across environments. Using Drosophila melanogaster, we estimated δ for viability in 22 different environments. These environments were simultaneously characterized for (1) stressfulness and (2) density dependence. Although stress and density dependence are moderately correlated with each other, inbreeding depression is much more strongly correlated with density dependence. These results suggest that mean selection across the genome is stronger in environments where competition is intense, rather than in environments that are stressful for other reasons. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.
Rollinson, Njal; Keith, Dave M; Houde, Aimee Lee S; Debes, Paul V; McBride, Meghan C; Hutchings, Jeffrey A
Captive-breeding programs can be implemented to preserve the genetic diversity of endangered populations such that the controlled release of captive-bred individuals into the wild may promote recovery. A common difficulty, however, is that programs are founded with limited wild broodstock, and inbreeding can become increasingly difficult to avoid with successive generations in captivity. Program managers must choose between maintaining the genetic purity of populations, at the risk of inbreeding depression, or interbreeding populations, at the risk of outbreeding depression. We evaluate these relative risks in a captive-breeding program for 3 endangered populations of Atlantic salmon (Salmo salar). In each of 2 years, we released juvenile F(1) and F(2) interpopulation hybrids, backcrosses, as well as inbred and noninbred within-population crosstypes into 9 wild streams. Juvenile size and survival was quantified in each year. Few crosstype effects were observed, but interestingly, the relative fitness consequences of inbreeding and outbreeding varied from year to year. Temporal variation in environmental quality might have driven some of these annual differences, by exacerbating the importance of maternal effects on juvenile fitness in a year of low environmental quality and by affecting the severity of inbreeding depression differently in different years. Nonetheless, inbreeding was more consistently associated with a negative effect on fitness, whereas the consequences of outbreeding were less predictable. Considering the challenges associated with a sound risk assessment in the wild and given that the effect of inbreeding on fitness is relatively predictable, we suggest that risk can be weighted more strongly in terms of the probable outcome of outbreeding. Factors such as genetic similarities between populations and the number of generations in isolation can sometimes be used to assess outbreeding risk, in lieu of experimentation. © 2014 Society for
Enders, Laramy S; Nunney, Leonard
Recent meta-analyses conducted across a broad range of taxa have demonstrated a strong linear relationship between the change in magnitude of inbreeding depression under stress and stress level, measured as fitness loss in outbred individuals. This suggests that a general underlying response may link stress and inbreeding depression. However, this relationship is based primarily on laboratory data, and it is unknown whether natural environments with multiple stressors and fluctuating stress levels alter how stress affects inbreeding depression. To test whether the same pattern persists in the field, we investigated the effect of seasonal variation on stress level and inbreeding depression in a 3-year field study measuring the productivity of captive populations of inbred and outbred Drosophila melanogaster. We found cold winter temperatures were most stressful and induced the greatest inbreeding depression. Furthermore, these data, collected under natural field conditions, conformed to the same predictive linear relationship seen in Drosophila laboratory studies, with inbreeding depression increasing by 0.17 lethal equivalents for every 10 per cent increase in stress level. Our results suggest that under natural conditions stress level is a primary determinant of the magnitude of inbreeding depression and should be considered when assessing extinction vulnerability in small populations.
Full Text Available This paper reports the first results of a survey on morphological traits in Bracco Italiano dog breed, and analyzes the effects of various levels of inbreeding on these measures. Traits were taken from 155 adult (mean age 4.18±2.60 years dogs (79 males and 76 females belonging to 57 different farms. For each animal, the following biometrical measurements were considered: height at withers (WH, height of chest (ChH, body length (BL, length at rump (RL, height at rump (RH, iliac width of rump (RIlW, ischiatic width of rump (RIsW, circumference of chest (ChC, circumference of cannon (CaC, length of ear (EL, and length of head (HL. The ratio of rump length/withers height (RL/WH, cannon circumference/chest circumference (CaC/ChC and head length/withers height (HL/WH were also calculated. ANOVA was used to test the differences between males and females and among farms in terms of morphological measurements and ratios. Significant differences between males and females were observed for many morphological traits. The measures coincided with what reported in the current breed standard, apart from the length of the rump, which was around ¼ of the withers height rather than the 1/3 required in the standard. No significant effect of inbreeding on conformation traits was observed.
Full Text Available Cognitive ability tests are widely assumed to measure maximal intellectual performance and predictive associations between intelligence quotient (IQ scores and later mental health problems. Very few epidemiologic studies have been done to demonstrate the relationship between familial inbreeding and modest cognitive impairments in children.We aimed to estimate the effect of inbreeding on children's cognitive behavior in comparison with non-inbred children.A cohort of 408 children (6 to 15 years of age was selected from inbred and non-inbred families of five Muslim populations of Jammu region. The Wechsler Intelligence Scales for Children (WISC was used to measure the verbal IQ (VIQ, performance IQ (PIQ and full scale IQ (FSIQ. Family pedigrees were drawn to access the family history and children's inbred status in terms of coefficient of inbreeding (F.We found significant decline in child cognitive abilities due to inbreeding and high frequency of mental retardation among offspring from inbred families. The mean differences (95% C.I. were reported for the VIQ, being -22.00 (-24.82, -19.17, PIQ -26.92 (-29.96, -23.87 and FSIQ -24.47 (-27.35,-21.59 for inbred as compared to non-inbred children (p<0.001 [corrected].The higher risk of being mentally retarded was found to be more obvious among inbred categories corresponding to the degree of inbreeding and the same accounts least for non-inbred children (p<0.0001. We observed an increase in the difference in mean values for VIQ, PIQ and FSIQ with the increase of inbreeding coefficient and these were found to be statistically significant (p<0.05. The regression analysis showed a fitness decline (depression for VIQ (R2 = 0.436, PIQ (R2 = 0.468 and FSIQ (R2 = 0.464 with increasing inbreeding coefficients (p<0.01.Our comprehensive assessment provides the evidence for inbreeding depression on cognitive abilities among children.
Stone, Judy L; Motten, Alexander F
Genetically based variation in outcrossing rate generates lineages within populations that differ in their history of inbreeding. According to some models, mating-system modifiers in such populations will demonstrate both linkage and identity disequilibrium with fitness loci, resulting in lineage-specific inbreeding depression. Other models assert that differences among families in levels of inbreeding depression are mainly attributable to random accumulation of genetic load, unrelated to variation at mating-system loci. We measured female reproductive success of selfed and outcrossed progeny from naturally occurring lineages of Datura stramonium, a predominantly self-fertilizing annual weed that has heritable variation in stigma-anther separation, a trait that influences selfing rates. Progeny from inbred lineages (as identified by high degree of anther-stigma overlap) showed equal levels of seed production, regardless of cross type. Progeny from mixed lineages (as identified by relatively high separation between anthers and stigma) showed moderate levels of inbreeding depression. We found a significant correlation between anther-stigma separation and relative fitness of selfed and outcrossed progeny, suggesting that family-level inbreeding depression may be related to differences among lineages in inbreeding history in this population. Negative inbreeding depression in putatively inbred lineages may be due in part to additive effects or to epistatic interactions among loci.
Jiménez-Lobato, V; Martínez-Borda, E; Núñez-Farfán, J; Valverde, P L; Cruz, L L; López-Velázquez, A; Santos-Gally, R; Arroyo, J
Plant populations invading new environments might compromise their fitness contribution to the next generation, because of the lack of native specialist pollinators and/or potential mates. Thus, changes in plant mating system and traits linked to it are expected in populations colonising new environments where selection would favour selfing and floral traits that maximise reproductive output. To test this, we studied native (Mexico) and non-native (Spain) populations of the obligate sexual reproducing annual weed Datura stramonium. Flower size, herkogamy, total number of seeds per plant, number of visits by and type of pollinators, and inbreeding depression were assessed in native and non-native populations. Finally, we measured phenotypic selection on corolla size and herkogamy in each population. Flower size and herkogamy showed wide and similar variation in both ranges. However, the largest average flower size was found in one non-native population whereas the highest average positive herkogamy was detected in one native population. On average, flowers in the native range received more visits by pollinators. Hawkmoths were the main visitors in the native populations while only bees were observed visiting flowers in Spain's populations. Only in the native range was inbreeding depression detected. Selection to reduce herkogamy was found only in one native population. Absence of both inbreeding depression and selection on floral traits suggest a change in mating system of D. stramonium in a new range where generalist pollinators may be promoting high reproductive success. Selection against deleterious alleles might explain the reduction of inbreeding depression, promoting the evolution of selfing. © 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.
Wu, Harry X; Hallingbäck, Henrik R; Sánchez, Leopoldo
In the domestication and breeding of tree species that suffer from inbreeding depression (ID), the long-term performance of different breeding strategies is poorly known. Therefore, seven tree breeding strategies including single population, subline, selfing, and nucleus breeding were simulated using a multi-locus model with additive, partial, and complete dominance allele effects, and with intermediate, U-shaped, and major allele distributions. The strategies were compared for genetic gain, inbreeding accumulation, capacity to show ID, the frequencies and fixations of unfavorable alleles, and genetic variances in breeding and production populations. Measured by genetic gain of production population, the nucleus breeding and the single breeding population with mass selection strategies were equal or superior to subline and single breeding population with within-family selection strategies in all simulated scenarios, in spite of their higher inbreeding coefficients. Inbreeding and cross-breeding effectively decreased ID and could in some scenarios produce genetic gains during the first few generations. However, in all scenarios, considerable fixation of unfavorable alleles rendered the purging performance of selfing and cross-breeding strategies ineffective, and resulted in substantial inferiority in comparison to the other strategies in the long-term. Copyright © 2016 Wu et al.
Vega-Trejo, Regina; Head, Megan L; Jennions, Michael D
It is often assumed that mating with close relatives reduces offspring fitness. In such cases, reduced offspring fitness may arise from inbreeding depression (i.e., genetic effects of elevated homozygosity) or from post-mating maternal investment. This can be due to a reduction in female investment after mating with genetically incompatible males ("differential allocation") or compensation for incompatibility ("reproductive compensation"). Here, we looked at the effects of mating with relatives on offspring fitness in mosquitofish, Gambusia holbrooki. In this species, females are assumed to be nonplacental and to allocate resources to eggs before fertilization, limiting differential allocation. We looked at the effects of mating with a brother or with an unrelated male on brood size, offspring size, gestation period, and early offspring growth. Mating with a relative reduced the number of offspring at birth, but there was no difference in the likelihood of breeding, gestation time, nor in the size or growth of these offspring. We suggest that due to limited potential for maternal effects to influence these traits that any reduction in offspring fitness, or lack thereof, can be explained by inbreeding depression rather than by maternal effects. We highlight the importance of considering the potential role of maternal effects when studying inbreeding depression and encourage further studies in other Poeciliid species with different degrees of placentation to test whether maternal effects mask or amplify any genetic effects of mating with relatives.
Kenney, John; Allendorf, Fred W.; McDougal, Charles; Smith, James L. D.
The number and size of tiger populations continue to decline owing to habitat loss, habitat fragmentation and poaching of tigers and their prey. As a result, tiger populations have become small and highly structured. Current populations have been isolated since the early 1970s or for approximately seven generations. The objective of this study is to explore how inbreeding may be affecting the persistence of remaining tiger populations and how dispersal, either natural or artificial, may reduce the potentially detrimental effect of inbreeding depression. We developed a tiger simulation model and used published levels of genetic load in mammals to simulate inbreeding depression. Following a 50 year period of population isolation, we introduced one to four dispersing male tigers per generation to explore how gene flow from nearby populations may reduce the negative impact of inbreeding depression. For the smallest populations, even four dispersing male tigers per generation did not increase population viability, and the likelihood of extinction is more than 90% within 30 years. Unless habitat connectivity is restored or animals are artificially introduced in the next 70 years, medium size wild populations are also likely to go extinct, with only four to five of the largest wild tiger populations likely to remain extant in this same period without intervention. To reduce the risk of local extinction, habitat connectivity must be pursued concurrently with efforts to increase population size (e.g. enhance habitat quality, increase habitat availability). It is critical that infrastructure development, dam construction and other similar projects are planned appropriately so that they do not erode the extent or quality of habitat for these populations so that they can truly serve as future source populations. PMID:24990671
Kenney, John; Allendorf, Fred W; McDougal, Charles; Smith, James L D
The number and size of tiger populations continue to decline owing to habitat loss, habitat fragmentation and poaching of tigers and their prey. As a result, tiger populations have become small and highly structured. Current populations have been isolated since the early 1970s or for approximately seven generations. The objective of this study is to explore how inbreeding may be affecting the persistence of remaining tiger populations and how dispersal, either natural or artificial, may reduce the potentially detrimental effect of inbreeding depression. We developed a tiger simulation model and used published levels of genetic load in mammals to simulate inbreeding depression. Following a 50 year period of population isolation, we introduced one to four dispersing male tigers per generation to explore how gene flow from nearby populations may reduce the negative impact of inbreeding depression. For the smallest populations, even four dispersing male tigers per generation did not increase population viability, and the likelihood of extinction is more than 90% within 30 years. Unless habitat connectivity is restored or animals are artificially introduced in the next 70 years, medium size wild populations are also likely to go extinct, with only four to five of the largest wild tiger populations likely to remain extant in this same period without intervention. To reduce the risk of local extinction, habitat connectivity must be pursued concurrently with efforts to increase population size (e.g. enhance habitat quality, increase habitat availability). It is critical that infrastructure development, dam construction and other similar projects are planned appropriately so that they do not erode the extent or quality of habitat for these populations so that they can truly serve as future source populations. © 2014 The Author(s) Published by the Royal Society. All rights reserved.
Vermeulen, Corneel J.; Bijlsma, R.; Loeschcke, Volker
of inbreeding effects in specific traits, such as age-specific mortality and life span, provide a good starting point, as a limited set of genes is expected to be involved. Results Here we report on a QTL mapping study on inbreeding related and temperature sensitive lethality in male Drosophila melanogaster...... and the molecular properties of genes that give rise to or modulate its deleterious effects is lacking. These questions warrant the detailed study of genetic loci giving rise to inbreeding depression. However, the complex and polygenic nature of general inbreeding depression makes this a daunting task. Study...... simple, being due mainly to a single recessive QTL on the left arm of chromosome 2. This locus colocalised with a QTL that conditioned variation in female life span, acting as an overdominant locus for this trait. Male life span was additionally affected by variation at the X-chromosome. Conclusion...
Full Text Available Experiments leading to the procurement of subsequent inbred generations were conducted in the years 2006- 2013. Seeds obtained from open pollination and after self-pollination of four strawberry cultivars (Teresa, Senga Sengana, Kent and Chandler and clone 1387 were used. These genotypes were evaluated for their tolerance to strong inbreeding under in vitro culture conditions. The aims of this study were to estimate the inbreeding depression of each of the progenies. During the investigation, the germination percentage as well as seedling viability were evaluated. The highest seed germination was shown for populations derived from ‘Teresa’ × open pollination (82% and ‘Kent’ (7 S4 (78%. Seeds derived from self-pollination resulted in the lowest germination - an average of 16.8%. Generally, seed germination was significantly lower for the five S1 offspring, whose depression was 0.62, in comparison with the S4 seedlings, whose depression was 0.31. Inbred offspring showed a depression in relation to the average weight of a single seedling of 0.08 in the case of S1 progeny, whereas in the case of S4 progeny it was 0.23. The highest germination energy was shown by ‘Kent’ (7 S4 seeds (74% and hybrids of ‘Teresa’ derived from open pollination (75%; whereas seeds obtained at the same time from self-pollination germinated 10.8% on average.
Full Text Available This research was conducted to determine inbreeding depression in S1 maize lines for reproductive and yield related traits, at NWFP Agricultural University, Peshawar, Pakistan, in two successive seasons during 2002. Maize variety"Pahari" was selfed for one generation and 63 S1 lines were evaluated using "lattice square design" with two replications along with the parental population. Days to mid silking and mid pollen shed (anthesis, plant height and ear height (cm, and 200 grain weight (g showed inbreeding depression with varying degrees. Severe inbreeding depression was observed for yield with the average of 709 kg ha-1. Inbreeding depression for 200 grains weight averaged 19 g, while for plant height and ear height it was calculated as 33 and 16 cm. Inbreeding depression for days to mid silking and pollen shed was lower as compared to morphological and yield components. Silking and pollen shed were delayed by 1.8 and 1.5 days on the average, respectively, as compared to the parental variety. Yield was significantly correlated with all maturity and morphological characters. Maturity characters were positively and significantly correlated with each other, showing good synchronization in maturity characters, while they were negatively and significantly correlated with yield components.
Bjelland, D W; Weigel, K A; Vukasinovic, N; Nkrumah, J D
The effects of increased pedigree inbreeding in dairy cattle populations have been well documented and result in a negative impact on profitability. Recent advances in genotyping technology have allowed researchers to move beyond pedigree analysis and study inbreeding at a molecular level. In this study, 5,853 animals were genotyped for 54,001 single nucleotide polymorphisms (SNP); 2,913 cows had phenotypic records including a single lactation for milk yield (from either lactation 1, 2, 3, or 4), reproductive performance, and linear type conformation. After removing SNP with poor call rates, low minor allele frequencies, and departure from Hardy-Weinberg equilibrium, 33,025 SNP remained for analyses. Three measures of genomic inbreeding were evaluated: percent homozygosity (FPH), inbreeding calculated from runs of homozygosity (FROH), and inbreeding derived from a genomic relationship matrix (FGRM). Average FPH was 60.5±1.1%, average FROH was 3.8±2.1%, and average FGRM was 20.8±2.3%, where animals with larger values for each of the genomic inbreeding indices were considered more inbred. Decreases in total milk yield to 205d postpartum of 53, 20, and 47kg per 1% increase in FPH, FROH, and FGRM, respectively, were observed. Increases in days open per 1% increase in FPH (1.76 d), FROH (1.72 d), and FGRM (1.06 d) were also noted, as well as increases in maternal calving difficulty (0.09, 0.03, and 0.04 on a 5-point scale for FPH, FROH, and FGRM, respectively). Several linear type traits, such as strength (-0.40, -0.11, and -0.19), rear legs rear view (-0.35, -0.16, and -0.14), front teat placement (0.35, 0.25, 0.18), and teat length (-0.24, -0.14, and -0.13) were also affected by increases in FPH, FROH, and FGRM, respectively. Overall, increases in each measure of genomic inbreeding in this study were associated with negative effects on production and reproductive ability in dairy cows. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc
Richardson, Jon; Smiseth, Per T
A recent theoretical model suggests that intraspecific competition is an important determinant of the severity of inbreeding depression. The reason for this is that intraspecific competition is density dependent, leading to a stronger negative effect on inbred individuals if they are weaker competitors than outbred ones. In support of this prediction, previous empirical work shows that inbred individuals are weaker competitors than outbred ones and that intraspecific competition often exacerbates inbreeding depression. Here, we report an experiment on the burying beetle Nicrophorus vespilloides, in which we recorded the outcome of competition over a small vertebrate carcass between an inbred or outbred male resident caring for a brood and a size-matched inbred or outbred male intruder. We found that inbred males were more successful as intruders in taking over a carcass from a male resident and were injured more frequently as either residents or intruders. Furthermore, inbred males gained less mass during the breeding attempt and had a shorter adult life span than outbred males. Finally, successful resident males reared a substantially smaller brood comprised of lighter larvae when the intruder was inbred than when it was outbred. Our results shows that inbred males increased their competitive effort, thus contradicting previous work suggesting that inbred males are weaker competitors. Furthermore, our results shows that inbred intruders impose a greater cost to resident males, suggesting that outbred individuals can suffer fitness costs as a result of competition with inbred ones.
Rupesh R Kariyat
Full Text Available The clonal weed Solanum carolinense exhibits plasticity in the strength of its self-incompatibility (SI system and suffers low levels of inbreeding depression (δ in the greenhouse. We planted one inbred and one outbred plant from each of eight maternal plants in a ring (replicated twice and monitored clonal growth, herbivory, and reproduction over two years. Per ramet δ was estimated to be 0.63 in year one and 0.79 in year two, and outbred plants produced 2.5 times more ramets than inbred plants in the spring of year two. Inbred plants also suffered more herbivore damage than outbred plants in both fields, suggesting that inbreeding compromises herbivore resistance. Total per genet δ was 0.85 over the two years, indicating that S. carolinense is unlikely to become completely self-compatible, and suggesting that plasticity in the SI system is part of a stable mixed-mating system permitting self-fertilization when cross pollen limits seed production.
Hofer, Michal; Pospíšil, Milan; Dušek, L.; Holá, Jiřina; Hoferová, Zuzana; Weiterová, Lenka
Roč. 235, č. 8 (2010), s. 928-931 ISSN 1535-3702 R&D Projects: GA ČR(CZ) GA305/08/0158 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : hematopoiesis * outbred mice * inbreeding depression Subject RIV: BO - Biophysics Impact factor: 2.954, year: 2010
Luijten, S.H.; Kery, M.; Oostermeijer, J.G.B.; Den, Nijs H.J.C.M.
1. The genetic constitution of populations may significantly affect demography. Founder populations or isolated remnants may show inbreeding depression, while established populations can be strongly adapted to the local environment. Gene exchange between populations can lead to better performance if heterozygosity levels are restored (heterosis), or to reduced performance if coadapted gene complexes are disrupted (outbreeding depression). 2. Five populations of the self-incompatible perennial Arnica montana (Asteraceae) were analysed for the demographic consequences of inbreeding and of intra- and interpopulation outcrossing, using both small and large populations as donors for the latter. We analysed seed production and seed weight and monitored growth, survival and flowering of offspring introduced as seeds and as 4-week-old seedlings in a 4-year field experiment. 3. Reduced seed set after selfing was probably due to the self-incompatibility system rather than to inbreeding depression. There was a significant increase for seed set after interpopulation crosses, which resulted from the alleviation of low mate availability in one of the small populations. 4. Significant inbreeding depression was observed for growth rates of plants introduced as seedlings. We found significant heterosis for flowering probability of plants introduced as seeds, but for plants introduced as seedlings, heterosis for seedling size and flowering probability was only marginally significant. Outbreeding depression was not observed. 5. The results of this study are important for reinforcement measures in small, remnant populations. Significant differences among populations for all measured fitness components suggest that reinforcement is best achieved using material from several populations. 6. The observed higher survival of seedlings as compared with seeds suggests that it is better to plant individuals than to sow. Sowing, however, is easier and cheaper, and was more likely to eliminate
Full Text Available Angiosperms evolved different systems to attract effective pollinators while reducing selfing in hermaphroditic flowers. Selfing ability can be advantageous when pollinators and/or mates are scarce, although inbreeding depression may largely reduce those advantages. Recent comparative analyses suggested endemic species tend to evolve self-compatibility but a better understanding of the associated reproductive and genetic tradeoffs is required. Experimental hand-pollinations under greenhouse conditions were conducted to investigate the selfing ability and estimate inbreeding depression up to the offspring’ first reproductive event in Ero dium cazorlanum, a narrow endemic species restricted to dolomite outcrops in SE Spanish mountains. We found autonomous selfing ineffective. Further, when experimentally applied, pollen of the same flower produced significantly fewer fruits and seeds compared to geitonogamous and cross pollinations. The number of seeds per fruit was significantly higher after cross pollinations and strong inbreeding depression accumulated through the life-cycle. Interestingly, individual plants exhibited broad variation in selfing ability with six out of 14 individuals producing no seed after geitonogamy. Understanding the consequences of individual variation in self compatibility deserves further investigation in the field now that we know that strong inbreeding depression may limit recruitment of selfed progeny.Las Angiospermas han desarrollado diversos sistemas para atraer polinizadores eficientes y al mismo tiempo reducir la posibilidad de autopolinización asociada al hermafroditismo. La capacidad de autopolinización puede ser ventajosa en situaciones de escasez de polinizadores y/o individuos reproductores, beneficios que pueden reducirse ampliamente a causa de la depresión por endogamia. Análisis filogenéticos recientes indicaron que las especies endémicas tienden a presentar sistemas de autocompatibilidad, por tanto
Hardy Olivier J
Full Text Available Abstract Background Understanding the mechanisms that control species genetic structure has always been a major objective in evolutionary studies. The association between genetic structure and species attributes has received special attention. As species attributes are highly taxonomically constrained, phylogenetically controlled methods are necessary to infer causal relationships. In plants, a previous study controlling for phylogenetic signal has demonstrated that Wright's FST, a measure of genetic differentiation among populations, is best predicted by the mating system (outcrossing, mixed-mating or selfing and that plant traits such as perenniality and growth form have only an indirect influence on FST via their association with the mating system. The objective of this study is to further outline the determinants of plant genetic structure by distinguishing the effects of mating system on gene flow and on genetic drift. The association of biparental inbreeding and inbreeding depression with population genetic structure, mating system and plant traits are also investigated. Results Based on data from 263 plant species for which estimates of FST, inbreeding (FIS and outcrossing rate (tm are available, we confirm that mating system is the main influencing factor of FST. Moreover, using an alternative measure of FST unaffected by the impact of inbreeding on effective population size, we show that the influence of tm on FST is due to its impact on gene flow (reduced pollen flow under selfing and on genetic drift (higher drift under selfing due to inbreeding. Plant traits, in particular perenniality, influence FST mostly via their effect on the mating system but also via their association with the magnitude of selection against inbred individuals: the mean inbreeding depression increases from short-lived herbaceous to long-lived herbaceous and then to woody species. The influence of perenniality on mating system does not seem to be related to
Silva, Marcel Müller Fernandes Pereira da; Diniz-Filho, José Alexandre Felizola
Despite methodological and theoretical advances in conservation genetics, data on genetic variation on broad regional spatial scales are still scarce, leading conservation planners to use general heuristic or simulation models for an integrated analysis of genetic, demographic and landscape parameters. Here, we extended previous results by evaluating spatial patterns of extinction by inbreeding depression under stochastic variation of environments for mammalian populations in 31 conservation ...
E. G. Kozar
Full Text Available The protected cultivation technology, through which the various inbred generations with the combination of economic valuable traits and different level of sterility can be produced, is used in order to accelerate the breeding program. However, there is a negative effect of inbreeding depression and self-incompatibility can often occur and cause the loss of valuable breeding forms. The aim of the work was to study the influence of steroidal glycosides capsicoside (SGC on exhibition of CMS, and morphobiological parameters of 13 inbred generations that were produced from fertile plant and partly sterile plants with level of sterility 10% and 50%. The seeds were soaked for 24 hours in water solution of SGC with concentration 10-3%, and in water control. Then the seeds were dried up and sown in the greenhouse. The stecklings and roots obtained were vernalized at 3-5Co. Mother plants were grown under 18 hour photoperiod in greenhouse with supplementary lighting. Inbreeding seeds were obtained in individual cloth isolators. It was shown that for all generations the treatment with SGC improved the seed germination (4-8% more, increased the root index and its length (12-24% more, decreased betanin content (22-48% less in comparison with control. The action of SGC on the other morphological and biochemical traits such as height of leaf rosette, leaf number, plant and root weight, head size, number of generative buds, and nitrate content was defined by the level of sterility of mother plant. The most expressed effect for all traits mentioned was seen in inbreeding generations of sterile plants with high level of sterility. After action effect of seed treatment with SGC on development of seed plants from inbreeding generations, not depending on sterility level of mother plants, showed the positive influence on plant habitus of seed mother plants, decreasing the plant height, but increasing stem number and functional parameters of microgametophyte in fertile
Pedersen, Kamilla Sofie; Pedersen, Louise Dybdahl; Sørensen, Anders Christian
Mating between closely related individuals often causes reduced fitness, which is termed ‘inbreeding depression’. Inbreeding is, therefore, a threat towards the persistence of animal and plant populations. Here we present methods and results from a practical for high-school and first-year univers......Mating between closely related individuals often causes reduced fitness, which is termed ‘inbreeding depression’. Inbreeding is, therefore, a threat towards the persistence of animal and plant populations. Here we present methods and results from a practical for high-school and first...... into vials before exposure to 38°C heat stress in a water bath for 1 h. Half an hour later the number of comatose inbred and control flies were scored and chi-square statistic procedures were used to test for different degrees of heat stress tolerance between the two lines of flies. The practical introduces...
Hu, Yibo; Nie, Yonggang; Wei, Wei; Ma, Tianxiao; Van Horn, Russell; Zheng, Xiaoguang; Swaisgood, Ronald R; Zhou, Zhixin; Zhou, Wenliang; Yan, Li; Zhang, Zejun; Wei, Fuwen
Inbreeding can have negative consequences on population and individual fitness, which could be counteracted by inbreeding avoidance mechanisms. However, the inbreeding risk and inbreeding avoidance mechanisms in endangered species are less studied. The giant panda, a solitary and threatened species, lives in many small populations and suffers from habitat fragmentation, which may aggravate the risk of inbreeding. Here, we performed long-term observations of reproductive behaviour, sampling of mother-cub pairs and large-scale genetic analyses on wild giant pandas. Moderate levels of inbreeding were found in 21.1% of mating pairs, 9.1% of parent pairs and 7.7% of panda cubs, but no high-level inbreeding occurred. More significant levels of inbreeding may be avoided passively by female-biased natal dispersal rather than by breeding dispersal or active relatedness-based mate choice mechanisms. The level of inbreeding in giant pandas is greater than expected for a solitary mammal and thus warrants concern for potential inbreeding depression, particularly in small populations isolated by continuing habitat fragmentation, which will reduce female dispersal and increase the risk of inbreeding. © 2017 John Wiley & Sons Ltd.
Malloure, B D; James, T Y
Many organisms display codispersal of offspring, but fewer display codispersal of compatible gametes. This mechanism enhances the ability of a species to colonize after long distance dispersal as a mechanism of reproductive assurance, but it also fosters inbreeding and potential reduction in fitness. Here we investigated both long distance dispersal and inbreeding in the bird's nest fungus Cyathus stercoreus, a dung and mulch-associated fungus with a splash cup fruiting body appearing like a miniature bird's nest of 'eggs' or peridioles that contain thousands of mating compatible meiotic spores. To investigate the genetic structure in the species, six North American urban populations were hierarchically sampled and genotyped using 10 microsatellite markers. We detected significant levels of inbreeding through heterozygote deficiencies at four loci, with global FIS=0.061. Dispersal limitation was suggested by both spatial autocorrelation and the detection of population structure between Louisiana and Michigan using clustering and F-statistics. Although inbreeding may facilitate colonization by the fungus, it has a negative effect on the fitness of populations as estimated from a 15% reduction in growth rates of inbred strains relative to outcrossed. Mating tests revealed that C. stercoreus has a higher estimated number of mating-type alleles (MAT-A= 39, MAT-B= 24) than other species of bird's nest fungi, which would increase its outcrossing efficiency. We speculate that the increased number of mating-type alleles is the result of a recent range and population size expansion into urban environments.
Full Text Available An assessment of reproductive behavior and inbreeding depression, if any, in critically endangered Eremostachys superba Royle ex Benth. (Labiatae was made to unveil the factors playing vital role in it’s reproductive biology and which may be responsible for the loss of fitness, viability and vigor of the species. Breeding experiments portrayed a failure of self-fertilization and a strong tendency towards out-breeding as seed set by xenogamy was highest (44.4%. However, the narrow restricted population of the type locality in Dehra Dun Siwaliks was just a ramet population sustained by clonal propagation of rhizomatous root stock, hence any out-crossing within these homozygous individuals also amounted to inbreeding. Further, there is no other population available within the range of normal seed dispersal mechanism or insect-pollinator-flight-range. The other populations reported are only from geographically distant region of Jammu and Kashmir state of India, which is too far a distance to be covered by the Nomia rustica West. and Ceratina heiroglyphica Sm., the oligophilic pollinators of E. superba, hence any crossing taking place also amounts to selfing in strict sense. Chances of induction of genetic variation by crossing between two different populations are remote. This was also supported by the data of seed production and germination experiments. Even the healthy seeds suffered from loss of fitness and failed to germinate under natural conditions. This strongly indicated prevalence of inbreeding depression and loss of fitness of the progeny right from the stage of germination, a phenomenon hazardous for sustenance and perpetuation of species leading to rarity.
Hauser, Thure Pavlo; Siegismund, H.R.
inbreeding depression, oubreeding effects, outcrossing, pollen fitness, selfing, Silene nutans, zygote survival......inbreeding depression, oubreeding effects, outcrossing, pollen fitness, selfing, Silene nutans, zygote survival...
Todd, Evelyn T; Ho, Simon Y W; Thomson, Peter C; Ang, Rachel A; Velie, Brandon D; Hamilton, Natasha A
The Thoroughbred horse has played an important role in both sporting and economic aspects of society since the establishment of the breed in the 1700s. The extensive pedigree and phenotypic information available for the Thoroughbred horse population provides a unique opportunity to examine the effects of 300 years of selective breeding on genetic load. By analysing the relationship between inbreeding and racing performance of 135,572 individuals, we found that selective breeding has not efficiently alleviated the Australian Thoroughbred population of its genetic load. However, we found evidence for purging in the population that might have improved racing performance over time. Over 80% of inbreeding in the contemporary population is accounted for by a small number of ancestors from the foundation of the breed. Inbreeding to these ancestors has variable effects on fitness, demonstrating that an understanding of the distribution of genetic load is important in improving the phenotypic value of a population in the future. Our findings hold value not only for Thoroughbred and other domestic breeds, but also for small and endangered populations where such comprehensive information is not available.
Costa e Silva, João; Potts, Brad M.; Lopez, Gustavo A.
Using native trees from near the northern and southern extremities of the relatively continuous eastern distribution of Eucalyptus globulus in Tasmania, we compared the progenies derived from natural open-pollination (OP) with those generated from within-region and long-distance outcrossing. Controlled outcrossing amongst eight parents - with four parents from each of the northern and southern regions - was undertaken using a diallel mating scheme. The progeny were planted in two field trials located within the species native range in southern Tasmania, and their survival and diameter growth were monitored over a 13-year-period. The survival and growth performances of all controlled cross types exceeded those of the OP progenies, consistent with inbreeding depression due to a combination of selfing and bi-parental inbreeding. The poorer survival of the northern regional (♀N♂N) outcrosses compared with the local southern regional outcrosses (♀S♂S) indicated differential selection against the former. Despite this mal-adaptation of the non-local ♀N♂N crosses at both southern sites, the survival of the inter-regional hybrids (♀N♂S and ♀S♂N) was never significantly different from that of the local ♀S♂S crosses. Significant site-dependent heterosis was detected for the growth of the surviving long-distance hybrids. This was expressed as mid-parent heterosis, particularly at the more northern planting site. Heterosis increased with age, while the difference between the regional ♀N♂N and ♀S♂S crosses remained insignificant at any age at either site. Nevertheless, the results for growth suggest that the fitness of individuals derived from long-distance crossing may be better at the more northern of the planting sites. Our results demonstrate the potential for early-age assessments of pollen dispersal to underestimate realised gene flow, with local inbreeding under natural open-pollination resulting in selection favouring the products of
João Costa E Silva
Full Text Available Using native trees from near the northern and southern extremities of the relatively continuous eastern distribution of Eucalyptus globulus in Tasmania, we compared the progenies derived from natural open-pollination (OP with those generated from within-region and long-distance outcrossing. Controlled outcrossing amongst eight parents - with four parents from each of the northern and southern regions - was undertaken using a diallel mating scheme. The progeny were planted in two field trials located within the species native range in southern Tasmania, and their survival and diameter growth were monitored over a 13-year-period. The survival and growth performances of all controlled cross types exceeded those of the OP progenies, consistent with inbreeding depression due to a combination of selfing and bi-parental inbreeding. The poorer survival of the northern regional (♀N♂N outcrosses compared with the local southern regional outcrosses (♀S♂S indicated differential selection against the former. Despite this mal-adaptation of the non-local ♀N♂N crosses at both southern sites, the survival of the inter-regional hybrids (♀N♂S and ♀S♂N was never significantly different from that of the local ♀S♂S crosses. Significant site-dependent heterosis was detected for the growth of the surviving long-distance hybrids. This was expressed as mid-parent heterosis, particularly at the more northern planting site. Heterosis increased with age, while the difference between the regional ♀N♂N and ♀S♂S crosses remained insignificant at any age at either site. Nevertheless, the results for growth suggest that the fitness of individuals derived from long-distance crossing may be better at the more northern of the planting sites. Our results demonstrate the potential for early-age assessments of pollen dispersal to underestimate realised gene flow, with local inbreeding under natural open-pollination resulting in selection favouring the
Kokko, Hanna; Ots, Indrek
Avoidance of incestuous matings is widely reported across many animal taxa, and the adaptive value of such behavior is explained through inbreeding depression. However, an old and somewhat neglected theoretical result predicts that inbred matings offer another, positive effect on the inclusive fitness of parents: an individual who mates with a relative will help that relative to spread genes identical by descent. This benefit can be substantial, if the additional mating achieved by the relative does not harm his mating success otherwise, and in the context of selfing in plants the phenomenon is well known. Here, we develop a model that derives expected values of inbreeding tolerance, that is, the magnitude of inbreeding depression that is required to make individuals avoid inbreeding, for different animal life histories and parental investment patterns. We also distinguish between simultaneous and sequential mate choice, and show that inbreeding tolerance should often be remarkably high in the latter scenario in particular, although egalitarian parental care will lead to lower tolerance. There is a mismatch between theory and data: the almost complete lack of cases where individuals prefer to mate incestuously is at odds with a large overlap between the predicted range of inbreeding tolerance and estimates of inbreeding depression found in nature. We discuss four different solutions to this enigma, and suggest that inbreeding tolerance, where it is found, should not always be attributed to a simple constraint that has prevented finding any other mate.
No significant inbreeding depression on body weight and fleece traits could be found. In general the results suggest that inbreeding at present is not a serious problem in the South African Dohne Merino breed. Keywords: Dohne Merino sheep; inbreeding depression. South African Journal of Animal Science Vol.
VANTREUREN, R; BIJLSMA, R; OUBORG, NJ; VANDELDEN, W
The effects of self-fertilization, within-population crosses (WPC) and between-population crosses (BPC) on progeny fitness were investigated in the greenhouse for Scabiosa columbaria populations of varying size. Plants grown from field collected seeds were hand pollinated to produce selfed, WPC, and
Van Etten, Megan L; Tate, Jennifer A; Anderson, Sandra H; Kelly, Dave; Ladley, Jenny J; Merrett, Merilyn F; Peterson, Paul G; Robertson, Alastair W
Interactions between species are especially sensitive to environmental changes. The interaction between plants and pollinators is of particular interest given the potential current global decline in pollinators. Reduced pollinator services can be compensated for in some plant species by self-pollination. However, if inbreeding depression is high, selfed progeny could die prior to reaching adulthood, leading to cryptic recruitment failure. To examine this scenario, pollinator abundance, pollen limitation, selfing rates and inbreeding depression were examined in 12 populations of varying disturbance levels in Sophora microphylla (Fabaceae), an endemic New Zealand tree species. High pollen limitation was found in all populations (average of 58 % reduction in seed production, nine populations), together with high selfing rates (61 % of offspring selfed, six populations) and high inbreeding depression (selfed offspring 86 % less fit, six populations). Pollen limitation was associated with lower visitation rates by the two endemic bird pollinators. The results suggest that for these populations, over half of the seeds produced are genetically doomed. This reduction in the fitness of progeny due to reduced pollinator service is probably important to population dynamics of other New Zealand species. More broadly, the results suggest that measures of seed production or seedling densities may be a gross overestimate of the effective offspring production. This could lead to cryptic recruitment failure, i.e. a decline in successful reproduction despite high progeny production. Given the global extent of pollinator declines, cryptic recruitment failure may be widespread. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: firstname.lastname@example.org.
Full Text Available Litter sizes in a cross between Brown and Black mink color types were observed through six generations. Litter size was significantly affected by yearly environmental variations. After adjusting for year effects, we found significant increases in litter size in the second and third generations (F2 and F3 after crossing. Thereafter, in the following generations, litter size dropped to a level comparable to the mean litter size of the midparent. Increased litter size in F2 compared to F1 indicated that maternal effects influenced litter size more than non-maternal effects. The heterosis was mainly caused by an increase in litter size compared to the Black parental line. This indicates that the Black line was affected by inbreeding depression prior to crossing. We also found that two-year old F1 females had significantly more offspring compared to one-year old F1 females.
Full Text Available Abstract We assessed the expected relationship between the level and the cost of inbreeding, measured either in terms of fitness, inbreeding depression or probability of extinction. First, we show that the assumption of frequent, slightly deleterious mutations do agree with observations and experiments, on the contrary to the assumption of few, moderately deleterious mutations. For the same inbreeding coefficient, populations can greatly differ in fitness according to the following: (i population size; larger populations show higher fitness (ii the history of population size; in a population that recovers after a bottleneck, higher inbreeding can lead to higher fitness and (iii population demography; population growth rate and carrying capacity determine the relationship between inbreeding and extinction. With regards to the relationship between inbreeding depression and inbreeding coefficient, the population size that minimizes inbreeding depression depends on the level of inbreeding: inbreeding depression can even decrease when population size increases. It is therefore clear that to infer the costs of inbreeding, one must know both the history of inbreeding (e.g. past bottlenecks and population demography.
Trinkel, Martina; Cooper, Dave; Packer, Craig; Slotow, Rob
Disease can dramatically influence the dynamics of endangered wildlife populations, especially when they are small and isolated, with increased risk of inbreeding. In Hluhluwe-iMfolozi Park (HiP), a small, enclosed reserve in South Africa, a large lion (Panthera leo) population arose from a small founder group in the 1960s and started showing conspicuous signs of inbreeding. To restore the health status of the HiP lion population, outbred lions were translocated into the existing population. In this study, we determined the susceptibility to bovine tuberculosis (bTB), and the prevalence of antibody to feline viruses of native lions, and compared the findings with those from translocated outbred lions and their offspring. Antibodies to feline herpesvirus, feline calicivirus, feline parvovirus, and feline coronavirus were present in the lion population, but there was no significant difference in antibody prevalence between native and translocated lions and their offspring, and these feline viruses did not appear to have an effect on the clinical health of HiP lions. However, feline immunodeficiency virus (FIV), which was previously absent from HiP, appears to have been introduced into the lion population through translocation. Within 7 yr, the prevalence of antibody to FIV increased up to 42%. Bovine tuberculosis posed a major threat to the inbred native lion population, but not to translocated lions and their offspring. More than 30% of the native lion population died from bTB or malnutrition compared with lions and their offspring. We have demonstrated that management of population genetics through supplementation can successfully combat a disease that threatens population persistence. However, great care must be taken not to introduce new diseases into populations through translocation.
Verweij, K.J.H.; Abdellaoui, A.; Veijola, J.; Sebert, S.; Koiranen, M.; Keller, M.C.; Jarvelin, M.R.; Zietsch, B.P.
Across animal species, offspring of closely related mates exhibit lower fitness, a phenomenon called inbreeding depression. Inbreeding depression in humans is less well understood because mating between close relatives is generally rare and stigmatised, confounding investigation of its effect on
Verweij, K.J.H.; Abdellaoui, A.; Veijola, J.; Sebert, S.; Koiranen, M.; Keller, M.C.; Järvelin, M.R.; Zietsch, B.P.
Across animal species, offspring of closely related mates exhibit lower fitness, a phenomenon called inbreeding depression. Inbreeding depression in humans is less well understood because mating between close relatives is generally rare and stigmatised, confounding investigation of its effect on
Vermeulen, Cornelis Joseph; Pedersen, Kamilla Sofie; Beck, Hans C
insight into the molecular interplay between intrinsic stress responses, inbreeding depression and temperature tolerance, we performed a proteomic characterization of a well-defined conditional inbreeding effect in a single line of Drosophila melanogaster, which suffers from extreme cold sensitivity...
Kristensen, Torsten Nygård; Knudsen, Morten Ravn; Loeschcke, Volker
Selection may reduce the deleterious consequences of inbreeding. This may be due to purging of recessive deleterious alleles or balancing selection favouring heterozygote offspring. Such selection is expected to be more efficient at slower compared to at faster rates of inbreeding. In this study ...
In the variety TKM6 a high yielding semidwarf mutant has been induced. This TKM6 mutant was used in test crosses with a number of other varieties and mutants to examine the extent of heterosis of dwarfs in rice and to select superior crosses. An excerpt of the published data is given. It appears from the backcross of the mutant with its original variety, that an increase in number of productive tillers occurs in the hybrid, leading to a striking grain yield increase, while the semi-dwarf culm length (the main mutant character) reverts to the normal phenotype. In the cross with IR8 on the other hand, there is only a minimal increase in tiller number but a substantial increase in TGW leading to more than 30% yield increase over the better parent
interaction of environment and inbreeding depression. (Bijlsma et al. 1999; Dahlgaard and Hoffmann 2000), and the effect of inbreeding on genetic and phenotypic variance (Lopez-Fanjul and Villaverde 1989; Fowler and. Whitlock 1999), have been under renewed examination. Parallel to this has been a renewed interest ...
Richardson, David S; Komdeur, Jan; Burke, Terry
The deleterious effects of inbreeding can be substantial in wild populations and mechanisms to avoid such matings have evolved in many organisms. In situations where social mate choice is restricted, extrapair paternity may be a strategy used by females to avoid inbreeding and increase offspring heterozygosity. In the cooperatively breeding Seychelles warbler, Acrocephalus sechellensis, neither social nor extrapair mate choice was used to avoid inbreeding facultatively, and close inbreeding occurred in approximately 5% of matings. However, a higher frequency of extra-group paternity may be selected for in female subordinates because this did reduce the frequency of mating between close relatives. Inbreeding resulted in reduced individual heterozygosity, which, against expectation, had an almost significant (P = 0.052), positive effect on survival. Conversely, low heterozygosity in the genetic mother was linked to reduced offspring survival, and the magnitude of this intergenerational inbreeding depression effect was environment-dependent. Because we controlled for genetic effects and most environmental effects (through the experimental cross-fostering of nestlings), we conclude that the reduced survival was a result of maternal effects. Our results show that inbreeding can have complicated effects even within a genetic bottlenecked population where the "purging" of recessive alleles is expected to reduce the effects of inbreeding depression.
Antonio Ismael Inácio Cardoso
Full Text Available The strategy for breeding F1 hybrid squash is to develop parental lines through self-pollination. However, it increases plant mean homozygosis, which is not the natural genetic state of a cross-pollinated species, and can cause "inbreeding depression". The objective of this work was to evaluate this depression with sucessive generations of self-pollination (without selection in Cucurbita moschata, cv. Piramoita. Populations were obtained from lines with one to four generations of self-pollination (obtained by the SSD method, from the original cv. Piramoita (population S0. Randomized blocks were used with five treatments (different generations of self-pollination - S0 to S4, six replicates and five plants per plot. Regression analysis was made by the Wright inbreeding coefficient (F to measure the homozygosis level effect on vigor loss. There was a linear reduction of mean weight and fruit length, seed production (number and weight per fruit with the increase of the homozygosis level; however inbreeding did not affect seed quality (weight of 100 seeds and germination.A estratégia utilizada no melhoramento genético visando híbridos F1 em abóbora é a obtenção de linhagens por autopolinização. Entretanto, a autopolinização aumenta a homozigose média das plantas, que não é a condição genética natural de espécies alógamas, e pode causar a "depressão por endogamia". Este trabalho teve como objetivo verificar se existe depressão por endogamia com sucessivas gerações de autofecundação (sem seleção em abóbora cultivar Piramoita. Foram obtidas populações a partir da mistura de linhagens com uma a quatro gerações de autofecundação (obtidas pelo método SSD, a partir da população original 'Piramoita' (S0. O delineamento experimental utilizado foi em blocos ao acaso com cinco tratamentos (diferentes gerações de autofecundação - S0 a S4, seis repetições e cinco plantas por parcela. Realizou-se análise de regress
Mikkelsen, Karina Aarup; Loeschcke, Volker; Kristensen, Torsten Nygaard
or 2 generations. These inbred lines were contrasted to non-inbred control lines. We investigated the effect of inbreeding and inbreeding rate in traits associated with fitness including heat, cold and desiccation stress resistance, egg-to-adult viability, development time, productivity, metabolic rate......The increased homozygosity due to inbreeding leads to expression of deleterious recessive alleles, which may cause inbreeding depression in small populations. The severity of inbreeding depression has been suggested to depend on the rate of inbreeding, with slower inbreeding being more effective...... and heat stress conditions. Reduced viability and increased developmental time were observed at stressful temperatures and inbreeding depression was on average more severe at stressful compared to benign temperatures...
Full Text Available In terms of sexual intercourse, the very last people we think about are our kin. Imagining inbreeding intercourse, whether it involves our closest kin or not, induces aversion in most people who invoke inbreeding depression problems or cultural considerations. Research has focused on the disgust felt when facing inbreeding intercourse between close kin but little is known about other responses. In this study, we considered the influence of fitness costs on aversive reactions by including disgust and emotional reaction as well as moral judgment and attitudes towards inbreeding: higher costs should induce a stronger aversive reaction. The fitness costs were manipulated by two factors: (i the degree of the participants’ involvement in the story (themselves, a sib or an unknown individual, and (ii the degree of relatedness between the two inbreeding people (brother/sister, uncle-aunt/niece-nephew, cousin. To test this hypothesis, 140 women read and assessed different inbreeding stories varying in the fitness costs incurred. Findings showed that the higher the fitness costs were, the greater the aversive reaction was in an overall way. First, our results fitted with previous studies that tested the influence of fitness costs on disgust. Second, and more interestingly, findings went further by examining overall aversion, showing that fitness costs could influence emotions felt as well as attitudes and behaviors towards inbreeding people. The higher the fitness costs were, the less inbreeding people were perceived as moral and the more they were considered as a nuisance. However, results regarding avoidance were more nuanced.
Lespiau, Florence; Kaminski, Gwenaël
In terms of sexual intercourse, the very last people we think about are our kin. Imagining inbreeding intercourse, whether it involves our closest kin or not, induces aversion in most people who invoke inbreeding depression problems or cultural considerations. Research has focused on the disgust felt when facing inbreeding intercourse between close kin but little is known about other responses. In this study, we considered the influence of fitness costs on aversive reactions by including disgust and emotional reaction as well as moral judgment and attitudes toward inbreeding: higher costs should induce a stronger aversive reaction. The fitness costs were manipulated by two factors: (i) the degree of the participants' involvement in the story (themselves, a sib or an unknown individual), and (ii) the degree of relatedness between the two inbreeding people (brother/sister, uncle-aunt/niece-nephew, cousin). To test this hypothesis, 140 women read and assessed different inbreeding stories varying in the fitness costs incurred. Findings showed that the higher the fitness costs were, the greater the aversive reaction was in an overall way. First, our results fitted with previous studies that tested the influence of fitness costs on disgust. Second, and more interestingly, findings went further by examining overall aversion, showing that fitness costs could influence emotions felt as well as attitudes and behaviors toward inbreeding people. The higher the fitness costs were, the less inbreeding people were perceived as moral and the more they were considered as a nuisance. However, results regarding avoidance were more nuanced.
Zhang, Qianqian; Calus, Mario P L; Guldbrandtsen, Bernt
Background: Levels of inbreeding in cattle populations have increased in the past due to the use of a limited number of bulls for artificial insemination. High levels of inbreeding lead to reduced genetic diversity and inbreeding depression. Various estimators based on different sources, e...
Bilde, T.; Maklakov, A.A.; Schilling, Nadia
decline in fecundity and hatching rates of eggs. This effect was mitigated by complete recovery in fecundity in the sib-nonsib treatment, whereas no rescue effect was detected in the hatching success of eggs. The rescue effect is best explained by post-mating discrimination against kin via differential...... male nonsibs; one male sib and one male nonsib. We assessed the effect of mating treatment on fecundity and hatching success of eggs after one and three generations of inbreeding. Inbreeding depression in F1 was not sufficient to detect inbreeding avoidance. In F3, inbreeding depression caused a major...
Tara N. Furstenau
Full Text Available Inbreeding in hermaphroditic plants can occur through two different mechanisms: biparental inbreeding, when a plant mates with a related individual, or self-fertilization, when a plant mates with itself. To avoid inbreeding, many hermaphroditic plants have evolved self-incompatibility (SI systems which prevent or limit self-fertilization. One particular SI system—homomorphic SI—can also reduce biparental inbreeding. Homomorphic SI is found in many angiosperm species, and it is often assumed that the additional benefit of reduced biparental inbreeding may be a factor in the success of this SI system. To test this assumption, we developed a spatially-explicit, individual-based simulation of plant populations that displayed three different types of homomorphic SI. We measured the total level of inbreeding avoidance by comparing each population to a self-compatible population (NSI, and we measured biparental inbreeding avoidance by comparing to a population of self-incompatible plants that were free to mate with any other individual (PSI. Because biparental inbreeding is more common when offspring dispersal is limited, we examined the levels of biparental inbreeding over a range of dispersal distances. We also tested whether the introduction of inbreeding depression affected the level of biparental inbreeding avoidance. We found that there was a statistically significant decrease in autozygosity in each of the homomorphic SI populations compared to the PSI population and, as expected, this was more pronounced when seed and pollen dispersal was limited. However, levels of homozygosity and inbreeding depression were not reduced. At low dispersal, homomorphic SI populations also suffered reduced female fecundity and had smaller census population sizes. Overall, our simulations showed that the homomorphic SI systems had little impact on the amount of biparental inbreeding in the population especially when compared to the overall reduction in
Bello-Bedoy, Rafael; Núñez-Farfán, Juan
Experiments show that inbred progenies are frequently more damaged by herbivores than outcrossed progenies, suggesting that selfing is costly when herbivores are present and can increase the magnitude of inbreeding depression in survival and reproductive components of fitness. The present study assesses whether inbreeding increases herbivory and estimates the magnitude of inbreeding depression on reproductive components of fitness in the annual plant Datura stramonium. Two experiments were performed under natural conditions of herbivory to assess the effect of inbreeding on plant damage in D. stramonium. In the first experiment, outcrossed progeny was generated using foreign pollen donors, whereas inbred progeny was produced by self-pollination. In both groups, survival, herbivore damage and reproductive components of fitness were measured. In the second experiment, inbred and outcrossed progenies were produced using only local pollen donors, and only damage by herbivores was measured. Despite yearly variation in damage caused by the same specialist herbivores, inbred progeny suffered consistently more damage than outcrossed progeny. There was a significant inbreeding depression for fruit number (delta = 0.3), seed number per fruit (delta = 0.19) and seed number per plant (delta = 0.43). Furthermore, significant genetic variation amongst families in the magnitude of inbreeding depression was observed. The results suggest that the plant's mating system modified the pattern of herbivory by specialist insects in D. stramonium. Inbred plants suffer not only from the genetic cost of low vigour but also from greater damage by herbivores. The mechanism by which inbreeding reduces plant resistance to herbivores remains unknown but is an interesting area for future research.
Bello-Bedoy, R; Núñez-Farfán, J
The ability of plants to respond to natural enemies might depend on the availability of genetic variation for the optimal phenotypic expression of defence. Selfing can affect the distribution of genetic variability of plant fitness, resistance and tolerance to herbivores and pathogens. The hypothesis of inbreeding depression influencing plant defence predicts that inbreeding would reduce resistance and tolerance to damage by natural enemies relative to outcrossing. In a field experiment entailing experimentally produced inbred and outcrossed progenies, we assessed the effects of one generation of selfing on Datura stramonium resistance and tolerance to three types of natural enemies, herbivores, weevils and a virus. We also examined the effect of damage on relative growth rate (RGR), flower, fruit, and seed production in inbred and outcrossed plants. Inbreeding significantly reduced plant defence to natural enemies with an increase of 4% in herbivore damage and 8% in viral infection. These results indicate inbreeding depression in total resistance. Herbivory increased 10% inbreeding depression in seed number, but viral damage caused inbred and outcrossed plants to have similar seed production. Inbreeding and outcrossing effects on fitness components were highly variable among families, implying that different types or numbers of recessive deleterious alleles segregate following inbreeding in D. stramonium. Although inbreeding did not equally alter all the interactions, our findings indicate that inbreeding reduced plant defence to herbivores and pathogens in D. stramonium. © 2010 The Authors. Journal of Evolutionary Biology © 2010 European Society For Evolutionary Biology.
Full Text Available Inbreeding is the mating of relatives that produce progeny having more homozygous alleles than non-inbred animals. Inbreeding increases numbers of recessive alleles, which is often associated with decreased performance known as inbreeding depression. The magnitude of inbreeding depression depends on the level of inbreeding in the animal. Level of inbreeding is expressed by the inbreeding coefficient. One breeding goal in livestock is uniform productivity while maintaining acceptable inbreeding levels, especially keeping inbreeding less than 20%. However, in closed herds without the introduction of new genetic sources high levels of inbreeding over time are unavoidable. One method that increases selection response and minimizes inbreeding is selection of individuals by weighting estimated breeding values with average relationships among individuals. Optimum genetic contribution theory (OGC uses relationships among individuals as weighting factors. The algorithm is as follows: i Identify the individual having the best EBV; ii Calculate average relationships ( r j ¯ between selected and candidates; iii Select the individual having the best EBV adjusted for average relationships using the weighting factor k, E B V * = E B V j ( 1 - k r j ¯ . iv Repeat process until the number of individuals selected equals number required. The objective of this study was to compare simulated results based on OGC selection under different conditions over 30 generations. Individuals (n = 110 were generated for the base population with pseudo random numbers of N~ (0, 3, ten were assumed male, and the remainder female. Each male was mated to ten females, and every female was assumed to have 5 progeny resulting in 500 individuals in the following generation. Results showed the OGC algorithm effectively controlled inbreeding and maintained consistent increases in selection response. Difference in breeding values between selection with OGC algorithm and by EBV only was 8
Bebbington, Kat; Spurgin, Lewis G.; Fairfield, Eleanor A.; Dugdale, Hannah L.; Komdeur, Jan; Burke, Terry; Richardson, David S.
Inbreeding results in more homozygous offspring that should suffer reduced fitness, but it can be difficult to quantify these costs for several reasons. First, inbreeding depression may vary with ecological or physiological stress and only be detectable over long time periods. Second, parental
Reid, Jane M; Arcese, Peter; Keller, Lukas F; Germain, Ryan R; Duthie, A Bradley; Losdat, Sylvain; Wolak, Matthew E; Nietlisbach, Pirmin
Extra-pair reproduction is widely hypothesized to allow females to avoid inbreeding with related socially paired males. Consequently, numerous field studies have tested the key predictions that extra-pair offspring are less inbred than females' alternative within-pair offspring, and that the probability of extra-pair reproduction increases with a female's relatedness to her socially paired male. However, such studies rarely measure inbreeding or relatedness sufficiently precisely to detect subtle effects, or consider biases stemming from failure to observe inbred offspring that die during early development. Analyses of multigenerational song sparrow (Melospiza melodia) pedigree data showed that most females had opportunity to increase or decrease the coefficient of inbreeding of their offspring through extra-pair reproduction with neighboring males. In practice, observed extra-pair offspring had lower inbreeding coefficients than females' within-pair offspring on average, while the probability of extra-pair reproduction increased substantially with the coefficient of kinship between a female and her socially paired male. However, simulations showed that such effects could simply reflect bias stemming from inbreeding depression in early offspring survival. The null hypothesis that extra-pair reproduction is random with respect to kinship therefore cannot be definitively rejected in song sparrows, and existing general evidence that females avoid inbreeding through extra-pair reproduction requires reevaluation given such biases. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.
Luijten, S.H.; Kery, M.; Oostermeijer, J.G.B.; den Nijs, J.C.M.
1. The genetic constitution of populations may significantly affect demography. Founder populations or isolated remnants may show inbreeding depression, while established populations can be strongly adapted to the local environment. Gene exchange between populations can lead to better performance if
Demontis, Ditte; Pertoldi, Cino; Loeschcke, Volker
over homozygous individuals by natural selection, either by associative over-dominance or balancing selection, or a combination of both. Furthermore, we found a significant polynomial correlation between genetic variance and wing size and shape in the fast inbred lines. This was caused by a greater......It is often hypothesized that slow inbreeding causes less inbreeding depression than fast inbreeding at the same absolute level of inbreeding. Possible explanations for this phenomenon include the more efficient purging of deleterious alleles and more efficient selection for heterozygote...... genetic variance than fast inbreeding. These results increase our understanding of the genetic basis of the common observation that slow inbred lines express less inbreeding depression than fast inbred lines. In addition, this has more general implications for the importance of selection in maintaining...
and the direction of heterosis for SOD, POX and CAT activ- ity; and identify promising parents and single cross-hybrids. (SCHs) having better inbuilt defense systems which could be used for breeding antioxidant-rich cabbage. Materials and methods. Sixteen cabbage genotypes (all inbreds) which included five female, viz.
Johnson, K.; Butts, I. A. E.; Smith, J. L.
The effects of inbreeding in both captive and wild‐caught species and populations have been reported to affect a wide variety of life history traits. Recently, the effects of inbreeding on reproductive traits such as sperm quality have become a subject of particular interest for conservation...... biology, evolutionary ecology, and management of captive populations. This study investigated the effects of inbreeding on sperm quality in a captive population of experimentally inbred and outbred lake trout, Salvelinus namaycush. It was found for moderately to highly inbred males (males with half......‐sib and full‐sib parents, respectively), that sperm quality traits (velocity, motility, linearity, longevity, spermatocrit and morphology) showed no apparent inbreeding depression. The apparent lack of inbreeding effects on sperm quality traits may be due to several factors including (i) no inbreeding...
Tavares, Orlanda; Cardoso, Sónia; Carvalho, Teresa; Sousa, Sofia Branco; Santiago, Rui
This paper analyses the inbreeding phenomena in Portuguese public universities. Inbreeding is defined as the recruitment of academics by the same institution that awarded their PhDs. Focusing on 1,217 PhD-holding Portuguese academics, belonging to four public universities and to six disciplinary areas, inbreeding is analysed in order to understand…
Nestler, R.B.; Nelson, A.L.
The effect of inbreeding in wildlife species has received attention from several sources. Recently the 'inbreeding theory' as a possible explanation of cycles in game populations was given careful consideration by a group of wildlife experts and geneticists. Scott's symposium (1944) consisting of comments received from eight authorities revealed unanimity in a decision that inbreeding is not the causative factor.
The extent of better parent heterosis for yield ranged from -31.14% (Dimtu x Tabor) to 114.1% (MAM-41 x Tabor). The maximum economic heterosis (60.58 %) was observed from the hybrid MAM-41 x Tabor .Significant (P<0.05 or P<0.01) better parent heterosis was also observed for yield-associated traits. Conclusions and ...
Cros, David; Denis, Marie; Bouvet, Jean-Marc; Sánchez, Leopoldo
To study the potential of genomic selection for heterosis resulting from multiplicative interactions between additive and antagonistic components, we focused on oil palm, where bunch production is the product of bunch weight and bunch number. We simulated two realistic breeding populations and compared current reciprocal recurrent selection (RRS) with reciprocal recurrent genomic selection (RRGS) over four generations. All breeding strategies aimed at selecting the best individuals in parental populations to increase bunch production in hybrids. For RRGS, we obtained the parental genomic estimated breeding values using GBLUP with hybrid phenotypes as data records and population specific allele models. We studied the effects of four RRGS parameters on selection response and genetic parameters: (1) the molecular data used to calibrate the GS model: in RRGS_PAR, we used parental genotypes and in RRGS_HYB we also used hybrid genotypes; (2) frequency of progeny tests (model calibration); (3) number of candidates and (4) number of genotyped hybrids in RRGS_HYB. We concluded that RRGS could increase the annual selection response compared to RRS by decreasing the generation interval and by increasing the selection intensity. With 1700 genotyped hybrids, calibration every four generations and 300 candidates per generation and population, selection response of RRGS_HYB was 71.8 % higher than RRS. RRGS_PAR with calibration every two generations and 300 candidates was a relevant alternative, as a good compromise between the annual response, risk around the expected response, increased inbreeding and cost. RRGS required inbreeding management because of a higher annual increase in inbreeding than RRS. RRGS appeared as a valuable method to achieve a long-term increase in the performance for a trait showing heterosis due to the multiplicative interaction between additive and negatively correlated components, such as oil palm bunch production.
Full Text Available Inbreeding depression has often been considered to be responsible for the deterioration of performance in aquaculture species. Despite a crucial impact that may result from inbreeding depression, comprehensive information reviewing this subject is limited. This study was aimed to gain information on the effect of inbreeding on the early performance of freshwater prawn. The study was performed by comparing performance of inbred and outbred populations. Inbred population was established by brother-sister mating (inbreeding rate of 25% while the outbred population was formed by mating unrelated individuals. Several fitness and productivity related traits including survival, the rate of larval development, stage dispersion and growth of larvae were evaluated. Results suggest that inbred families performed poorer than that of the outbred in survival. However, inbreeding depression did not seem to occur in other traits including the rate of larval development, larval stage dispersion and growth. This study implies that to maintain genetic quality of farmed prawn stocks, inbreeding rate in farmed population must be controlled not to exceed that level. Implications that these findings may have on aquaculture practices and possible alternatives for the solutions are discussed.
Full Text Available Abstract Background Inbreeding can slow population growth and elevate extinction risk. A small number of unrelated immigrants to an inbred population can substantially reduce inbreeding and improve fitness, but little attention has been paid to the sex-specific effects of immigrants on such "genetic rescue". We conducted two subsequent experiments to investigate demographic consequences of inbreeding and genetic rescue in guppies. Results Populations established from pairs of full siblings that were descended either from two generations of full-sibling inbreeding or unrelated outbred guppies did not grow at different rates initially, but when the first generation offspring started breeding, outbred-founded populations grew more slowly than inbred-founded populations. In a second experiment, adding two outbred males to the inbred populations resulted in significantly faster population growth than in control populations where no immigrants were added. Adding females resulted in growth at a rate intermediate to the control and male-immigrant treatments. Conclusion The slower growth of the outbred-founded than inbred-founded populations is the opposite of what would be expected under inbreeding depression unless many deleterious recessive alleles had already been selectively purged in the inbreeding that preceded the start of the experiment, and that significant inbreeding depression occurred when the first generation offspring in outbred-founded populations started to inbreed. The second experiment revealed strong inbreeding depression in the inbred founded populations, despite the apparent lack thereof in these populations earlier on. Moreover, the fact that the addition of male immigrants resulted in the highest levels of population growth suggests that sex-specific genetic rescue may occur in promiscuous species, with male rescue resulting in higher levels of outbreeding than female rescue.
Rantala, Markus J; Viitaniemi, Heidi; Roff, Derek A
Although numerous studies on vertebrates suggest that inbreeding reduces their resistance against parasites and pathogens, studies in insects have found contradictory evidence. In this study we tested the effect of 1 generation of brother-sister mating (inbreeding) on potential and realized immune responses and other life-history traits in Tenebrio molitor. We found that inbreeding reduced adult mass, pre-adult survival and increased development time, suggesting that inbreeding reduced the condition of the adults and thus potentially made them more susceptible to physiological stress. However, we found no significant effect of inbreeding on the potential immune response (encapsulation response), but inbreeding reduced the realized immune response (resistance against the entomopathogenic fungi, Beauveria bassiana). There was a significant family effect on encapsulation response, but no family effect on the resistance against the entomopathogenic fungi. Given that this latter trait showed significant inbreeding depression and that the sample size for the family-effect analysis was small it is likely that the lack of a significant family effect is due to reduced statistical power, rather than the lack of a heritable basis to the trait. Our study highlights the importance of using pathogens and parasites in immunoecological studies.
∗E-mail: email@example.com. mask the deleterious traits and the hybrids have a better performance than parents. In one of the researches on effect of quantitative trait loci. (QTL) to heterosis in rice Xiao et al. (1995) stated that dom- inance is the major genetic basis of heterosis, while in other researches Li et al.
Ujvari, Beata; Klaassen, Marcel; Raven, Nynke; Russell, Tracey; Vittecoq, Marion; Hamede, Rodrigo; Thomas, Frédéric; Madsen, Thomas
Genetic diversity is essential for adaptive capacities, providing organisms with the potential of successfully responding to intrinsic and extrinsic challenges. Although a clear reciprocal link between genetic diversity and resistance to parasites and pathogens has been established across taxa, the impact of loss of genetic diversity by inbreeding on the emergence and progression of non-communicable diseases, such as cancer, has been overlooked. Here we provide an overview of such associations and show that low genetic diversity and inbreeding associate with an increased risk of cancer in both humans and animals. Cancer being a multifaceted disease, loss of genetic diversity can directly (via accumulation of oncogenic homozygous mutations) and indirectly (via increased susceptibility to oncogenic pathogens) impact abnormal cell emergence and escape of immune surveillance. The observed link between reduced genetic diversity and cancer in wildlife may further imperil the long-term survival of numerous endangered species, highlighting the need to consider the impact of cancer in conservation biology. Finally, the somewhat incongruent data originating from human studies suggest that the association between genetic diversity and cancer development is multifactorial and may be tumour specific. Further studies are therefore crucial in order to elucidate the underpinnings of the interactions between genetic diversity, inbreeding and cancer. © 2018 The Author(s).
Vermeulen, Corneel J.; Bijlsma, R.; Loeschcke, Volker
of inbreeding-related and conditionally expressed lethality in Drosophila melanogaster. The lethal effect was triggered by exposure to a cold shock. We used a North Carolina crossing Design 3 to establish the mapping population, as well as to estimate the average dominance ratio and heritability. We found two......Inbreeding depression is a central theme within genetics, and is of specific interest for researchers within evolutionary and conservation genetics and animal and plant breeding. Inbreeding effects are thought to be caused by the joint expression of conditional and unconditional deleterious alleles....... Whenever the expression of deleterious alleles is conditional, this can result in extreme environmental sensitivity in certain inbred lineages. Analysis of conditional lethal effects can reveal some of the loci that are sensitive to inbreeding. We performed a QTL (quantitative trait locus) mapping study...
Bussiman, F O; Perez, B C; Ventura, R V; Peixoto, M G C D; Curi, R A; Balieiro, J C C
Genetic improvement, without control of inbreeding, can go to loss of genetic variability, reducing the potential for genetic gains in the domestic populations. The aim of this study was to analyze the population structure and the inbreeding depression in Campolina horses. Phenotype information from 43 465 individuals was analyzed, data provided by the Campolina Breeders Association. A pedigree file containing 107 951 horses was used to connected the phenotyped individuals. The inbreeding coefficient was performed by use of the diagonal of the relationship matrix and the genealogical parameters were computed using proper softwares. The effective population size was estimated based on the rate of inbreeding and census information, and the stratification of the population was verified by the average relationship coefficient between animals born in different regions of Brazil. The effects of inbreeding on morphological traits were made by the use of inbreeding coefficient as a covariate in the model of random regression. The inbreeding coefficient increased from 1990 on, impacting effective population size and, consequently, shrinking genetic variability. The paternal inbreeding was greater than maternal, which may be attributed to the preference for inbred animals in reproduction. The average genetic relationship coefficient of animals born in different states was lower than individuals born within the same state. The increase in the inbreeding coefficient was negatively associated with all studied traits, showing the importance to avoid genetic losses in the long term. Although results do not indicate a severe narrowing of the population until the present date, the average relationship coefficient shows signs of increase, which could cause a drastic reduction in genetic variability if inbred mating is not successfully controlled in the Campolina horse population.
R. McQuillan (Ruth); N. Eklund (Niina); N. Pirastu (Nicola); M. Kuningas (Maris); B.P. McEvoy (Brian); T. Esko (Tõnu); T. Corre (Tanguy); G. Davies (Gail); M. Kaakinen (Marika); L.-P. Lyytikäinen (Leo-Pekka); K. Kristiansson (Kati); A.S. Havulinna (Aki); M. Gögele (Martin); V. Vitart (Veronique); A. Tenesa (Albert); Y.S. Aulchenko (Yurii); C. Hayward (Caroline); A. Johansson (Åsa); M. Boban (Mladen); S. Ulivi (Shelia); A. Robino (Antonietta); V. Boraska (Vesna); W. Igl (Wilmar); S.H. Wild (Sarah); L. Zgaga (Lina); N. Amin (Najaf); E. Theodoratou (Evropi); O. Polasek (Ozren); S. Girotto; L.M. Lopez (Lorna); C. Sala (Cinzia); J. Lahti (Jari); T. Laatikainen (Tiina); I. Prokopenko (Inga); M. Kals (Mart); J. Viikari (Jorma); J. Yang (Joanna); A. Pouta (Anneli); K. Estrada Gil (Karol); A. Hofman (Albert); N.B. Freimer (Nelson); N.G. Martin (Nicholas); M. Kähönen (Mika); L. Milani (Lili); M. Heliovaara (Markku); E. Vartiainen (Erkki); K. Räikkönen (Katri); C. Masciullo (Corrado); J.M. Starr (John); A.A. Hicks (Andrew); L. Esposito (Laura); I. Kolcic (Ivana); S.M. Farrington (Susan); B.A. Oostra (Ben); T. Zemunik (Tatijana); H. Campbell (Harry); M. Kirin (Mirna); M. Pehlic (Marina); F. Faletra (Flavio); D.J. Porteous (David J.); G. Pistis (Giorgio); E. Widen (Elisabeth); V. Salomaa (Veikko); S. Koskinen (Seppo); K. Fischer (Krista); T. Lehtimäki (Terho); A.C. Heath (Andrew); M.I. McCarthy (Mark); F. Rivadeneira Ramirez (Fernando); G.W. Montgomery (Grant); H.W. Tiemeier (Henning); A.L. Hartikainen; P.A.F. Madden (Pamela); P. d' Adamo (Pio); N. Hastie (Nick); U. Gyllensten (Ulf); A.F. Wright (Alan); C.M. van Duijn (Cornelia); M.G. Dunlop (Malcolm); I. Rudan (Igor); P. Gasparini (Paolo); P.P. Pramstaller (Peter Paul); I.J. Deary (Ian); D. Toniolo (Daniela); K. Hagen (Knut); A. Jula (Antti); O. Raitakari (Olli); A. Metspalu (Andres); M. Perola (Markus); M.-R. Jarvelin (Marjo-Riitta); A.G. Uitterlinden (André); P.M. Visscher (Peter); J.F. Wilson (James)
textabstractStature is a classical and highly heritable complex trait, with 80%-90% of variation explained by genetic factors. In recent years, genome-wide association studies (GWAS) have successfully identified many common additive variants influencing human height; however, little attention has
Kristensen, Torsten N; Pedersen, Kamilla S; Vermeulen, Cornelis J
Developments in molecular and systems biology have enabled novel approaches to be used in the study of inbreeding. Mechanistic and functional studies using ‘omic' technologies can increase the understanding of the consequences of inbreeding, from the level of DNA to that of population growth...
Smallbone, Willow; van Oosterhout, Cock; Cable, Jo
Inbreeding can threaten population persistence by reducing disease resistance through the accelerated loss of gene diversity (i.e. heterozygosity). Such inbreeding depression can affect many different fitness-related traits, including survival, reproductive success, and parasite susceptibility. Empirically quantifying the effects of inbreeding on parasite resistance is therefore important for ex-situ conservation of vertebrates. The present study evaluates the disease susceptibility of individuals bred under three different breeding regimes (inbred, crossed with full siblings; control, randomly crossed mating; and fully outbred). Specifically, we examined the relationship between inbreeding coefficient (F-coefficient) and susceptibility to Gyrodactylus turnbulli infection in a live bearing vertebrate, the guppy Poecilia reticulata. Host-breeding regime significantly affected the trajectories of parasite population growth on individual fish. Inbred fish showed significantly higher mean parasite intensity than fish from the control and outbred breeding regimes, and in addition, inbred fish were slower in purging their gyrodactylid infections. We discuss the role of inbreeding on the various arms of the immune system, and argue that the increased disease susceptibility of inbred individuals could contribute to the extinction vortex. This is one of the first studies to quantify the effects of inbreeding and breeding regime on disease susceptibility in a captive bred vertebrate of wild origin, and it highlights the risks faced by small (captive-bred) populations when exposed to their native parasites. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.
Moreno, Eulalia; Pérez-González, Javier; Carranza, Juan; Moya-Laraño, Jordi
Captive breeding of endangered species often aims at preserving genetic diversity and to avoid the harmful effects of inbreeding. However, deleterious alleles causing inbreeding depression can be purged when inbreeding persists over several generations. Despite its great importance both for evolutionary biology and for captive breeding programmes, few studies have addressed whether and to which extent purging may occur. Here we undertake a longitudinal study with the largest captive population of Cuvier's gazelle managed under a European Endangered Species Programme since 1975. Previous results in this population have shown that highly inbred mothers tend to produce more daughters, and this fact was used in 2006 to reach a more appropriate sex-ratio in this polygynous species by changing the pairing strategy (i.e., pairing some inbred females instead of keeping them as surplus individuals in the population). Here, by using studbook data we explore whether purging has occurred in the population by investigating whether after the change in pairing strategy a) inbreeding and homozygosity increased at the population level, b) fitness (survival) increased, and c) the relationship between inbreeding and juvenile survival, was positive. Consistent with the existence of purging, we found an increase in inbreeding coefficients, homozygosity and juvenile survival. In addition, we showed that in the course of the breeding programme the relationship between inbreeding and juvenile survival was not uniform but rather changed over time: it was negative in the early years, flat in the middle years and positive after the change in pairing strategy. We highlight that by allowing inbred individuals to mate in captive stocks we may favour sex-ratio bias towards females, a desirable managing strategy to reduce the surplus of males that force most zoos to use ethical culling and euthanizing management tools. We discuss these possibilities but also acknowledge that many other effects
Full Text Available Captive breeding of endangered species often aims at preserving genetic diversity and to avoid the harmful effects of inbreeding. However, deleterious alleles causing inbreeding depression can be purged when inbreeding persists over several generations. Despite its great importance both for evolutionary biology and for captive breeding programmes, few studies have addressed whether and to which extent purging may occur. Here we undertake a longitudinal study with the largest captive population of Cuvier's gazelle managed under a European Endangered Species Programme since 1975. Previous results in this population have shown that highly inbred mothers tend to produce more daughters, and this fact was used in 2006 to reach a more appropriate sex-ratio in this polygynous species by changing the pairing strategy (i.e., pairing some inbred females instead of keeping them as surplus individuals in the population. Here, by using studbook data we explore whether purging has occurred in the population by investigating whether after the change in pairing strategy a inbreeding and homozygosity increased at the population level, b fitness (survival increased, and c the relationship between inbreeding and juvenile survival, was positive. Consistent with the existence of purging, we found an increase in inbreeding coefficients, homozygosity and juvenile survival. In addition, we showed that in the course of the breeding programme the relationship between inbreeding and juvenile survival was not uniform but rather changed over time: it was negative in the early years, flat in the middle years and positive after the change in pairing strategy. We highlight that by allowing inbred individuals to mate in captive stocks we may favour sex-ratio bias towards females, a desirable managing strategy to reduce the surplus of males that force most zoos to use ethical culling and euthanizing management tools. We discuss these possibilities but also acknowledge that many
Yang, Mei; Wang, Xuncheng; Ren, Diqiu; Huang, Hao; Xu, Miqi; He, Guangming; Deng, Xing Wang
Heterosis is most frequently manifested by the substantially increased vigorous growth of hybrids compared with their parents. Investigating genomic variations in natural populations is essential to understand the initial molecular mechanisms underlying heterosis in plants. Here, we characterized the genomic architecture associated with biomass heterosis in 200 Arabidopsis hybrids. The genome-wide heterozygosity of hybrids makes a limited contribution to biomass heterosis, and no locus shows an obvious overdominance effect in hybrids. However, the accumulation of significant genetic loci identified in genome-wide association studies (GWAS) in hybrids strongly correlates with better-parent heterosis (BPH). Candidate genes for biomass BPH fall into diverse biological functions, including cellular, metabolic, and developmental processes and stimulus-responsive pathways. Important heterosis candidates include WUSCHEL , ARGOS , and some genes that encode key factors involved in cell cycle regulation. Interestingly, transcriptomic analyses in representative Arabidopsis hybrid combinations reveal that heterosis candidate genes are functionally enriched in stimulus-responsive pathways, including responses to biotic and abiotic stimuli and immune responses. In addition, stimulus-responsive genes are repressed to low-parent levels in hybrids with high BPH, whereas middle-parent expression patterns are exhibited in hybrids with no BPH. Our study reveals a genomic architecture for understanding the molecular mechanisms of biomass heterosis in Arabidopsis , in which the accumulation of the superior alleles of genes involved in metabolic and cellular processes improve the development and growth of hybrids, whereas the overall repressed expression of stimulus-responsive genes prioritizes growth over responding to environmental stimuli in hybrids under normal conditions.
Kristensen, Torsten Nygård; Barker, J. Stuart F.; Pedersen, Kamilla Sofie
The majority of experimental studies of the effects of population bottlenecks on fitness are performed under laboratory conditions, which do not account for the environmental complexity that populations face in nature. In this study, we test inbreeding depression in multiple replicates of inbred ...
Karin J H Verweij
Full Text Available Across animal species, offspring of closely related mates exhibit lower fitness, a phenomenon called inbreeding depression. Inbreeding depression in humans is less well understood because mating between close relatives is generally rare and stigmatised, confounding investigation of its effect on fitness-relevant traits. Recently, the availability of high-density genotype data has enabled quantification of variation in distant inbreeding in 'outbred' human populations, but the low variance of inbreeding detected from genetic data in most outbred populations means large samples are required to test effects, and only a few traits have yet been studied. However, it is likely that isolated populations, or those with a small effective population size, have higher variation in inbreeding and therefore require smaller sample sizes to detect inbreeding effects. With a small effective population size and low immigration, Northern Finland is such a population. We make use of a sample of ∼5,500 'unrelated' individuals in the Northern Finnish Birth Cohort 1966 with known genotypes and measured phenotypes across a range of fitness-relevant physical and psychological traits, including birth length and adult height, body mass index (BMI, waist-to-hip ratio, blood pressure, heart rate, grip strength, educational attainment, income, marital status, handedness, health, and schizotypal features. We find significant associations in the predicted direction between individuals' inbreeding coefficient (measured by proportion of the genome in runs of homozygosity and eight of the 18 traits investigated, significantly more than the one or two expected by chance. These results are consistent with inbreeding depression effects on a range of human traits, but further research is needed to replicate and test alternative explanations for these effects.
Silva Ricardo Machado da
Full Text Available The phenomenon of heterosis has been exploited extensively in maize (Zea mays L. breeding. The objective of this study was to evaluate the genetic potential of ten maize populations for ear yield following the diallel mating scheme. Six parental populations were obtained through phenotypic selection of open-pollinated ears in Rio Verde, GO, Brazil, (GO populations and four parental populations were synthesized in Piracicaba, SP, Brazil (GN populations: GO-D (DENTADO, GO- F (FLINT, GO-A (AMARELO, GO-B (BRANCO, GO-L (LONGO, GO-G (GROSSO, GN-01, GN-02, GN-03 and GN-04. Experiments were carried out in three environments: Anhembi (SP and Rio Verde (GO in 1998/99 (normal season crop and Piracicaba (SP in 1999 (off-season crop. All experiments were in completely randomized blocks with six replications. Analysis of variance grouped over environments showed high significance for heterosis and its components, although mid-parent heterosis and average heterosis were of low expression. The interaction treatments x environments was not significant. Total mid-parent heterosis effects ranged from de -4.3% to 17.3% with an average heterosis of 3.37%. Population with the highest yield (7.4 t ha-1 and with the highest effect of population (v i = 0.746 was GN-03, while the highest yielding cross was GO-B x GN-03 with 7,567 t ha-1. The highest specific heterosis effect (s ii' = 0.547 was observed in the cross GO-B x GN-03.
Jensen, Palle; Overgaard, Johannes; Loeschcke, Volker; Schou, Mads Fristrup; Malte, Hans; Kristensen, Torsten Nygaard
Inbreeding increases homozygosity, which is known to affect the mean and variance of fitness components such as growth, fecundity and mortality rate. Across inbred lines inbreeding depression is typically observed and the variance between lines is increased in inbred compared to outbred lines. It has been suggested that damage incurred from increased homozygosity entails energetic cost associated with cellular repair. However, little is known about the effects of inbreeding on standard metabolic rate. Using stop-flow respirometry we performed repeated measurements of metabolic rate in replicated lines of inbred and outbred Drosophila melanogaster at stressful low, benign and stressful high temperatures. The lowest measurements of metabolic rate in our study are always associated with the low activity period of the diurnal cycle and these measurements therefore serve as good estimates of standard metabolic rate. Due to the potentially added costs of genetic stress in inbred lines we hypothesized that inbred individuals have increased metabolic rate compared to outbred controls and that this is more pronounced at stressful temperatures due to synergistic inbreeding by environment interactions. Contrary to our hypothesis we found no significant difference in metabolic rate between inbred and outbred lines and no interaction between inbreeding and temperature. Inbreeding however effected the variance; the variance in metabolic rate was higher between the inbred lines compared to the outbred control lines with some inbred lines having very high or low standard metabolic rate. Thus genetic drift and not inbreeding per se seem to explain variation in metabolic rate in populations of different size. Copyright © 2014 Elsevier Ltd. All rights reserved.
This report discusses the clonal planting stock offers many advantages to the forest products industry. Advanced-generation breeding strategies should be designed to maximize within-family variance and at the same time allow the capture of heterosis. Certainly there may be a conflict in the choice of breeding strategy based on the trait of interest. It may be that the majority of the traits express heterosis due to overdominance. Alternatively, disease resistance is expressed as the lack of a specific metabolite or infection court then the homozygous recessive genotype may be the most desirable. Nonetheless, as the forest products industry begins to utilize the economic advantages of clonal forestry, breeding strategies will have to be optimized for these commercial plant materials. Here, molecular markers can be used to characterize the nature of heterosis and therefore define the appropriate breeding strategy.
Zhu, Chen; Zhang, Xiaohui; Zhao, Qiran; Chen, Qihui
In genetics, heterosis refers to the phenomenon that cross-breeding within species leads to offspring that are genetically fitter than their parents and exhibit improved phenotypic characteristics. Based on the theory of heterosis and existing genetic evidence, offspring of "hybrid" marriages (spouses originating from different states/provinces/countries/areas), though relatively rare due to physical boundaries, may exhibit greater genetic fitness in terms of intelligence, height, or physical attractiveness (the "distance-performance" hypothesis). This study explores whether heterosis is a contributing factor to offspring's educational attainment in China by applying a high-dimensional fixed effects (HDFE) modelling framework to the unique 0.1% micro-sample of the 2000 Chinese Population Census data. Concerning potential endogeneity of hybrid marriages, we conduct a series of robustness checks. Reassuringly, the estimated heterosis effect remains significantly positive across various measurements, after controlling for parental educational attainments/height, environmental influences, and over a thousand region and region-by-year fixed effects. The effects in male and higher-educated offspring are found to be stronger. Results are replicated when analyzing body height using data from the China Health and Nutrition Survey. Although endogeneity of "hybrid marriages" may not be completely ruled out, the current study sheds light on the potentially beneficial effects of interprovincial migration on population-level human capital accumulation, and we hope that this paper can intrigue future studies that further address endogeneity. The implied heterosis effect could, therefore, be profound for Homo sapiens as a species from an evolutionary point of view. An additional important implication is that the overall genetic influences of parents on offspring's performance may be further decomposed into a conventional heredity effect and a heterosis effect that has been
Cornelis J Vermeulen
Full Text Available Inbreeding depression is a widespread phenomenon of central importance to agriculture, medicine, conservation biology and evolutionary biology. Although the population genetic principles of inbreeding depression are well understood, we know little about its functional genomic causes. To provide insight into the molecular interplay between intrinsic stress responses, inbreeding depression and temperature tolerance, we performed a proteomic characterization of a well-defined conditional inbreeding effect in a single line of Drosophila melanogaster, which suffers from extreme cold sensitivity and lethality. We identified 48 differentially expressed proteins in a conditional lethal line as compared to two control lines. These proteins were enriched for proteins involved in hexose metabolism, in particular pyruvate metabolism, and many were found to be associated with lipid particles. These processes can be linked to known cold tolerance mechanisms, such as the production of cryoprotectants, membrane remodeling and the build-up of energy reserves. We checked mRNA-expression of seven genes with large differential protein expression. Although protein expression poorly correlated with gene expression, we found a single gene (CG18067 that, after cold shock, was upregulated in the conditional lethal line both at the mRNA and protein level. Expression of CG18067 also increased in control flies after cold shock, and has previously been linked to cold exposure and chill coma recovery time. Many differentially expressed proteins in our study appear to be involved in cold tolerance in non-inbred individuals. This suggest the conditional inbreeding effect to be caused by misregulation of physiological cold tolerance mechanisms.
and serious genetic variation in the population. Inbreeding depression was observed for survival trait although the levels of inbreeding coefficient were acceptable in all of the breeds investigated in this study. Therefore, the general policy in the flocks should be continued to avoid mating between close relative parents and use of enough sires and dams selected per annum. Estimated inbreeding coefficients for Baluchi and Iranblack breeds showed high degree of close mating in these herd and due to the significant effect of inbreeding on survival, it is suggested that this breeding stations should use a breeding plan to avoid mating of close relative animals.
Validación de un método de selección para rendimiento en alfalfa basado en la depresión por endocría Validation of a selection technique for improving alfalfa forage yield based on inbreeding depression
Full Text Available La rápida depresión por endocría en alfalfa obedece a la pérdida de interacciones alélicas intra-locus en plantas tri y tetraalélicas. Éstas podrían identificarse por una prueba de autofecundación y luego combinarse en una variedad sintética con mayor rendimiento forrajero. El objetivo de este trabajo fue evaluar la utilidad de la prueba de progenie S1 para identificar genotipos tri y tetraalélicos. Se desarrollaron tres poblaciones sintéticas experimentales (PSE de alfalfa según tres métodos de selección, partiendo de una población original (PO. El primero, seleccionando las plantas madres que presentaron mayor depresión por endocría (≥65% en el rendimiento de sus progenies S1; el segundo, seleccionando las plantas de la PO que no formaron semilla S1; el último consistió en la selección fenotípica tradicional de las plantas de la PO con mayores rendimientos (15% superior. Las seleccionadas fueron polinizadas y cosechadas manualmente, conformando las PSE 1, 2 y 3, respectivamente. Se evaluó la producción de forraje acumulada de cada PSE y PO durante la temporada. Todas las PSE superaron (pRapid inbreeding depression in alfalfa is due to loss of intraallelic interactions in tri- and tetraallelic plants. These plants could be identified by using a S1 progeny test and then combined into a higher yielding synthetic variety. The objective of this study was to evaluate the usefulness of S1 progeny test to identify tri and tetraallelic genotypes. Three alfalfa synthetic experimental populations (PSE were developed by applying three selection methods to an original plant population (PO. The first one, selected those plants whose S1 progenies exhibited higher inbreeding depression (≥65% on forage production; the second one, selected the plants of the PO that did not produce S1 seed; the last one, consisted on traditional phenotypic selection of PO plants with higher forage yield (15% superior. The elite were manually
The eff'ect of migration on inbreeding is moclelled fbr small populations with immigrants from a large unrelated population. Different migration rates and numbers fbr the two sexes are assumed, and a general recursion equation for inbreeding progress derived, which can be shown to lead to an equilibrium inbreeding ...
Aug 26, 2016 ... My results indicate that levels of inbreeding in parasites are impacted by demographic and/or transmission dynamics (subdivided mating, aggregated transmission dynamics and host spatial structure), and that this inbreeding is poorly estimated by 'equilibrium' levels of inbreeding calculated assuming ...
Jul 5, 2010 ... heterosis; LSD, least significant difference; CV, co-variance. million hectares of with a total ... The North West Frontier Province of the country shared an area of .... Table 1. Mean squares for flowers per cluster, fruits per cluster, fruit length, fruit width, fruit weight and yield per plant of tomato during 2008.
Ramesh K. Singh
Mar 6, 2018 ... inheritance for horticultural traits and ToLCV resistance in tomato. RAMESH K. ... Therefore, the aim of this study was to see the diversity between the interspecific crosses and effect of heterosis, and inheritance for the morphological ...... indicated their similar genetic characters or dominant tax- onomical ...
Nov 30, 2013 ... ABSTRACT. Objective: A study to estimate better parent and economic heterosis in an 8x8 diallel crosses of common beans. (Phaseolus Vulgaris L.) was undertaken at Mandura, North Western Ethiopia. Methodology and Results: Eight parents and their 28 F1 diallel crosses were grown in a randomized ...
Standard heterosis of the crop parameters ranged from -8.22% for harvest index to 191.57% for number of pods per plant, while for seed yield per plant it ranged from -16.64 to 66.09%. Both additive and non additive gene actions were important in controlling days to 50% flowering, pod length, percent oil content, plant ...
For coffee quality parameters, the effect of parents' leaf tip color on the magnitude of heterosis was observed to be more important than the parents' geographical origin. Five out of six hybrids having both parents green leaf tip color (Kaffa x Kaffa and Kaffa x Sidamo) exhibited SH of 1 to 16% for the overall coffee quality.
May 3, 2012 ... Heterosis or hybrid vigor can play a vital role in increasing the yield quality of pumpkin. It refers to the phenomenon in which F1 hybrid obtained by crossing of two genetically dissimilar inbred lines or genotypes, shows increased or decreased vigor over the better parent or mid parent value . In cucurbits,.
A study was conducted on heterosis, combining ability and genetic parameters of yield and yield components in rice. Five lines were crossed with two testers in line × tester manner to produce ten F1 hybrids. Results show that general combining ability (GCA) effect was only significant for total number of kernels per panicle, ...
A crossbreeding experiment using Cameroon indigenous (CF) and German Dahlem Red (GR) chickens was undertaken to determine production performance and heterosis estimates of body weight of cockerels and laying hens at various ages and and egg production traits in layers. Four genetic groups were involved, ...
A study was conducted to estimate heterosis of six (6) tomato genotypes involving two parents at the experimental field of Horticulture division of CSIR - Crops Research Institute, Kumasi during the rainy season of 2014-2015. Analysis of variance showed significant differences among genotypes for all the traits revealing the ...
1970-01-01Solanum verrucosum (2n = 24) is a self-compatible, highly fertile species. This conclusion is drawn from the results of studies on 21 various introductions of this species. In spite of self-compatibility and good male and female fertility, the species generally needs a pollinating agent to
Ginn, B R
Identifying the physical basis of heterosis (or "hybrid vigor") has remained elusive despite over a hundred years of research on the subject. The three main theories of heterosis are dominance theory, overdominance theory, and epistasis theory. Kacser and Burns (1981) identified the molecular basis of dominance, which has greatly enhanced our understanding of its importance to heterosis. This paper aims to explain how overdominance, and some features of epistasis, can similarly emerge from the molecular dynamics of proteins. Possessing multiple alleles at a gene locus results in the synthesis of different allozymes at reduced concentrations. This in turn reduces the rate at which each allozyme forms soluble oligomers, which are toxic and must be degraded, because allozymes co-aggregate at low efficiencies. The model developed in this paper can explain how heterozygosity impacts the metabolic efficiency of an organism. It can also explain why the viabilities of some inbred lines seem to decline rapidly at high inbreeding coefficients (F > 0.5), which may provide a physical basis for truncation selection for heterozygosity. Finally, the model has implications for the ploidy level of organisms. It can explain why polyploids are frequently found in environments where severe physical stresses promote the formation of soluble oligomers. The model can also explain why complex organisms, which need to synthesize aggregation-prone proteins that contain intrinsically unstructured regions (IURs) and multiple domains because they facilitate complex protein interaction networks (PINs), tend to be diploid while haploidy tends to be restricted to relatively simple organisms. Copyright © 2017 Elsevier Ltd. All rights reserved.
PAMELA S., SOLTIS; DOUGLAS E., SOLTIS; Department of Botany, Washington State University; Department of Botany, Washington State University
Mating systems of 18 species of homosporous ferns follow a bimodal distribution, similar to that observed for seed plants (Schemske and Lande, 1985). Most species are highly outcrossing, a few are inbreeding, and two species examined to date have mixed mating systems. Equisetum arvense and several species of lycopods are also highly outcrossing. Several mechanisms, including inbreeding depression, antheridiogen, and ontogenetic sequences that result in effectively unisexual gametophytes, prom...
Daetwyler, H.D.; Villanueva, B.; Bijma, P.; Woolliams, J.A.
Traditional selection methods, such as sib and best linear unbiased prediction (BLUP) selection, which increased genetic gain by increasing accuracy of evaluation have also led to an increased rate of inbreeding per generation (¿FG). This is not necessarily the case with genome-wide selection, which
Lieshout, Emile; Tomkins, Joseph L; Simmons, Leigh W
Environmental and genetic stress have well-known detrimental effects on ejaculate quality, but their concomitant effect on male fitness remains poorly understood. We used competitive fertilization assays to expose the effects of stress on offensive sperm competitive ability in the beetle Callosobruchus maculatus, a species where ejaculates make up more than 5% of male body mass. To examine the effects of environmental and genetic stress, males derived from outcrosses or sib matings were heat shocked at 50°C for 50 min during the pupal stage, while their siblings were maintained at a standard rearing temperature of 28°C. Heat-shocked males achieved only half the offensive paternity success of their siblings. While this population exhibited inbreeding depression in body size, sperm competitiveness was unaffected by inbreeding, nor did the effect of heat shock stress on sperm competitiveness depend on inbreeding status. In contrast, pupal emergence success was increased by 34% among heat-stressed individuals, regardless of their inbreeding status. Heat-shocked males' ejaculate size was 19% reduced, but they exhibited 25% increased mating duration in single mating trials. Our results highlight both the importance of stress in postcopulatory sexual selection, and the variability among stressors in affecting male fitness.
Wu Lianrong; Li Zhengchao; Qiu Qingshu
Six peanut varieties with special testa color were arranged in pairs of 10 cross combinations, and 3 agronomic characters and 7 yield characters were tested for their heterosis. The results showed that the main stem height had the most powerful heterosis among tested agronomic characters. Among yield characters, the synthetic characters--pod yield per plant and seed yield per plant had better heterosis, each has 8 combinations showed over-parent heterosis with ranges of 7.1%-73.4% and 12.1%-71.5%, respectively. The heterosis among combinations also has significant difference. In all characters except the No. of filled pods per plant, the tested white variety has more powerful heterosis than red variety when they were used as female parent
Full Text Available The main goal of hybrid wheat breeding is the identification of parents with high specific combining ability for grain yield and other agronomic traits. This kind of data facilitate the development of hybrid combinations with high level of heterosis in first filial generation (F1 generation. The use of species from the hexaploid wheat group (e.g. Triticum spelta L. Triticum compactum HOST... is representing an opportunity for the increase of heterosis level in the germplasm of common wheat (Triticum aestivum L.. The study of combining ability and heterosis effect in hexaploid wheat group was carried out using crosses between thirteen inbred lines of common wheat (6 lines x 7 testers and inter-species crosses (T. aestivum L. × T. spelta L., T. aestivum L. × T. compactum HOST, T. aestivum L. × T. sphaerococcum PERCIV., T. aestivum L. × T. macha DEKAPR. et MENABDE, T. aestivum L. × T. petropavlovskyi UDACZ. et MIGUSCH, T. aestivum L. × T. vavilovii (THUM. JAKUBZ.. The 42 common wheat F1 hybrids were tested during two seasons (2010/11 and 2011/12 on the Selection center Ptuj. The experiment was carried out in a randomized block design with four replications. The 43 interspecies F1 hybrids were tested on the same location in the season 2011/12 and the experiment was designed as an randomized block with three replications. The results were analyzed using statistical package AGROBASE generation II and STATGRAPHICS Centurion XVI. The analysis of variance was significant for both, GCA and SCA variances (P < 0,01. Generally, SCA variances were lower than GCA variances. We could state, that the improvement of heterosis level in the common wheat germplasm through the use of relatives with the same genome (genome BAD is possible. As an example we can point out the interspecies F1 hybrid between common wheat variety Garcia and an accession of the Triticum sphaerococcum PERCIV. species (accession number 01C0201227.
The combined heterotic effects were negative for Hen Day Production (HDP), Feed efficiency (FEf), Age at Sexual Maturity (ASM), and mortality from day old to 21 weeks of age (-0.16, -4.33, -9.15 and -67.74% respectively). Positive but low heterosis was obtained for BWF (0.76), and EW (11.28) and WG, FEf, EN, ASM, HDP ...
Assunção,Aracelle; Brasil,Edward Madureira; Oliveira,Jaison Pereira de; Reis,Américo José dos Santos; Pereira,André Ferreira; Bueno,Luíce Gomes; Ramos,Michelle Ribeiro
Heterosis and its components were evaluated in a diallel crossing system of sweet corn. In the 38 treatments, eigth parents, 28 hybrids and two controls were used, arranged in a randomized block design with three replications.The diallel analysis followed the methodology of Gardner and Eberhart (1966). The following traits were evaluated: male and female flowering, plant and ear height, ear index (number of ears/number of plants), ºBrix, total ear weight, standard ear weight, industrial yield...
Penny A Becker
Full Text Available The conservation of many fragmented and small populations of endangered African wild dogs (Lycaon pictus relies on understanding the natural processes affecting genetic diversity, demographics, and future viability. We used extensive behavioural, life-history, and genetic data from reintroduced African wild dogs in South Africa to (1 test for inbreeding avoidance via mate selection and (2 model the potential consequences of avoidance on population persistence. Results suggested that wild dogs avoided mating with kin. Inbreeding was rare in natal packs, after reproductive vacancies, and between sibling cohorts (observed on 0.8%, 12.5%, and 3.8% of occasions, respectively. Only one of the six (16.7% breeding pairs confirmed as third-order (or closer kin consisted of animals that were familiar with each other, while no other paired individuals had any prior association. Computer-simulated populations allowed to experience inbreeding had only a 1.6% probability of extinction within 100 years, whereas all populations avoiding incestuous matings became extinct due to the absence of unrelated mates. Populations that avoided mating with first-order relatives became extinct after 63 years compared with persistence of 37 and 19 years for those also prevented from second-order and third-order matings, respectively. Although stronger inbreeding avoidance maintains significantly more genetic variation, our results demonstrate the potentially severe demographic impacts of reduced numbers of suitable mates on the future viability of small, isolated wild dog populations. The rapid rate of population decline suggests that extinction may occur before inbreeding depression is observed.
Full Text Available Genetic improvement through selective breeding relies on the genetically-controlled phenotypic variability in the character of interest. Therefore, the extent of phenotypic variability in the population to be selected is an important parameter, as it potentially influences the population’s response to selection. This study was aimed to investigate the effect of inbreeding on the survivability, growth, and phenotypic variability of giant freshwater prawn (GFP, Macrobrachium rosenbergii. Two GFP populations of different inbreeding levels, namely 25% and 0%, respectively, were formed by mating of individual broodstock with known pedigree. Study was conducted for two months starting from newly hatched larvae up to nursery stage (30 day-old post larva. Phenotypic variability profile, expressed in the morphometric mean and coefficient of variation (CV of twenty one morphometric characters were measured and evaluated. Results showed that in general, the inbred populations had lower values in the mean of all characters (100%, indicating that they suffered from inbreeding depression. Similarly, a lower CV values were observed in sixteen (75% of the morphometric characters measured, indicating a potential reduced of genetic gain when they are used in selective breeding program. These results suggest the importance of controlling inbreeding level in breeding population that adverse effects resulted resulted from inbreeding can be minimized.
Sidharth Prasad Mishra
Full Text Available A study was carried out on the captive tigers of Nandankanan zoo, Odisha, India, to conclude any deleterious effect of inbreeding on mortality. A pedigree path analysis of 342 tigers was done to estimate the inbreeding coefficient of each tiger from the available pedigree information since the inception of zoological park in 1964. Percentage of animal with different range of inbreeding coefficient was classified based on their normal and white body coat colour. The correlation values between sex, colour and inbreeding coefficient with mortality were also estimated. The colour and inbreeding coefficient was found to be significantly (p<0.05 correlated with the mortality. The inbreeding was found to be significant (p<0.05 with white colour of tiger.
Although heterosis is well established in grain and forage sorghum [Sorghum bicolor (L.) Moench], reports of heterosis in sweet sorghum are limited to results from grain sorghum x sweet sorghum hybrids. Recent development of cytoplasmic male-sterile sweet sorghum lines allows creation of sweet sorg...
Song, G.S.; Zhai, H.L.; Peng, Y.G.; Zhang, L.; Wei, G.; Chen, X.Y.; Xiao, Y.G.; Wang, L.; Chen, Y.J.; Wu, B.; Chen, B.; Zhang, Y.; Chen, H.; Feng, X.J.; Gong, W.K.; Liu, Y.; Yin, Z.J.; Wang, F.; Liu, G.Z.; Xu, H.L.; Wei, X.L.; Zhao, X.L.; Ouwerkerk, P.B.F.; Hankemeier, T.; Reijmers, T.; Heijden, R. van der; Lu, C.M.; Wang, M.; Greef, J. van der; Zhu, Z.
Heterosis is a biological phenomenon whereby the offspring from two parents show improved and superior performance than either inbred parental lines. Hybrid rice is one of the most successful apotheoses in crops utilizing heterosis. Transcriptional profiling of F1 super-hybrid rice Liangyou-2186 and
Garrett Vieira, Filipe Jorge; Fumagalli, Matteo; Albrechtsen, Anders
Most methods for Next-Generation Sequencing (NGS) data analyses incorporate information regarding allele frequencies using the assumption of Hardy-Weinberg Equilibrium (HWE) as a prior. However, many organisms including domesticated, partially selfing or with asexual life cycles show strong......-Maximization (EM) algorithm. We assess the impact of taking inbreeding into account when calling genotypes or estimating the Site Frequency Spectrum (SFS), and demonstrate a marked increase in accuracy on low coverage highly inbred samples. We demonstrate the applicability and efficacy of these methods in both...
In South Africa, the Dairy Swiss breed, which originated in Switzerland, consists of 27 breeders and 1135 breeding cows. Pedigree information on the breed was analysed to determine its effective population size (Ne) and rate of inbreeding. The rate of inbreeding was 0.08% per year and 0.38% per generation.
Mar 9, 2013 ... Abstract. In South Africa, the Dairy Swiss breed, which originated in Switzerland, consists of 27 breeders and. 1135 breeding cows. Pedigree information on the breed was analysed to determine its effective population size (Ne) and rate of inbreeding. The rate of inbreeding was 0.08% per year and 0.38% ...
Revealing gene action for production characteristics by inbreeding, based on a long-term selection ... The gene action involved in the expression of production characters was investigated, using the effect of the theoretical inbreeding ..... and predicted selection responses for growth, fat and lean traits in mice. J. Anim. Sci.
Data of the Elsenburg Dormer sheep stud which was kept closed since its inception, were collected over a period of 50 years (1941-1990). These data were analysed to monitor the increase in actual level of inbreeding and to investigate the effect of inbreeding on some early growth and reproduction traits. In total, 9 551 ...
of migration rates is judged by the maximum difference ( 1 - k) in inbreeding between a subpopulation, of size N, and a con- ceptual aggregate random ... inbreeding coefficient of a subpopulation (single island) with migration from a very large noninbred population, ll(4M + l). ...... WH Freeman and Company, New York.
192 individual inbreeding coefficients on natural and artificial selection cannot be ruled out. The effect of inbreeding on production and reproduction traits in Merino sheep has been the subject of many studies and reviews (Morley, 1954; Doney,. 1957; Lax & Brown, 1967; Turner & Young, 1969; Dolling,. 1970' Lamberson ...
In sheep populations with small effective population sizes (Ne), inbreeding is a major concern because genetic variation has to be maintained. A panel of 28 microsatellite markers was used to measure the inbreeding level in three separate Merino flocks bred for superfine wool (CR), low parasite resistance (LR) or high ...
Tabadkani, Seyed Mohammad; Nozari, Jamasb; Lihoreau, Mathieu
Animals have evolved strategies to optimally balance costs and benefits of inbreeding. In social species, these adaptations can have a considerable impact on the structure, the organization, and the functioning of groups. Here, we consider how selection for inbreeding avoidance fashions the social behavior of arthropods, a phylum exhibiting an unparalleled richness of social lifestyles. We first examine life histories and parental investment patterns determining whether individuals should actively avoid or prefer inbreeding. Next, we illustrate the diversity of inbreeding avoidance mechanisms in arthropods, from the dispersal of individuals to the rejection of kin during mate choice and the production of unisexual broods by females. Then, we address the particular case of haplodiploid insects. Finally, we discuss how inbreeding may drive and shape the evolution of arthropods societies along two theoretical pathways.
Nichols, Hazel J; Cant, Michael A; Sanderson, Jennifer L
Females of many animal species seek mating opportunities with multiple males, despite being able to obtain sufficient sperm to father their offspring from a single male. In animals that live in stable social groups, females often choose to mate outside their group resulting in extra-group paternity (EGP). One reason proposed to explain female choice for extra-group males is to obtain compatible genes, for example, in order to avoid inbreeding depression in offspring. The benefits of such extra-group paternities could be substantial if they result in fitter, outbred offspring. However, avoiding inbreeding in this way could be costly for females, for example, through retaliation by cuckolded males or through receiving aggression while prospecting for extra-group mating opportunities. We investigate the costs and benefits of EGP in the banded mongoose Mungos mungo , a cooperatively breeding mammal in which within-group mates are sometimes close relatives. We find that pups born to females that mate with extra-group males are more genetically heterozygous are heavier and are more likely to survive to independence than pups born to females that mate within their group. However, extra-group matings also involve substantial costs as they occur during violent encounters that sometimes result in injury and death. This appears to lead femalebanded mongooses to adaptively adjust EGP levels according to the current risk of inbreeding associated with mating within the group. For group-living animals, the costs of intergroup interactions may help to explain variation in both inbreeding rates and EGP within and between species.
Sandner, Tobias Michael; Matthies, Diethart
Populations of many hemiparasitic plants are fragmented and threatened by inbreeding depression (ID). In addition, they may also be strongly affected by a lack of suitable host species. However, nothing is known about possible interactive effects of inbreeding and host quality for parasitic plants. Poor host quality represents a special type of biotic stress and the magnitude of ID is often expected to be higher in more stressful environments. We studied the effects of inbreeding and the quality of host species for the declining root hemiparasite Rhinanthus alectorolophus Selfed and open-pollinated parasites from two natural populations were grown (1) with 13 potential host species and (2) with 15 four-species mixtures. ID differed among host species and mixtures. In the first experiment, ID was highest in parasites grown with good hosts and declined with stress intensity. In the second experiment, ID was not influenced by stress intensity, but was highest in mixtures of hosts from only one functional group and lowest in mixtures containing three functional groups. Both parasite performance with individual host species and the damage to these host species differed between parasites from the two study populations. Our results contradict the common assumption that ID is generally higher in more stressful environments. In addition, they support the importance of diverse host communities for hemiparasitic plants. The differences in host quality between the two parasite populations indicate genetic variation in the adaptation to individual hosts and in host-specific virulence. However, inbreeding did not affect specific host-parasite interactions. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: firstname.lastname@example.org.
Echeverri A. Álvaro
Full Text Available El objetivo del presente estudio fue estimar la heterosis, la aptitud combinatoria general (ACG y la aptitud combinatoria específica (ACE en un cruzamiento dialélico entre diez cultivares de pimentón usando las metodología propuesta por Griffing (1956b, método experimental 4, Modelo I (modificado por Hallauer y Miranda, 1988. Los parentales con valores más altos de heterosis relativa (HR y heterobelriosis (HB fueron LPUNAL (155,87% y 138,69%, Avelar (136,84% y 119,18%, y L363-46-672 (130,95% y 113,22%, los que participaron en la formación de cuatro de los diez cruzamientos más destacados por rendimiento. El análisis de varianza para aptitud combinatoria, mostró que en la transmisión y expresión de los caracteres evaluados, actúan en forma conjunta y altamente significativa tanto los efectos génicos aditivos (ACG como los 110 aditivos (A CE, pero con predominio de los primeros (Griffing, 1956. Los mayores valores de ACG para rendimiento fueron observados en LPUNAL-Palmira y Avelar (87.0 y 79.9, respectivamente.
Khlat, M; Khoury, M
The demographic and quantitative genetic aspects of consanguineous marriages are reviewed before epidemiologic principles are applied to the hundreds of studies reviewed, and 3 in particular. Consanguineous unions range from cousin-cousin to more distant relatedness, and their prevalence varies by culture. Prevalence is highest in Arab countries, followed by India, Japan, Brazil and Israel. They are most common in lower educational and socioeconomic groups, the traditionally religious, and the early married, but are declining with modernization. Consanguinity is measured by geneticists by the inbreeding coefficient, the mean consanguinity of a population, and the concept of genetic load. Recessive genes may be deleterious or beneficial if heterozygous in local conditions. Bayesian statistics can predict by the coefficient of increase the probability of disease in offspring as a function of consanguinity and disease characteristics. Inbreeding generally increases prereproductive mortality; crude mortality increases with inbreeding in proportion to the mortality rate. Morbidity increases significantly with inbreeding in many diseases studies in many countries. Epidemiologic studies usually measure inbreeding effects in terms of genetic load, which is not readily translatable into morbidity and mortality. Several methods of computing results of epidemiologic studies are discussed, as well as methodological study design problems. Confounding is the most difficult problem in these studies, because of the difficulty in selecting non-inbred controls. Future inbreeding studies should be interpreted based on both genetic and epidemiologic grounds to illuminate the role of genetic factors and the relevance of inbreeding to disease and public health.
Full Text Available Fixed heterosis resulting from favorable interactions between the genes on their homoeologous genomes in an allopolyploid is considered analogous to classical heterosis accruing from interactions between homologous chromosomes in heterozygous plants of a diploid species. It has been hypothesized that fixed heterosis may be one of the causes of low classical heterosis in allopolyploids. We used Indian mustard (Brassica juncea, 2n = 36; AABB as a model system to analyze this hypothesis due to ease of its resynthesis from its diploid progenitors, B. rapa (2n = 20; AA and B. nigra (2n = 16; BB. Both forms of heterosis were investigated in terms of ploidy level, gene action and genetic diversity. To facilitate this, eleven B. juncea genotypes were resynthesized by hybridizing ten near inbred lines of B. rapa and nine of B. nigra. Three half diallel combinations involving resynthesized B. juncea (11×11 and the corresponding progenitor genotypes of B. rapa (10×10 and B. nigra (9×9 were evaluated. Genetic diversity was estimated based on DNA polymorphism generated by SSR primers. Heterosis and genetic diversity in parental diploid species appeared not to predict heterosis and genetic diversity at alloploid level. There was also no association between combining ability, genetic diversity and heterosis across ploidy. Though a large proportion (0.47 of combinations showed positive values, the average fixed heterosis was low for seed yield but high for biomass yield. The genetic diversity was a significant contributor to fixed heterosis for biomass yield, due possibly to adaptive advantage it may confer on de novo alloploids during evolution. Good general/specific combiners at diploid level did not necessarily produce good general/specific combiners at amphiploid level. It was also concluded that polyploidy impacts classical heterosis indirectly due to the negative association between fixed heterosis and classical heterosis.
Thirstrup, Janne Pia; Larsen, Peter Foged; Pertoldi, Cino
Crosses between different mink lines from 3 Danish mink farms that use different breeding strategies were studied to estimate heterosis and variance components for litter size. The study was designed to analyze crosses between lines of the same color type, between different color types, and between...... animals originating from different farms. Effect of heterosis, color type, and variance components were estimated using Average information REML (AI-REML) algorithm implemented in the DMU package for analyzing multivariate mixed models. Females from 7 generations that gave birth to at least 1 offspring...... of the born litter; d2) were estimated. The results showed that mink of the Black color type potentially produced smaller litters compared to mink of the other studied color types. We found significant general maternal effect of heterosis for litter size. Analyses of specific heterosis showed a significant...
Full Text Available In this research, the mid-parent heterosis and the levels of phenolic, flavonoids compounds and antioxidants activity among two selected sweet corn parental lines and their F1 hybrid Zaharina were evaluated. Substantial positive mid-parent heterosis (MPH was found for parent-hybrid triplet for ear weight and for plant height. Among all other traits, insertion height had the greatest heterosis and ear diameter had the lowest. Negative mid-parent heterosis exhibited only the trait 1000-kernel weight. Data analysis indicated significant differences in the contents of total phenolic content, total flavonoids content, water-soluble antioxidant capacity, lipid-soluble antioxidant capacity, and antioxidant activity among parent-hybrid triplet. The results suggest that F1 hybrid Zaharina can be considered as good source of natural antioxidants since it extracts were found to possess high antioxidant activity.
Orchids are among the most beautiful flowers and endangered due to habitat destruction and overcollection. Cattleya walkeriana is one of the most beautiful flowers joining the small sized plant with medium large and heavily scented flowers. It is widely known and appreciated by its beautiful clones and it has much to offer ...
Lopez Cesar Gabriel
Full Text Available Corn silage is a high-quality forage crop used in many areas of the world. Although vegetative and reproductivecomponents of the plant must be considered, breeding programs in temperate regions are mainly based on the Reid xLancaster heterotic pattern that has undergone several cycles of improvement for grain yield. Moreover, hybrids selected forforage production are early maturing genotypes not adapted to warm-temperate or subtropical areas. Consequently, exoticgermplasm should be considered as a source of materials for breeding programs. Eight landraces were crossed following adiallel mating design. Interpopulation crosses showed high heterosis for ear, stover, and whole plant dry matter yield (EY, SY,and WY, respectively. On average, crosses had higher SY than checks, but lower EY. Considering WY, two interpopulationcrosses had higher means than all commercial checks, indicating the potential of the germplasm evaluated. Two compositeswere selected and different breeding strategies are discussed.
Dhillon, B S; Singh, J
The present investigation involved crosses among 20 elite yellow maize populations. These were evaluated in four environments in a randomized block design with four replications in each environment. Variety Cuba was observed to be the best general combiner for grain yield, followed by St Croix and Prolific. No clear association could be discerned between general combining ability (GCA) effects for grain yield and its components, and mean grain yield performance and GCA effects. Heterosis was observed in general and all the crosses involving Cuba yielded better than the midparent. The five hybrids, Kisan × Cuba, Antigua 3D × St Croix, Prolific × St Croix, Vijay × Antigua Gr. I and A 23 × Cuba, yielded more than the standard check. Significant yield superiority of these varietal hybrids over the best commercial composite (Jawahar) suggested the possibility of their commercial exploitation.
The explanation for heterosis phenomenon is based on ideas: (i) every trait of an organism depends on many genes. (ii) Inbreeding depression and heterosis are related to individual genetic diversity. To assess individual genetic diversity ofan organism, I suggest the term number of genetic properties. Assessing the ...
Woolliams, J.A.; Bijma, P.
Tractable forms of predicting rates of inbreeding (F) in selected populations with general indices, nonrandom mating, and overlapping generations were developed, with the principal results assuming a period of equilibrium in the selection process. An existing theorem concerning the relationship
Fuster, V; Morales, B; Mesa, M S; Martin, J
The relationships among the frequency of consanguineous marriages, inbreeding coefficient, period, village size, and altitude are analyzed for three rural valleys belonging to the Sierra de Gredos (central Spain). These valleys occupy an area of about 30 x 80 km2, and the average total number of inhabitants for the period 1877-1970 was 58,621. Information about a sample of 23,744 weddings celebrated between 1875 and 1974 was obtained from 48 village parish registers. The mean inbreeding level up to second cousins for the whole area was 0.0012. A high percentage of inbreeding variation (83%) can be explained by each village's census size, resulting in a different interslope consanguinity pattern consisting of higher inbreeding levels in most northern localities in the Gredos mountains. This north-south geographic trend is consistent with results on blood polymorphisms from the same area (Mesa et al. 1994).
John R Garbe
Full Text Available Inbreeding and relatedness in wild panda populations are important parameters for panda conservation. Habitat loss and fragmentation are expected to increase inbreeding but the actual inbreeding levels in natural panda habitats were unknown. Using 150,025 SNPs and 14,926 SNPs selected from published whole-genome sequences, we estimated genomic inbreeding coefficients and relatedness of 49 pandas including 34 wild pandas sampled from six habitats. Qinling and Liangshan pandas had the highest levels of inbreeding and relatedness measured by genomic inbreeding and coancestry coefficients, whereas the inbreeding levels in Qionglai and Minshan were 28-45% of those in Qinling and Liangshan. Genomic coancestry coefficients between pandas from different habitats showed that panda populations from the four largest habitats, Minshan, Qionglai, Qinling and Liangshan, were genetically unrelated. Pandas between these four habitats on average shared 66.0-69.1% common alleles and 45.6-48.6% common genotypes, whereas pandas within each habitat shared 71.8-77.0% common alleles and 51.7-60.4% common genotypes. Pandas in the smaller populations of Qinling and Liangshan were more similarly to each other than pandas in the larger populations of Qionglai and Minshan according to three genomic similarity measures. Panda genetic differentiation between these habitats was positively related to their geographical distances. Most pandas separated by 200 kilometers or more shared no common ancestral alleles. The results provided a genomic quantification of the actual levels of inbreeding and relatedness among pandas in their natural habitats, provided genomic confirmation of the relationship between genetic diversity and geographical distances, and provided genomic evidence to the urgency of habitat protection.
Curik, I.; Zechner, P.; Sölkner, J.; Achmann, R.; Bodo, I.; Dovc, P.; Kavar, T.; Marti, E.; Brem, G.
While the negative effects of inbreeding and reduced heterozygosity on fecundity and survival are well established, only a few investigations have been carried out concerning their influence on morphological traits. This topic is of particular interest for a small and closed population such as the Lipizzan horse. Thus, 27 morphological traits were measured in 360 Lipizzan mares and were regressed on the individual inbreeding coefficients, as well as on the individual heterozygosity and mean s...
Garbe, John R; Prakapenka, Dzianis; Tan, Cheng; Da, Yang
Inbreeding and relatedness in wild panda populations are important parameters for panda conservation. Habitat loss and fragmentation are expected to increase inbreeding but the actual inbreeding levels in natural panda habitats were unknown. Using 150,025 SNPs and 14,926 SNPs selected from published whole-genome sequences, we estimated genomic inbreeding coefficients and relatedness of 49 pandas including 34 wild pandas sampled from six habitats. Qinling and Liangshan pandas had the highest levels of inbreeding and relatedness measured by genomic inbreeding and coancestry coefficients, whereas the inbreeding levels in Qionglai and Minshan were 28-45% of those in Qinling and Liangshan. Genomic coancestry coefficients between pandas from different habitats showed that panda populations from the four largest habitats, Minshan, Qionglai, Qinling and Liangshan, were genetically unrelated. Pandas between these four habitats on average shared 66.0-69.1% common alleles and 45.6-48.6% common genotypes, whereas pandas within each habitat shared 71.8-77.0% common alleles and 51.7-60.4% common genotypes. Pandas in the smaller populations of Qinling and Liangshan were more similarly to each other than pandas in the larger populations of Qionglai and Minshan according to three genomic similarity measures. Panda genetic differentiation between these habitats was positively related to their geographical distances. Most pandas separated by 200 kilometers or more shared no common ancestral alleles. The results provided a genomic quantification of the actual levels of inbreeding and relatedness among pandas in their natural habitats, provided genomic confirmation of the relationship between genetic diversity and geographical distances, and provided genomic evidence to the urgency of habitat protection.
Santos, Luciana L; da Fonseca, Cleusa G; Vaintraub, Marco T; Vaintraub, Patricia; Januário, José N; de Aguiar, Marcos J B; Raquel Santos Carvalho, Maria
Estimates of allele frequencies for recessive diseases are generally based on the frequency of affected individuals (q(2)). However, these estimates can be strongly biased due to inbreeding in the population. The purpose of this study was to gain a better understanding of how inbreeding in the Minas Gerais State population affects phenylketonuria (PKU) incidence in the state and to determine the inbreeding coefficient based on microsatellites. Inbreeding coefficients of samples of 104 controls and 76 patients with PKU were estimated through a microsatellite approach. Besides, the amount and distribution of genetic variation within and among patients with PKU and control samples were characterized. No genetic differentiation was observed between the samples. However, the Fis value found for samples of patients with PKU (0.042) was almost 15 times higher than that found among controls (0.003). When corrected by the inbreeding coefficient found among the controls, the PKU allele frequency decreased to 0.0057. The results enables us to infer that at least 35% of the PKU recessive homozygotes from the Minas Gerais population could be due to consanguineous marriages and suggest that microsatellites can be an useful approach to estimate inbreeding coefficients. (c) 2010 Wiley-Liss, Inc.
Amuzu-Aweh, E N; Bijma, P; Kinghorn, B P; Vereijken, A; Visscher, J; van Arendonk, J Am; Bovenhuis, H
Prediction of heterosis has a long history with mixed success, partly due to low numbers of genetic markers and/or small data sets. We investigated the prediction of heterosis for egg number, egg weight and survival days in domestic white Leghorns, using ∼400 000 individuals from 47 crosses and allele frequencies on ∼53 000 genome-wide single nucleotide polymorphisms (SNPs). When heterosis is due to dominance, and dominance effects are independent of allele frequencies, heterosis is proportional to the squared difference in allele frequency (SDAF) between parental pure lines (not necessarily homozygous). Under these assumptions, a linear model including regression on SDAF partitions crossbred phenotypes into pure-line values and heterosis, even without pure-line phenotypes. We therefore used models where phenotypes of crossbreds were regressed on the SDAF between parental lines. Accuracy of prediction was determined using leave-one-out cross-validation. SDAF predicted heterosis for egg number and weight with an accuracy of ∼0.5, but did not predict heterosis for survival days. Heterosis predictions allowed preselection of pure lines before field-testing, saving ∼50% of field-testing cost with only 4% loss in heterosis. Accuracies from cross-validation were lower than from the model-fit, suggesting that accuracies previously reported in literature are overestimated. Cross-validation also indicated that dominance cannot fully explain heterosis. Nevertheless, the dominance model had considerable accuracy, clearly greater than that of a general/specific combining ability model. This work also showed that heterosis can be modelled even when pure-line phenotypes are unavailable. We concluded that SDAF is a useful predictor of heterosis in commercial layer breeding.
Kessing, Lars Veddel; Bukh, Jens Otto Drachmann
, that these diagnostic criteria represent an oversimplification, which has blurred the concept of depression. We suggest a greater emphasis on the depressed mood as the core symptom of depression, which may increase the specificity of the diagnosis. Furthermore, basic principles for the treatment of depression......The prevalence of depression is not clearly established, but estimated to 3-4% in a Danish questionnaire study. Lifetime's prevalences of 12-17% are reported in other community samples. In the current diagnostic system depression is defined categorically and operationally. It has been argued...
Kessing, Lars Veddel; Bukh, Jens Drachmann
The prevalence of depression is not clearly established, but estimated to 3-4% in a Danish questionnaire study. Lifetime's prevalences of 12-17% are reported in other community samples. In the current diagnostic system depression is defined categorically and operationally. It has been argued......, that these diagnostic criteria represent an oversimplification, which has blurred the concept of depression. We suggest a greater emphasis on the depressed mood as the core symptom of depression, which may increase the specificity of the diagnosis. Furthermore, basic principles for the treatment of depression...
Little, Bertis B; Malina, Robert M
We analyzed inbreeding using surname isonymy in an indigenous genetic isolate. The subjects were residents of a rural Zapotec-speaking community in the valley of Oaxaca, southern Mexico. The community can be classified as a genetic isolate with an average gene flow of indigenous Mexican populations. A total of 2,149 individuals had valid surname patronym-matronym pairings, including 484 deceased ancestors. Surname isonymy analysis methods were used to estimate total inbreeding and to segregate it into random and nonrandom components. The surname isonymy coefficient computed from 119 isonymous surname pairings (119/2,149) was 0.0554. The estimated inbreeding coefficient from surname isonymy was 0.0138 (0.0554/4). The random and nonrandom components of inbreeding were F(r) = 0.0221 and F(n) = -0.0091, respectively. The results suggest that consanguinity is culturally avoided. Nonrandom inbreeding decreased total inbreeding by about 41%. Total estimated inbreeding by surname isonymy was 0.0138, which is similar to inbreeding estimated from a sample of pedigrees, 0.01. Socially prescribed inbreeding avoidance substantially lowered total F through negative nonrandom inbreeding. Even in the situation of genetic isolation and small effective population size (N(e)), estimated inbreeding is lower than may have otherwise occurred if inbreeding were only random. However, among the poorest individuals, socially prescribed jural rules for inbreeding avoidance failed to operate. Thus the preponderance of inbreeding appears to occur among the poor, economically disadvantaged in the community.
... system. Doctors use them to treat things like insomnia or anxiety . But if depressant drugs (like sedatives, tranquilizers, or barbiturates) are abused, they can cause addiction , serious injury, or death. Depressants are usually ...
Shang, Lianguang; Ma, Lingling; Wang, Yumei; Su, Ying; Wang, Xiaocui; Li, Yuhua; Abduweli, Abdugheni; Cai, Shihu; Liu, Fang; Wang, Kunbo; Hua, Jinping
Plant height, which shows dynamic development and heterosis, is a major trait affecting plant architecture and has an indirect influence on economic yield related to biological yield in cotton. In the present study, we carried out dynamic analysis for plant height and its heterosis by quantitative trait loci (QTL) mapping at multiple developmental stages using two recombinant inbred lines (RILs) and their backcross progeny. At the single-locus level, 47 QTL were identified at five developmental stages in two hybrids. In backcross populations, QTL identified at an early stage mainly showed partial effects and QTL detected at a later stage mostly displayed overdominance effects. At the two-locus level, we found that main effect QTL played a more important role than epistatic QTL in the expression of heterosis in backcross populations. Therefore, this study implies that the genetic basis of plant height heterosis shows dynamic character and main effect QTL with dominance determines heterosis for plant height in Upland cotton. Copyright © 2016 Shang et al.
Song, Gui-Sheng; Zhai, Hong-Li; Peng, Yong-Gang; Zhang, Lei; Wei, Gang; Chen, Xiao-Ying; Xiao, Yu-Guo; Wang, Lili; Chen, Yue-Jun; Wu, Bin; Chen, Bin; Zhang, Yu; Chen, Hua; Feng, Xiu-Jing; Gong, Wan-Kui; Liu, Yao; Yin, Zhi-Jie; Wang, Feng; Liu, Guo-Zhen; Xu, Hong-Lin; Wei, Xiao-Li; Zhao, Xiao-Ling; Ouwerkerk, Pieter B F; Hankemeier, Thomas; Reijmers, Theo; van der Heijden, Rob; Lu, Cong-Ming; Wang, Mei; van der Greef, Jan; Zhu, Zhen
Heterosis is a biological phenomenon whereby the offspring from two parents show improved and superior performance than either inbred parental lines. Hybrid rice is one of the most successful apotheoses in crops utilizing heterosis. Transcriptional profiling of F(1) super-hybrid rice Liangyou-2186 and its parents by serial analysis of gene expression (SAGE) revealed 1183 differentially expressed genes (DGs), among which DGs were found significantly enriched in pathways such as photosynthesis and carbon-fixation, and most of the key genes involved in the carbon-fixation pathway exhibited up-regulated expression in F(1) hybrid rice. Moreover, increased catabolic activity of corresponding enzymes and photosynthetic efficiency were also detected, which combined to indicate that carbon fixation is enhanced in F(1) hybrid, and might probably be associated with the yield vigor and heterosis in super-hybrid rice. By correlating DGs with yield-related quantitative trait loci (QTL), a potential relationship between differential gene expression and phenotypic changes was also found. In addition, a regulatory network involving circadian-rhythms and light signaling pathways was also found, as previously reported in Arabidopsis, which suggest that such a network might also be related with heterosis in hybrid rice. Altogether, the present study provides another view for understanding the molecular mechanism underlying heterosis in rice.
Hou Guangyun; Jing Liling
A complete delia cross (no reciprocal hybrid) was made using 5 wheat mutants with distinctive characters. The heterosis and combining ability of 8 agronomic characters were studied in 10 crosses F 1 and 5 parents. The dominance degree of F 1 indicated that except for the remarkable negative heterosis for heading-date, the positive heterosis was remarkable for all the other 7 characters. The performance of parents was significantly related to the gca effects. However, gca effects were not completely consistent with the value of heterosis. As germplasm resources, dwarf-stalk mutant 890376 was the best for reducing plant height. A large grain mutant, Hesheng 2, was the best for increasing 1000-grain weight. An early maturity mutant 890236 was the best for earlier heading and fillering ability. A large head mutant 890018 was the best for improving head length, number of spikelets per head, number of grain per head and grain weight per head. To sum up, the above 4 distinctive mutants were very useful for improving the characters corresponding with their mutated characters. For some characters, the cross will have a bigger sca effects if its parents have a bigger gca effects. However, it is not the same for all their characters. Sca effects of crosses were significantly related to the heterosis over mean parent
Full Text Available Plant height, which shows dynamic development and heterosis, is a major trait affecting plant architecture and has an indirect influence on economic yield related to biological yield in cotton. In the present study, we carried out dynamic analysis for plant height and its heterosis by quantitative trait loci (QTL mapping at multiple developmental stages using two recombinant inbred lines (RILs and their backcross progeny. At the single-locus level, 47 QTL were identified at five developmental stages in two hybrids. In backcross populations, QTL identified at an early stage mainly showed partial effects and QTL detected at a later stage mostly displayed overdominance effects. At the two-locus level, we found that main effect QTL played a more important role than epistatic QTL in the expression of heterosis in backcross populations. Therefore, this study implies that the genetic basis of plant height heterosis shows dynamic character and main effect QTL with dominance determines heterosis for plant height in Upland cotton.
There is ample evidence that depression is000 a common comorbid health issue in people with type 1 or type 2 diabetes. Reviews have also concluded that depression in diabetes is associated with higher HbA1c levels, less optimal self-care behaviours, lower quality of life, incident vascular...... complications and higher mortality rates. However, longitudinal studies into the course of depression in people with type 1 diabetes remain scarce. In this issue of Diabetologia, Kampling and colleagues (doi: 10.1007/s00125-016-4123-0 ) report the 5 year trajectories of depression in adults with newly diagnosed...... type 1 diabetes (mean age, 28 years). Their baseline results showed that shortly after the diagnosis of type 1 diabetes a major depressive episode was diagnosed in approximately 6% of participants, while 8% suffered from an anxiety disorder. The longitudinal depression data showed that, in a 5 year...
... and insomnia References American Psychiatric Association. Depressive disorders. Diagnostic and Statistical Manual of Mental Disorders . 5th ed. Arlington, VA: American Psychiatric Publishing; 2013: ...
David E Carr
Full Text Available Inbreeding in plants typically reduces individual fitness but may also alter ecological interactions. This study examined the effect of inbreeding in the mixed-mating annual Mimulus guttatus on visitation by pollinators (Bombus impatiens in greenhouse experiments. Previous studies of M. guttatus have shown that inbreeding reduced corolla size, flower number, and pollen quantity and quality. Using controlled crosses, we produced inbred and outbred families from three different M. guttatus populations. We recorded the plant genotypes that bees visited and the number of flowers probed per visit. In our first experiment, bees were 31% more likely to visit outbred plants than those selfed for one generation and 43% more likely to visit outbred plants than those selfed for two generations. Inbreeding had only a small effect on the number of flowers probed once bees arrived at a genotype. These differences were explained partially by differences in mean floral display and mean flower size, but even when these variables were controlled statistically, the effect of inbreeding remained large and significant. In a second experiment we quantified pollen viability from inbred and self plants. Bees were 37-54% more likely to visit outbred plants, depending on the population, even when controlling for floral display size. Pollen viability proved to be as important as floral display in predicting pollinator visitation in one population, but the overall explanatory power of a multiple regression model was weak. Our data suggested that bees use cues in addition to display size, flower size, and pollen reward quality in their discrimination of inbred plants. Discrimination against inbred plants could have effects on plant fitness and thereby reinforce selection for outcrossing. Inbreeding in plant populations could also reduce resource quality for pollinators, potentially resulting in negative effects on pollinator populations.
Brown, A. Ross; Hosken, David J.; Balloux, François; Bickley, Lisa K.; LePage, Gareth; Owen, Stewart F.; Hetheridge, Malcolm J.; Tyler, Charles R.
Exposure to environmental chemicals can have negative consequences for wildlife and even cause localized population extinctions. Resistance to chemical stress, however, can evolve and the mechanisms include desensitized target sites, reduced chemical uptake and increased metabolic detoxification and sequestration. Chemical resistance in wildlife populations can also arise independently of exposure and may be spread by gene flow between populations. Inbreeding—matings between closely related individuals—can have negative fitness consequences for natural populations, and there is evidence of inbreeding depression in many wildlife populations. In some cases, reduced fitness in inbred populations has been shown to be exacerbated under chemical stress. In chemical testing, both inbred and outbred laboratory animals are used and for human safety assessments, iso-genic strains (virtual clones) of mice and rats are often employed that reduce response variation, the number of animals used and associated costs. In contrast, for environmental risk assessment, strains of animals are often used that have been selectively bred to maintain heterozygosity, with the assumption that they are better able to predict adverse effects in wild, genetically variable, animals. This may not necessarily be the case however, as one outbred strain may not be representative of another or of a wild population. In this paper, we critically discuss relationships between genetic variation, inbreeding and chemical effects with the intention of seeking to support more effective chemical testing for the protection of wildlife. PMID:19833649
Cizza, G; Ravn, Pernille; Chrousos, G P
Existing studies of the relationship between depression and osteoporosis have been heterogeneous in their design and use of diagnostic instruments for depression, which might have contributed to the different results on the comorbidity of these two conditions. Nevertheless, these studies reveal a...
Johansen, Jon O. J.
Nyhederne er fulde af historier om depression. Overskrifter som: ’Danskerne propper sig med lykkepiller’ eller ‘depression er stadigvæk tabu’ går tit igen i dagspressen. Men hvor er nuancerne, og hvorfor gider vi læse de samme historier igen og igen? Måske er det fordi, vores egne forestillinger er...
Abaskuliev, A A; Skoblo, G V
An increased frequency of consanguineous marriages among the parents of schizophrenic patients in comparison with the control group of exogenous-somatic patients (infections, trauma) was found. Endogamy among the parents of schizophrenic patients and the control group was practically the same. The data obtained indicate a certain, but not the leading, role of inbreeding in the etiology of schizophrenia.
The statistical model included the fixed effects of herd-year-season, age of the cow at calving, calving interval, inbreeding as a discrete or continuous variable and random effects of direct additive genetic, permanent environment of the cow and the residual effects. The multitrait derivative-free REML algorithm was used to ...
Analysis of genetic diversity and estimation of inbreeding coefficient within Caspian horse population using microsatellite markers. ... structure and to the assessment of genetic diversity that may be helpful to horse breeders in designing and managing breeding or conservation strategies for the Caspian horse breed.
Kingma, Sjouke A.; Hall, Michelle L.; Peters, Anne
Extrapair (EP) mating can enable females to reduce the negative effects of inbreeding. However, opportunities for EP mating are often ecologically or demographically constrained, and it is unclear whether and how females can overcome these constraints. Here, we show that fitness costs from
Short communication: Effective population size and inbreeding rate of indigenous Nguni cattle under in situ conservation in the low-input communal production ... as not at risk of extinction, while the individual enterprises were classified as being endangered-maintained without the exchange of germ plasm among them.
Presence of inbreeding during a selection experiment with Merino sheep. GJ Erasmus, AO de Lange, GJ Delport, JJ Olivier. Abstract. No Abstract. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL.
inbreeding coefficient on the mean of the characters in a two-way selection experiment for the slope (b) and intercept. (Ln (a)) of the ... ln (a) selection group, as well as average daily f-eed intake (Phase I and 2) of the b selection group. Die genewerking wat ..... exposed to natural selection for an extended period under con-.
Manenti, Tommaso; Pertoldi, Cino; Nasiri Moghadam, Neda
The ability to move is essential for many behavioural traits closely related to fitness. Here we studied the effect of inbreeding on locomotor activity (LA) of Drosophila melanogaster at different ages under both dark and light regimes. We expected to find a decreased LA in inbred lines compared...
Sørensen, Anders Christian; Norberg, Elise
In Denmark there are small populations of five Nordic sheep breeds, two of which are Danish in origin. The purpose of this study was to estimate trends in inbreeding for these breeds. All five breeds have been recording pedigrees for decades, so pedigree completeness is adequate. The rate...
... don't have the right balance of chemicals. Hormonal factors – Menstrual cycle changes, pregnancy, miscarriage, postpartum period, perimenopause, and menopause may all cause a woman to develop depression. ...
Sell-Kubiak, Ewa; Czarniecki, Łukasz; Strabel, Tomasz
The aim of this study was to evaluate observed and future inbreeding level in Polish Holstein-Friesian cattle population. In total, over 9.8 mln animals were used in the analysis coming from the pedigree of Polish Federation of Cattle Breeders and Dairy Farmers. Inbreeding level, as an average per birth year, was estimated with the method accounting for missing parent information with the assumption of year 1950 as the base year of the population. If an animal had no ancestral records, an average inbreeding level from its birth year was assigned. Twice the average inbreeding level served as relatedness of the animal to the population, which enabled estimation of inbreeding in its offspring. The future inbreeding of potential offspring was estimated as an average of animals (bulls and cows) available for mating in a certain year. It was observed that 30-50% of animals born between 1985 and 2015 had no relevant ancestral information, which is caused by a high number of new animals and/or entire farms entering the national milk recordings. For the year 2015, the observed inbreeding level was 3.30%, which was more than twice the inbreeding with the classical approach (without missing parent information) and higher by 0.4% than the future inbreeding. The average increase of inbreeding in years 2010-2015 was 0.10%, which is similar to other countries monitored by World Holstein-Friesian Federation. However, the values might be underestimated due to low pedigree completeness. The estimates of future inbreeding suggested that observed inbreeding could be even lower and also increase slower, which indicates a constant need to monitor rate of increase in inbreeding over time. The most important aspect of presented results is the necessity to advise individual farmers to keep precise recordings of the matings on their farm in order to improve the pedigree completeness of Polish Holstein-Friesian and to use suitable mating programs to avoid too rapid growth of inbreeding.
In this study, eight drought tolerant lines and their diallel crosses were tested separately in randomized complete block design under normal and high plant densities that combined with well watered and drought stress to estimate performance, heterosis and combining ability for grain yield. Both types of genotypes gave ...
This study was conducted to determine the heterosis and combining ability of eight elite maize genotypes. The eight parents were selected based on per se and top-cross performance. The parents were crossed in diallel fashion. The resulting crosses and their parents were evaluated in a randomised complete block design ...
Wang, Xinjun; Cao, Haihe; Zhang, Dengfeng; Li, Bo; He, Yan; Li, Jiansheng; Wang, Shoucai
Maize (Zea mays L.) is one of the most important crops because of the remarkable properties of its hybrid, which is responsible for the high commercial value of hybrid maize. The genetic basis of heterosis (hybrid vigor) is not well understood. A differential display technique was performed to identify genes with differential expression across twelve maize inbred lines and thirty-three hybrids during ear development. An incomplete diallel design was used to investigate the relationship between the global framework of differential gene expression and heterosis. It was found that the genes belonging to MONO pattern (i.e., genes expressed in both parental lines and in hybrid) was the highest in percentage among the total five patterns and illustrated that the properties of differentially expressed genes are not entirely responsible for heterosis. Furthermore, a larger number of differentially expressed genes in hybrid, which serves as a major reservoir for generating novel phenotypes that exhibit heterosis of certain agronomic traits during early development and differentiation of maize ear. Moreover, there were some silent genesin hybrids that are responsible for the arrest or abortion of spikelets and for the increase in kernels weight.
Kurt H. Johnsen; John E. Major; Judy Loo; Donald McPhee
Abstract: Work from the 1970s indicated that, relative to either parent species, crosses between red spruce (Picea rubens Sarg.) and black spruce (Picea mariana (Mill.) B.S.P.) were inferior with respect to both growth and photosynthesis. We re-examined the hypothesis that there is negative heterosis in hybrids...
Full Text Available Tomato as a highly nutritious vegetable crop is widely grown in the world. Hybrid seed is preferably used for tomato production. Identification of superior hybrid combination is one of the most important steps in the hybrid breeding programs. Breeding of high yielding hybrids is expensive and involves testing large numbers of hybrid combinations in multi-environment trials. Successful prediction of heterosis from the genetic similarity of their parents based on molecular markers has been reported in several crops and can be very helpful in hybrid breeding. The present study was carried out to evaluate genetic divergent among tomato lines and to assess the relationship between genetic distance and heterosis among them. Thirty genotypes were examined for DNA polymorphism, using amplified fragment length polymorphisms (AFLPs. A total of 165 polymorphic variants were generated and genetic distances ranged from 0.04 to 0.23. Our result indicated that AFLP markers were successful in identification of polymorphism and genetic distances among tomato lines, but correlation of genetic distance based on AFLPs with mid-parent heterosis of yield, fruit weight, fruit number and fruit durability time was low and not useful for predicting heterosis in tomato genotypes.
A modified three way cross between the advanced generation of the tomato hybrids and an exotic variety with giant fruit size was initiated. The resulting hybrids were evaluated to determine the magnitude of heterosis in floral traits and fruit size. Highly significant differences were observed among the genotypes in all the ...
Nausheen; Farhatullah; Hussain, I.; Khalil, I.; Amanullah
An experiment was carried out at the University of Agriculture, Peshawar during 2012-13 using a set of F /sub 1/ hybrids of B. carinata for estimating heterosis and heterobeltiosis for important yield and quality parameters. The experimental material comprised of six B. carinata parental genotypes viz. C-88, C-89, C-90, C-93, C-95, C-97 and their 30 F /sub 1/ hybrids as direct crosses. A randomized complete block design with two replicates was used for field evaluation of 36 B. carinata genotypes (6 parental lines and 30 F /sub 1/ hybrids). Significant genetic variation was observed for primary branches plant /sup 1/, main raceme length, seed yield plant /sup 1/, oil and protein content among parents as well as F /sub 1/ hybrids. The highest heterosis and heterobeltiosis for primary branches (24.25 vs. 12.30 percentage) and main raceme length (37.31 vs. 22.93 percentage) was recorded for F /sub 1/ hybrids C-88 * C-93 and C-89 * C-97, respectively. Hybrid C-93 * C-90 had the highest positive heterosis for seed yield plant /sup 1/ (23.33 percentage). For protein content, the maximum heterosis was recorded for hybrid C-88 * C-89 (11.34 percentage). Similarly, F /sub 1/ hybrid C-88 * C-97 showed maximum heterosis for oil content (14.41 percentage). The highest heterobeltiosis was exhibited by hybrids C-90 * C-97 for seed yield (9.53 percentage) , C-89 * C-90 for oil content (7.61 percentage) and C-93 * C-97 for protein content (4.11 percentage). Based on high mean performance and heterotic values, aforemntioned hybrids and their corresponding parental lines will be exploited further for commercial hybrid production. (author)
Miller, Mark P.; Haig, Susan M.; Ballou, Jonathan D.; Steel, E. Ashley
Understanding and estimating inbreeding is essential for managing threatened and endangered wildlife populations. However, determination of inbreeding rates in natural populations is confounded by incomplete parentage information. We present an approach for quantifying inbreeding rates for populations with incomplete parentage information. The approach exploits knowledge of pedigree configurations that lead to inbreeding coefficients of F = 0.25 and F = 0.125, allowing for quantification of Pr(I|k): the probability of observing pedigree I given the fraction of known parents (k). We developed analytical expressions under simplifying assumptions that define properties and behavior of inbreeding rate estimators for varying values of k. We demonstrated that inbreeding is overestimated if Pr(I|k) is not taken into consideration and that bias is primarily influenced by k. By contrast, our new estimator, incorporating Pr(I|k), is unbiased over a wide range of values of kthat may be observed in empirical studies. Stochastic computer simulations that allowed complex inter- and intragenerational inbreeding produced similar results. We illustrate the effects that accounting for Pr(I|k) can have in empirical data by revisiting published analyses of Arabian oryx (Oryx leucoryx) and Red deer (Cervus elaphus). Our results demonstrate that incomplete pedigrees are not barriers for quantifying inbreeding in wild populations. Application of our approach will permit a better understanding of the role that inbreeding plays in the dynamics of populations of threatened and endangered species and may help refine our understanding of inbreeding avoidance mechanisms in the wild.
Schou, Mads Fristrup; Kristensen, Torsten Nygaard; Loeschcke, Volker
Environmental changes may stress organisms and stimulate an adaptive phenotypic response. Effects of inbreeding often interact with the environment and can decrease fitness of inbred individuals exposed to stress more so than that of outbred individuals. Such an interaction may stem from a reduced...... ability of inbred individuals to respond plastically to environmental stress; however, this hypothesis has rarely been tested. In this study, we mimicked the genetic constitution of natural inbred populations by rearing replicate Drosophila melanogaster populations for 25 generations at a reduced...... shape across temperatures in inbred compared to control populations. Given that the norms of reaction for the noninbred control populations are adaptive, we conclude that a reduced ability to induce an adaptive phenotypic response to temperature changes is not a general consequence of inbreeding...
Curik, I; Zechner, P; Sölkner, J; Achmann, R; Bodo, I; Dovc, P; Kavar, T; Marti, E; Brem, G
While the negative effects of inbreeding and reduced heterozygosity on fecundity and survival are well established, only a few investigations have been carried out concerning their influence on morphological traits. This topic is of particular interest for a small and closed population such as the Lipizzan horse. Thus, 27 morphological traits were measured in 360 Lipizzan mares and were regressed on the individual inbreeding coefficients, as well as on the individual heterozygosity and mean squared distances (mean d(2)) between microsatellite alleles within an individual. Both individual heterozygosity and mean d(2) were based on 17 microsatellite loci dispersed over 14 chromosomes. The results obtained by multivariate analysis reveal significant effects of stud (P morphological traits were observed in the Lipizzan horse.
Bierne, N; Tsitrone, A; David, P
Associative overdominance, the fitness difference between heterozygotes and homozygotes at a neutral locus, is classically described using two categories of models: linkage disequilibrium in small populations or identity disequilibrium in infinite, partially selfing populations. In both cases, only equilibrium situations have been considered. In the present study, associative overdominance is related to the distribution of individual inbreeding levels (i.e., genomic autozygosity). Our model integrates the effects of physical linkage and variation in inbreeding history among individual pedigrees. Hence, linkage and identity disequilibrium, traditionally presented as alternatives, are summarized within a single framework. This allows studying nonequilibrium situations in which both occur simultaneously. The model is applied to the case of an infinite population undergoing a sustained population bottleneck. The effects of bottleneck size, mating system, marker gene diversity, deleterious genomic mutation parameters, and physical linkage are evaluated. Bottlenecks transiently generate much larger associative overdominance than observed in equilibrium finite populations and represent a plausible explanation of empirical results obtained, for instance, in marine species. Moreover, the main origin of associative overdominance is random variation in individual inbreeding whereas physical linkage has little effect.
Liu, Yong-Jie; Gao, Shi-Qing; Tang, Yi-Miao; Gong, Jie; Zhang, Xiao; Wang, Yong-Bo; Zhang, Li-Ping; Sun, Ren-Wei; Zhang, Quan; Chen, Zhao-Bo; Wang, Xiang; Guo, Cai-Juan; Zhang, Sheng-Quan; Zhang, Feng-Ting; Gao, Jian-Gang; Sun, Hui; Yang, Wei-Bing; Wang, Wei-Wei; Zhao, Chang-Ping
Transcriptome analysis was carried out for wheat seedlings and spikes from hybrid Jingmai 8 and both inbred lines to unravel mechanisms underlying heterosis. Heterosis, known as one of the most successful strategies for increasing crop yield, has been widely exploited in plant breeding systems. Despite its great importance, the molecular mechanism underlying heterosis remains elusive. In the present study, RNA sequencing (RNA-seq) was performed on the seedling and spike tissues of the wheat (Triticum aestivum) hybrid Jingmai 8 (JM8) and its homozygous parents to unravel the underlying mechanisms of wheat heterosis. In total, 1686 and 2334 genes were identified as differentially expressed genes (DEGs) between the hybrid and the two inbred lines in seedling and spike tissues, respectively. Gene Ontology analysis revealed that DEGs from seedling tissues were significantly enriched in processes involved in photosynthesis and carbon fixation, and the majority of these DEGs expressed at a higher level in JM8 compared to both inbred lines. In addition, cell wall biogenesis and protein biosynthesis-related pathways were also significantly represented. These results confirmed that a combination of different pathways could contribute to heterosis. The DEGs between the hybrid and the two inbred progenitors from the spike tissues were significantly enriched in biological processes related to transcription, RNA biosynthesis and molecular function categories related to transcription factor activities. Furthermore, transcription factors such as NAC, ERF, and TIF-IIA were highly expressed in the hybrid JM8. These results may provide valuable insights into the molecular mechanisms underlying wheat heterosis.
Eriksen, Stine Aistrup
Use of antidepressants is associated with an increased risk of fractures, and may be a result of both negative effects on the skeleton as well as increased risk of falling; however, the specific mechanisms are not yet known. Vitamin D play important roles for bone and muscle, and has previously...... shown positive effects in lowering the risk of osteoporosis and risk of falling. In addition, vitamin D may improve mental health, and deficiency of vitamin D is a common condition among patients suffering from depression. This thesis investigates bone and factors related to fall risk (including muscle...
Vardarajan, Badri N; Schaid, Daniel J; Reitz, Christiane; Lantigua, Rafael; Medrano, Martin; Jiménez-Velázquez, Ivonne Z; Lee, Joseph H; Ghani, Mahdi; Rogaeva, Ekaterina; St George-Hyslop, Peter; Mayeux, Richard P
Inbreeding can be associated with a modification of disease risk due to excess homozygosity of recessive alleles affecting a wide range of phenotypes. We estimated the inbreeding coefficient in Caribbean Hispanics and examined its effects on risk of late-onset Alzheimer disease. The inbreeding coefficient was calculated in 3,392 subjects (1,451 late-onset Alzheimer disease patients and 1,941 age-matched healthy controls) of Caribbean Hispanic ancestry using 177,997 nearly independent single-nucleotide polymorphisms from genome-wide array. The inbreeding coefficient was estimated using the excess homozygosity method with and without adjusting for admixture. The average inbreeding coefficient in Caribbean Hispanics without accounting for admixture was F = 0.018 (±0.048), suggesting a mating equivalent to that of second cousins or second cousins once removed. Adjusting for admixture from three parent populations, the average inbreeding coefficient was found to be 0.0034 (±0.019) or close to third-cousin mating. Inbreeding coefficient was a significant predictor of Alzheimer disease when age, sex, and APOE genotype were used as adjusting covariates (P = 0.03). The average inbreeding coefficient of this population is significantly higher than that of the general Caucasian populations in North America. The high rate of inbreeding resulting in increased frequency of recessive variants is advantageous for the identification of rare variants associated with late-onset Alzheimer disease.Genet Med 17 8, 639-643.
Islam, Md. Shofiqul
ryegrass for the development of improved varieties. During his PhD studies, Mohammad Shofiqul Islam studied the feasibility of developing novel hybrid breeding schemes based on cytoplasmic male sterility (CMS) systems in perennial ryegrass. He successfully completed the assembly and annotation of a male......-fertile perennial ryegrass mitochondrial genome, and identified candidate genes responsible for the CMS phenotype by comparing male-fertile and male-sterile mitochondrial genomes. His findings constitute a good basis for continuing research to produce hybrid grass varieties to address the future needs......, breeding activities have been carried out to improve the population and develop synthetic varieties. This does not fully exploit the potential of heterosis, however. Hybrid breeding is an alternative strategy and provides opportunities to fully exploit the genetically available heterosis in perennial...
Maciel, Gabriel M; Luz, José MQ; Campos, Saulo FB; Finzi, Rafael R; Azevedo, Breno NR
ABSTRACT High heterosis values can be obtained using hybrid okra seeds. However, despite high heterotic values, it is very difficult to produce hybrid okra seeds. The objective of this study was to evaluate an experimental methodology of hybridization. Two different methods of hybridization were used: traditional manual hybridization with complete emasculation followed by hand pollination (artificial) and, an experimental methodology, performing manual hybridization with incomplete emasculati...
Crossa, J; Gardner, C O; Mumm, R F
Thirteen maize (Zea mays L.) populations including five adapted, five adapted x exotic, two composites of adapted and exotic, and one exotic selected for adaptability were crossed in a diallel mating system. The parents and 78 crosses and nine check hybrids were evaluated for grain yield and plant height in five environments. The Gardner-Eberhart model Analysis II indicated that additive and nonadditive gene effects accounted for 60 and 40% of the total variation among populations, respectively, for grain yield and 86% and 14% of the total variation, respectively, for plant height. Components of heterosis were significant in the combined analysis for both traits. Adapted Corn Belt populations tended to have higher performance in crosses and greater values of variety heterosis than 50% adapted populations. 'Nebraska Elite Composite', 'Corn Belt' x 'Mexican', and 'Corn Belt' x 'Brazilian' showed high mean yields in crosses, however, they were not among those with high estimates of variety heterosis. One exotic population ('Tuxpeno' x 'Antigua Grupo 2') and three adapted populations ['307 Composite', 'NB(S1)C-3', and 'NK(S1)C-3'] might be combined together to form a high-yielding population. It may be possible to synthesize two useful populations for reciprocal recurrent selection by grouping 'Tuxpeno' x 'Antiqua Grupo 2', 'NB(S1)C-3', and 'NS(FS)LFW-8' into one population and 'NK(S1)C-3', 'Krug'x'Tabloncillo', and '307 Composite' in the other one.
Full Text Available Heritability, potential ratio, and heterosis of soybean (Glycine max [L.] Merrill resistance to soybean mosaic virus. The use of soybean cultivars with resistance to SMV is a way for controlling soybean mosaic disease. The objective of this research was to estimate the disease severity, the narrow sense heritability, potential ratio and heterosis of resistance character and number of pithy pods, number of healthy seeds, and healthy seeds weight per plant of ten F1 populations of soybean crossing result to SMV infection. The experiment was arranged in a randomized complete block design in two replications. Observed characters were disease severity, number of pithy pods, number of healthy seeds, and healthy seeds weight per plant. The result of this research showed that 1 the crossing combinations those which were resistant to SMV (lower disease severity were Yellow Bean x Tanggamus, Tanggamus x Orba, and Tanggamus x Taichung, 2 the narrow sense heritability of disease severity was included in medium criteria, 3 number of pithy pods belonged to high criteria, and 4 number of healthy seeds and healthy seeds weight per plant were included in low criteria. The crossing combinations that had low estimation value of heterosis and heterobeltiosis of resistance to SMV infection were Yellow Bean x Taichung, Bean x Tanggamus and Tanggamus x B3570. Disease severity or resistance to SMV is influenced by genetic and environmental factors.
Melchinger, A E; Lee, M; Lamkey, K R; Hallauer, A R; Woodman, W L
Changes that may have occurred over the past 50 years of hybrid breeding in maize (Zea maize L.) with respect to heterosis for yield and heterozygosity at the molecular level are of interest to both maize breeders and quantitative geneticists. The objectives of this study were twofold: The first, to compare two diallels produced from six older maize inbreds released in the 1950's and earlier and six newer inbreds released during the 1970's with respect to (a) genetic variation for restriction fragment length polymorphisms (RFLPs) and (b) the size of heterosis and epistatic effects, and the second, to evaluate the usefulness of RFLP-based genetic distance measures in predicting heterosis and performance of single-cross hybrids. Five generations (parents, F1; F2, and backcrosses) from the 15 crosses in each diallel were evaluated for grain yield and yield components in four Iowa environments. Genetic effects were estimated from generation means by ordinary diallel analyses and by the Eberhart-Gardner model. Newer lines showed significantly greater yield for inbred generations than did older lines but smaller heterosis estimates. In most cases, estimates of additive x additive epistatic effects for yield and yield components were significantly positive for both groups of lines. RFLP analyses of inbred lines included two restriction enzymes and 82 genomic DNA clones distributed over the maize genome. Eighty-one clones revealed polymorphisms with at least one enzyme. In each set, about three different RFLP variants were typically found per RFLP locus. Genetic distances between inbred lines were estimated from RFLP data as Rogers' distance (RD), which was subdivided into general (GRD) and specific (SRD) Rogers' distances within each diallel. The mean and range of RDs were similar for the older and newer lines, suggesting that the level of heterozygosity at the molecular level had not changed. GRD explained about 50% of the variation among RD values in both sets. Cluster
Trotta, Vincenzo; Cavicchi, Sandro; Guerra, Daniela
Inbreeding is expected to increase the variability in size and shape within populations. The distinct effects of inbreeding on size and shape suggest that they are governed by different developmental pathways. One unresolved question is whether the non-allometric shape component is partially unco...
Horta, Hugo; Sato, Machi; Yonezawa, Akiyoshi
This study analyses why and how academic inbreeding as a recruitment practice continues to prevail in Japan, a country with a mature higher education system, where high rates of academic inbreeding endure in most of the research-oriented universities in spite of several higher education reforms. Based on a qualitative analysis, we disclose three…
Pedigree information on the registered South African Ayrshire (n = 47 116), Guernsey (n = 18 766), Holstein (n = 892 458) and Jersey (n = 314 403) breeds was analyzed to determine the rate of inbreeding and effective population sizes for the period 1960 to 2003. Inbreeding coefficients were calculated using the Animal ...
Pearcy, M; Hardy, O; Aron, S
Thelytokous parthenogenesis, that is, the production of diploid daughters from unfertilized eggs, may involve various cytological mechanisms, each having a different impact on the genetic structure of populations. Here, we determined the cytological mechanism of thelytokous parthenogenesis and its impact on inbreeding in the ant Cataglyphis cursor, a species where queens use both sexual and asexual reproduction to produce, respectively, workers and new queens. It has been suggested that thelytokous parthenogenesis in C. cursor might have been selected for to face high queen mortality and, originally, to allow workers to replace the queen when she passes away. We first determined the mode of thelytokous parthenogenesis by comparing the rate of transition to homozygosity at four highly polymorphic loci to expectations under the different modes of parthenogenesis. Our data show that thelytoky is achieved through automictic parthenogenesis with central fusion. We then estimated the proportion of colonies headed by worker-produced queens in a natural population. We designed a model linking the observed homozygosity in queens to the proportion of queens produced by workers, based on the assumption that (i) parthenogenesis is automictic with central fusion and (ii) queen lineage is asexually produced, resulting in an increase of the inbreeding over generations, whereas workers are sexually produced and therefore not inbred. Our results indicate that more than 60% of the colonies should be headed by a worker-produced queen, suggesting that queen's lifespan is low in this species.
Dipierri, José; Rodríguez-Larralde, Alvaro; Barrai, Italo; Camelo, Jorge López; Redomero, Esperanza Gutiérrez; Rodríguez, Concepción Alonso; Ramallo, Virginia; Bronberg, Rubén; Alfaro, Emma
Population isolates are an important tool in identifying and mapping genes of Mendelian diseases and complex traits. The geographical identification of isolates represents a priority from a genetic and health care standpoint. The purpose of this study is to analyze the spatial distribution of consanguinity by random isonymy (F ST) in Argentina and its relationship with the isolates previously identified in the country. F ST was estimated from the surname distribution of 22.6 million electors registered for the year 2001 in the 24 provinces, 5 geographical regions, and 510 departments of the country. Statistically significant spatial clustering of F ST was determined using the SaTScan V5.1 software. F ST exhibited a marked regional and departamental variation, showing the highest values towards the North and West of Argentina. The clusters of high consanguinity by random isonymy followed the same distribution. Recognized Argentinean genetic isolates are mainly localized at the north of the country, in clusters of high inbreeding. Given the availability of listings of surnames in high-capacity storage devices for different countries, estimating F ST from them can provide information on inbreeding for all levels of administrative subdivisions, to be used as a demographic variable for the identification of isolates within the country for public health purposes.
Brown, M.E.; Converse, Sarah; Chandler, Jane N.; Crosier, A. L.; Lynch, W.; Wildt, D.E.; Keefer, C. L.; Songsasen, Nucharin
All living whooping cranes (Grus americana) are descended from 16 or fewer birds that remained alive in the early 1940s, a bottleneck that puts the species at potential risk for inbreeding depression. Although AI is commonly used in the management of the captive population of this species, little is known about seminal traits or factors affecting sperm quality in the whooping crane. In the present study, semen samples were collected from 29 adult males (age 3–27 years) during the early (March), mid (April) and late (May) breeding season over 2 consecutive years. The effects of donor age, time within reproductive season and level of inbreeding on seminal characteristics were analysed using regression and information–theoretic model selection. Only time within reproductive season significantly affected seminal traits, with total numbers of spermatozoa and proportions of pleiomorphisms increasing across the season. We conclude that, even with a highly restricted number of founders, there is no discernible influence of inbreeding (at the levels described) on sperm output or quality. Furthermore, although there is variance in seminal quality, the whooping crane produces significant numbers of motile spermatozoa throughout the breeding season, similar to values reported for the greater sandhill crane (Grus canadensis tabida).
Severns, Paul M; Liston, Aaron; Wilson, Mark V
Small population size, genetic diversity, and spatial patterns of vegetative spread are important aspects to consider when managing populations of rare clonal plant species. We used 5 variable nuclear simple sequence repeat nDNA loci to determine the extent of genet rhizome spread, examine the possibility of very small population sizes, and project how Bombus spp. (bumblebee) foraging may impact selfing (through geitonogamy) for a threatened lupine (Lupinus oreganus Heller) that sprawls through nonadventitious rhizomes. Genotyping identified 1 genet (27 × 13 m) that dominated about 30% of a study site, whereas 15 genets spread a maximum average distance of about 5.5 m (range 1.6 -27.1 m) and appeared to be well integrated with intervening genets. We found unexpectedly high genotype diversity, no evidence of a recent genetic bottleneck, and 5 of 6 patches had mean fixation index values that were near Hardy-Weinberg Equilibrium expectations. If the median maximum Bombus foraging distance observed in lupine patches (1.2 m) occurred within genotyped populations, a typical foraging flight would have >80% chance of occurring between different genets. Our study demonstrates that inferences associated with clonality, small population size, and inbreeding depression should be directly evaluated for rare vegetatively spreading plants.
Venu, R C; Ma, Jianbing; Jia, Yulin; Liu, Guangjie; Jia, Melissa H; Nobuta, Kan; Sreerekha, M V; Moldenhauer, Karen; McClung, Anna M; Meyers, Blake C; Wang, Guo-Liang
To identify the genes responsible for yield related traits, and heterosis, massively parallel signature sequencing (MPSS) libraries were constructed from leaves, roots and meristem tissues from the two parents, 'Nipponbare' and '93-11', and their F1 hybrid. From the MPSS libraries, 1-3 million signatures were obtained. Using cluster analysis, commonly and specifically expressed genes in the parents and their F1 hybrid were identified. To understand heterosis in the F1 hybrid, the differentially expressed genes in the F1 hybrid were mapped to yield related quantitative trait loci (QTL) regions using a linkage map constructed from 131 polymorphic simple sequence repeat markers with 266 recombinant inbred lines derived from a cross between Nipponbare and 93-11. QTLs were identified for yield related traits including days to heading, plant height, plant type, number of tillers, main panicle length, number of primary branches per main panicle, number of kernels per main panicle, total kernel weight per main panicle, 1000 grain weight and total grain yield per plant. Seventy one QTLs for these traits were mapped, of which 3 QTLs were novel. Many highly expressed chromatin-related genes in the F1 hybrid encoding histone demethylases, histone deacetylases, argonaute-like proteins and polycomb proteins were located in these yield QTL regions. A total of 336 highly expressed transcription factor (TF) genes belonging to 50 TF families were identified in the yield QTL intervals. These findings provide the starting genomic materials to elucidate the molecular basis of yield related traits and heterosis in rice.
R C Venu
Full Text Available To identify the genes responsible for yield related traits, and heterosis, massively parallel signature sequencing (MPSS libraries were constructed from leaves, roots and meristem tissues from the two parents, 'Nipponbare' and '93-11', and their F1 hybrid. From the MPSS libraries, 1-3 million signatures were obtained. Using cluster analysis, commonly and specifically expressed genes in the parents and their F1 hybrid were identified. To understand heterosis in the F1 hybrid, the differentially expressed genes in the F1 hybrid were mapped to yield related quantitative trait loci (QTL regions using a linkage map constructed from 131 polymorphic simple sequence repeat markers with 266 recombinant inbred lines derived from a cross between Nipponbare and 93-11. QTLs were identified for yield related traits including days to heading, plant height, plant type, number of tillers, main panicle length, number of primary branches per main panicle, number of kernels per main panicle, total kernel weight per main panicle, 1000 grain weight and total grain yield per plant. Seventy one QTLs for these traits were mapped, of which 3 QTLs were novel. Many highly expressed chromatin-related genes in the F1 hybrid encoding histone demethylases, histone deacetylases, argonaute-like proteins and polycomb proteins were located in these yield QTL regions. A total of 336 highly expressed transcription factor (TF genes belonging to 50 TF families were identified in the yield QTL intervals. These findings provide the starting genomic materials to elucidate the molecular basis of yield related traits and heterosis in rice.
Venu, R. C.; Ma, Jianbing; Jia, Yulin; Liu, Guangjie; Jia, Melissa H.; Nobuta, Kan; Sreerekha, M. V.; Moldenhauer, Karen; McClung, Anna M.; Meyers, Blake C.; Wang, Guo-Liang
To identify the genes responsible for yield related traits, and heterosis, massively parallel signature sequencing (MPSS) libraries were constructed from leaves, roots and meristem tissues from the two parents, ‘Nipponbare’ and ‘93-11’, and their F1 hybrid. From the MPSS libraries, 1–3 million signatures were obtained. Using cluster analysis, commonly and specifically expressed genes in the parents and their F1 hybrid were identified. To understand heterosis in the F1 hybrid, the differentially expressed genes in the F1 hybrid were mapped to yield related quantitative trait loci (QTL) regions using a linkage map constructed from 131 polymorphic simple sequence repeat markers with 266 recombinant inbred lines derived from a cross between Nipponbare and 93-11. QTLs were identified for yield related traits including days to heading, plant height, plant type, number of tillers, main panicle length, number of primary branches per main panicle, number of kernels per main panicle, total kernel weight per main panicle, 1000 grain weight and total grain yield per plant. Seventy one QTLs for these traits were mapped, of which 3 QTLs were novel. Many highly expressed chromatin-related genes in the F1 hybrid encoding histone demethylases, histone deacetylases, argonaute-like proteins and polycomb proteins were located in these yield QTL regions. A total of 336 highly expressed transcription factor (TF) genes belonging to 50 TF families were identified in the yield QTL intervals. These findings provide the starting genomic materials to elucidate the molecular basis of yield related traits and heterosis in rice. PMID:24743656
Full Text Available Evaluated was effect of mating (random vs. maximum avoidance of inbreeding under BLUP EBV selection strategy. Existing population structure was under Monte Carlo stochastic simulation analyzed from the point to minimize increase of inbreeding. Maximum avoidance of inbreeding under BLUP selection resulted into comparable increase of inbreeding then random mating in average of 10 generation development. After 10 generations of simulation of mating strategy was observed ΔF= 6,51 % (2 sires, 5,20 % (3 sires, 3,22 % (4 sires resp. 2,94 % (5 sires. With increased number of sires selected, decrease of inbreeding was observed. With use of 4, resp. 5 sires increase of inbreeding was comparable to random mating with phenotypic selection. For saving of genetic diversity and prevention of population loss is important to minimize increase of inbreeding in small populations. Classical approach was based on balancing ratio of sires and dams in mating program. Contrariwise in the most of commercial populations small number of sires was used with high mating ratio.
Full Text Available Se estimó la media y la heterosis de la longevidad en obreras de abejas Apis mellifera. El expe-rimento fue desarrollado en el Apiario del Departamento de Genética de la Facultad de Medi-cina de la USP-Ribeirão Preto-Brasil y en Jaboticabal-SP, de 03/1997 a 05/1999. Seleccionamos 8 matrices inseminadas del apiário-USP (2africanizadas, 2italianas, 2cárnicasy 2italianas*cárnicos y 2 matrices (grupo-testigo de abejas Africanizadas-Silvestres.
This paper begins with the overthrow of the concept of combining ability in crossbreeding by the concept of heritability. The reason is that general combining ability changes with the number and kind of pure strains in the foundation stock and hence special combining ability changes also, so that work with different kinds of pure strains in the foundation stock cannot be compared. Hence combining ability is useless as a parameter to predict the amount of heterosis expected in the next generation. On the other hand, since each cross has a separate heritability, it can be applied to a cross population just as successfully as in purebreeding. Since the same concept holds in both cases, resort to any other concept would be superfluous. That's why combining ability must be rejected. Another reason (not given in the full text) is, an infinite number of pure strains would be required in the foundation stock for its results to be comparable with those of the heritability theory, which disposes of its utility altogether. The main content of the thesis is then the centennial enigma of heterosis can be resolved by Descarte's theoretic method of deduction. Accordingly we start from the definition of heterosis. [formula: see text] where H is heterosis, F1 is the first generation offspring, MP is the mean of the parents or midparent, and from the use of a binomial random variable and its extension to the multinomial case derive the basic relations of heterosis with its components. Starting with second degree statistics, we obtain [formula: see text] where V and cov stand for variance and covariance. The equations of heterosis are [formula: see text] where N is number of genes controlling a trait, a = (Pi - Pj)/2, d is deviation from midparent, while the variance components are all indicated by their names under the respective terms. It turns out that all these can be easily computed from the data so that the problem becomes a simple one which any college student may solve. In
Rabon, David R; Waddell, William
Captive-breeding programs have been widely used in the conservation of imperiled species, but the effects of inbreeding, frequently expressed in traits related to fitness, are nearly unavoidable in small populations with few founders. Following its planned extirpation in the wild, the endangered red wolf (Canis rufus) was preserved in captivity with just 14 founders. In this study, we evaluated the captive red wolf population for relationships between inbreeding and reproductive performance and fitness. Over 30 years of managed breeding, the level of inbreeding in the captive population has increased, and litter size has declined. Inbreeding levels were lower in sire and dam wolves that reproduced than in those that did not reproduce. However, there was no difference in the inbreeding level of actual litters and predicted litters. Litter size was negatively affected by offspring and paternal levels of inbreeding, but the effect of inbreeding on offspring survival was restricted to a positive influence. There was no apparent relationship between inbreeding and method of rearing offspring. The observable effects of inbreeding in the captive red wolf population currently do not appear to be a limiting factor in the conservation of the red wolf population. Additional studies exploring the extent of the effects of inbreeding will be required as inbreeding levels increase in the captive population.
Leimu, Roosa; Vergeer, Philippine; Angeloni, Francesco; Ouborg, N Joop
Habitat fragmentation and climate change are recognized as major threats to biodiversity. The major challenge for present day plant populations is how to adapt and cope with altered abiotic and biotic environments caused by climate change, when at the same time adaptive and evolutionary potential is decreased as habitat fragmentation reduces genetic variation and increases inbreeding. Although the ecological and evolutionary effects of fragmentation and climate change have been investigated separately, their combined effects remained largely unexplored. In this review, we will discuss the individual and joint effects of habitat fragmentation and climate change on plants and how the abilities and ways in which plants can respond and cope with climate change may be compromised due to habitat fragmentation.
Lázaro José Chaves
Full Text Available This study aimed to evaluate QPM populations and their crosses for grain oil content to determine theheterosis and its components. Ninety-six hybrids and their 21 parents were analyzed and separated in the groups dent andflint, in the partial diallelic/diallel intergroup scheme. The oil content was extracted from dry matter by the Soxhlet method inthree replicates for each genotypic material and attained mean values of 5.04g 100g-1 and 4.78g 100g-1, respectively, in thegroups dent and flint. Among the hybrid crosses, CMS 456 x CMS 463 (6.84g 100g-1 presented the highest value. Althoughthe average heterosis (-9.83% indicates average dominance of the alleles for low oil content, combinations with positive totalheterosis were observed. In this sense, the best populations under the focus of improvement for high oil content were ZQP101and ZQP103, both of the dent group, and CMS52, BR473, CMS455c and CMS465 of the flint group. Hence, it was concludedthat there is genetic variability and significant heterosis in the genotypes under study.
Full Text Available One effort for improving the productivity of Indonesian local ducks in particular as a meat types is by crossing among the local ducks. Crossbreeding is a fast breeding program for improving some commercial traits. Crossing between two lines or different breed are often used in production systems to utilized the advantage of heterosis (hybrid vigor. Crossbreeding is expected to produce new synthetic strains of duck that perform better than their parents. This study aims to utilize the heterosis and determine best cross, and to study the performance changes due to crossbreeding. The statistical design used in this study was a randomized complete design (RCD consisting of 4 treatments with 6 replications, each replication consisting of five ducks. The treatments used were the crossing of the pure Cihateup ♂ x Cihateup ♀ (CC, line Alabio ♂ x Alabio ♀ (AA, Alabio ♂ x Cihateup ♀ (AC cross as well as Cihateup ♂ x Alabio ♀ (CA cross. This study using male ducklings first hybrid (F1. The results show that the CA is better than AC in the final live weight (7.05%, weight gain (7.32%, carcass weight (9.24% and carcass yield (2.55%. Fleshy carcass cuts such as breast meat of AA (6.13% is better when compared to the others, but the highest percentage of meat percentage of the thigh is the AC (10.13%. Duck crossesing CA possess superior properties more and economic value compared with the duck AC.
Full Text Available Heterosis has been mostly used in hot pepper breeding and production, but the molecular basis of heterosis has not been extensively studied. In this study, comparative transcriptomes analysis of parental lines (D6, D7 and F1 hybrids (D6×D7 and D7×D6 was performed. A total of 0.6 billion raw reads, and 0.44 billion high-quality reads were obtained after the filtering process. Statistical analysis of genes with presence/deletion variations showed that, there were 1068 (6.20% and 780 (4.56% genes in the "single parent express consistent type" in the direct (D6×D7 and reciprocal (D7×D6 F1 hybrids, respectively. More genes fit into the non-additive expression type in two F1 hybrids compared to the parents, and less than 8% of the genes belong to the additive expression type. 66.08% in direct and 62.96% in reciprocal F1 hybrids belong to the epistatic dominance expression pattern. There were more differentially expressed genes (DEGs between the two parental lines (351 than between the two hybrids (17. The results of gene ontology (GO analysis showed that there were obvious differences in electron transmission and photorespiration between two F1 hybrids. GO terms for regulating plant hypersensitive responses, and MAPK pathways were only enriched in the direct hybrid (D6×D7.
Full Text Available Deleterious alleles have long been proposed to play an important role in patterning phenotypic variation and are central to commonly held ideas explaining the hybrid vigor observed in the offspring of a cross between two inbred parents. We test these ideas using evolutionary measures of sequence conservation to ask whether incorporating information about putatively deleterious alleles can inform genomic selection (GS models and improve phenotypic prediction. We measured a number of agronomic traits in both the inbred parents and hybrids of an elite maize partial diallel population and re-sequenced the parents of the population. Inbred elite maize lines vary for more than 350,000 putatively deleterious sites, but show a lower burden of such sites than a comparable set of traditional landraces. Our modeling reveals widespread evidence for incomplete dominance at these loci, and supports theoretical models that more damaging variants are usually more recessive. We identify haplotype blocks using an identity-by-decent (IBD analysis and perform genomic prediction analyses in which we weigh blocks on the basis of complementation for segregating putatively deleterious variants. Cross-validation results show that incorporating sequence conservation in genomic selection improves prediction accuracy for grain yield and other fitness-related traits as well as heterosis for those traits. Our results provide empirical support for an important role for incomplete dominance of deleterious alleles in explaining heterosis and demonstrate the utility of incorporating functional annotation in phenotypic prediction and plant breeding.
Yang, Jinliang; Mezmouk, Sofiane; Baumgarten, Andy; Buckler, Edward S; Guill, Katherine E; McMullen, Michael D; Mumm, Rita H; Ross-Ibarra, Jeffrey
Deleterious alleles have long been proposed to play an important role in patterning phenotypic variation and are central to commonly held ideas explaining the hybrid vigor observed in the offspring of a cross between two inbred parents. We test these ideas using evolutionary measures of sequence conservation to ask whether incorporating information about putatively deleterious alleles can inform genomic selection (GS) models and improve phenotypic prediction. We measured a number of agronomic traits in both the inbred parents and hybrids of an elite maize partial diallel population and re-sequenced the parents of the population. Inbred elite maize lines vary for more than 350,000 putatively deleterious sites, but show a lower burden of such sites than a comparable set of traditional landraces. Our modeling reveals widespread evidence for incomplete dominance at these loci, and supports theoretical models that more damaging variants are usually more recessive. We identify haplotype blocks using an identity-by-decent (IBD) analysis and perform genomic prediction analyses in which we weigh blocks on the basis of complementation for segregating putatively deleterious variants. Cross-validation results show that incorporating sequence conservation in genomic selection improves prediction accuracy for grain yield and other fitness-related traits as well as heterosis for those traits. Our results provide empirical support for an important role for incomplete dominance of deleterious alleles in explaining heterosis and demonstrate the utility of incorporating functional annotation in phenotypic prediction and plant breeding.
Groszmann, Michael; Gonzalez-Bayon, Rebeca; Lyons, Rebecca L; Greaves, Ian K; Kazan, Kemal; Peacock, W James; Dennis, Elizabeth S
Plant hybrids are extensively used in agriculture to deliver increases in yields, yet the molecular basis of their superior performance (heterosis) is not well understood. Our transcriptome analysis of a number of Arabidopsis F1 hybrids identified changes to defense and stress response gene expression consistent with a reduction in basal defense levels. Given the reported antagonism between plant immunity and growth, we suggest that these altered patterns of expression contribute to the greater growth of the hybrids. The altered patterns of expression in the hybrids indicate decreases to the salicylic acid (SA) biosynthesis pathway and increases in the auxin [indole-3-acetic acid (IAA)] biosynthesis pathway. SA and IAA are hormones known to control stress and defense responses as well as plant growth. We found that IAA-targeted gene activity is frequently increased in hybrids, correlating with a common heterotic phenotype of greater leaf cell numbers. Reduced SA concentration and target gene responses occur in the larger hybrids and promote increased leaf cell size. We demonstrated the importance of SA action to the hybrid phenotype by manipulating endogenous SA concentrations. Increasing SA diminished heterosis in SA-reduced hybrids, whereas decreasing SA promoted growth in some hybrids and phenocopied aspects of hybrid vigor in parental lines. Pseudomonas syringae infection of hybrids demonstrated that the reductions in basal defense gene activity in these hybrids does not necessarily compromise their ability to mount a defense response comparable to the parents.
Full Text Available Six maize inbred lines for which we assumed that have a similar genetic background were selected for the study. Inbred lines were crossed according to incomplete diallel design and fifteen hybrid combinations were obtained. Hybrid combinations and their parental lines were used in our study. The objective of the study was to examine genetic polymorphism of parental lines, as well as to determine relationships between SSR genetic distance and values of high parent heterosis and specific combining abilities for grain yield. By using 19 SSR primers we classified inbred lines in two groups. First cluster consists of inbred lines L1, L2, L3, L4 and L5, while inbred line L6 formed second cluster, indicating different heterotic background in comparison to the other five inbred lines. The Spearman’s correlation coefficients between SSR based genetic distance and specific combining abilities for grain yield had a value of (r=0,53*, while positive correlation were also found between genetic distance and high parent heterosis (r=0,57*. [Projekat Ministarstva nauke Republike Srbije, br. TR31068
Full Text Available The ovulatory shift modulates emotions related to female sexuality. Because fertility status only affects the individual's own opportunity cost, the adaptive value of this shift is expected to stem from self-regulation. To test this assumption we asked women to contemplate various inbreeding descriptions: 1 they themselves having sex with male relatives; 2 their sister having sex with their common male relatives; and 3 an unrelated woman having sex with her male relatives (in 1, but not 2 and 3, negative fitness consequences are affected by the participant's fertility. We dichotomized the dependent variable disgust (ceiling vs. non-ceiling and analyzed the interaction between fertility status and description type. The ovulatory shift was stronger in descriptions where they themselves were described as engaging in inbreeding. A smaller increase was also found in reactions to others engaging in inbreeding. We explain the latter effect as due to self-reflection.
Antfolk, Jan; Lieberman, Debra; Albrecht, Anna; Santtila, Pekka
The ovulatory shift modulates emotions related to female sexuality. Because fertility status only affects the individual's own opportunity cost, the adaptive value of this shift is expected to stem from self-regulation. To test this assumption we asked women to contemplate various inbreeding descriptions: 1) they themselves having sex with male relatives; 2) their sister having sex with their common male relatives; and 3) an unrelated woman having sex with her male relatives (in 1, but not 2 and 3, negative fitness consequences are affected by the participant's fertility). We dichotomized the dependent variable disgust (ceiling vs. non-ceiling) and analyzed the interaction between fertility status and description type. The ovulatory shift was stronger in descriptions where they themselves were described as engaging in inbreeding. A smaller increase was also found in reactions to others engaging in inbreeding. We explain the latter effect as due to self-reflection.
Shang, Lianguang; Wang, Yumei; Cai, Shihu; Wang, Xiaocui; Li, Yuhua; Abduweli, Abdugheni; Hua, Jinping
Based on two recombinant inbred line (RIL) populations, two corresponding backcross (BC) populations were constructed to elucidate the genetic basis of heterosis in Upland cotton (Gossypium hirsutum L.). The yield, and yield components, of these populations were evaluated in three environments. At the single-locus level, 78 and 66 quantitative trait loci (QTL) were detected using composite interval mapping in RIL and BC populations, respectively, and 29 QTL were identified based on mid-parental heterosis (MPH) data of two hybrids. Considering all traits together, a total of 50 (64.9%) QTL with partial dominance effect, and 27 (35.1%) QTL for overdominance effect were identified in two BC populations. At the two-locus level, 120 and 88 QTL with main effects (M-QTL), and 335 and 99 QTL involved in digenic interactions (E-QTL), were detected by inclusive composite interval mapping in RIL and BC populations, respectively. A large number of QTL by environment interactions (QEs) for M-QTL and E-QTL were detected in three environments. For most traits, average E-QTL explained a larger proportion of phenotypic variation than did M-QTL in two RIL populations and two BC populations. It was concluded that partial dominance, overdominance, epistasis, and QEs all contribute to heterosis in Upland cotton, and that partial dominance resulting from single loci and epistasis play a relatively more important role than other genetic effects in heterosis in Upland cotton. Copyright © 2016 Shang et al.
Shang, Lianguang; Liang, Qingzhi; Wang, Yumei; Zhao, Yanpeng; Wang, Kunbo; Hua, Jinping
QTL mapping based on backcross and RIL populations suggests that epistasis together with partial dominance, over-dominance and their environmental interactions of QTLs play an important role in yield heterosis in upland cotton. A backcross population (BC) was constructed to explore the genetic basis of heterosis in upland cotton (Gossypium hirsutum L.). For yield and yield components, recombinant inbred line (RIL) and BC populations were evaluated simultaneously at three different locations. A total of 35 and 30 quantitative trait loci (QTLs) were detected based on the RILs and BC data, respectively. Six (16.7 %) additive QTLs, 19 (52.8 %) partial dominant QTLs and 11 (30.6 %) over-dominant QTLs were detected by single-locus analysis using composite interval mapping in BC population. QTLs detected for mid-parent heterosis (MPH) were mostly related to those detected in the BC population. No significant correlation was found between marker heterozygosity and performance. It indicated that heterozygosity was not always favorable for performance. Two-locus analysis revealed 46, 25 and 12 QTLs with main effects (M-QTLs), and 55, 63 and 33 QTLs involved in digenic interactions (E-QTLs) were detected for yield and yield components in RIL, BC and MPH, respectively. A large number of M-QTLs and E-QTLs showed QTL by environment interactions (QEs) in three environments. These results suggest that epistasis together with partial dominance, over-dominance and QEs all contribute to yield heterosis in upland cotton.
Norberg, Elise; Sørensen, Lydia Henriette; Byskov, Kenneth
Use of systematic crossbreeding in dairy cattle has been increasing the last decades. The aim of this study was to estimate the effect of breed and heterosis on protein yield (PY), somatic cell score (SCS) and days from calving to first insemination (CFI) in first lactation crosses between Danish...
Vuylsteke, M.; Kuiper, M.; Stam, P.
In this paper, a novel approach towards the prediction of hybrid performance and heterosis is presented. Here, we describe an approach based on: (i) the assessment of associations between AFLPÒ22 AFLPÒ is a registered trademark of Keygene N.V. ,33 The methylation AFLPÒ method is subject to a patent
Perez, B C; Balieiro, J C C; Ventura, R V; Bruneli, F A T; Peixoto, M G C D
Inbreeding has been associated with the impairment of reproductive performance in many cattle breeds. Although the usage of reproductive biotechnologies has been increasing in bovine populations, not much attention has been given to the impact of inbreeding over cow's performance on artificial reproduction. The objective of this study was to estimate the impact of inbreeding on in vitro embryo production in a Guzerá breed population. The inbreeding coefficient (F), calculated as half of the co-ancestry of the individual's parents, was used as an estimate of inbreeding. The inbreeding coefficients of the donor, sire (used on in vitro fertilization) and of the embryos were included, separately, in the proposed models either as classificatory or continuous variables (linear and quadratic effects). The percentage of non-inbred individuals (or embryos) and mean F of donors, embryos and sires were 29.38%; 35.76%; 42.86% and 1.98±2.68; 1.32±3.13; 2.08±2.79, respectively. Two different models were considered, one for oocyte production traits and other for embryo production traits. The increase of F of the donor significantly (P0.05) effects were observed for the sire (father of the embryos) inbreeding coefficient over the traits analysed. Embryo's F influenced (Pproduction may, in the long-term, have negative implications on the number of embryos obtained per cow and increase the relative costs of the improvement programmes based on this technology. High levels of inbreeding should be avoided when selecting Guzerá female donors and planning in vitro fertilization mating.
Full Text Available The nature and magnitude of heterosis and combining ability was studied in 18 F1 hybrids involving three CMS lines and six testers using line × tester analysis. The analysis of variance for combining ability of all the traits showed that variances due to treatments, parents, hybrids were highly significant. The line ‘CRMS 32A’ and testers viz. ‘Super rice-8’, ‘R 1099-2569-1-1’ and ‘Jitpiti’ were identified as good general combiners. The significant differences between lines x testers interaction indicates that SCA attributed heavily in the expression of these traits and demonstrates the importance of dominance or non additive variances for all the traits. The hybrid ‘CRMS 32A’/‘R 1099-2569-1-1’ and ‘APMS 6A’/‘Super rice-8’ were promising for grain yield. The magnitude of relative heterosis, heterobeltiosis and standard heterosis were also estimated for different characters. A high degree of relative heterosis was observed for grain yield (20.45- 82.37% in the hybrids viz., ‘CRMS 32A’/‘Super rice-8’, ‘APMS 6A’/‘Super rice-8’, ‘APMS 6A’/‘Jitpiti’ and ‘CRMS 32A’/‘R 1099-2569-1-1’. While, a higher degree of: heterobeltiosis (13.60 -68.37% was observed for grain yield in the hybrids viz., ‘CRMS 32A’/‘Super rice-8’, ‘CRMS 32A’/‘R 1099-2569-1-1’, ‘APMS 6A’/’Super rice-8’ and ‘APMS 6A’/’Jitpiti’. A high degree of standard heterosis was observed for grain yield in the hybrid ‘CRMS 32A’/‘R 1099-2569-1-1’. The hybrid ‘CRMS 32A’/ ‘R 1099-2569-1-1’ recorded a high degree of relative heterosis (62.01%, heterobeltiosis (57.35% and standard heterosis (15.05 and 25.51% over check hybrids, ‘Mahamaya’ and ‘Indirasona’, respectively that can be tested on yield trials for its further testing over locations.
Leimu, Roosa; Kloss, Lena; Fischer, Markus
Pathogenesis-related proteins, chitinases (CHT) and β-1,3-glucanases (GLU), are stress proteins up-regulated as response to extrinsic environmental stress in plants. It is unknown whether these PR proteins are also influenced by inbreeding, which has been suggested to constitute intrinsic genetic stress, and which is also known to affect the ability of plants to cope with environmental stress. We investigated activities of CHT and GLU in response to inbreeding in plants from 13 Ragged Robin (Lychnis flos-cuculi) populations. We also studied whether activities of these enzymes were associated with levels of herbivore damage and pathogen infection in the populations from which the plants originated. We found an increase in pathogenesis-related protein activity in inbred plants from five out of the 13 investigated populations, which suggests that these proteins may play a role in how plants respond to intrinsic genetic stress brought about by inbreeding in some populations depending on the allele frequencies of loci affecting the expression of CHT and the past levels of inbreeding. More importantly, we found that CHT activities were higher in plants from populations with higher levels of herbivore or pathogen damage, but inbreeding reduced CHT activity in these populations disrupting the increased activities of this resistance-related enzyme in populations where high resistance is beneficial. These results provide novel information on the effects of plant inbreeding on plant-enemy interactions on a biochemical level.
Full Text Available Pathogenesis-related proteins, chitinases (CHT and β-1,3-glucanases (GLU, are stress proteins up-regulated as response to extrinsic environmental stress in plants. It is unknown whether these PR proteins are also influenced by inbreeding, which has been suggested to constitute intrinsic genetic stress, and which is also known to affect the ability of plants to cope with environmental stress. We investigated activities of CHT and GLU in response to inbreeding in plants from 13 Ragged Robin (Lychnis flos-cuculi populations. We also studied whether activities of these enzymes were associated with levels of herbivore damage and pathogen infection in the populations from which the plants originated. We found an increase in pathogenesis-related protein activity in inbred plants from five out of the 13 investigated populations, which suggests that these proteins may play a role in how plants respond to intrinsic genetic stress brought about by inbreeding in some populations depending on the allele frequencies of loci affecting the expression of CHT and the past levels of inbreeding. More importantly, we found that CHT activities were higher in plants from populations with higher levels of herbivore or pathogen damage, but inbreeding reduced CHT activity in these populations disrupting the increased activities of this resistance-related enzyme in populations where high resistance is beneficial. These results provide novel information on the effects of plant inbreeding on plant-enemy interactions on a biochemical level.
Full Text Available Abstract This study was designed to reveal any differences in effects of fast created versus total inbreeding on reproduction and body weights in mice. A line selected for large litter size for 124 generations (H and a control line (K maintained without selection for the same number of generations were crossed (HK and used as a basis for the experiment. Within the HK cross, full sib, cousin or random mating were practised for two generations in order to create new inbreeding (IBF at a fast rate. In the first generation of systematic mating, old inbreeding was regenerated in addition to creation of new inbreeding from the mating design giving total inbreeding (IBT. The number of pups born alive (NBA and body weights of the animals were then analysed by a model including both IBT and IBF. The IBT of the dam was in the present study found to reduce the mean NBA with -0.48 (± 0.22 (p F was -0.42 (± 0.27. For the trait NBA per female mated, the effect of IBT was estimated to be -0.45 (± 0.29 per 10% increase in the inbreeding coefficient and the effect of IBF was -0.90 (± 0.37 (p F of the dam could be found on sex-ratio and body weights at three and six weeks of age in a population already adjusted for IBT.
Lin, Zibei; Shi, Fan; Hayes, Ben J; Daetwyler, Hans D
Heuristic genomic inbreeding controls reduce inbreeding in genomic breeding schemes without reducing genetic gain. Genomic selection is increasingly being implemented in plant breeding programs to accelerate genetic gain of economically important traits. However, it may cause significant loss of genetic diversity when compared with traditional schemes using phenotypic selection. We propose heuristic strategies to control the rate of inbreeding in outbred plants, which can be categorised into three types: controls during mate allocation, during selection, and simultaneous selection and mate allocation. The proposed mate allocation measure GminF allocates two or more parents for mating in mating groups that minimise coancestry using a genomic relationship matrix. Two types of relationship-adjusted genomic breeding values for parent selection candidates ([Formula: see text]) and potential offspring ([Formula: see text]) are devised to control inbreeding during selection and even enabling simultaneous selection and mate allocation. These strategies were tested in a case study using a simulated perennial ryegrass breeding scheme. As compared to the genomic selection scheme without controls, all proposed strategies could significantly decrease inbreeding while achieving comparable genetic gain. In particular, the scenario using [Formula: see text] in simultaneous selection and mate allocation reduced inbreeding to one-third of the original genomic selection scheme. The proposed strategies are readily applicable in any outbred plant breeding program.
A. HUSSAIN, P. AKHTAR, S. ALI, M. YOUNAS1 AND M. SHAFIQ2
Full Text Available Pedigree records of 17250 Thalli sheep with 17030 lambings maintained at the Livestock Experiment Station, Rakh Ghulaman, Distt. Bhakkar, Pakistan during the period from 1975 to 2004 were utilized in the present study. Average values for birth weight, weights at 60 and 90 days of age, weaning weight and pre-weaning average daily gain were 4.11 ± 0.82, 11.58 ± 3.57, 14.92 ± 4.56, 18.95 ± 4.56 and 0.12 ± 0.04 kg, respectively. Coefficients of inbreeding ranged from 10.15 to 37.50 percent for 295 animals, being 1.70 percent of the flock. Inbreeding significantly (P<0.01 affected birth and 60 days weight. Birth weight and 60 days weight decreased by 0.051 and 0.048 kg for each 1 percent increase in the level of inbreeding. However, inbreeding had non significant effect on weight at 90 days of age, weaning weight and pre-weaning average daily gain. The regression values for these traits were 0.010, 0.083 and 0.105, respectively. It was concluded that inbreeding showed deleterious effects only in early stages of life but as the lambs grew older the effect of inbreeding on pre-weaning traits diminished.
Full Text Available Inbreeding has been one of central issues with regard to genetic quality of aquaculture species, including giant fresh water prawn (GFP. Conventional methods for the estimation of inbreeding level are available, such as pedigree analyses which requires a good pedigree record which, unfortunately, is rarely available. Likewise, microsatellite molecular markers commonly applied to obtain the coefficient inbreeding estimates are both laborious and expensive. Hence, an alternative method of inbreeding assessment which is relatively easy but reliable is in need. This study was aimed to explore the applicability of RAPD fingerprinting, which is known to be simple and affordable, to estimate inbreeding level of GFP population. Three GFP populations namely inbred, outbred, and farm populations with inbreeding level of 25%, 0%, and unknown, respectively, were genotyped using five polymorphic RAPD primers. The inbreeding levels mentioned within the first two populations were determined using pedigree analysis. RAPD banding patterns were then used to calculate band sharing index (BSI and inbreeding coefficient (F. Assessment of the applicability of inbreeding level estimates obtained by RAPD markers was performed by comparing them to those estimated by pedigree analysis. Results show that RAPD fingerprinting was capable of delineating populations differing in their inbreeding coefficients. The pattern resulted from molecular inbreeding coefficient within the inbred and outbred groups, was congruent with that shown by pedigree analysis, while the farm population showed closeness to the inbred group. While the accuracy of the estimate needs to be verified further, this study suggests that RAPD fingerprinting is applicable to estimate population inbreeding level, particularly due to its technical simplicity and cost affordability.
James H. Haido
Full Text Available Steel fiber is considered as the most commonly used constructional fibers in concrete structures. The formulation of new nonlinearities to predict the static performance of steel fiber concrete composite structures is considered essential. Present study is devoted to investigate the efficiency of utilizing heterosis finite elements analysis in static analysis of steel fibrous beams. New and simple material nonlinearities are proposed and used in the formulation of these elements. A computer program coded in FORTRAN was developed to perform current finite element static analysis with considering four cases of elements stiffness matrix determination. The results are compared with the experimental data available in literature in terms of central deflections, strains, and failure form, good agreement was found. Suitable outcomes have been observed in present static analysis with using of tangential stiffness matrix and stiffness matrix in second iteration of the load increment.
Saccheri, I J; Wilson, I J; Nichols, R A; Bruford, M W; Brakefield, P M
Polymorphic enzyme and minisatellite loci were used to estimate the degree of inbreeding in experimentally bottlenecked populations of the butterfly, Bicyclus anynana (Satyridae), three generations after founding events of 2, 6, 20, or 300 individuals, each bottleneck size being replicated at least four times. Heterozygosity fell more than expected, though not significantly so, but this traditional measure of the degree of inbreeding did not make full use of the information from genetic markers. It proved more informative to estimate directly the probability distribution of a measure of inbreeding, sigma2, the variance in the number of descendants left per gene. In all bottlenecked lines, sigma2 was significantly larger than in control lines (300 founders). We demonstrate that this excess inbreeding was brought about both by an increase in the variance of reproductive success of individuals, but also by another process. We argue that in bottlenecked lines linkage disequilibrium generated by the small number of haplotypes passing through the bottleneck resulted in hitchhiking of particular marker alleles with those haplotypes favored by selection. In control lines, linkage disequilibrium was minimal. Our result, indicating more inbreeding than expected from demographic parameters, contrasts with the findings of previous (Drosophila) experiments in which the decline in observed heterozygosity was slower than expected and attributed to associative overdominance. The different outcomes may both be explained as a consequence of linkage disequilibrium under different regimes of inbreeding. The likelihood-based method to estimate inbreeding should be of wide applicability. It was, for example, able to resolve small differences in sigma2 among replicate lines within bottleneck-size treatments, which could be related to the observed variation in reproductive viability.
Lefort-Buson, Marianne; Guillot-Lemoine, Brigitte; Dattée, Yvette
The paper deals with a comparison of different indicators of genetic divergence between rapeseed parental lines : the relationship coefficient defined by MALÈCOT the generalized distance D2 of Mahalanobis, and a new G2 parameter close to HANSON & CASAS' R2. The purpose of the authors is to discuss the advantages of their simultaneous use in the prediction of both heterosis values and F1 performances of hybrids from parental lines. Relationships between heterosis values and genetic distanc...
Full Text Available Combining ability and heterosis were estimated for ornamental and vegetative traits of four petunia (Petunia hybrida Hort. inbred lines viz. L5 (P1, L8 (P2, L11 (P3 and L17 (P4 and their diallel hybrids in horticultural research farm of Ferdowsi University of Mashhad, Iran in 2011. The measured traits were plant height at first flower, number of leaf to first flower, flower diameter, flower tube length, internode length, stem diameter, plant height at flowering stage, plant spreading, number of branches per plant, leaf length and width. The results of combining ability for all studied traits revealed that both additive and non-additive gene effects contributed to the inheritance of the traits. Estimates of general combining ability effects showed that parent P3 was a good general combiner for most of the studied traits. For flower diameter, hybrid combination P1 � P2 had the highest significant positive specific combining ability effects. Reciprocal effects were significant for all traits and hybrid combination P1 � P2 had the highest significant positive reciprocal effects for flower tube length and plant height. Heterosis was found significant relative to both the mid parent and batter parent for all traits. For flower diameter, the highest positive values of heterotic effects were recorded in hybrid combination P2 � P3 both relative to the parental mean (37.3% and relative to the better parent (33.9%. It is obvious that heterotic effects represent an important resource in hybrid breeding of petunia.
Full Text Available Combining ability and heterosis were estimated for ornamental and vegetative traits of four petunia (Petunia hybrida Hort. inbred lines viz. L5 (P1, L8 (P2, L11 (P3 and L17 (P4 and their diallel hybrids in horticultural research farm of Ferdowsi University of Mashhad, Iran in 2011. The measured traits were plant height at first flower, number of leaf to first flower, flower diameter, flower tube length, internode length, stem diameter, plant height at flowering stage, plant spreading, number of branches per plant, leaf length and width. The results of combining ability for all studied traits revealed that both additive and non-additive gene effects contributed to the inheritance of the traits. Estimates of general combining ability effects showed that parent P3 was a good general combiner for most of the studied traits. For flower diameter, hybrid combination P1 P2 had the highest significant positive specific combining ability effects. Reciprocal effects were significant for all traits and hybrid combination P1 P2 had the highest significant positive reciprocal effects for flower tube length and plant height. Heterosis was found significant relative to both the mid parent and batter parent for all traits. For flower diameter, the highest positive values of heterotic effects were recorded in hybrid combination P2 P3 both relative to the parental mean (37.3% and relative to the better parent (33.9%. It is obvious that heterotic effects represent an important resource in hybrid breeding of petunia.
Abul Kalam Azad Mohammad
Full Text Available In rabi season 2012, six diversed maize inbred lines were crossed in all possible combinations without reciprocals by using a half diallel mating design to obtain 15 single cross. Inbred parents and their F1 single crosses with a check were evaluated in rabi season 2013 to evaluate the role of general and specific combining ability and heterosis for some quantitative traits. Significant general combining ability variances was observed only for cob height and specific combining ability variances were observed for plant height, cob height, cob length, cob girth, number of kernels per cob, cob weight and hundred grain weight. The GCA/SCA ratio was less than unity for all studied traits except shelling percentage; this means that these traits are pre-dominantly controlled by non-additive gene action. Based on GCA estimates, it could be concluded that the best combiners were ML01, ML05 and ML29 inbred lines for most of the studied traits. This result indicated that these inbred lines could be considered as good combiners for improving these traits. Significant positive SCA effects were found for all studied traits except number of kernels per row and shelling percentage. Based on SCA effects, it could be concluded that the crosses ML01×ML02, ML02×ML05, ML02×ML29 and ML05×ML15 could be exploited by the maize breeders to increase maize yield. Three F1 hybrids such as ML02×ML15, ML02×ML29 and ML05×ML15 proved to be the outstanding hybrids to immediate further steps for commercial cultivation. In a conclusive decision the F1 hybrid, ML02×ML29 was the best combination as evaluated through combining ability and standard heterosis.
Jansson, M; Laikre, L
One problem in modern dogs is a high occurrence of physical diseases, defects and disorders. Many breeds exhibit physical problems that affect individual dogs throughout life. A potential cause of these problems is inbreeding that is known to reduce the viability of individuals. We investigated the possible correlation between recent inbreeding and health problems in dogs and used studbook data from 26 breeds provided by the Swedish Kennel Club for this purpose. The pedigrees date back to the mid-20th century and comprise 5-10 generations and 1 000-50 000 individuals per pedigree over our study period of 1980-2010. We compared levels of inbreeding and loss of genetic variation measured in relation to the number of founding animals during this period in the investigated dog breeds that we classified as 'healthy' (11 breeds) or 'unhealthy' (15) based on statistics on the extent of veterinary care obtained from Sweden's four largest insurance companies for pets. We found extensive loss of genetic variation and moderate levels of recent inbreeding in all breeds examined, but no strong indication of a difference in these parameters between healthy versus unhealthy breeds over this period. Thus, recent breeding history with respect to rate of inbreeding does not appear to be a main cause of poor health in the investigated dog breeds in Sweden. We identified both strengths and weaknesses of the dog pedigree data important to consider in future work of monitoring and conserving genetic diversity of dog breeds. © 2013 The Authors Journal of Animal Breeding and Genetics Published by Blackwell Verlag GmbH.
Ng, Danny W.-K.; Miller, Marisa; Yu, Helen H.; Huang, Tien-Yu; Kim, Eun-Deok; Lu, Jie; Xie, Qiguang; McClung, C. Robertson; Chen, Z. Jeffrey
Hybrid plants and animals often show increased levels of growth and fitness, a phenomenon known as hybrid vigor or heterosis. Circadian rhythms optimize physiology and metabolism in plants and animals. In plant hybrids and polyploids, expression changes of the genes within the circadian regulatory network, such as CIRCADIAN CLOCK ASSOCIATED1 (CCA1), lead to heterosis. However, the relationship between allelic CCA1 expression and heterosis has remained elusive. Here, we show a parent-of-origin effect on altered circadian rhythms and heterosis in Arabidopsis thaliana F1 hybrids. This parent-of-origin effect on biomass heterosis correlates with altered CCA1 expression amplitudes, which are associated with methylation levels of CHH (where H = A, T, or C) sites in the promoter region. The direction of rhythmic expression and hybrid vigor is reversed in reciprocal F1 crosses involving mutants that are defective in the RNA-directed DNA methylation pathway (argonaute4 and nuclear RNA polymerase D1a) but not in the maintenance methylation pathway (methyltransferase1 and decrease in DNA methylation1). This parent-of-origin effect on circadian regulation and heterosis is established during early embryogenesis and maintained throughout growth and development. PMID:24894042
Ng, Danny W-K; Miller, Marisa; Yu, Helen H; Huang, Tien-Yu; Kim, Eun-Deok; Lu, Jie; Xie, Qiguang; McClung, C Robertson; Chen, Z Jeffrey
Hybrid plants and animals often show increased levels of growth and fitness, a phenomenon known as hybrid vigor or heterosis. Circadian rhythms optimize physiology and metabolism in plants and animals. In plant hybrids and polyploids, expression changes of the genes within the circadian regulatory network, such as CIRCADIAN CLOCK ASSOCIATED1 (CCA1), lead to heterosis. However, the relationship between allelic CCA1 expression and heterosis has remained elusive. Here, we show a parent-of-origin effect on altered circadian rhythms and heterosis in Arabidopsis thaliana F1 hybrids. This parent-of-origin effect on biomass heterosis correlates with altered CCA1 expression amplitudes, which are associated with methylation levels of CHH (where H = A, T, or C) sites in the promoter region. The direction of rhythmic expression and hybrid vigor is reversed in reciprocal F1 crosses involving mutants that are defective in the RNA-directed DNA methylation pathway (argonaute4 and nuclear RNA polymerase D1a) but not in the maintenance methylation pathway (methyltransferase1 and decrease in DNA methylation1). This parent-of-origin effect on circadian regulation and heterosis is established during early embryogenesis and maintained throughout growth and development. © 2014 American Society of Plant Biologists. All rights reserved.
Nowak, Carsten; Jost, Daniel; Vogt, Christian; Oetken, Matthias; Schwenk, Klaus; Oehlmann, Joerg
Inbreeding and loss of genetic variation are considered to be major threats to small and endangered populations. The reduction of fitness due to inbreeding is believed to be more severe under stressful environmental conditions. We generated nine strains of the ecotoxicological model organism Chironomus riparius of different inbreeding levels in order to test the hypothesis that the inbreeding level and thus the degree of genome-wide homozygosity influences the life-history under cadmium exposure. Therefore, midge populations were exposed to a gradient of sediment-bound cadmium. The level of genetic variation in the used strains was assessed using microsatellite markers. In the life-cycle tests, inbreeding reduced fitness within C. riparius populations both under control and stressed conditions. However, differences between genetically diverse and impoverished strains were greatest at high cadmium exposure. Overall, inbreeding effects were not only dependent on cadmium concentrations in the sediment, but also on the life-history trait investigated. While some parameters where only affected by inbreeding, others were altered by both, inbreeding and cadmium. For the larval developmental time, a significant interaction was found between inbreeding and cadmium stress. While all strains showed a similar developmental time under control conditions, high rates of inbreeding led to a significantly delayed emergence time under high cadmium concentrations, resulting in longer generation periods and reduced population growth rates as population-relevant effects. The results show, that bioassays with C. riparius are affected by the level of inbreeding within Chironomus test strains. Pollution stress is therefore likely to affect the survival of rare and endangered populations more severe than that of large and genetically diverse ones
Luo, Junyuan; Wang, Peng; Yu, Sibin; Mou, Tongmin; Zheng, Xingfei; Hu, Zhongli
Background Combining ability effects are very effective genetic parameters in deciding the next phase of breeding programs. Although some breeding strategies on the basis of evaluating combining ability have been utilized extensively in hybrid breeding, little is known about the genetic basis of combining ability. Combining ability is a complex trait that is controlled by polygenes. With the advent and development of molecular markers, it is feasible to evaluate the genetic bases of combining ability and heterosis of elite rice hybrids through QTL analysis. Methodology/Principal Findings In the present study, we first developed a QTL-mapping method for dissecting combining ability and heterosis of agronomic traits. With three testcross populations and a BCRIL population in rice, biometric and QTL analyses were conducted for ten agronomic traits. The significance of general combining ability and special combining ability for most of the traits indicated the importance of both additive and non-additive effects on expression levels. A large number of additive effect QTLs associated with performance per se of BCRIL and general combining ability, and dominant effect QTLs associated with special combining ability and heterosis were identified for the ten traits. Conclusions/Significance The combining ability of agronomic traits could be analyzed by the QTL mapping method. The characteristics revealed by the QTLs for combining ability of agronomic traits were similar with those by multitudinous QTLs for agronomic traits with performance per se of BCRIL. Several QTLs (1–6 in this study) were identified for each trait for combining ability. It demonstrated that some of the QTLs were pleiotropic or linked tightly with each other. The identification of QTLs responsible for combining ability and heterosis in the present study provides valuable information for dissecting genetic basis of combining ability. PMID:22291881
Wang, Yumei; Hua, Jinping
Determination of genetic basis of heterosis may promote hybrid production in Upland cotton (Gossypium hirsutum L.). This study was designed to explore the genetic mechanism of heterosis for yield and yield components in F2: 3 and F2: 4 populations derived from a hybrid ‘Xinza No. 1’. Replicated yield field trials of the progenies were conducted in 2008 and 2009. Phenotypic data analyses indicated overdominance in F1 for yield and yield components. Additive and dominance effects at single-locus level and digenic epistatic interactions at two-locus level were analyzed by 421 marker loci spanning 3814 cM of the genome. A total of 38 and 49 QTLs controlling yield and yield components were identified in F2: 3 and F2: 4 populations, respectively. Analyses of these QTLs indicated that the effects of partial dominance and overdominance contributed to heterosis in Upland cotton simultaneously. Most of the QTLs showed partial dominance whereas 13 QTLs showing overdominance in F2:3 population, and 19 QTLs showed overdominance in F2:4. Among them, 21 QTLs were common in both F2: 3 and F2: 4 populations. A large number of two-locus interactions for yield and yield components were detected in both generations. AA (additive × additive) epistasis accounted for majority portion of epistatic effects. Thirty three complementary two-locus homozygotes (11/22 and 22/11) were the best genotypes for AA interactions in terms of bolls per plant. Genotypes of double homozygotes, 11/22, 22/11 and 22/22, performed best for AD/DA interactions, while genotype of 11/12 performed best for DD interactions. These results indicated that (1) partial dominance and overdominance effects at single-locus level and (2) epistasis at two-locus level elucidated the genetic basis of heterosis in Upland cotton. PMID:26618635
Full Text Available BACKGROUND: Combining ability effects are very effective genetic parameters in deciding the next phase of breeding programs. Although some breeding strategies on the basis of evaluating combining ability have been utilized extensively in hybrid breeding, little is known about the genetic basis of combining ability. Combining ability is a complex trait that is controlled by polygenes. With the advent and development of molecular markers, it is feasible to evaluate the genetic bases of combining ability and heterosis of elite rice hybrids through QTL analysis. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we first developed a QTL-mapping method for dissecting combining ability and heterosis of agronomic traits. With three testcross populations and a BCRIL population in rice, biometric and QTL analyses were conducted for ten agronomic traits. The significance of general combining ability and special combining ability for most of the traits indicated the importance of both additive and non-additive effects on expression levels. A large number of additive effect QTLs associated with performance per se of BCRIL and general combining ability, and dominant effect QTLs associated with special combining ability and heterosis were identified for the ten traits. CONCLUSIONS/SIGNIFICANCE: The combining ability of agronomic traits could be analyzed by the QTL mapping method. The characteristics revealed by the QTLs for combining ability of agronomic traits were similar with those by multitudinous QTLs for agronomic traits with performance per se of BCRIL. Several QTLs (1-6 in this study were identified for each trait for combining ability. It demonstrated that some of the QTLs were pleiotropic or linked tightly with each other. The identification of QTLs responsible for combining ability and heterosis in the present study provides valuable information for dissecting genetic basis of combining ability.
Xu, Su-Xia; Liu, Jie; Liu, Gong-She
A challenge to maize breeders is to predict and identify inbred lines that can produce highly heterotic hybrids precisely. In the present study we surveyed the genetic diversity among 15 elite inbred lines of maize in China with SSR markers and assessed the relationship between SSR marker and hybrid yield/yield heterosis in a diallel set of 105 crosses. Forty-three SSR primers selected from all sixty-three primers gave stable profiles amplified in the sample of 15 inbred lines, which could clearly resolve on 4% metaphor agarose gel. The average number of alleles per SSR locus was 4.44 with a range from 2 to 9. The polymorphism information content (PIC) for the SSR loci varied from 0.28 to 0.81 with a mean of 0.6281. Genetic similarity (GS) among 15 lines was estimated with 191 alleles identified as raw data, the Nei's coefficient of GS ranged from 0.492 for 478 vs HZ4 up to 0.745 for E28 to ZH64 with a mean of 0.619. The cluster diagram based upon the SSR data grouped the 15 lines into families consistent with the yield heterotic response of these. Genetic distance (GD) based on SSR data was significantly correlated with hybrid yield/yield heterosis, the correlation coefficient (r) being 0.5432 and 0.4271 in 1999 and 0.4305 and 0.3614 in 1998 field test, respectively, whereas the determination coefficient (r2) was lower. The correlation between GD based on SSR data and hybrid yield/yield heterosis changed alone with the difference of number and pedigree relationship among parents that were used in this study. SSR makers showed high polymorphism and could be used to assess the relationship between inbred lines of maize, but it was difficult to predict the yield heterosis of maize.
Full Text Available Abstract. The aim of this paper was to study the influence of the degree of heterosis (compared to higher parent value- HP and mean parental values- MP on the signs, survival and duration of development in F hybrids of Bombyx mori L. from different geographical origin, fed by artificial diet. The study was conducted 1 at the Training Experimental Station of the Sericulture section of the Faculty of Agriculture at Trakia University. A total of 10 hybrids were tested featuring 6 breeds from the genetic bank of Sericulture and Agriculture Experiment Station (SAES-Vratsa. Silkworms were reared with artificial diet containing 15% powder of dried mulberry leaf produced at SAES-Vratsa and prepared by methods, developed by the manufacturer, whereby 250g of dry substance and 675ml of distilled water are homogenized using a mixer. The mixture is cured thermally in a microwave for 10min. at ~800W. The receptivity of specimens was -st determined based on the results from the survival and the duration in the I age of the larval stage. In heterogeneous crossbreds higher survival rate in the first age is exhibited by hybrids in which a Japanese type breed was used as dam. Homogeneous crossbreds created with the participation of Japanese breeds excel in both analyzed traits those involving a Chinese type. For the survival trait heterosis manifestations to higher parent value (HP and mean parental values (MP, were detected in the majority of hybrids (90.91%. Regarding the duration of development, heterosis effect to MP was observed in all F hybrids, 1 while to HP heterosis is exhibited by 60% of the tested F hybrids.
Jensen, Palle; Overgaard, Johannes; Loeschcke, Volker
in replicated lines of inbred and outbred Drosophila melanogaster at stressful low, benign and stressful high temperatures. The lowest measurements of metabolic rate in our study are always associated with the low activity period of the diurnal cycle and these measurements therefore serve as good estimates...... of standard metabolic rate. Due to the potentially added costs of genetic stress in inbred lines we hypothesized that inbred individuals have increased metabolic rate compared to outbred controls and that this is more pronounced at stressful temperatures due to synergistic inbreeding by environment...... interactions. Contrary to our hypothesis we found no significant difference in metabolic rate between inbred and outbred lines and no interaction between inbreeding and temperature. Inbreeding however effected the variance; the variance in metabolic rate was higher between the inbred lines compared...
Full Text Available An observed case of inbreeding in a pack ot wild dogs Lycaon pictus in the Kruger National Park, Republic of South Africa, provides evidence for the phenomenon of dominance reversal in this species. This is believed to be the first recorded instance of inbreeding in Lycaon. Emigration of subordinate females from established packs of wild dogs has been documented in the Serengeti National Park and Ngorongoro Conservation Area in northern Tanzania, as well as in the Kruger National Park. However, the newly subordinate (ex-dominant female in the pack in which inbreeding has occurred has not emigrated in the 16 months since the change in her status. A possible explanation for this behaviour is given. As a result of this reversal, the pack contains at least two females capable of breeding, the subordinate of which is at least two years older than the dominant. This is considered the first record of such a breeding structure in Lycaon.
Hedrick, Philip W; Kardos, Marty; Peterson, Rolf O; Vucetich, John A
Inbreeding, relatedness, and ancestry have traditionally been estimated with pedigree information, however, molecular genomic data can provide more detailed examination of these properties. For example, pedigree information provides estimation of the expected value of these measures but molecular genomic data can estimate the realized values of these measures in individuals. Here, we generate the theoretical distribution of inbreeding, relatedness, and ancestry for the individuals in the pedigree of the Isle Royale wolves, the first examination of such variation in a wild population with a known pedigree. We use the 38 autosomes of the dog genome and their estimated map lengths in our genomic analysis. Although it is known that the remaining wolves are highly inbred, closely related, and descend from only 3 ancestors, our analyses suggest that there is significant variation in the realized inbreeding and relatedness around pedigree expectations. For example, the expected inbreeding in a hypothetical offspring from the 2 remaining wolves is 0.438 but the realized 95% genomic confidence interval is from 0.311 to 0.565. For individual chromosomes, a substantial proportion of the whole chromosomes are completely identical by descent. This examination provides a background to use when analyzing molecular genomic data for individual levels of inbreeding, relatedness, and ancestry. The level of variation in these measures is a function of the time to the common ancestor(s), the number of chromosomes, and the rate of recombination. In the Isle Royale wolf population, the few generations to a common ancestor results in the high variance in genomic inbreeding. © The American Genetic Association 2016. All rights reserved. For permissions, please e-mail: email@example.com.
Full Text Available The degree of homozygosity of some 39 Thoroughbred horses was estimated from microsatellite analysis data. The power of inbreeding was detected towards horse pedigree. We suggested the use of genetic analysis of microsatellite loci of DNA for the determination of actual level of inbreeding.
Reid, Jane M; Duthie, A Bradley; Wolak, Matthew E; Arcese, Peter
One hypothesis explaining extra-pair reproduction is that socially monogamous females mate with extra-pair males to adjust the coefficient of inbreeding (f) of extra-pair offspring (EPO) relative to that of within-pair offspring (WPO) they would produce with their socially paired male. Such adjustment of offspring f requires non-random extra-pair reproduction with respect to relatedness, which is in turn often assumed to require some mechanism of explicit pre-copulatory or post-copulatory kin discrimination. We propose three demographic processes that could potentially cause mean f to differ between individual females' EPO and WPO given random extra-pair reproduction with available males without necessarily requiring explicit kin discrimination. Specifically, such a difference could arise if social pairings formed non-randomly with respect to relatedness or persisted non-randomly with respect to relatedness, or if the distribution of relatedness between females and their sets of potential mates changed during the period through which social pairings persisted. We used comprehensive pedigree and pairing data from free-living song sparrows (Melospiza melodia) to quantify these three processes and hence investigate how individual females could adjust mean offspring f through instantaneously random extra-pair reproduction. Female song sparrows tended to form social pairings with unrelated or distantly related males slightly less frequently than expected given random pairing within the defined set of available males. Furthermore, social pairings between more closely related mates tended to be more likely to persist across years than social pairings between less closely related mates. However, these effects were small and the mean relatedness between females and their sets of potential extra-pair males did not change substantially across the years through which social pairings persisted. Our framework and analyses illustrate how demographic and social structuring within
del Giacco Stefano
Full Text Available Abstract Background Association studies consist in identifying the genetic variants which are related to a specific disease through the use of statistical multiple hypothesis testing or segregation analysis in pedigrees. This type of studies has been very successful in the case of Mendelian monogenic disorders while it has been less successful in identifying genetic variants related to complex diseases where the insurgence depends on the interactions between different genes and the environment. The current technology allows to genotype more than a million of markers and this number has been rapidly increasing in the last years with the imputation based on templates sets and whole genome sequencing. This type of data introduces a great amount of noise in the statistical analysis and usually requires a great number of samples. Current methods seldom take into account gene-gene and gene-environment interactions which are fundamental especially in complex diseases. In this paper we propose to use a non-parametric additive model to detect the genetic variants related to diseases which accounts for interactions of unknown order. Although this is not new to the current literature, we show that in an isolated population, where the most related subjects share also most of their genetic code, the use of additive models may be improved if the available genealogical tree is taken into account. Specifically, we form a sample of cases and controls with the highest inbreeding by means of the Hungarian method, and estimate the set of genes/environmental variables, associated with the disease, by means of Random Forest. Results We have evidence, from statistical theory, simulations and two applications, that we build a suitable procedure to eliminate stratification between cases and controls and that it also has enough precision in identifying genetic variants responsible for a disease. This procedure has been successfully used for the beta-thalassemia, which is
Pedersen, Kamilla Sofie; Kristensen, Torsten Nygaard; Loeschcke, Volker
to an increased between-line variation in metabolite profiles compared to outbred lines. In contrast to previous observations revealing interactions between inbreeding and environmental stress on gene expression patterns and life-history traits, the effect of inbreeding on the metabolite profile was similar...... and five inbred lines were studied by nuclear magnetic resonance spectroscopy after exposure to benign temperature, heat stress, or cold stress. In both the absence and the presence of temperature stress, metabolite levels were significantly different among inbred and outbred lines. The major effect...
Abdel-Moneam, M A; Attia, A N; El-Emery, M I; Fayed, E A
In 2007, five maize inbred lines were crossed in all possible combinations without reciprocals by using a half diallel crosses mating design to obtain 10 single cross. Inbred parents and their F1 single crosses were evaluated through 2008 season to evaluate the role of general and specific combining ability and heterosis for some agronomic traits. Results indicated that mean squares of genotypes were highly significant for all studied traits, i.e., ear diameter, ear length, number of kernels/row, 100-kernel weight, ear yield per plant, grain yield per plant and shelling percentage. General Combining Ability (GCA) and Specific Combining Ability (SCA) mean squares were highly significant for all studied traits. The GCA/SCA ratio was less than unity for all studied traits; this means that these traits are predominantly controlled by non-additive gene action. Significant positive GCA effects were found for all studied traits. Based on GCA estimates, it could be concluded that the best combiners were Rg5 and Rg8 inbred lines for most of studied traits. This result indicated that these inbred lines could be considered as good combiners for improving these traits. Significant positive SCA effects were found for all studied traits. Based on SCA effects, it could be concluded that the best crosses for ear diameter and 100-kernels weigh was G507AxG516; for ear length was G516xRg8; for kernels number/row was G516xG278; for ear yield/plant, grain yield/plant and Shelling percentage was G278xRg5. These crosses could be selected and used in breeding programs for improving these traits. Results showed positive significant heterosis values for all studied traits. The best crosses over both their mid-parents and better-parents for ear diameter and 100-kernel weigh was G507AxG516; for ear length and kernels number/row was G516xG278; for ear yield/plant and grain yield/plant was G278xRg8 and for Shelling percentage was G278xRg5.
Opatová, Pavlína; Ihle, M.; Albrechtová, Jana; Tomášek, Oldřich; Kempenaers, B.; Forstmeier, W.; Albrecht, Tomáš
Roč. 6, č. 1 (2016), s. 295-304 ISSN 2045-7758 R&D Projects: GA ČR(CZ) GAP506/12/2472 Institutional support: RVO:68081766 Keywords : gamete performance * genetic quality * sperm abnormality * sperm morphology * sperm velocity Subject RIV: EG - Zoology Impact factor: 2.440, year: 2016
Kristensen, Torsten Nygård; Loeschcke, Volker; Bilde, Trine
Populations are from time to time exposed to stressful temperatures. Their thermal resistance levels are determined by inherent and plastic mechanisms, which are both likely to be under selection in natural populations. Previous studies on Drosophila species have shown that inherent resistance...
João Alencar de Sousa
Full Text Available This study was carried out to obtain estimates of heterosis in crosses between seven eggplant cultivars (Embu = E; Santa Genebra = SG; Viserba = V; Aubergine de Barbentane = AB; Florida Market 10 = FM; Black Beauty = BB, and Melitino = M and two breeding lines (B-14-07 = B1 and B-31-06 = B2. The F1 hybrids used were: E x FM; E x BB; E x M; E x B1; E x B2; SG x FM; SG x BB; SG x M; SG x B1; SG x B2; V x FM; V x B1; V x B2; AB x FM; AB x M; AB x B1; AB x B2 and M x FM. Cultivars, lines and hybrids were evaluated at the ESAL experimental field in Lavras, MG, from February to October 1992. A randomized complete block design with three replications was used. Significant heterosis relative to the parental means was detected for all traits studied. Their values ranged from +41.23% to +113.31% for total fruit yield, from -11.45% to +26.17% for average fruit weight, and from +27.98% to +141.81% for early production. Heterosis relative to the superior parent ranged from +13.89% to +92.51% for total fruit yield. Hybrid pairs: SG x FM and AB x B1, V x FM and AB x FM, E x M and AB x B1 were the most heterotic relative to the parental mean for total fruit production, mean fruit weight and early production, respectively. The hybrids displaying highest heterosis relative to the superior parent for total yield were AB x B1 and SG x FM.Este trabalho visou obter estimativas da heterose em cruzamentos entre sete cultivares de berinjela (Embu = E, Santa Genebra = SG, Viserba = V, Aubergine de Barbentane = AB, Florida Market 10 = FM, Black Beauty = BB e Melitino = M e duas linhagens (B-14-07 = B1 e B-31-06 = B2. Os híbridos F1 utilizados foram: E x FM; E x BB; E x M; E x B1; E x B2; SG x FM; SG x BB; SG x M; SG x B1; SG x B2; V x FM; V x B1; V x B2; AB x FM; AB x M; AB x B1; AB x B2 e M x FM. O trabalho foi conduzido no campus da ESAL em Lavras-MG, de fevereiro a outubro de 1992. O delineamento empregado foi o de blocos casualizados completos com três repeti
Koelewijn, H.P.; Damme, van J.M.M.
1 Male steriles (MS) must have a fitness advantage relative to hermaphrodites (H) if they are to be maintained in gynodioecious species. We report experiments in which we disentangle the relative contributions of seed size, inbreeding and maternal sex to the fitness advantage of male steriles in
Netherlands, New Zealand, Switzerland and the United States. Semen from Taurus, the local AI company, is also used extensively in the South African dairy industry. Literature estimates of rate of inbreeding and effective population size are not currently available for the South African dairy cattle breeds even though the.
Agarwala, R; Schäffer, A A; Tomlin, J F
We describe a large genealogy data base, which can be searched by computer, of 295,095 Amish and Mennonite individuals. The data base was constructed by merging our existing Anabaptist Genealogy Database 2.0 containing approximately 85,000 individuals with a genealogy file containing approximately 242,000 individuals, kindly provided by Mr. James Hostetler. The merging process corrected thousands of inconsistencies and eliminated hundreds of duplicate individuals. Geneticists have long been interested in Anabaptist populations because they are closed and have detailed written genealogies. The creation of an enlarged and unified data base affords the opportunity to examine inbreeding trends and correlates in these populations. We show the following results. The frequency of consanguineous marriages shows steady increase over time and reached approximately 85% for individuals born in 1940-1959. Among consanguineous marriages, the median kinship coefficient stayed stable in the 19th century, but rose from 0.0115 to 0.0151 in the 20th century. There are statistically significant associations (p < 0.0001) between inbreeding and family size and interbirth intervals in the 20th century. There is an association (p < 0.0005) between inbreeding and early death for individuals born in 1920-1959. However, this association reverses dramatically (p < 0.0005 in the opposite direction) for individuals born in 1960-1979. We tested for an association between inbreeding and being the mother of twins, but found none.
Pedersen, Louise Dybdahl; Pedersen, Asger Roer; Bijlsma, Kuke
in benign and stressful environments using Drosophila melanogaster as a model organism. Male sterility was compared in 21 inbred lines and five non-inbred control lines at 25.0 and 29.0 °C. The effect of inbreeding on sterility was significant only at 29.0 °C. This stress-induced increase in sterility...
Koelewijn, H.P.; Van Damme, J.M.M.
Male steriles (MS) must have a fitness advantage relative to hermaphrodites (H) if they are to be maintained in gynodioecious species. We report experiments in which we disentangle the relative contributions of seed size, inbreeding and maternal sex to the fitness advantage of male steriles in
Habitat fragmentation has been recognized as one of the major threats to plant population persistence. Fragmented small and isolated populations are expected to be seriously affected by inbreeding and genetic drift. Gene flow through seed and pollen dispersal may counterbalance the negative
Swillen, Ine; Vanoverbeke, Joost; De Meester, Luc
Several studies have emphasized that inbreeding depression (ID) is enhanced under stressful conditions. Additionally, one might imagine a loss of adaptively plastic responses which may further contribute to a reduction in fitness under environmental stress. Here, we quantified ID in inbred families of the cyclical parthenogen Daphnia magna in the absence and presence of fish predation risk. We test whether predator stress affects the degree of ID and if inbred families have a reduced capacity to respond to predator stress by adaptive phenotypic plasticity. We obtained two inbred families through clonal selfing within clones isolated from a fish pond. After mild purging under standardized conditions, we compared life history traits and adaptive plasticity between inbred and outbred lineages (directly hatched from the natural dormant egg bank of the same pond). Initial purging of lineages under standardized conditions differed among inbred families and exceeded that in outbreds. The least purged inbred family exhibited strong ID for most life history traits. Predator-induced stress hardly affected the severity of ID, but the degree to which the capacity for adaptive phenotypic plasticity was retained varied strongly among the inbred families. The least purged family overall lacked the capacity for adaptive phenotypic plasticity, whereas the family that suffered only mild purging exhibited a potential for adaptive plasticity that was comparable to the outbred population. We thus found that inbred offspring may retain the capacity to respond to the presence of fish by adaptive phenotypic plasticity, but this strongly depends on the parental clone engaging in selfing. PMID:26257883
Klieve, H M; Kinghorn, B P; Barwick, S A
Stochastic simulation was used to evaluate a range of selection strategies with respect to both additive genetic response and inbreeding. Strategies involving selection on BLUP ebvs or individual phenotype, followed by random mating, were compared with mate selection strategies which used portfolio analysis to give joint consideration to genetic merit and inbreeding. An adapted Mean Of Total Absolute Deviations (MOTAD) method was used in a mate selection model to define optimal matings with regard to aggregate genetic merit and inbreeding for a base population h(2) of 0.2. Compared with random mating following selection on BLUP ebvs, inbreeding levels after 10 years of selection were able to be reduced under BLUP plus mate selection from ∼.23 to as little as .11. Additive genetic gain was either little compromised or increased. The results suggest that information linking expected levels of genetic merit and inbreeding can be used to find the preferred selection strategy. ZUSAMMENFASSUNG: Gemeinsame Kontrolle von Zuchtfortschritt und Inzucht bei Partnerselektion Es wurde stochastische Simulation zur Auswertung einer Reihe von Selektionsstrategien hinsichtlich Zuchtwertzuwachs und Inzucht verwendet. Strategien mit Selektion auf der Basis von BLUP ebvs oder individuellem Phänotyp mit nachfolgender Zufallspaarung wurden mit Partnerselektionsstrategien verglichen, die Portfolioanalyse zur gemeinsamen Beachtung von Zuchtwert und Inzucht verwendeten. Eine Methode adaptierter MITTELWERTE TOTALER ABSOLUTER ABWEICHUNGEN (MOTAD) Methode wurde beim Partnerselektionsmodell zur Definition optimaler Paarungen in Hinblick auf Gesamtzuchtwert und Inzucht bei einer Populationsheritabilität von 0,2 verwendet. Verglichen mit Zufallspaarung nach Selektion auf BLUP ebvs waren die Inzuchtgrade nach 10 Selektionsjahren von 0,23 auf 0,11 reduziert und additiver Zuchtfortschritt war dabei wenig beeinträchtigt oder nahm sogar zu. Die Ergebnisse weisen darauf hin, daß Information, die
Full Text Available Maintaining genetic variation and controlling the increase in inbreeding are crucial requirements in animal conservation programs. The most widely accepted strategy for achieving these objectives is to maximize the effective population size by minimizing the global coancestry obtained from a particular pedigree. However, for most natural or captive populations genealogical information is absent. In this situation, microsatellites have been traditionally the markers of choice to characterize genetic variation, and several estimators of genealogical coefficients have been developed using marker data, with unsatisfactory results. The development of high-throughput genotyping techniques states the necessity of reviewing the paradigm that genealogical coancestry is the best parameter for measuring genetic diversity. In this study, the Illumina PorcineSNP60 BeadChip was used to obtain genome-wide estimates of rates of coancestry and inbreeding and effective population size for an ancient strain of Iberian pigs that is now in serious danger of extinction and for which very accurate genealogical information is available (the Guadyerbas strain. Genome-wide estimates were compared with those obtained from microsatellite and from pedigree data. Estimates of coancestry and inbreeding computed from the SNP chip were strongly correlated with genealogical estimates and these correlations were substantially higher than those between microsatellite and genealogical coefficients. Also, molecular coancestry computed from SNP information was a better predictor of genealogical coancestry than coancestry computed from microsatellites. Rates of change in coancestry and inbreeding and effective population size estimated from molecular data were very similar to those estimated from genealogical data. However, estimates of effective population size obtained from changes in coancestry or inbreeding differed. Our results indicate that genome-wide information represents a
Das, Bidhan Kanti; Mukherjee, D P
The present study is an attempt to understand the genetical effects of inbreeding on the process of growth. The inbred and non-inbred subjects were selected on the basis of extensive pedigrees of five generations in the Telaga, an endogamous population of Kharagpur, India. Preference was given to cousins belonging to the same kindreds while selecting control sample so that environmental variation was minimized. Altogether 633 boys and 614 girls of different inbreeding levels aged five to twenty years were measured for stature. Analysis has been done in different levels of inbreeding in each age and sex on mean annual increments and variances of increments. The results revealed that comparison of annual increment for each age between boys and girls with different degrees of inbreeding and application of the one-tailed t-test of significance does not provide any evidence of inbreeding effect on mean increment for stature studied in either sex. This might indicate the absence of marked dominant/recessive effects of genes determining annual increments in body size rather than the absence of genetical control of increments due to growth. Moreover, it is noteworthy that the variance of annual increment due to growth (which is estimated indirectly) consistently increases with increase of inbreeding level with only a few exceptions. The exceptions occur more often in girls than in boys, which can be explained by greater environmental stress and selection pressure and variation in X-linked inbreeding among girls. This would be worthwhile to verify in longitudinal growth data in future. Increased variances of annual increment with inbreeding, in the absence of change of mean increment on inbreeding, would indicate the influence of additive autosomal genes for the process of physical growth in children in either sex. A close scrutiny of the annual increments for the measurements in all the four levels of inbreeding in either sex fails to bring out any consistent trend of
Dae Kwan Ko
Full Text Available Heterosis has been widely used in agriculture, but the molecular mechanism for this remains largely elusive. In Arabidopsis hybrids and allopolyploids, increased photosynthetic and metabolic activities are linked to altered expression of circadian clock regulators, including CIRCADIAN CLOCK ASSOCIATED1 (CCA1. It is unknown whether a similar mechanism mediates heterosis in maize hybrids. Here we report that higher levels of carbon fixation and starch accumulation in the maize hybrids are associated with altered temporal gene expression. Two maize CCA1 homologs, ZmCCA1a and ZmCCA1b, are diurnally up-regulated in the hybrids. Expressing ZmCCA1 complements the cca1 mutant phenotype in Arabidopsis, and overexpressing ZmCCA1b disrupts circadian rhythms and biomass heterosis. Furthermore, overexpressing ZmCCA1b in maize reduced chlorophyll content and plant height. Reduced height stems from reduced node elongation but not total node number in both greenhouse and field conditions. Phenotypes are less severe in the field than in the greenhouse, suggesting that enhanced light and/or metabolic activities in the field can compensate for altered circadian regulation in growth vigor. Chromatin immunoprecipitation-sequencing (ChIP-seq analysis reveals a temporal shift of ZmCCA1-binding targets to the early morning in the hybrids, suggesting that activation of morning-phased genes in the hybrids promotes photosynthesis and growth vigor. This temporal shift of ZmCCA1-binding targets correlated with nonadditive and additive gene expression in early and late stages of seedling development. These results could guide breeding better hybrid crops to meet the growing demand in food and bioenergy.
Ko, Dae Kwan; Rohozinski, Dominica; Song, Qingxin; Taylor, Samuel H; Juenger, Thomas E; Harmon, Frank G; Chen, Z Jeffrey
Heterosis has been widely used in agriculture, but the molecular mechanism for this remains largely elusive. In Arabidopsis hybrids and allopolyploids, increased photosynthetic and metabolic activities are linked to altered expression of circadian clock regulators, including CIRCADIAN CLOCK ASSOCIATED1 (CCA1). It is unknown whether a similar mechanism mediates heterosis in maize hybrids. Here we report that higher levels of carbon fixation and starch accumulation in the maize hybrids are associated with altered temporal gene expression. Two maize CCA1 homologs, ZmCCA1a and ZmCCA1b, are diurnally up-regulated in the hybrids. Expressing ZmCCA1 complements the cca1 mutant phenotype in Arabidopsis, and overexpressing ZmCCA1b disrupts circadian rhythms and biomass heterosis. Furthermore, overexpressing ZmCCA1b in maize reduced chlorophyll content and plant height. Reduced height stems from reduced node elongation but not total node number in both greenhouse and field conditions. Phenotypes are less severe in the field than in the greenhouse, suggesting that enhanced light and/or metabolic activities in the field can compensate for altered circadian regulation in growth vigor. Chromatin immunoprecipitation-sequencing (ChIP-seq) analysis reveals a temporal shift of ZmCCA1-binding targets to the early morning in the hybrids, suggesting that activation of morning-phased genes in the hybrids promotes photosynthesis and growth vigor. This temporal shift of ZmCCA1-binding targets correlated with nonadditive and additive gene expression in early and late stages of seedling development. These results could guide breeding better hybrid crops to meet the growing demand in food and bioenergy.
Thirstrup, Janne Pia; Pertoldi, Cino; Larsen, Peter Foged
Litter sizes in a cross between Brown and Black mink color types were observed through six generations. Litter size was significantly affected by yearly environmental variations. After adjusting for year effects, we found significant increases in litter size in the second and third generations (F2...... and F3) after crossing. Thereafter, in the following generations, litter size dropped to a level comparable to the mean litter size of the midparent. Increased litter size in F2 compared to F1 indicated that maternal effects influenced litter size more than non-maternal effects. The heterosis was mainly...
Williams, J L; Aguilar, I; Rekaya, R; Bertrand, J K
Current genetic evaluations are performed separately for each breed. Multiple breed genetic evaluations, however, assume a common base among breeds, enabling producers to compare cattle of different breed makeup. Breed and heterosis effects are needed in a multibreed evaluation because databases maintained by breed associations include few crossbred animals, which may not be enough to accurately estimate these effects. The objective of this study was to infer breed effects, maternal effects, direct heterosis effects, and maternal heterosis effects for growth and carcass traits using least squares means estimates from crossbreeding studies published in the literature from 1976 to 1996. The data set was formed by recording each least squares mean along with the breed composition, maternal breed composition, and direct and maternal heterozygosity. Each trait was analyzed using a single trait fixed effect model, which included study as a fixed effect and breed composition and heterozygosity as covariates. Breed solutions for each trait were expressed relative to the Angus breed. Direct breed effects for weaning weight ranged from -7.0 +/- 0.67 kg (British Dairy) to 29.3 +/- 0.74 kg (Simmental), and maternal effects ranged from -11.7 +/- 0.24 kg (Hereford) to 31.1 +/- 2.22 kg (Gelbvieh). Direct breed effects for birth weight ranged from -0.5 +/- 0.14 kg (British Dairy) to 10.1 +/- 0.46 kg (Continental Beef), and maternal effects ranged from -7.2 +/- 0.13 kg (Brahman) to 6.0 +/- 1.07 kg (Continental Beef). Direct breed effects ranged from -17.9 +/- 1.64 kg (Brahman) to 21.6 +/- 1.95 kg (Charolais), from -6.5 +/- 1.29 kg (Brahman) to 55.8 +/- 1.47 kg (Continental Beef), from -8.1 +/- 0.48 cm(2) (Shorthorn) to 21.0 +/- 0.48 cm(2) (Continental Beef), and from -1.1 +/- 0.02 cm (Continental Beef) to 0 +/- 0.00 cm (Angus) for postweaning BW gain, carcass weight, LM area, and fat thickness, respectively. The use of literature estimates to predict direct and maternal breed and
Antfolk, Jan; Lieberman, Debra; Santtila, Pekka
It is expected that in humans, the lowered fitness of inbred offspring has produced a sexual aversion between close relatives. Generally, the strength of this aversion depends on the degree of relatedness between two individuals, with closer relatives inciting greater aversion than more distant relatives. Individuals are also expected to oppose acts of inbreeding that do not include the self, as inbreeding between two individuals posits fitness costs not only to the individuals involved in th...
Herrera-Paz, Edwin Francisco
The isonymic method has been amply used to assess the approximate genetic structure of human communities. The objective of the study was to evaluate the magnitude of genetic isolation and inbreeding customs in 57 communities from three rural municipalities of Honduras using isonymy techniques. The list of 408 different surnames from 20712 voters registered in the national electoral organism, residing in the 57 Honduran communities, was used for this study. For each community, random (IR), non-random (IN), and total (IT) isonymy values were calculated in order to assess inbreeding coefficients FST, FIS and FIT. High consanguinity due to isolation and to endogamous customs was unveiled in many communities. Significant deviation from the exogamous behavior typical of many human populations was observed in the three studied municipalities, when compared to other Honduran populations. The studied communities present high consanguinity due to isolation, ethnic segregation and/or endogamous customs.
G. Q. Tang
Full Text Available The accumulation of inbreeding and the loss of genetic diversity is a potential problem in the modern swine breeds in China. Therefore, the purpose of this study was to analyze the pedigrees of Chinese Duroc (CD, Landrace (CL and Yorkshire (CY swine to estimate the past and current rates of inbreeding, and to identify the main causes of genetic diversity loss. Pedigree files from CD, CL and CY containing, 4529, 16,776 and 22,600 records, respectively, were analyzed. Pedigree completeness indexes of the three breeds, accounting for one generation back, were 83.72, 93.93 and 93.59%, respectively. The estimated average annual inbreeding rates for CD, CL and CY in recent three years were 0.21, 0.19 and 0.13%, respectively. The estimated average percentage of genetic diversity loss within each breed in recent three years was about 8.92, 2.19, and 3.36%, respectively. The average relative proportion of genetic diversity loss due to unequal contributions of founders in CD, CL and CY was 69.09, 57.95 and 60.57%, and due to random genetic drift was 30.91, 42.05 and 39.43%, respectively. The estimated current effective population size for CD, CL and CY was 76, 117 and 202, respectively. Therefore, CD has been found to have lost considerable genetic diversity, demanding priority for optimizing the selection and mating to control future coancestry and inbreeding. Unequal contribution of founders was a major cause of genetic diversity loss in Chinese swine breeds and random genetic drift also showed substantial impact on the loss of diversity.
Urszula M. Marcinkowska; Fhionna R. Moore; Markus J. Rantala
In order to avoid inbreeding, humans and other animals develop a strong sexual aversion to individuals with whom they have lived closely in infancy and early childhood (usually biological siblings), a phenomenon called the "Westermarck effect" or negative sexual imprinting. The mechanisms underlying this phenomenon, however, remain unclear. For example, it is not known whether negative imprinting is based only on actual sexual aversion to brothers and sisters or also on generalizing the trait...
Sutherland, D A T; Honaker, C F; Dorshorst, B; Andersson, L; Siegel, P B
During the domestication of farm animals, humans have manipulated genetic variation for growth and reproduction through artificial selection. Here, data are presented for growth, reproductive, and behavior traits for the red junglefowl, a line of White Plymouth Rock chickens, and their F 1 and F 2 reciprocal crosses. Intra- and intergenerational comparisons for growth related traits reflected considerable additive genetic variation. In contrast, those traits associated with reproduction exhibited heterosis. The role of sexual selection was seen in the evolution of prominent secondary sexual ornaments that lend to female choice and male-male competition. The large differences between parental lines in fearfulness to humans were only mitigated slightly in the intercross generations. Whereas, overall F 1 generation heterosis was not transferred to the F 2 , there was developmental stability in the F 2 , as measured by relative asymmetry of bilateral traits. Through multigenerational analyses between the red junglefowl and the domestic White Plymouth Rocks, we observed plasticity and considerable residual genetic variation. These factors likely facilitated the adaptability of the chicken to a broad range of husbandry practices throughout the world.
Vuylsteke, M; Kuiper, M; Stam, P
In this paper, a novel approach towards the prediction of hybrid performance and heterosis is presented. Here, we describe an approach based on: (i) the assessment of associations between AFLP(R) markers and hybrid performance and specific combining ability (SCA) across a set of hybrids; and (ii) the assumption that the joint effect of genetic factors (loci) determined this way can be obtained by addition. Estimated gene effects for grain yield varied from additive, partial dominance to overdominance. This procedure was applied to 53 interheterotic hybrids out of a 13 by 13 half-diallel among maize inbreds, evaluated for grain yield. The hybrid value, representing the joint effect of the genetic factors, accounted for up to 62.4% of the variation in the hybrid performance observed, whereas the corresponding efficiency of the SCA model was 36.8%. Efficiency of the prediction for hybrid performance was evaluated by means of a cross-validation procedure for grain yield of (i) the 53 interheterotic hybrids and (ii) 16 hybrids partly related to the 13 by 13 half-diallel. Comparisons in prediction efficiency with the 'distance' model were made. Because the map position of the selected markers is known, putative quantitative trait loci (QTL) affecting grain yield, in terms of hybrid performance or heterosis, are identified. Some QTL of grain yield detected in the present study were located in the vicinity of loci reported earlier as having quantitative effects on grain yield.
Gupta, D; Kovács, I
Hybrids obtained from two series of diallel crosses made between six o 2 converted inbred lines on the one hand and their normal analogues on the other were compared for twenty-five characters including yield and several of the yield components, including the parents. Observations on simple inter-character correlation coefficients presented here have shown that the majority of the correlations at the o 2 level are of the same order as at the normal level. A number of correlations of the o 2 type are inferior to those of their normal analogues, whereas a few are favoured by the o 2 gene including the correlation of grain yield with kernels per row. A measure of heterosis for each hybrid over its mid-parent also demonstrated that the o 2 types show poorer heterosis in more cases than do their normal counterparts. Still, in nearly 40 percent of the cases the o 2 hybrids were found to be more heterotic than their normal analogues, particularly for the various maturity characters and several of the yield components. Thus, the possibility of improvement exists in breeding maize with the opaque-2 gene.
Norberg, Elise; Byskov, Kenneth; Kargo, Morten
During the last decade the use of systematic crossbreeding in dairy cattle herds has been increasing in Denmark. The aim of this study was to estimate the effect of breed proportion and heterosis on milk production traits. The study was based on records on milk yield (MY), protein yield (PY......, a random genetic effect of the cow and a residual. Data was analyzed using AI-REML in the DMU package. The effect of breed proportions was estimated relatively to a pure DH. For MY, a pure DR was estimated to give 259 kg less than a pure DH, while a pure DJ gave 1838 kg less than a pure DH. For PY...... between DH and DR was estimated to 177 kg, 5.8 kg and 8.4 kg for MY, PY and FY, respectively. Corresponding figures for crosses between DH and DJ was 320 kg, 13.4 kg and 17.5 kg, while crosses between DR and DJ gave heterosis estimates of 380 kg, 14.3 kg and 20.2 for MY, PY and FY, respectively...
Robinson, S P; Simmons, L W; Kennington, W J
Estimates of inbreeding and relatedness are commonly calculated using molecular markers, although the accuracy of such estimates has been questioned. As a further complication, in many situations, such estimates are required in populations with reduced genetic diversity, which is likely to affect their accuracy. We investigated the correlation between microsatellite- and pedigree-based coefficients of inbreeding and relatedness in laboratory populations of Drosophila melanogaster that had passed through bottlenecks to manipulate their genetic diversity. We also used simulations to predict expected correlations between marker- and pedigree-based estimates and to investigate the influence of linkage between loci and null alleles. Our empirical data showed lower correlations between marker- and pedigree-based estimates in our control (nonbottleneck) population than were predicted by our simulations or those found in similar studies. Correlations were weaker in bottleneck populations, confirming that extreme reductions in diversity can compromise the ability of molecular estimates to detect recent inbreeding events. However, this result was highly dependent on the strength of the bottleneck and we did not observe or predict any reduction in correlations in our population that went through a relatively severe bottleneck of N = 10 for one generation. Our results are therefore encouraging, as molecular estimates appeared robust to quite severe reductions in genetic diversity. It should also be remembered that pedigree-based estimates may not capture realized identity-by-decent and that marker-based estimates may actually be more useful in certain situations. © 2013 John Wiley & Sons Ltd.
Full Text Available The buffalo is a native animal of Iran and there were 500,000 buffaloes in Iran that over 80 per cent of its population concentrated in the north and north- west (Azerbaijan province and 18 per cent in the south (Khuzestan province of the country. Buffaloes reread in rural condition as multi purpose animals in Khuzestan. For mating, farmer use owns herd sire also artificial insemination is limited in the rural condition that may be inbred animals so affect the production performance. The aim of this investigation was estimate the inbreeding coefficient and its affect on some production performance. Data of 200 herds were used from the record sheets of herds under recording program of Animal Breeding Center during period 1990 to 2002 in the Khuzestan province. These results showed mostly herds only one sir and rarely two sires have been used. Inbreeding coefficient was 25 percent in some progeny and high-inbred buffaloes had a low performance. According to results of this study it could be concluded that farmers to avoid inbreeding should use other herd sire and artificial insemination also practical recording scheme and genetically selection to genetic improvement should be included in buffaloes of Iran.
Meyer, Susan E; Ghimire, Sudeep; Decker, Samuel; Merrill, Keith R; Coleman, Craig E
We investigated the frequency of outcrossing in downy brome (Bromus tectorum L.), a cleistogamous weedy annual grass, in both common garden and wild populations, using microsatellite and single nucleotide polymorphic (SNP) markers. In the common garden study, 25 lines with strongly contrasting genotypes were planted in close proximity. We fingerprinted 10 seed progeny from 8 individuals of each line and detected 15 first-generation heterozygotes for a t-value (corrected for cryptic crosses) of 0.0082. Different genotypes were significantly overrepresented as maternal versus paternal parents of heterozygotes, suggesting gender-function-dependent genetic control of outcrossing rates. In 4 wild populations (>300 individuals each), expected heterozygosity ranged from 0.149 to 0.336, whereas t-values ranged from 0.0027 to 0.0133, indicating high levels of both genetic diversity and inbreeding. Up to a third of the individuals in each population belonged to groups with identical or nearly identical SNP genotypes, whereas many of the remaining individuals were members of loose clusters of apparently related plants that probably represent descendants from past outcrossing events. Strict inbreeding in some lineages within a population with occasional outcrossing in others may be related to positive selection on adaptive syndromes associated with specific inbreeding lineages, or possibly to among-lineage differences in genetic regulation of outcrossing.
Shannon J O'Leary
Full Text Available In contrast to freshwater fish it is presumed that marine fish are unlikely to spawn with close relatives due to the dilution effect of large breeding populations and their propensity for movement and reproductive mixing. Inbreeding is therefore not typically a focal concern of marine fish management. We measured the effective number of breeders in 6 New York estuaries for winter flounder (Pseudopleuronectes americanus, a formerly abundant fish, using 11 microsatellite markers (6-56 alleles per locus. The effective number of breeders for 1-2 years was remarkably small, with point estimates ranging from 65-289 individuals. Excess homozygosity was detected at 10 loci in all bays (FIS = 0.169-0.283 and individuals exhibited high average internal relatedness (IR; mean = 0.226. These both indicate that inbreeding is very common in all bays, after testing for and ruling out alternative explanations such as technical and sampling artifacts. This study demonstrates that even historically common marine fish can be prone to inbreeding, a factor that should be considered in fisheries management and conservation plans.
Bouchebti, Sofia; Durier, Virginie; Pasquaretta, Cristian; Rivault, Colette; Lihoreau, Mathieu
Many animals have evolved strategies to reduce risks of inbreeding and its deleterious effects on the progeny. In social arthropods, such as the eusocial ants and bees, inbreeding avoidance is typically achieved by the dispersal of breeders from their native colony. However studies in presocial insects suggest that kin discrimination during mate choice may be a more common mechanism in socially simpler species with no reproductive division of labour. Here we examined this possibility in the subsocial cockroach Nauphoeta cinerea, a model species for research in sexual selection, where males establish dominance hierarchies to access females and control breeding territories. When given a binary choice between a sibling male and a non-sibling male that had the opportunity to establish a hierarchy prior to the tests, females mated preferentially with the dominant male, irrespective of kinship or body size. Despite the lack of kin discrimination during mate choice, inbred-mated females incurred significant fitness costs, producing 20% less offspring than outbred-mated females. We discuss how the social mating system of this territorial cockroach may naturally limit the probability of siblings to encounter and reproduce, without the need for evolving active inbreeding avoidance mechanisms, such as kin recognition. PMID:27655156
Pölkki, Mari; Krams, Indrikis; Kangassalo, Katariina; Rantala, Markus J
In many species of animals, individuals advertise their quality with sexual signals to obtain mates. Chemical signals such as volatile pheromones are species specific, and their primary purpose is to influence mate choice by carrying information about the phenotypic and genetic quality of the sender. The deleterious effects of consanguineous mating on individual quality are generally known, whereas the effect of inbreeding on sexual signalling is poorly understood. Here, we tested whether inbreeding reduces the attractiveness of sexual signalling in the mealworm beetle, Tenebrio molitor, by testing the preferences for odours of inbred and outbred (control) individuals of the opposite sex. Females were more attracted to the odours produced by outbred males than the odours produced by inbred males, suggesting that inbreeding reduces the attractiveness of male sexual signalling. However, we did not find any difference between the attractiveness of inbred and outbred female odours, which may indicate that the quality of females is either irrelevant for T. molitor males or quality is not revealed through female odours.
Christensen, A F
Pre-Columbian Mixtec social organization was distinguished by the tight endogamy of the ruling class, which included many consanguineous marriages. It was also characterized by a vigorous historical and genealogical tradition. The historical documents, or codices, provide materials for the calculation of the levels of inbreeding present before the Spanish Conquest. A genealogical analysis of inbreeding was performed on the combined pedigree, which spanned the tenth through sixteenth centuries, of all individuals connected by ancestry, descent, or marriage with Lord 8 Deer Jaguar Claw of Tilantongo (A.D. 1063-1115). Sixty of the 217 couples (27.65%) were consanguineous. When only couples of wholly known grandparentage were considered (N = 39), F = 0.1051. The mean F of all couples, even those where one spouse was of unknown parentage, was 0.0243. Over the 550 years of the pedigree the maximum F in any 52-year period was 0.1324. This level of inbreeding is sufficient to produce noticeable effects on population structure and affinities over time.
Full Text Available Many animals have evolved strategies to reduce risks of inbreeding and its deleterious effects on the progeny. In social arthropods, such as the eusocial ants and bees, inbreeding avoidance is typically achieved by the dispersal of breeders from their native colony. However studies in presocial insects suggest that kin discrimination during mate choice may be a more common mechanism in socially simpler species with no reproductive division of labour. Here we examined this possibility in the subsocial cockroach Nauphoeta cinerea, a model species for research in sexual selection, where males establish dominance hierarchies to access females and control breeding territories. When given a binary choice between a sibling male and a non-sibling male that had the opportunity to establish a hierarchy prior to the tests, females mated preferentially with the dominant male, irrespective of kinship or body size. Despite the lack of kin discrimination during mate choice, inbred-mated females incurred significant fitness costs, producing 20% less offspring than outbred-mated females. We discuss how the social mating system of this territorial cockroach may naturally limit the probability of siblings to encounter and reproduce, without the need for evolving active inbreeding avoidance mechanisms, such as kin recognition.
Full Text Available Theoretical models of sexual selection predict that both males and females of many species should benefit by selecting their mating partners. However, empirical evidence testing and validating this prediction is scarce. In particular, whereas inbreeding avoidance is expected to induce sexual conflicts, in some cases both partners could benefit by acting in concert and exerting mutual mate choice for non-assortative pairings. We tested this prediction with the gregarious cockroach Blattella germanica (L.. We demonstrated that males and females base their mate choice on different criteria and that choice occurs at different steps during the mating sequence. Males assess their relatedness to females through antennal contacts before deciding to court preferentially non-siblings. Conversely, females biased their choice towards the most vigorously courting males that happened to be non-siblings. This study is the first to demonstrate mutual mate choice leading to close inbreeding avoidance. The fact that outbred pairs were more fertile than inbred pairs strongly supports the adaptive value of this mating system, which includes no "best phenotype" as the quality of two mating partners is primarily linked to their relatedness. We discuss the implications of our results in the light of inbreeding conflict models.
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En Colombia se carece de información referente al tipo de control genético en la arveja que gobierna la precocidad, el rendimiento y sus componentes. El objetivo de este trabajo fue evaluar la habilidad combinatoria y heterosis en cuatro líneas y tres variedades comerciales de arveja, para once variables agronómicas. Se desarrolló un diseño dialélico (Griffing, método 1, modelo 1 con siete materiales, bajo condiciones de la Sabana de Bogotá. Se hizo el análisis de varianza y se obtuvieron los valores estimados para habilidad combinatoria general (HCG y específica (HCE, y se calcularon los valores de heterosis sobre la media parental (HMP y sobre el mejor padre (HBP. La HCG fue altamente significativa para ocho de los caracteres evaluados y la HCE fue significativa para: nudos hasta la primera flor, longitud de vaina, número de semillas por vaina y peso de 100 semillas. Las variedades ‘Pequinegra’, ‘Santa Isabel’ e ‘ICA Tominé’ fueron los mejores combinadores generales. La variedad ‘Pequinegra’ tuvo efectos recíprocos altamente significativos en caracteres asociados con precocidad. En cuanto a la evaluación de heterosis, los híbridos F1 tuvieron un mejor comportamiento que la media de sus parentales en cinco de los componentes de rendimiento. Aún cuando sólo tres de las progenies en estudio fueron más precoces que el mejor padre, para la HMP se hallaron valores negativos que indican precocidad para más de la mitad de los cruces evaluados. Se encontró una asociación importante entre el tamaño de la vaina y el peso de 100 semillas.
Ekechukwu, Nkiru E; Baeshen, Rowida; Traorè, Sékou F; Coulibaly, Mamadou; Diabate, Abdoulaye; Catteruccia, Flaminia; Tripet, Frédéric
The success of vector control strategies aiming to decrease disease transmission via the release of sterile or genetically-modified male mosquitoes critically depends on mating between laboratory-reared males and wild females. Unfortunately, mosquito colonization, laboratory rearing, and genetic manipulations can all negatively affect male competitiveness. Heterosis is commonly used to produce domestic animals with enhanced vigor and homogenous genetic background and could therefore potentially improve the mating performance of mass-reared male mosquitoes. Here, we produced enhanced hybrid males of the malaria mosquito Anopheles coluzzii by crossing two strains colonized >35 and 8 years ago. We compared the amount of sperm and mating plug proteins they transferred to females, as well as their insemination rate, reproductive success and longevity under various experimental conditions. Across experiments, widespread adaptations to laboratory mating were detected in the older strain. In large-group mating experiments, no overall hybrid advantage in insemination rates and the amount of sperm and accessory gland proteins transferred to females was detected. Despite higher sperm activity, hybrid males did not appear more fecund. However, individual-male mating and laboratory-swarm experiments revealed that hybrid males, while inseminating fewer females than older inbred males, were significantly more fertile, producing larger mating plugs and drastically increasing female fecundity. Heterotic males also showed increased longevity. These results validate the use of heterosis for creating hybrid males with improved fitness from long-established inbred laboratory strains. Therefore, this simple approach could facilitate disease control strategies based on male mosquito releases with important ultimate benefits to human health. Copyright © 2015 Ekechukwu et al.
Cain, Bradley; Wandera, Antony B; Shawcross, Susan G; Edwin Harris, W; Stevens-Wood, Barry; Kemp, Stephen J; Okita-Ouma, Benson; Watts, Phillip C
A central premise of conservation biology is that small populations suffer reduced viability through loss of genetic diversity and inbreeding. However, there is little evidence that variation in inbreeding impacts individual reproductive success within remnant populations of threatened taxa, largely due to problems associated with obtaining comprehensive pedigree information to estimate inbreeding. In the critically endangered black rhinoceros, a species that experienced severe demographic reductions, we used model selection to identify factors associated with variation in reproductive success (number of offspring). Factors examined as predictors of reproductive success were age, home range size, number of nearby mates, reserve location, and multilocus heterozygosity (a proxy for inbreeding). Multilocus heterozygosity predicted male reproductive success (p58%) and correlated with male home range size (p 44%). Such effects were not apparent in females, where reproductive success was determined by age (p < 0.01, explained deviance 34%) as females raise calves alone and choose between, rather than compete for, mates. This first report of a 3-way association between an individual male's heterozygosity, reproductive output, and territory size in a large vertebrate is consistent with an asymmetry in the level of intrasexual competition and highlights the relevance of sex-biased inbreeding for the management of many conservation-priority species. Our results contrast with the idea that wild populations of threatened taxa may possess some inherent difference from most nonthreatened populations that necessitates the use of detailed pedigrees to study inbreeding effects. Despite substantial variance in male reproductive success, the increased fitness of more heterozygous males limits the loss of heterozygosity. Understanding how individual differences in genetic diversity mediate the outcome of intrasexual competition will be essential for effective management, particularly
Antfolk, Jan; Lieberman, Debra; Santtila, Pekka
It is expected that in humans, the lowered fitness of inbred offspring has produced a sexual aversion between close relatives. Generally, the strength of this aversion depends on the degree of relatedness between two individuals, with closer relatives inciting greater aversion than more distant relatives. Individuals are also expected to oppose acts of inbreeding that do not include the self, as inbreeding between two individuals posits fitness costs not only to the individuals involved in the sexual act, but also to their biological relatives. Thus, the strength of inbreeding aversion should be predicted by the fitness costs an inbred child posits to a given individual, irrespective of this individual's actual involvement in the sexual act. To test this prediction, we obtained information about the family structures of 663 participants, who reported the number of same-sex siblings, opposite-sex siblings, opposite-sex half siblings and opposite-sex cousins. Each participant was presented with three different types of inbreeding scenarios: 1) Participant descriptions, in which participants themselves were described as having sex with an actual opposite-sex relative (sibling, half sibling, or cousin); 2) Related third-party descriptions, in which participants' actual same-sex siblings were described as having sex with their actual opposite-sex relatives; 3) Unrelated third-party descriptions, in which individuals of the same sex as the participants but unrelated to them were described as having sex with opposite-sex relatives. Participants rated each description on the strength of sexual aversion (i.e., disgust-reaction). We found that unrelated third-party descriptions elicited less disgust than related third-party and participant descriptions. Related third-party and participant descriptions elicited similar levels of disgust suggesting that the strength of inbreeding aversion is predicted by inclusive fitness costs. Further, in the related and unrelated conditions
Full Text Available It is expected that in humans, the lowered fitness of inbred offspring has produced a sexual aversion between close relatives. Generally, the strength of this aversion depends on the degree of relatedness between two individuals, with closer relatives inciting greater aversion than more distant relatives. Individuals are also expected to oppose acts of inbreeding that do not include the self, as inbreeding between two individuals posits fitness costs not only to the individuals involved in the sexual act, but also to their biological relatives. Thus, the strength of inbreeding aversion should be predicted by the fitness costs an inbred child posits to a given individual, irrespective of this individual's actual involvement in the sexual act. To test this prediction, we obtained information about the family structures of 663 participants, who reported the number of same-sex siblings, opposite-sex siblings, opposite-sex half siblings and opposite-sex cousins. Each participant was presented with three different types of inbreeding scenarios: 1 Participant descriptions, in which participants themselves were described as having sex with an actual opposite-sex relative (sibling, half sibling, or cousin; 2 Related third-party descriptions, in which participants' actual same-sex siblings were described as having sex with their actual opposite-sex relatives; 3 Unrelated third-party descriptions, in which individuals of the same sex as the participants but unrelated to them were described as having sex with opposite-sex relatives. Participants rated each description on the strength of sexual aversion (i.e., disgust-reaction. We found that unrelated third-party descriptions elicited less disgust than related third-party and participant descriptions. Related third-party and participant descriptions elicited similar levels of disgust suggesting that the strength of inbreeding aversion is predicted by inclusive fitness costs. Further, in the related and
Kristensen, Torsten Nygård; Loeschcke, Volker; Hoffmann, Ary A.
Inbreeding effects have been detected in captive populations of threatened species, but the extent to which these effects translate into fitness under field conditions is mostly unknown. We address this issue by comparing the performance of replicated noninbred and inbred Drosophila lines under...... conditions and involve traits not easily measured under laboratory conditions. More generally, inbreeding effects measured in captive populations may not necessarily predict their field performance, and programs to purge captive populations of deleterious alleles may not necessarily lead to fitness benefits...
Li, Yangyang; Wang, Cheng; Liu, Xinye; Song, Jian; Li, Hongjian; Sui, Zhipeng; Zhang, Ming; Fang, Shuang; Chu, Jinfang; Xin, Mingming; Xie, Chaojie; Zhang, Yirong; Sun, Qixin; Ni, Zhongfu
Heterosis has been widely used in agriculture, but the underlying molecular principles are still largely unknown. During seed germination, we observed that maize (Zea mays) hybrid B73/Mo17 was less sensitive than its parental inbred lines to exogenous abscisic acid (ABA), and endogenous ABA content in hybrid embryos decreased more rapidly than in the parental inbred lines. ZmABA8ox1b, an ABA inactivation gene, was consistently more highly up-regulated in hybrid B73/Mo17 than in its parental inbred lines at early stages of seed germination. Moreover, ectopic expression of ZmABA8ox1b obviously promoted seed germination in Arabidopsis Remarkably, microscopic observation revealed that cell expansion played a major role in the ABA-mediated maize seed germination heterosis, which could be attributed to the altered expression of cell wall-related genes. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.
Pedersen, L D; Sørensen, A C; Berg, P
We used computer simulations to investigate to what extent true inbreeding, i.e. identity-by-descent, is affected by the use of marker-assisted selection (MAS) relative to traditional best linear unbiased predictions (BLUP) selection. The effect was studied by varying the heritability (h2 = 0.04 vs....... 0.25), the marker distance (MAS vs. selection on the gene, GAS), the favourable QTL allele effect (α = 0.118 vs. 0.236) and the initial frequency of the favourable QTL allele (p = 0.01 vs. 0.1) in a population resembling the breeding nucleus of a dairy cattle population. The simulated genome...... consisted of two chromosomes of 100 cM each in addition to a polygenic component. On chromosome 1, a biallelic QTL as well as 4 markers were simulated in linkage disequilibrium. Chromosome 2 was selectively neutral. The results showed that, while reducing pedigree estimated inbreeding, MAS and GAS did...
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Pandey, Sarita K; Dasgupta, Tapash; Rathore, Abhishek; Vemula, Anilkumar
The genetic distance analysis for selection of suitable parents has been established and effectively used in many crops; however, there is dearth of conclusive report of relationship of genetic distance analysis with heterosis in sesame. In the present study, an attempt was made to estimate the associations of genetic distances using SSR (GDSSR), seed-storage protein profiling (GDSDS) and agro-morphological traits (GDMOR) with hybrid performance. Seven parents were selected from 60 exotic and Indian genotypes based on genetic distance from clustering pattern based on SSR, seed-storage protein, morphological traits and per se performance. For combining ability analysis, 7 parents and 21 crosses generated from 7 × 7 half diallel evaluated at two environments in a replicated field trial during pre-kharif season of 2013. Compared with the average parents yield (12.57 g plant -1 ), eight hybrids had a significant (P < 0.01) yield advantage across environments, with averages of 26.94 and 29.99% for better-parent heterosis (BPH) and mid-parent heterosis (MPH), respectively, across environments. Highly significant positive correlation was observed between specific combining ability (SCA) and per se performance (0.97), while positive non-significant correlation of BPH with GDSSR (0.048), and non-significant negative correlations with GDMOR (- 0.01) and GDSDS (- 0.256) were observed. The linear regressions of SCA on MPH, BPH and per se performance of F 1 s were significant with R 2 value of 0.88, 0.84 and 0.95 respectively. The present findings revealed a weak association of GDSSR with F 1 's performance; however, SCA has appeared as an important factor in the determination of heterosis and per se performance of the hybrids. The present findings also indicated that parental divergence in the intermediate group would likely produce high heterotic crosses in sesame.
Full Text Available The objective of this study was to estimate the breed-direct, breed-maternal and heterosis effects from data obtained for weaning and yearling weights of Brahman and its crosses with Charolais, Simmental, Brown Swiss breeds in a beef herd in Tabasco, Mexico. The climate of the region is tropical humid. Data were obtained on 1217 calves born from 1995 to 2007; among the 16 breed-group combinations one was purebred mating (Brahman, 3 two-breed static crosses, 7 three-breed static crosses and 5 backcrosses. Cows were fed in paddocks of Jaragua grass (Hyparrenia rufa of poor condition and invaded with native grass of Paspalum and Axonopous genera. Calves remained with their dams until weaning. They were weighed at weaning and about one year of age. Calve weights from the record cards kept at the ranch were used to calculate adjusted weaning (W240 and yearling weights (W365. During the 13 year period of data collection, 711 cows and heifers were inseminated with semen of 23 Charolais (Ch, 50 Simmental (Si, 19 Brown Swiss (BS and 15 Brahman (Br unrelated sires. Also 32 Br bulls were used for natural mating. A multiple regression procedure was used to obtain estimates of the breed-direct, breed-maternal and direct heterosis effects for W240 and W365. The overall means and standard errors for W240 and W365 were 178.5+0.89 and 219.9+1.78 kg, respectively. The analysis of variance showed significant (P0.20 for W365. Except for the Si x Br negative heterosis value for W240, all heterosis effects were positive but nonsignicant (P>0.12.
Full Text Available Reciprocal cross effects with respect to larval salivary secretory protein levels were studied in the interspecific fertile reciprocal hybrids by crossing Drosophila nasuta nasuta, and Drosophila nasuta albomicans. These proteins are produced copiously during the third larval instar stage and are believed to play a role in the attachment of pupa to the substratum prior to pupariation as well as in insect immunity. Quantitative variations were encountered among the reciprocal hybrids. Significant heterosis was observed between D. n. nasuta and the F1 hybrid female of a cross between D. n. albomicans female and D. n. nasuta male (21.39% while the F1 hybrids of a cross between D. n. nasuta female and D. n. albomicans male showed a marginal increase (4.24% from the mid parent level. The glue secretions were correlated to total cell number but independent of gland size. SDS PAGE revealed a considerable heterosis with respect to X-linked protein fractions. Here we report sex specific biochemical heterosis. However the X-linked fractions undergo dosage compensation in both parents and hybrids indicating strict regulatory control.
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This paper analyzes the impact of academic inbreeding in relation to academic research, and proposes a new conceptual framework for its analysis. We find that mobility (or lack of) at the early research career stage is decisive in influencing academic behaviors and scientific productivity. Less mobile academics have more inward oriented…
Brouwer, Lyanne; van de Pol, Martijn; Atema, Els; Cockburn, Andrew
In cooperative breeders, the tension between the opposing forces of kin selection and kin competition is at its most severe. Although philopatry facilitates kin selection, it also increases the risk of inbreeding. When dispersal is limited, extra-pair paternity might be an important mechanism to
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Banik, S Datta
The present study reports inbreeding effects on mean palmar dermatoglyphic characteristics: triradial count on palm, maximal atd angle, adt angle, td ridge count, ab ridge count, main line index (MLI) and ab ridge breadth. Samples were drawn from adult males belonging to three endogamous sections representing Hindu caste Telaga of Kharagpur (West Midnapore), Ansari Muslims of Nandigram (East Midnapore) and Sheik-Sunni Muslims of Braddhaman in West Bengal, India. Consistent trend of higher mean triradial number, adt angle, and lower mean td ridge count, ab ridge count, and ab ridge breadth was observed in inbred sections compared to their non-inbred relatives in three social groups. Copyright © 2013 Elsevier GmbH. All rights reserved.
Pedersen, L D; Sørensen, A C; Berg, P
) with an initial frequency of the favorable allele of 0.1, and initially explaining 25% of the genetic variance as well as 4 markers were simulated in linkage disequilibrium, all positioned at chromosome 1. Chromosome 2 was selectively neutral, and consisted of a single neutral locus. The results showed......This study investigated whether selection using genotype information reduced the rate and level of true inbreeding, that is, identity by descent, at a selectively neutral locus as well as a locus under selection compared with traditional BLUP selection. In addition, the founder representation...... at these loci and the within-family selection at the nonneutral locus were studied. The study was carried out using stochastic simulation of a population resembling the breeding nucleus of a dairy cattle population for 25 yr. Each year, 10 proven bulls were selected across herds along with 100 dams from within...
Pedigree analysis constitutes a classical approach for the study of the evolution of genetic diversity, genetic structure, history and breeding practices within a given breed. As a consequence of selection pressure, management in closed populations and historical bottlenecks, many dog breeds have experienced considerable inbreeding and show (on the basis of a pedigree approach) comparable diversity loss compared to other domestic species. This evolution is linked to breeding practices such as the overuse of popular sires or mating between related animals. The popular sire phenomenon is the most problematic breeding practice, since it has also led to the dissemination of a large number of inherited defects. The practice should be limited by taking measures such as restricting the number of litters (or offspring) per breeding animal. Copyright © 2011 Elsevier Ltd. All rights reserved.
Full Text Available Genomic selection (GS provides an attractive option for accelerating genetic gain in perennial ryegrass ( improvement given the long cycle times of most current breeding programs. The present study used simulation to investigate the level of genetic gain and inbreeding obtained from GS breeding strategies compared with traditional breeding strategies for key traits (persistency, yield, and flowering time. Base population genomes were simulated through random mating for 60,000 generations at an effective population size of 10,000. The degree of linkage disequilibrium (LD in the resulting population was compared with that obtained from empirical studies. Initial parental varieties were simulated to match diversity of current commercial cultivars. Genomic selection was designed to fit into a company breeding program at two selection points in the breeding cycle (spaced plants and miniplot. Genomic estimated breeding values (GEBVs for productivity traits were trained with phenotypes and genotypes from plots. Accuracy of GEBVs was 0.24 for persistency and 0.36 for yield for single plants, while for plots it was lower (0.17 and 0.19, respectively. Higher accuracy of GEBVs was obtained for flowering time (up to 0.7, partially as a result of the larger reference population size that was available from the clonal row stage. The availability of GEBVs permit a 4-yr reduction in cycle time, which led to at least a doubling and trebling genetic gain for persistency and yield, respectively, than the traditional program. However, a higher rate of inbreeding per cycle among varieties was also observed for the GS strategy.
José Branco de Miranda Filho
for breeding purposes was the objective of this study. Ten maize varieties (populations, previously selected for resistance to Puccinia polysora, Phaeosphaeria maydis, Physopella zeae, Exserohilum turcicum and corn stunt complex, were evaluated under the diallel crossing scheme. Varieties and crosses were evaluated in acid and low fertility soil. Analyzed traits were: ear yield (EY, plant height (PH, and ear height (EH. Varieties PMI 8701, CMS 57NF, PMI 9401 CMS 58ND and AMARILLO DENTADO DMR showed the highest yields (above 3.5 t/ ha per se representing more than 70% in relation to check yield. Heterosis showed significance for all traits, but among the components of heterosis only average heterosis was significant for EY and specific heterosis for EH. General combining ability effects (gi were significant for all traits, and their highest EY estimates (t/ha were for PMI 8701 (0.150, BR 105 (0.120, CMS 59 (0.106. The cross CMS 57NF x PMI 8701, with yield of 5.11 t/ha (above both hybrid checks and heterosis of 23.7% above mid-parent, may be indicated as a potentially useful heterotic group. Varieties PMI 8701, CMS 57NF, PMI 9401 and CMS 58ND were considered the most promising intrapopulation breeding programs, for acid soils.
KEY-WORDS: Heterosis; acidity stress; combining ability; germplasm.
Bilde, T.; Maklakov, Alexei A.; Meisner, Katrine
Background Sex differences in lifespan are ubiquitous throughout the animal kingdom but the causes underlying this phenomenon remain poorly understood. Several explanations based on asymmetrical inheritance patterns (sex chromosomes or mitochondrial DNA) have been proposed, but these ideas have...... rarely been tested experimentally. Alternatively, sexual dimorphism in lifespan could result from sex-specific selection, caused by fundamental differences in how males and females optimize their fitness by allocating resources into current and future reproduction. Results Here we used sex......-specific responses to inbreeding to study the genetic architecture of lifespan and mortality rates in Callosobruchus maculatus, a seed beetle that shows sexual dimorphism in lifespan. Two independent assays revealed opposing sex-specific responses to inbreeding. The combined data set showed that inbred males live...
M.M. Osorio-Arce; JosÃ© C. Segura
The objective of this study was to estimate the breed-direct, breed-maternal and heterosis effects from data obtained for weaning and yearling weights of Brahman and its crosses with Charolais, Simmental, Brown Swiss breeds in a beef herd in Tabasco, Mexico. The climate of the region is tropical humid. Data were obtained on 1217 calves born from 1995 to 2007; among the 16 breed-group combinations one was purebred mating (Brahman), 3 two-breed static crosses, 7 three-breed static crosses and 5...
Sultanova, Zahida; Andic, Muhammed; Carazo, Pau
Sex differences in ageing and lifespan are ubiquitous in nature. The "unguarded-X" hypothesis (UXh) suggests they may be partly due to the expression of recessive mutations in the hemizygous sex chromosomes of the heterogametic sex, which could help explain sex-specific ageing in a broad array of taxa. A prediction central to the UX hypothesis is that inbreeding will decrease the lifespan of the homogametic sex more than the heterogametic sex, because only in the former does inbreeding increase the expression of recessive deleterious mutations. In this study, we test this prediction by examining the effects of inbreeding on the lifespan and fitness of male and female Drosophila melanogaster across different social environments. We found that, across social environments, inbreeding resulted in a greater reduction of female than male lifespan, and that inbreeding effects on fitness did not seem to counterbalance sex-specific effects on lifespan, suggesting the former are maladaptative. Inter- and intra-sexual correlation analyses also allowed us to identify evidence of an underlying joint genetic architecture for inbreeding effects on lifespan. We discuss these results in light of the UXh and other alternative explanations, and suggest that more attention should be paid to the possibility that the "unguarded-X" may play an important role in the evolution of sex-specific lifespan. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.
Costello, Cecily M; Creel, Scott R; Kalinowski, Steven T; Vu, Ninh V; Quigley, Howard B
We tested the hypothesis that sex-biased natal dispersal reduces close inbreeding in American black bears, a solitary species that exhibits nearly complete male dispersal and female philopatry. Using microsatellite DNA and spatial data from reproductively mature bears (>or= 4 years old), we examined the spatial genetic structure of two distinct populations in New Mexico from 1993 to 2000. As predicted, relatedness (r) and the frequency of close relationships (parent-offspring or full siblings) decreased with distance among female dyads, but little change was observed among male or opposite-sex dyads. Neighbouring females were more closely related than neighbouring males. The potential for inbreeding was low. Most opposite-sex pairs that lived sufficiently close to facilitate mating were unrelated, and few were close relatives. We found no evidence that bears actively avoided inbreeding in their selection of mates from this nearby pool, as mean r and relationship frequencies did not differ between potential and actual mating pairs (determined by parentage analysis). These basic patterns were apparent in both study areas despite a nearly two-fold difference in density. However, the sex bias in dispersal was less pronounced in the lower-density area, based on proportions of bears with male and female relatives residing nearby. This result suggests that male bears may respond to reduced competition by decreasing their rate or distance of dispersal. Evidence supports the hypothesis that inbreeding avoidance is achieved by means of male-biased dispersal but also indicates that competition (for mates or resources) modifies dispersal patterns.
Collevatti, Rosane G.; Leite, Kelly C.E.; Miranda, Guilherme H.B. de; Rodrigues, Flavio H.G.
We report the genetic structure, relatedness and mating structure of a population of the endangered giant anteater Myrmecophaga tridactyla Linnaeus, 1758 in the Emas National Park, Brazil, based on variability at five microsatellite loci. Additionally, we addressed the hypothesis that the M. tridactyla population studied has low levels of polymorphism and high levels of inbreeding and relatedness and that animals with overlapping home range are highly related. All five microsatellite loci dis...
Moula, Nassim; Philippe, François-Xavier; Antoine-Moussiaux, Nicolas; Leroy, Pascal; Michaux, Charles
In Belgium, as generally in Europe, the dominant position of the high producing commercial strains specialized in meat or eggs production threats of extinction the local traditional breeds. In this work, a follow up of the changes in populations size, and the rates of inbreeding of the Belgian poultry breeds, has been carried out in 2005 and 2010. About forty breeds were concerned. The Belgian hen breeds being overwhelmingly under threat of extinction, because of the low number of individu...
Trevisan, Maíra; De Bortoli, Sergio A; Vacari, Alessandra M; Laurentis, Valéria L; Ramalho, Dagmara G
Although the parasitoid Cotesia flavipes (Cameron) has proven effective in controlling sugarcane borer Diatraea saccharalis (Fabricius) for many years, concern has arisen over the quality of individuals produced at large scales. The parasitoid has been reared in laboratories in Brazil for more than 40 years, with no new introductions of new populations during that period. Since the quality of the parasitoids was not verified at the time of the species' introduction in Brazil, we do not know if there has been any reduction in quality so far. However, it is possible to determine whether the parasitoid could reduce in quality in future generations. Thus, the objective of this research was to assess the quality of these insects over 10 generations and look for evidence of any loss in quality. We used two populations: one from a biofactory that has been maintained in the laboratory for over 40 years, and an inbred laboratory population. Both were bred, and compared for 10 generations. We wanted to determine what happened to the quality of the parasitoid after 10 generations in an extreme inbreeding situation. To assure inbreeding, newly emerged females were forced to mate with a sibling. Individual females were then allowed to parasitize larvae of D. saccharalis. We performed evaluations for each generation until the tenth generation, and recorded the sex ratio, percentage emergence, number of offspring/females, and longevity of both males and females. Results of the measurements of biological characteristics demonstrated random significant differences between populations; best results were obtained intermittently for both the biofactory population and the inbred population. No significant differences across generations for the same population were observed. Thus, rearing of a C. flavipes population subjected to inbreeding for 10 generations was not sufficient to reveal any deleterious effects of inbreeding.
Tian, Tao; Chen, Zaizhong; Wang, Mosang; Hu, Yulong; Wang, Weiji
Ten microsatellite markers were used to analyze the levels of genetic diversity and inbreeding in a hatchery release population of Rhopilema esculentum Kishinouye (Scyphozoa: Rhizostomatidae). A total of 85 alleles were detected in 600 individuals. Within-population levels of observed ( H o) and expected ( H e) heterozygosity ranged from 0.152 to 0.839 (mean=0.464) and from 0.235 to 0.821 (mean=0.618), respectively. The polymorphism information content (PIC) of each marker ranged from 0.207 to 0.795 with an average of 0.580, indicating that the hatchery population maintained a high level of genetic diversity. Inbreeding levels were estimated in the hatchery population and the inbreeding coefficient was 0.203. This result revealed that a certain level of inbreeding occurred within the population. Meanwhile, we also determined genetic diversity at the clone level. Several polyps from the same scyphistomae were genotyped at the ten microsatellite loci and there was virtually no difference in their genotypes. Furthermore, we calculated the probabilities of exclusion. When both parents were known, the average exclusion probability of ten loci was 99.99%. Our data suggest that the ten microsatellite markers can not only be used to analyze the identity of individuals but they can also be applied to parentage identification. Our research provides a theoretical basis and technical support for genetic diversity detection and reasonable selection of R. esculentum hatchery populations. These findings support the use of releasing studies and conservation of R. esculentum germplasm resources.
Reid, Jane M.; Bocedi, Greta; Nietlisbach, Pirmin; Duthie, A. Bradley; Wolak, Matthew E.; Gow, Elizabeth A.; Arcese, Peter
Female extra‐pair reproduction in socially monogamous systems is predicted to cause cuckolded socially‐paired males to conditionally reduce paternal care, causing selection against extra‐pair reproduction and underlying polyandry. However, existing models and empirical studies have not explicitly considered that cuckolded males might be related to their socially‐paired female and/or to her extra‐pair mate, and therefore be related to extra‐pair offspring that they did not sire but could rear. Selection against paternal care, and hence against extra‐pair reproduction, might then be weakened. We derive metrics that quantify allele‐sharing between within‐pair and extra‐pair offspring and their mother and her socially‐paired male in terms of coefficients of kinship and inbreeding. We use song sparrow (Melospiza melodia) paternity and pedigree data to quantify these metrics, and thereby quantify the joint effects of extra‐pair reproduction and inbreeding on a brood's total allelic value to its socially‐paired parents. Cuckolded male song sparrows were almost always detectably related to extra‐pair offspring they reared. Consequently, although brood allelic value decreased substantially following female extra‐pair reproduction, this decrease was reduced by within‐pair and extra‐pair reproduction among relatives. Such complex variation in kinship within nuclear families should be incorporated into models considering coevolutionary dynamics of extra‐pair reproduction, parental care, and inbreeding. PMID:27174154
Banks, Sam C; Lindenmayer, David B
Animal dispersal is highly non-random and has important implications for the dynamics of populations in fragmented habitat. We identified interpatch dispersal events from genetic tagging, parentage analyses and assignment tests and modelled the factors associated with apparent emigration and post-dispersal settlement choices by individual male agile antechinus (Antechinus agilis, a marsupial carnivore of south-east Australian forests). Emigration decisions were best modelled with on data patch isolation and inbreeding risk. The choice of dispersal destination by males was influenced by inbreeding risk, female abundance, patch size, patch quality and matrix permeability (variation in land cover). Males were less likely to settle in patches without highly unrelated females. Our findings highlight the importance of individual-level dispersal data for understanding how multiple processes drive non-randomness in dispersal in modified landscapes. Fragmented landscapes present novel environmental, demographic and genetic contexts in which dispersal decisions are made, so the major factors affecting dispersal decisions in fragmented habitat may differ considerably from unfragmented landscapes. We show that the spatial scale of genetic neighbourhoods can be large in fragmented habitat, such that dispersing males can potentially settle in the presence of genetically similar females after moving considerable distances, thereby necessitating both a choice to emigrate and a choice of where to settle to avoid inbreeding. © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.
Ortega, Encarnación; Martínez-García, Pedro J; Dicenta, Federico; Egea, José
A homozygous self-compatible almond, originated from self-fertilization of a self-compatible genotype and producing a reasonable yield following open pollination, exhibited a very high fruit drop rate when self-pollinated. To investigate whether fruit dropping in this individual is related to an abnormal development of the embryo sac following self-fertilization, histological sections of ovaries from self and cross-pollinated flowers were observed by light microscopy. Additionally, the presence of pollen tubes in the ovary and fruit set were determined for both types of pollination. Despite pollen tubes reached the ovary after both pollinations, differences in embryo sac and endosperm development after fertilization were found. Thus, while for cross-fertilized ovules a pro-embryo and an endosperm with abundant nuclei were generally observed, most self-fertilized ovules remained in a previous developmental stage in which the embryo sac was not elongated and endosperm nuclei were absent. Although 30 days after pollination fruit set was similar for both pollination types, at 60 days it was significantly reduced for self-pollination. These results provide evidence that the high fruit drop in this genotype is the consequence of a disrupted development of the endosperm, what could be an expression of its high level of inbreeding.
Lehtonen, Jussi; Kokko, Hanna
A large proportion of studies in systems science focus on processes involving a mixture of positive and negative feedbacks, which are also common themes in evolutionary ecology. Examples of negative feedback are density dependence (population regulation) and frequency-dependent selection (polymorphisms). Positive feedback, in turn, plays a role in Fisherian ‘runaway’ sexual selection, the evolution of cooperation, selfing and inbreeding tolerance under purging of deleterious alleles, and the evolution of sex differences in parental care. All these examples feature self-reinforcing processes where the increase in the value of a trait selects for further increases, sometimes via a coevolutionary feedback loop with another trait. Positive feedback often leads to alternative stable states (evolutionary endpoints), making the interpretation of evolutionary predictions challenging. Here, we discuss conceptual issues such as the relationship between self-reinforcing selection and disruptive selection. We also present an extension of a previous model on parental care, focusing on the relationship between the operational sex ratio and sexual selection, and the influence of this relationship on the evolution of biparental or uniparental care. PMID:22144384
Harrison, X A; York, J E; Cram, D L; Young, A J
In many cooperatively breeding species, females mate extra-group, the adaptive value of which remains poorly understood. One hypothesis posits that females employ extra-group mating to access mates whose genotypes are more dissimilar to their own than their social mates, so as to increase offspring heterozygosity. We test this hypothesis using life history and genetic data from 36 cooperatively breeding white-browed sparrow weaver (Plocepasser mahali) groups. Contrary to prediction, a dominant female's relatedness to her social mate did not drive extra-group mating decisions and, moreover, extra-group mating females were significantly more related to their extra-group sires than their social mates. Instead, dominant females were substantially more likely to mate extra-group when paired to a dominant male of low heterozygosity, and their extra-group mates (typically dominants themselves) were significantly more heterozygous than the males they cuckolded. The combined effects of mating with extra-group males of closer relatedness, but higher heterozygosity resulted in extra-group-sired offspring that were no more heterozygous than their within-group-sired half-siblings. Our findings are consistent with a role for male-male competition in driving extra-group mating and suggest that the local kin structure typical of cooperative breeders could counter potential benefits to females of mating extra-group by exposing them to a risk of inbreeding. © 2013 John Wiley & Sons Ltd.
Lehtonen, Jussi; Kokko, Hanna
A large proportion of studies in systems science focus on processes involving a mixture of positive and negative feedbacks, which are also common themes in evolutionary ecology. Examples of negative feedback are density dependence (population regulation) and frequency-dependent selection (polymorphisms). Positive feedback, in turn, plays a role in Fisherian 'runaway' sexual selection, the evolution of cooperation, selfing and inbreeding tolerance under purging of deleterious alleles, and the evolution of sex differences in parental care. All these examples feature self-reinforcing processes where the increase in the value of a trait selects for further increases, sometimes via a coevolutionary feedback loop with another trait. Positive feedback often leads to alternative stable states (evolutionary endpoints), making the interpretation of evolutionary predictions challenging. Here, we discuss conceptual issues such as the relationship between self-reinforcing selection and disruptive selection. We also present an extension of a previous model on parental care, focusing on the relationship between the operational sex ratio and sexual selection, and the influence of this relationship on the evolution of biparental or uniparental care.
Full Text Available The socially parasitic ant genus Myrmoxenus varies strongly in fundamental life history traits, such as queen-worker ratio, the timing of sexual production, and mating behavior. Myrmoxenus queens generally take over nests of Temnothorax ants, kill the resident queen by throttling, and force the workers to take care of the social parasite's brood. Young queens of M. ravouxi and other species produce large numbers of workers, which during "slave-raids" pillage host pupae from neighboring Temnothorax colonies to increase the workforce in their own nests. Other species, such as M. corsicus, have lost caste polyphenism and rear only male and female sexual offspring. Using sequences of the genes CO I/CO II and wingless we reconstruct the phylogeny of Myrmoxenus and document that the worker caste was lost convergently at least three times. Furthermore, mating in the nest and inbreeding obviously also evolved in parallel from ancestors whose sexuals presumably mated during nuptial flights. Myrmoxenus might thus provide a suitable model to investigate caste differentiation and the plasticity of mating behavior in Hymenoptera.
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Heteroses materna e individual para ganho de peso pré-desmama em bovinos Nelore × Hereford e Nelore × Angus Maternal and individual heterosis for preweaning daily gain in Nellore × Hereford and Nellore × Angus cattle
Full Text Available Foram utilizados dados de 62.985 animais das raças Nelore, Hereford, Angus e produtos de cruzamentos Nelore × Angus e Nelore × Hereford de rebanhos comerciais a fim de estimar os efeitos de heterose materna e individual para o ganho médio diário no período pré-desmama (GMD. Os valores obtidos de heterose individual e materna considerando-se o valor médio de GMD da população representam um acréscimo de 6,2% e 11,2% no GMD para os animais F1 e filhos de vacas F1, respectivamente. A heterose materna correspondeu a 64,5% da heterose total. Animais cruzados Bos taurus × Bos indicus obtêm GMD maior do que o dos animais das raças puras.Data on 62.985 Nellore, Hereford, Angus and Nellore × Angus and Nellore × Hereford crossbred calves were analyzed to estimate maternal and individual heterosis for preweaning daily weight gain (PWD. The individual and maternal heterosis of average daily weight gain showed improvements of 6.2 and 11.2% for PWD of F1 calves and for calves borne from F1 dams. Maternal heterosis corresponded to 64.5% of total heterosis. Bos taurus × Bos indicus crossbred cattle have a PWD larger than the average of purebred cattle.
Full Text Available A study of the viability of small populations of Hymenoptera is a matter of importance to gain a better zoological, ethological, genetical and ecological knowledge of these insects, and for conservation purposes, mainly because of the consequences to the survival of colonies of many species of bees, wasps, and ants. Based on the Whiting (1943 principle, Kerr & Vencovski (1982 presented a hypothesis that states that viable populations of stingless bees (Meliponini should have at least 40 colonies to survive. This number was later extended to 44 colonies by Kerr (1985. This would be necessary to avoid any substantial amount of homozygosis in the pair of chromosomic sexual loci, by keeping at least six different sexual gene alleles in a reproductive population. In most cases this would prevent the production of useless diploid males. However, several facts weigh against considering this as a general rule. From 1990 to 2001, 287 colony divisions were made, starting with 28 foundation colonies, in the inbreeding and population experiments with the Meliponini reported here. These experiments constitute the most extensive and longest scientific research ever made with Meliponini bees. In ten different experiments presented here, seven species (one with two subspecies of Meliponini bees were inbred in five localities inside their wide-reaching native habitats, and in two localities far away from these habitats. This was done for several years. On the whole, the number of colonies increased and the loss of colonies over the years was small. In two of these experiments, although these populations were far (1,000 km and 1,200 km from their native habitat, their foundation colonies were multiplied successfuly. It was possible to build up seven strong and three expanding medium populations, starting with one, two, three or even five colonies. However, in six other cases examined here, the Whiting (1943 principle and the hypothesis of Kerr & Vencovski (1982
Cubry, Philippe; Scotti, Ivan; Oddou-Muratorio, Sylvie; Lefèvre, François
Q ST is a differentiation parameter based on the decomposition of the genetic variance of a trait. In the case of additive inheritance and absence of selection, it is analogous to the genic differentiation measured on individual loci, F ST . Thus, Q ST -F ST comparison is used to infer selection: selective divergence when Q ST > F ST , or convergence when Q ST definition of Q-statistics was extended to two-level hierarchical population structures with Hardy-Weinberg equilibrium. Here, we generalize the Q-statistics framework to any hierarchical population structure. First, we developed the analytical definition of hierarchical Q-statistics for populations not at Hardy-Weinberg equilibrium. We show that the Q-statistics values obtained with the Hardy-Weinberg definition are lower than their corresponding F-statistics when F IS > 0 (higher when F IS framework in a hierarchical population structure. We show that, while differentiation at the lower hierarchical level (Q SR ) is a monotonic function of migration, differentiation at the upper level (Q RT ) is not. In the case of additive inheritance, we show that inbreeding inflates the variance of Q RT , which can increase the frequency of Q RT > F RT cases. We also show that dominance drastically reduces Q-statistics below F-statistics for any level of the hierarchy. Therefore, high values of Q-statistics are good indicators of selection, but low values are not in the case of dominance. © 2017 John Wiley & Sons Ltd.
Rosane G. Collevatti
Full Text Available We report the genetic structure, relatedness and mating structure of a population of the endangered giant anteater Myrmecophaga tridactyla Linnaeus, 1758 in the Emas National Park, Brazil, based on variability at five microsatellite loci. Additionally, we addressed the hypothesis that the M. tridactyla population studied has low levels of polymorphism and high levels of inbreeding and relatedness and that animals with overlapping home range are highly related. All five microsatellite loci displayed low levels of polymorphism and of expected and observed heterozygosity. The low level of polymorphism and high inbreeding showed by the population studied may be the outcome of high mortality and reduction in population size due to recurrent fire events in the Emas National Park, as reported in 1994. The reduction in population size may have led to a higher frequency of mating between closely related animals, augmented by the isolation of the population in the park because of the expansion of agricultural land and fragmentation of the Cerrado environment. The natural history of M. tridactyla and the phylopatric (sex-biased dispersal behavior of females should increase the effects of isolation and bottlenecking, decreasing gene flow and increasing inbreeding. However, the low levels of polymorphism found in this population may simply be due to the natural history and evolution of M. tridactyla as reported for other species. The genetic structure and dynamics of this population needs to be investigated more profoundly in order to provide sound data for the design of conservation strategies for M. tridactyla in the Emas National Park.
Wetzel, Daniel P; Stewart, Ian R K; Westneat, David F
We investigated the link between heterozygosity and the reaction norm attributes of reproductive performance in female house sparrows (Passer domesticus). We collected data on clutch size, egg size, hatching success and nestling survival in 2816 nesting attempts made by 791 marked individuals over a 16-year period. Pedigree analysis revealed no evidence of inbreeding. Neither parent-offspring regression nor an animal model revealed significant heritability in clutch or egg size. We selected 42 females that laid at least seven clutches at our study site and used a survey of 21 autosomal microsatellite loci to estimate heterozygosity for each female. We controlled for phenotypic plasticity and found that both clutch and egg size showed significant positive correlations with heterozygosity. We found no evidence that heterozygosity influenced the slope of individual reaction norms. Further analysis suggested that clutch size was affected by heterozygosity across the genome, but egg size had more complex relationships, with evidence favouring the influence of multiple loci. Given the apparent lack of inbreeding and large population size, our results suggest associative overdominance as the likely mechanism for the impact of heterozygosity, but also created a puzzle about the process producing associations between neutral markers and the genes affecting clutch size or egg size. One possible explanation is a long-term residual effect of the historical bottleneck that occurred when house sparrows were introduced into North America. The existence of heterozygosity-fitness correlations in a population with considerable phenotypic plasticity and little inbreeding implies that the effects of heterozygosity may be more significant than previously thought. © 2011 Blackwell Publishing Ltd.
Brown, Anthony P; Greenway, Ryan; Morgan, Samuel; Quackenbush, Corey R; Giordani, Luca; Arias-Rodriguez, Lenin; Tobler, Michael; Kelley, Joanna L
Populations with limited ranges can be highly vulnerable to changes in their environment and are, thus, of high conservation concern. Populations that experience human-induced range reductions are often highly inbred and lack genetic diversity, but it is unknown whether this is also the case for populations with naturally small ranges. The fishes Poecilia sulphuraria (listed as critically endangered) and Poecilia thermalis, which are endemic to small hydrogen sulphide-rich springs in southern Mexico, are examples of such populations with inherently small habitats. We used geometric morphometrics and population genetics to quantify phenotypic and genetic variation within and among two populations of P. sulphuraria and one population of P. thermalis. Principal component analyses revealed phenotypic and genetic differences among the populations. Evidence for inbreeding was low compared to populations that have undergone habitat reduction. The genetic data were also used to infer the demographic history of these populations to obtain estimates for effective population sizes and migration rates. Effective population sizes were large given the small habitats of these populations. Our results imply that these three endemic extremophile populations should each be considered separately for conservation purposes. Additionally, this study suggests that populations in naturally small habitats may have lower rates of inbreeding and higher genetic diversity than expected, and therefore may be better equipped to handle environmental perturbations than anticipated. We caution, however, that the inferred lack of inbreeding and the large effective population sizes could potentially be a result of colonization by genetically diverse ancestors. © 2017 John Wiley & Sons Ltd.
Henryon, M; Berg, P; Sørensen, A C
We reasoned that mating animals by minimising the covariance between ancestral contributions (MCAC mating) will generate less inbreeding and at least as much genetic gain as minimum-coancestry mating in breeding schemes where the animals are truncation-selected. We tested this hypothesis by stoch......We reasoned that mating animals by minimising the covariance between ancestral contributions (MCAC mating) will generate less inbreeding and at least as much genetic gain as minimum-coancestry mating in breeding schemes where the animals are truncation-selected. We tested this hypothesis...
Full Text Available Brassica juncea (AjAjBjBj, is an allotetraploid that arose from two diploid species, B. rapa (ArAr and B. nigra (BnBn. It is an old oilseed crop with unique favorable traits, but the genetic improvement on this species is limited. We developed an approach to broaden its genetic base within several generations by intensive selection. The Ar subgenome from the Asian oil crop B. rapa (ArAr and the Bc subgenome from the African oil crop B. carinata (BcBcCcCc were combined in a synthesized allohexaploid (ArArBcBcCcCc, which was crossed with traditional B. juncea to generate pentaploid F1 hybrids (ArAjBcBjCc, with subsequent self-pollination to obtain newly synthesized B. juncea (Ar/jAr/jBc/jBc/j. After intensive cytological screening and phenotypic selection of fertility and agronomic traits, a population of new-type B. juncea was obtained and was found to be genetically stable at the F6 generation. The new-type B. juncea possesses good fertility and rich genetic diversity and is distinctly divergent but not isolated from traditional B. juncea, as revealed by population genetic analysis with molecular markers. More than half of its genome was modified, showing exotic introgression and novel variation. In addition to the improvement in some traits of the new-type B. juncea lines, a considerable potential for heterosis was observed in inter-subgenomic hybrids between new-type B. juncea lines and traditional B. juncea accessions. The new-type B. juncea exhibited a stable chromosome number and a novel genome composition through multiple generations, providing insight into how to significantly broaden the genetic base of crops with subgenome introgression from their related species and the potential of exploring inter-subgenomic heterosis for hybrid breeding.
Niveles y efectos de la consanguinidad en variables de comportamiento durante la tienta y la lidia en dos ganaderías de reses bravas de Colombia Levels and effects of inbreeding on performance traits during tempt and fight from two fighting bull farms in Colombia
David Calero Quintero
GUA were 6.6 and 5.8%; and 4.2 and 6%, respectively. Means and standard deviations of inbreeding in EGC and GUA were 4.9±6.6 and 4.2±4.2% for the all animals, 4.5±5.8 and 6.0±3.4% for the last time studied , and 10.6±5.8 and 6.51±3.5% taking in to account only those that were related. The effect of some variables with the inbreeding had positive effects in those responsible for the ‘toreabilidad’ and style, and depressive on the force of the animals. The current inbreeding in these populations is medium; however, mating should be planned for an appropriate handling and to reduce increases in inbreeding.
Liu, H; Henryon, M; Sørensen, A C
We tested the hypothesis that mating strategies with genomic information realise lower rates of inbreeding (∆F) than with pedigree information without compromising rates of genetic gain (∆G). We used stochastic simulation to compare ∆F and ∆G realised by two mating strategies with pedigree and genomic information in five breeding schemes. The two mating strategies were minimum-coancestry mating (MC) and minimising the covariance between ancestral genetic contributions (MCAC). We also simulated random mating (RAND) as a reference point. Generations were discrete. Animals were truncation-selected for a single trait that was controlled by 2000 quantitative trait loci, and the trait was observed for all selection candidates before selection. The criterion for selection was genomic-breeding values predicted by a ridge-regression model. Our results showed that MC and MCAC with genomic information realised 6% to 22% less ∆F than MC and MCAC with pedigree information without compromising ∆G across breeding schemes. MC and MCAC realised similar ∆F and ∆G. In turn, MC and MCAC with genomic information realised 28% to 44% less ∆F and up to 14% higher ∆G than RAND. These results indicated that MC and MCAC with genomic information are more effective than with pedigree information in controlling rates of inbreeding. This implies that genomic information should be applied to more than just prediction of breeding values in breeding schemes with truncation selection.
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Fareed, Mohd; Kaisar Ahmad, Mir; Azeem Anwar, Malik; Afzal, Mohammad
The aim of our study was to understand the relationship between consanguineous marriages and reproductive outcomes. A total of 999 families were recruited from five Muslim populations of Jammu region. Family pedigrees were drawn to access the family history and inbreeding status in terms of coefficient of inbreeding (F). Fertility, mortality, secondary sex ratio, selection intensity, and lethal equivalents were measured using standard methods. The significant differences for gross fertility was found to be higher among inbred groups as compared to the unrelated families (P child mortality rates (i.e., U5MR and U18MR) have presented a persuasive increase with an upsurge in the homozygosity level. The mortality rate was found to be maximum among families with the highest value of coefficient of inbreeding (F). The selection intensity (SI) also showed inflations among families with respect to their increasing inbreeding coefficients. The greater values of lethal equivalents per gamete (LEs/gamete) were observed for autosomal inheritance in comparison with sex-linked inheritance. Our conclusive assessment brings out the deleterious consequence of consanguineous marriages on reproductive outcomes.
Brown, Jacqueline A.; Russell, Samantha; Rasor, Kaitlin
Depression is among the most common mental disorders in the United States. Its diagnosis is often related to impairment of functioning across several domains, including how an individual thinks, feels, and participates in daily activities. Although depression has a relatively high prevalence among adults, the rate is alarmingly higher among…
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Lucas Souto Bignotto
Full Text Available To assess the genetic potential of white corn for corn grits, 28 hybrids resulting from diallel crosses of eight parents, including parents and S1 generations, were evaluated. The combining abilities and levels of heterosis and inbreeding depression were estimated. The parents used were the main white maize hybrids of the Brazilian germplasm. The combinations HT 9332 x HT 392, IAC Nelore x HT 9332, IAC Nelore x HT 932, and IPR 119 x IAC Nelore are promising for reciprocal recurrent selection programs targeting higher grain yield. Hybrid IPR 127 was indicated as a source of industrial lines with favorable traits for dry-rolled corn production. Hybrid IAC Nelore had the lowest estimate of inbreeding depression and was recommended for the breeding of lines and participation in higher-yielding hybrids and composites.
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Paty Castilleja Sánchez
Full Text Available Seed production, quality, germination and seedling establishment are indicators of reproductive success in conifers. Monitoring of these parameters is essential to determine the viability of populations for the purposes of conservation. We analyze cone and seed traits as indicators of reproductive success in the endangered Rzedowski´s pine (Pinus rzedowskii (Madrigal et Caballero and near-threatened veitchii pine (Pinus ayacahuite var. veitchii (Shaw in west-central Michoacán, Mexico. These traits were systematically quantified and their variation assessed using Generalized Linear Mixed Models (GLMMs. We found that the reproductive success of Rzedowski’s pine seems to be critical, presenting low seed efficiency (17.10%, germination (5.0% and seedling establishment (27.7%, with high levels of inbreeding (0.79. In contrast, veitchii pine presents moderate seed efficiency (54.9%, high germination (71.5% and seedling establishment (84%–97% and low inbreeding (0.33. Reproductive indicators differed significantly among zones and populations for each species, where fragment sizes mainly affected seed production and efficiency. This result indicates that fragmentation has played a more important role in the reproductive success of Rzedowski’s pine than in veitchii pine, perhaps by limiting pollen flow among zones and populations and producing higher levels of inbreeding and lower seed efficiency in the former species. We propose a conservation strategy for these important pine species in order to increase their long-term genetic viability.
Avaliação das heteroses materna e individual sobre o ganho de peso do nascimento ao desmame em bovinos Angus x Nelore Evaluation of maternal and individual heterosis on preweaning gain of Angus x Nellore calves
Vanerlei Mozaquatro Roso
Full Text Available Dados de 17.796 bovinos Angus x Nelore pertencentes a 50 rebanhos associados ao "Programa Natura", localizados nos Estados de Goiás, Minas Gerais, Mato Grosso, Mato Grosso do Sul, Paraná, Rio Grande do Sul, São Paulo e Tocantins foram analisados para estimar os efeitos das heteroses materna e individual sobre o ganho de peso do nascimento ao desmame. O modelo estatístico utilizado nas análises continha os efeitos fixos da média geral, grupo contemporâneo, heterozigoses materna e individual (covariáveis, efeitos aleatórios de touro (aditivo, vaca (efeito materno composto, segregação mendeliana e resíduo. Para estimar os efeitos, utilizou-se um procedimento iterativo, que alternava análises genéticas para grupos contemporâneos e efeitos aditivos+maternos sobre o ganho de peso pré-ajustado para heteroses e análises, com o objetivo de estimar os efeitos das covariáveis sobre o ganho de peso pré-ajustado para grupo contemporâneo e efeitos aditivos+maternos. O processo foi finalizado quando as estimativas se tornaram estáveis. Os resultados indicaram relação linear positiva entre as heterozigoses e as heteroses materna e individual. Foram obtidos valores de 15,46% (22,62 kg para heterose materna e 9,10% (13,31 kg para heterose individual. Com base no grau de dificuldade para estimar os efeitos de heterose no presente trabalho, é necessário precaução ao sugerir a simples inclusão das heterozigoses no modelo estatístico e deixar que o ajuste se realize automaticamente.Records from 17,796 Angus x Nellore cattle out of 50 Associated Herds from the "Program Nature", in the states of Goiás, Minas Gerais, Mato Grosso, Mato Grosso do Sul, Paraná, Rio Grande do Sul, São Paulo and Tocantins were analyzed in order to estimate the effects of maternal and individual heterosis on the weight gain from birth to weaning. The used statistical model included the fixed effects of a general mean and contemporary groups, maternal and
Sanint P. Rodrigo
Full Text Available
An analysis of heterosis and combining ability of traits related with per plant production was carried out using a diallel crossing between different tomato cultivars, Lycopersicon esculentum Mill (six parents and 15 F, hybrids from all possible crossing in one direction, according to the methodology proposed by Griffing (1956, selecting experimental method 2, and model 1. In the genetic variation of all traits related to per plant production, the general combining ability (addite gene action and specific combining abilyty (non-aditive gene action effects participate jointly and in high1y significant manner. Hybrids Motelle x Angela I 5200, Motelle x Zarnbao y Licapal 21 x Zarnbao, exhibited high s.c.a. effects for the trait per plant production. Former effects related to high heterosis make these hybrids promising for later marketing.
Se analizó la heterosis y la habilidad combinatoria para el carácter producción por planta y sus componentes, a partir de un cruzamiento dialélico (6 progenitores, 15 híbridos F1 sin incluir los recíprocos utilizando el método experimental 2, modelo 1 propuesto por Griffing (1956. Se encontraron diferencias altamente significativas para los efectos de h.c.g. y de h.c.e. para todos los caracteres estudiados. Los híbridos Motelle x Angela I 5100, Motelle x Zambao y Licapal-21 x Zambao presentaron altos efectos de h.c.e. para el carácter producción por planta. Los anteriores efectos asociados con altas heteroheltiosis hacen que estos híbridos sean promisorios para posterior comercialización.
Yuan, Michael L; Dean, Samantha H; Longo, Ana V; Rothermel, Betsie B; Tuberville, Tracey D; Zamudio, Kelly R
Herbivorous vertebrates rely on complex communities of mutualistic gut bacteria to facilitate the digestion of celluloses and hemicelluloses. Gut microbes are often convergent based on diet and gut morphology across a phylogenetically diverse group of mammals. However, little is known about microbial communities of herbivorous hindgut-fermenting reptiles. Here, we investigate how factors at the individual level might constrain the composition of gut microbes in an obligate herbivorous reptile. Using multiplexed 16S rRNA gene sequencing, we characterized the faecal microbial community of a population of gopher tortoises (Gopherus polyphemus) and examined how age, genetic diversity, spatial structure and kinship influence differences among individuals. We recovered phylotypes associated with known cellulolytic function, including candidate phylum Termite Group 3, suggesting their importance for gopher tortoise digestion. Although host genetic structure did not explain variation in microbial composition and community structure, we found that fine-scale spatial structure, inbreeding, degree of relatedness and possibly ontogeny shaped patterns of diversity in faecal microbiomes of gopher tortoises. Our findings corroborate widespread convergence of faecal-associated microbes based on gut morphology and diet and demonstrate the role of spatial and demographic structure in driving differentiation of gut microbiota in natural populations. © 2015 John Wiley & Sons Ltd.
Marcos V Faria
Full Text Available A utilização de híbridos de cebola no Brasil ainda é recente e são escassas as informações referentes aos ganhos por heterose. Contudo, a primeira etapa para a exploração da heterose é a avaliação do germoplasma disponível. Devido à necessidade de genótipos adaptados às condições climáticas paranaenses, o presente trabalho teve como objetivo avaliar o desempenho agronômico de 19 híbridos e 50 linhagens de cebola, bem como o ganho heterótico de seis desses híbridos avaliados na região Centro-Sul do Paraná. O delineamento experimental foi em blocos casualizados com três repetições. Foi avaliada a produção e a massa média de bulbos, a classificação comercial, a cerosidade das folhas e o ciclo. De modo geral os híbridos foram superiores às linhagens na produtividade e massa média de bulbos e apresentaram menor ciclo. O ganho heterótico nos híbridos ficou evidenciado nos cruzamentos avaliados, indicando que híbridos podem ser viáveis para cultivo na região. Os híbridos 2572, 2573 e 2578 são promissores, pois aliam alta produtividade, ciclo mais precoce e melhor classificação dos bulbos. As linhagens 2507-1 e 2983 proporcionam elevado ganho heterótico para a produtividade do híbrido 2857, o qual foi classificado no grupo de genótipos mais precoces, demonstrando a existência de correlação inversa entre esses dois caracteres.The use of onion hybrids in Brazil is still recent, with little information regarding the gains from heterosis. However, the first step to exploit the heterosis is the evaluation of available germplasm. Due to the need for genotypes adapted to the climatic conditions of South-Central region of Paraná state, Brazil, this study aimed to evaluate the agronomic performance of 19 hybrids and 50 inbred lines of onion, as well as the heterotic gain of six of these hybrids. The experimental design was randomized blocks with three replications. The evaluated traits were yield, average
not only buffer or amplify effects , but which may also increase the risk of recurrent or persistent depression in the mother. These findings are also important in terms of providing appropriate help with the aim of preventing adverse developmental outcomes in the child. For a large group of PPD mothers......Background: In three academic articles, this PhD thesis investigates maternal postpartum depression (PPD) as a risk factor for the infant-mother attachment and infant development. Previous studies have been contradictory with respect to the question of whether PPD can have long term effects...... months with the Bayley Scales of Infant and Toddler Development, third edition. Additionally, at 13 months infant-mother attachment security was assessed using Strange Situation Procedure. Results: We found that even in a well-functioned sample, symptoms of depression in the postpartum period...
Moshe, Hagar; Gal, Ram; Barnea-Ygael, Noam; Gulevsky, Tatiana; Alyagon, Uri; Zangen, Abraham
Approximately one third of all major depression patients fail to respond to conventional pharmacological antidepressants, and brain stimulation methods pose a promising alternative for this population. Recently, based on repeated multifactorial selective inbreeding of rats for depressive-like behaviors, we introduced a novel animal model for MDD. Rats from this Depressive Rat Line (DRL) exhibit inherent depressive-like behaviors, which are correlated with lower levels of brain-derived neurotrophic factor (BDNF) in specific brain regions. In addition, DRL rats do not respond to antidepressant medication but respond to electroconvulsive treatment, and they can thus be utilized to test the effectiveness of brain stimulation on hereditary, medication-resistant depressive-like behaviors. To test the effect of sub-convulsive electrical stimulation (SCES) of the prelimbic cortex, using TMS-like temporal pattern of stimulation, on depressive-like behaviors and regional BDNF levels in DRL rats. SCES sessions were administered daily for 10 days through chronically implanted electrodes. Temporal stimulation parameters were similar to those used in TMS for major depression in human patients. Depressive-like behaviors were assayed after treatment, followed by brain extraction and regional BDNF measurements. SCES normalized both the depressive-like behaviors and the reduced BDNF levels observed in DRL rats. Correlation analyses suggest that changes in specific behaviors are mediated, at least in part, by BDNF expression in reward-related brain regions. Brain stimulation is effective in a drug-resistant, inherited animal model for depression. BDNF alterations in specific regions may mediate different antidepressant effects. Copyright © 2016 Elsevier Inc. All rights reserved.
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Ingram, Colleen M; Troendle, Nicholas J; Gill, Clare A; Braude, Stanton; Honeycutt, Rodney L
The role of genetic relatedness in the evolution of eusociality has been the topic of much debate, especially when contrasting eusocial insects with vertebrates displaying reproductive altruism. The naked mole-rat, Heterocephalus glaber, was the first described eusocial mammal. Although this discovery was based on an ecological constraints model of eusocial evolution, early genetic studies reported high levels of relatedness in naked mole-rats, providing a compelling argument that low dispersal rates and consanguineous mating (inbreeding as a mating system) are the driving forces for the evolution of this eusocial species. One caveat to accepting this long-held view is that the original genetic studies were based on limited sampling from the species' geographic distribution. A growing body of evidence supports a contrary view, with the original samples not representative of the species-rather reflecting a single founder event, establishing a small population south of the Athi River. Our study is the first to address these competing hypotheses by examining patterns of molecular variation in colonies sampled from north and south of the Athi and Tana rivers, which based on our results, serve to isolate genetically distinct populations of naked mole-rats. Although colonies south of the Athi River share a single mtDNA haplotype and are fixed at most microsatellite loci, populations north of the Athi River are considerably more variable. Our findings support the position that the low variation observed in naked mole-rat populations south of the Athi River reflects a founder event, rather than a consequence of this species' unusual mating system. © 2015 John Wiley & Sons Ltd.
Marina S Ascunce
Full Text Available Understanding the evolution of parasites is important to both basic and applied evolutionary biology. Knowledge of the genetic structure of parasite populations is critical for our ability to predict how an infection can spread through a host population and for the design of effective control methods. However, very little is known about the genetic structure of most human parasites, including the human louse (Pediculus humanus. This species is composed of two ecotypes: the head louse (Pediculus humanus capitis De Geer, and the clothing (body louse (Pediculus humanus humanus Linnaeus. Hundreds of millions of head louse infestations affect children every year, and this number is on the rise, in part because of increased resistance to insecticides. Clothing lice affect mostly homeless and refugee-camp populations and although they are less prevalent than head lice, the medical consequences are more severe because they vector deadly bacterial pathogens. In this study we present the first assessment of the genetic structure of human louse populations by analyzing the nuclear genetic variation at 15 newly developed microsatellite loci in 93 human lice from 11 sites in four world regions. Both ecotypes showed heterozygote deficits relative to Hardy-Weinberg equilibrium and high inbreeding values, an expected pattern given their parasitic life history. Bayesian clustering analyses assigned lice to four distinct genetic clusters that were geographically structured. The low levels of gene flow among louse populations suggested that the evolution of insecticide resistance in lice would most likely be affected by local selection pressures, underscoring the importance of tailoring control strategies to population-specific genetic makeup and evolutionary history. Our panel of microsatellite markers provides powerful data to investigate not only ecological and evolutionary processes in lice, but also those in their human hosts because of the long
Full Text Available The objective of the present study was to evaluate the effect of a relatively more frequent occurrence of lower coefficients of inbreeding in a population of Holstein cattle on the exterior characters. The exterior of inbred cows (on the level of Fx = 1.56 – 4.00% was compared with their outbreed contemporaries, i.e. half-sisters from the same father. Evaluations of the exterior of both inbred cows and contemporaries were conducted on the same day, 60-180 days after the first calving, in the same barn and using the valid mode of operation “Linear description and evaluation of the exterior of Holstein cattle”. The group consisted of 212 inbred cows and 521 contemporaries. This monitoring is part of a more extensive study dealing with the effect of low levels of Fx coefficients on the characters of milk performance. On that score, the evaluations primarily include characters that are associated with milk production.The group of inbred cows was compared with their contemporaries and the increased variability of all the evaluated characters (Vx was studied. The increased variability was particularly due to the wider variance of characters and/or due to the more frequent occurrence of the characters, in inbred animals including both biological extremes (maximum and minimum. Compared to the contemporaries the average values of exterior characters of inbred animals were lower. The most marked decrease in the values was detected for the fore udder attachment (0.28 points, i.e. 5.5 % and for the total evaluation of the legs (-0.80 points, i.e. a 1.04% decrease. Although the worsening of the exterior of inbred animals involved all the characters under study, compared to the outbreed contemporaries the differences on the studied level of Fx were not statistically significant.
Kardos, Marty; Qvarnström, Anna; Ellegren, Hans
Individual inbreeding and historical demography can be estimated by analyzing runs of homozygosity (ROH), which are indicative of chromosomal segments of identity by descent (IBD). Such analyses have so far been rare in natural populations due to limited genomic resources. We analyzed ROH in whole genome sequences from 287 Ficedula flycatchers representing four species, with the objectives of evaluating the causes of genome-wide variation in the abundance of ROH and inferring historical demography. ROH were clearly more abundant in genomic regions with low recombination rate. However, this pattern was substantially weaker when ROH were mapped using genetic rather than physical single nucleotide polymorphism (SNP) coordinates in the genome. Empirical results and simulations suggest that high ROH abundance in regions of low recombination was partly caused by increased power to detect the very long IBD segments typical of regions with a low recombination rate. Simulations also showed that hard selective sweeps (but not soft sweeps or background selection) likely contributed to variation in the abundance of ROH across the genome. Comparisons of the abundance of ROH among several study populations indicated that the Spanish pied flycatcher population had the smallest historical effective population size ( N e ) for this species, and that a putatively recently founded island (Baltic) population had the smallest historical N e among the collared flycatchers. Analysis of pairwise IBD in Baltic collared flycatchers indicated that this population was founded <60 generations ago. This study provides a rare genomic glimpse into demographic history and the mechanisms underlying the genome-wide distribution of ROH. Copyright © 2017 by the Genetics Society of America.
Márcio Costa Rodrigues
Full Text Available The objective of this work was to investigate heterosis and its components in 16 white grain maize populations presenting high quality protein. These populations were divided according to grain type in order to establish different heterosis groups. The crosses were carried out according to a partial diallel cross design among flint and dent populations. Seven agronomic traits were evaluated in three environments while four leaf diseases and incidence of corn stunt were evaluated in one. Least square procedure was applied to the normal equation X'Xbeta = X'Y, to estimate the model effects and their respective sum of squares. Among the heterosis components, in diallel analysis, significance for average heterosis in grain yield, number of days to female flowering and to all evaluated diseases was detected. Specific heterosis was significant for days to female flowering and resistance to Puccinia polysora. Results concerned to grain yield trait indicate that populations with superior performance in dent group, no matter what flint population group is used in crosses, tend to generate superior intervarietal hybrids. In decreasing order of preference, the dent type populations CMS 476, ZQP/B 103 and ZQP/B 101 and the flint type CMS 461, CMS 460, ZQP/B 104 and ZQP/B 102 are recommended to form composites.O objetivo deste trabalho foi investigar a heterose e seus componentes em 16 populações de milho de grãos brancos, de alta qualidade protéica. Estas populações foram divididas de acordo com o tipo de grão, para estabelecer grupos heteróticos diferentes. Os cruzamentos foram realizados entre populações dentadas e duras, seguindo o esquema dialélico parcial. Sete caracteres agronômicos foram avaliados em três locais, e quatro doenças foliares e a incidência de enfezamento, em um. O procedimento de quadrados mínimos foi aplicado à equação normal X'Xbeta = X'Y, para estimar os efeitos do modelo e suas respectivas somas de quadrados
Beaurepaire, Alexis L; Krieger, Klemens J; Moritz, Robin F A
Varroa destructor is the most devastating parasite of the Western honeybee, Apis mellifera. In the light of the arm race opposing the host and its parasite, the population dynamics and genetic diversity of these organisms are key parameters. However, the life cycle of V. destructor is characterized by extreme inbreeding due to full sibling mating in the host brood cells. We here present an equation reflecting the evolution of inbreeding in such a clonal system, and compare our predictions with empirical data based on the analysis of seven microsatellite markers. This comparison revealed that the mites perform essentially incestuous mating in the beginning of the brood season. However, this pattern changes with the development of mite infestation. Despite the fact that the overall level of genetic diversity of the mites remained low through the season, multiple inbred lineages were identified in the mites we sampled in June. As a response to the decrease of brood availability and the increase of the parasite population in parallel in the colonies, these lineages recombined towards the end of the season as mites co-infest brood cells. Our results suggest that the ratio of the number of mite per brood cell in the colony determines the genetic structure of the populations of V. destructor. This intracolonial population dynamics has great relevance for the selection of acaricide resistance in V. destructor. If chemical treatments occur before the recombination phase, inbreeding will greatly enhance the fixation of resistance alleles at the colony level. Copyright © 2017 Elsevier B.V. All rights reserved.
Verweij, Karin J H; Yang, Jian; Lahti, Jari; Veijola, Juha; Hintsanen, Mirka; Pulkki-Råback, Laura; Heinonen, Kati; Pouta, Anneli; Pesonen, Anu-Katriina; Widen, Elisabeth; Taanila, Anja; Isohanni, Matti; Miettunen, Jouko; Palotie, Aarno; Penke, Lars; Service, Susan K; Heath, Andrew C; Montgomery, Grant W; Raitakari, Olli; Kähönen, Mika; Viikari, Jorma; Räikkönen, Katri; Eriksson, Johan G; Keltikangas-Järvinen, Liisa; Lehtimäki, Terho; Martin, Nicholas G; Järvelin, Marjo-Riitta; Visscher, Peter M; Keller, Matthew C; Zietsch, Brendan P
Personality traits are basic dimensions of behavioral variation, and twin, family, and adoption studies show that around 30% of the between-individual variation is due to genetic variation. There is rapidly growing interest in understanding the evolutionary basis of this genetic variation. Several evolutionary mechanisms could explain how genetic variation is maintained in traits, and each of these makes predictions in terms of the relative contribution of rare and common genetic variants to personality variation, the magnitude of nonadditive genetic influences, and whether personality is affected by inbreeding. Using genome-wide single nucleotide polymorphism (SNP) data from > 8000 individuals, we estimated that little variation in the Cloninger personality dimensions (7.2% on average) is due to the combined effect of common, additive genetic variants across the genome, suggesting that most heritable variation in personality is due to rare variant effects and/or a combination of dominance and epistasis. Furthermore, higher levels of inbreeding were associated with less socially desirable personality trait levels in three of the four personality dimensions. These findings are consistent with genetic variation in personality traits having been maintained by mutation-selection balance. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Axholm, Ida; Haxgart, Nina; Ranum, Kasper; Svendsen, Astrid Helmer
350.000.000 people worldwide have a depression and 150.000 Danes are affected every year. Depresion is defined by WHO from it’s syptoms. The diagnose is given from a point system for the patient’s symptoms, for instance HAM-D scale and MADRS scale Serotonin in the brain is synthesized from L-tryptophan in the presynaptic parts of the neuron and is released into the synapse as a transmitter drug. According to the serotonin theory, the concentration of serotonin in the brain is low in depressio...
Rechenberg, Kaitlyn; Humphries, Debbie
Depression is the leading cause of mental disability worldwide. Women who are depressed during pregnancy are at a higher risk for preterm delivery, preeclampsia, birth difficulties, and postpartum depression. The treatment of depression in conventional medicine has focused on physiological factors that lead to impaired neurotransmitter function and treatments to improve neurotransmitter function. Pharmaceutical substances pose risks for pregnant and lactating women, and lower risk options are preferred. Micronutrients, including certain B vitamins, folate, and docosahexaenoic acid (DHA), play a role in the synthesis and absorption of neurotransmitters. Experimental studies suggest that supplementation with specific micronutrients may alleviate depressive symptoms and improve birth outcomes in patients with perinatal depression. Alternative treatments for depression, including nutritional supplements, are an important treatment option for depressive symptoms while limiting potential side effects and treatment costs. This article explores the biological basis of perinatal depression and reviews the potential benefits of non-pharmacological interventions.
One out of 2 Americans report drinking on a routine basis, making the excessive consumption of alcohol the third leading cause of preventable death in America (). Alcoholism and depression are common comorbidities that home healthcare professionals frequently encounter. To achieve the best patient outcomes, alcoholism should be addressed initially. Although all age groups are at risk, alcoholism and depression occur in more than 8 percent of older adults. Prevention through identifying alcohol use early in adolescence is vital to reduce the likelihood of alcohol dependence. This article provides an overview of the long-term effects of alcohol abuse, including alcoholic cirrhosis and hepatic encephalopathy. The diagnostic criteria for substance dependence and ideas for nonthreatening screening questions to use with patients who are adolescent or older are discussed. While providing patient care, home healthcare nurses share the patient's intimate home environment. This environment is perceived as a safe haven by the patient and home care nurses can take advantage of counseling and treatment opportunities in this nonthreatening environment.
Montoya S. Camilo
Full Text Available En la presente investigación se revisaron 4948 datos referentes a lactancias de vacas en razas B taurus y B indicus, los cuales se obtuvieron entre los años 1986 y 1994 en las Ganaderías La Unión y La K, localizadas en los municipios Plato y Santa Ana en el departamento de Magdalena; San Fernando Pinillos y Magangué en el departamento de Bolívar; y Playones de Sucre y Buenavista en el departamento de Sucre. Para determinar la influencia de los diferentes efectos tanto genéticos como no genéticos sobre las características a estudiar, se utilizó el programa de mínimos cuadrados de Harvey (1988. Los efectos tenidos en cuenta en los modelos para las características leche vendible, días de lactancia e intervalo entre partos fueron: El grupo genético materno, la época y año de parto, número de parto, y hato. Como cavariables se tuvieron en cuenta el peso al destete, la producción de leche duración de la lactancia y el intervalo entre partos según el modelo a estudiar. De los factores 110 genéticos la gran mayoría dieron efecto significativo a los niveles del (P~0.05; no presentaron significancia la época para la duració1l de la lactancia y el grupo genético para el intervalo entre partos; y las covariables intervalo entre partos para la producción de leche y producción de leche en el modelo para el intervalo entre partos. La estimación de la heterosis se hizo una vez realizados los contrastes ortogonales entre los grupos genéticos para las características en las cuales el grupo racial presentó significancia en los ANAVAS. La heterosis obtenida para la producción de leche teniendo como base el promedio de las raza Criolla y el promedio entre el Criollo y el Cebú fue respectivamente: ½ Taurus-1/2 Criollo (17.95% y 22.5%; ½ Taurus - ½ Cebú (9% y 14%; Trihíbrido (7.7% y 11. 7%; ¼ Taurus- ¾ Cebú (5% y 9%; ½ Cebú- ½ Criollo (1.05% y 4.8%; y el ¾ Cebú- ½ Criollo (-7.88% y -4.46%; todas altamente
Paula de Souza Guimarães
Full Text Available O objetivo deste trabalho foi avaliar a produtividade de híbridos simples de milho obtidos de cruzamentos dialélicos entre linhagens divergentes, estimar a capacidade de combinação das linhagens e confirmar se a divergência genética entre as linhagens, obtida por marcadores moleculares, é correlacionada com a heterose dos híbridos simples no campo. Trinta e seis híbridos resultantes do dialelo parcial e as 12 linhagens parentais foram avaliadas em Campinas em blocos ao acaso, com três repetições e duas testemunhas. A capacidade de combinação das linhagens foi estimada de acordo com o modelo 4 de Griffing. Estimaram-se a correlação matricial, mediante a estatística de Mantel, entre heterose, produtividade e capacidade específica de combinação com divergência genética por AFLP e SSR. Destacou-se o híbrido PM518 x L111 e as linhagens PM518, IP4035 e L111 apresentaram efeitos positivos da capacidade geral de combinação. As estimativas de heterose variaram de 927 a 6.698 kg ha-1. Houve correlação entre heterose e divergência genética por AFLP e SSR. No entanto, a divergência genética não foi suficiente para determinar a capacidade específica de combinação nem a produtividade dos híbridos.The objective of this work was to evaluate grain yield of maize single cross hybrids obtained from diallel crosses among contrasting lines, to estimate the combining ability of the lines, and finally to confirm if the genetic diversity among those lines assessed by molecular markers is correlated with single cross hybrids heterosis. The 36 single cross hybrids resulting from partial diallel and 12 parental lines were evaluated in Campinas in randomized block design, with three replicates and two control lines checks. General combining ability of the lines was estimated according to Griffing model 4. Correlations among matrices were estimated through Mantel statistics, considering heterosis, yield and specific combining ability with
Maria Elisa Ayres Guidetti Zagatto Paterniani
heterosis Thirty-six single-crosses resulting from partial diallel and the 12 parental lines were evaluated in Campinas, State of São Paulo, in randomized block design, with tree replicates and two commercial checks. The following traits were evaluated: plant and ear height, ear weight and grain weight. Individual variance analysis of hybrids were performed, and the averages were compared by Tukey test (P<0.05. General combining ability of the lines was obtained according to Geraldi e Miranda Filho. Correlations among matrices were estimated through Mantel statistics, considering heterosis, yield and specific combining ability with genetic divergence assessed by AFLP and SSR. The hybrid PM624 x IP398 exhibited outstanding yield capacity and the lines VER266 and L105 showed positive GCA for grain yield. Estimate heterosis ranged from -559 to 6.320 kg ha-1. No significant correlation was observed between heterosis, specific combination ability or grain yield with genetic distance assessed by AFLP and SSR. Therefore, no prediction of hybrids performance could be made on the basis of the genetic divergence of the parent lines.
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Josué Maldonado Ferreira
an 8x8 lattice, with five and four replications in Palmeira and Londrina, Paraná, Brazil, respectively. The results of the populations per se showed different performances for each local, but BR 106, Cabo Roxo, Palha Roxa, Ouro Verde e Comum Antigo x Sabugo Fino showed higher grain yield means in both places, that did not differ significantly to the means of the commercial checks (AG1051 and C125. The average heterosis effects were significant for grain yield, plant height, ear placement and root lodging percentage, without local interactions. The top-crosses produced 10.2% (Palmeira and 8.5% (Londrina more than the same populations per se. The populations Palha Roxa; Milho Sem Nome; Pintado e Comum Antigo x Sabugo Fino showed the highest effects of general combining ability for grain yield and took part in the better composite predictions.
Vallejo Cabrera Franco Alirio
Full Text Available Se realizó el análisis de la heterosis y de la habilidad combinatoria entre 21 cultivares de tomate, para el carácter producción por planta y sus componentes a partir de un cruzamiento dialélico (6 progenitores, 15 híbridos F1, sin incluir los recíprocos: utilizando el método experimental 2, modelo I propuesto por Griffing (1956. Se encontraron diferencias altamente significativas para los efectos de hcg y de hce para todos los caracteres a excepción del carácter producción de frutos de primera (frutos de más de 180 g. Los híbridos Motelle x Ángela I 5100, Motelle x Zambao y Licapal 21 x Zambao presentaron altos efectos de h c e para el carácter producción por planta. Los anteriores efectos asociados con altas heterobeltiosis hacen que estos híbridos sean promisorios para una posterior comercialización.An analysis of heterosis and combining ability of traits related with per plant production was carried out using a diallele crossing between different tomate cultivars, Lycopersicon esculentum Mill (six parent and 15 F1 hybrids from as possible crossing in one direction, according to the methodology proposed by Griffing (1956, selecting experimental method 2, and model 1. In the genetic variation of all traits related to per plant production, except in first class fruit trait, the general combining ability (gen non addite action effects participate jointly and in highly significant manner. Hybrids Motelle x Angela I 5100, Motelle x Zambao y Licapal21 x Zambao, exhibited high s c a effects for the trait per plant production. Former effects related to high heterobeltyosis make these hybrids promising for later marketing.
Hames, Jennifer L; Hagan, Christopher R; Joiner, Thomas E
Humans have an intrinsic need for social connection; thus, it is crucial to understand depression in an interpersonal context. Interpersonal theories of depression posit that depressed individuals tend to interact with others in a way that elicits rejection, which increases their risk for future depression. In this review, we summarize the interpersonal characteristics, risk factors, and consequences of depression in the context of the relevant theories that address the role of interpersonal processes in the onset, maintenance, and chronicity of depression. Topics reviewed include social skills, behavioral features, communication behaviors, interpersonal feedback seeking, and interpersonal styles as they relate to depression. Treatment implications are discussed in light of the current research on interpersonal processes in depression, and the following future directions are discussed: developing integrative models of depression, improving measurement of interpersonal constructs, examining the association between interpersonal processes in depression and suicide, and tailoring interventions to target interpersonal processes in depression.
Valbuena-Ureña, E; Soler-Membrives, A; Steinfartz, S; Orozco-terWengel, P; Carranza, S
Endemic species with restricted geographic ranges potentially suffer the highest risk of extinction. If these species are further fragmented into genetically isolated subpopulations, the risk of extinction is elevated. Habitat fragmentation is generally considered to have negative effects on species survival, despite some evidence for neutral or even positive effects. Typically, non-negative effects are ignored by conservation biology. The Montseny brook newt (Calotriton arnoldi) has one of the smallest distribution ranges of any European amphibian (8 km 2 ) and is considered critically endangered by the International Union for Conservation of Nature. Here we apply molecular markers to analyze its population structure and find that habitat fragmentation owing to a natural barrier has resulted in strong genetic division of populations into two sectors, with no detectable migration between sites. Although effective population size estimates suggest low values for all populations, we found low levels of inbreeding and relatedness between individuals within populations. Moreover, C. arnoldi displays similar levels of genetic diversity to its sister species Calotriton asper, from which it separated around 1.5 million years ago and which has a much larger distribution range. Our extensive study shows that natural habitat fragmentation does not result in negative genetic effects, such as the loss of genetic diversity and inbreeding on an evolutionary timescale. We hypothesize that species in such conditions may evolve strategies (for example, special mating preferences) to mitigate the effects of small population sizes. However, it should be stressed that the influence of natural habitat fragmentation on an evolutionary timescale should not be conflated with anthropogenic habitat loss or degradation when considering conservation strategies.
Rihmer, Zoltán; Seregi, Krisztina; Rihmer, Annamária
The prevalence of depression in Parkinson's disease is around 40%, but, unfortunately, such depression is frequently unrecognized and untreated. However, recognition and appropriate treatment of depression in patients with Parkinson's disease is essential for clinical practice. This review focuses on the epidemiology, pathophysiology and treatment of depression associated with Parkinson's disease.
Abdellaoui, Abdel; Hottenga, Jouke-Jan; Xiao, Xiangjun; Scheet, Paul; Ehli, Erik A; Davies, Gareth E; Hudziak, James J; Smit, Dirk J A; Bartels, Meike; Willemsen, Gonneke; Brooks, Andrew; Sullivan, Patrick F; Smit, Johannes H; de Geus, Eco J; Penninx, Brenda W J H; Boomsma, Dorret I
The effects of inbreeding on the health of offspring can be studied by measuring genome-wide autozygosity as the proportion of the genome in runs of homozygosity (F roh) and relate F roh to outcomes such as psychiatric phenotypes. To successfully conduct these studies, the main patterns of variation for genome-wide autozygosity between and within populations should be well understood and accounted for. Within population variation was investigated in the Dutch population by comparing autozygosity between religious and non-religious groups. The Netherlands have a history of societal segregation and assortment based on religious affiliation, which may have increased parental relatedness within religious groups. Religion has been associated with several psychiatric phenotypes, such as major depressive disorder (MDD). We investigated whether there is an association between autozygosity and MDD, and the extent to which this association can be explained by religious affiliation. All F roh analyses included adjustment for ancestry-informative principal components (PCs) and geographic factors. Religious affiliation was significantly associated with autozygosity, showing that F roh has the ability to capture within population differences that are not captured by ancestry-informative PCs or geographic factors. The non-religious group had significantly lower F roh values and significantly more MDD cases, leading to a nominally significant negative association between autozygosity and depression. After accounting for religious affiliation, MDD was not associated with F roh, indicating that the relation between MDD and inbreeding was due to stratification. This study shows how past religious assortment and recent secularization can have genetic consequences in a relatively small country. This warrants accounting for the historical social context and its effects on genetic variation in association studies on psychiatric and other related traits.
... on thoughts, behaviors, and feelings related to depression Interpersonal psychotherapy , or IPT, which focuses on working on relationships Dialectical behavior therapy , or DBT, which is especially useful when depression ...
... or making it worse. Cognitive behavioral therapy (CBT), interpersonal therapy (IPT), and problem-solving therapy are examples of evidence-based talk therapy treatments for depression. Treatment for depression should be personalized. Some men, ...
... active and engaged. The most worrisome complication of depression is suicide. Men make up most suicides among older adults. ... such as 911) if you are thinking about suicide (taking your own ... and think they may have depression, contact their provider.
... Are Here: Home → Multiple Languages → All Health Topics → Postpartum Depression URL of this page: https://medlineplus.gov/languages/ ... V W XYZ List of All Topics All Postpartum Depression - Multiple Languages To use the sharing features on ...
Depression and Bipolar Support Alliance Crisis Hotline Information Coping with a Crisis Suicide Prevention Information Psychiatric Hospitalization ... sign-up Education info, training, events Mood Disorders Depression Bipolar Disorder Anxiety Screening Center Co-occurring Illnesses/ ...
... a Psychiatrist Addiction and Substance Use Disorders ADHD Anxiety Disorders Autism ... Depression (major depressive disorder) is a common and serious medical illness that negatively affects how you feel, the way ...
Vinberg, Maj; Levinsen, Mette Frandsen; Kessing, Lars Vedel
Depression is considered resistant when two treatment attempts with antidepressants from different classes fail to produce significant clinical improvement. In cases of treatment-resistant depression, it is recommended to reevaluate the diagnosis, clarify comorbidity, substance abuse and lack of ...
... page: //medlineplus.gov/ency/patientinstructions/000648.htm Recognizing teen depression To use the sharing features on this ... teen's life. Be Aware of the Risk for Teen Depression Your teen is more at risk for ...
... medlineplus.gov/ency/patientinstructions/000325.htm Learning about depression To use the sharing features on this page, ... trigger or reason. What are the Signs of Depression? You may notice some or all of the ...
... this page: //medlineplus.gov/ency/patientinstructions/000570.htm Depression - stopping your medicines To use the sharing features ... prescription medicines you may take to help with depression, anxiety, or pain. Like any medicine, there are ...
... best live chat Live Help Fact Sheets Share Depression Thursday, 01 September 2016 In every pregnancy, a ... risk. This sheet talks about whether exposure to depression may increase the risk for birth defects over ...
Everyone has down days and times when they feel sad. But depression is more than feeling sad or having a bad day. You may have depression if you feel sad every day (or most days) for at least two weeks.
... gov/ency/patientinstructions/000790.htm Heart disease and depression To use the sharing features on this page, ... a heart attack or heart surgery Signs of Depression It is pretty common to feel down or ...
Buntrock, Claudia; Berking, Matthias; Smit, Filip
BACKGROUND: Psychological interventions for the prevention of depression might be a cost-effective way to reduce the burden associated with depressive disorders. OBJECTIVE: To evaluate the cost-effectiveness of a Web-based guided self-help intervention to prevent major depressive disorder (MDD......) in people with subthreshold depression (sD). METHODS: A pragmatic randomized controlled trial was conducted with follow-up at 12 months. Participants were recruited from the general population via a large statutory health insurance company and an open access website. Participants were randomized to a Web......-based guided self-help intervention (ie, cognitive-behavioral therapy and problem-solving therapy assisted by supervised graduate students or health care professionals) in addition to usual care or to usual care supplemented with Web-based psycho-education (enhanced usual care). Depression-free years (DFYs...
Anand Tamatam; Farhath Khanum; Amarinder Singh Bawa
Depression is a term that has been used to describe a variety of ailments, ranging from minor to incapacitating. Clinically significant depression, termed as major depression, is a serious condition characterized not only by depressed mood but also by a cluster of somatic, cognitive, and motivational symptoms. Significant research efforts are aimed to understand the neurobiological as well as psychiatric disorders, and the evaluation of treatment of these disorders is still based solely on th...
The paper discusses the topical problem of depression in cerebrovascular diseases. It shows its possible causes, mechanisms of occurrence, clinical picture and negative impact on the course of cerebrovascular disease and recovery of neurological functions. There is a bilateral association between stroke and depression: on the one hand, stroke is a risk factor for the development of depression and, on the other, depression is a both direct and indirect risk factor for the development of stroke...
Henn, Fritz [East Patchogue, NY
Methods for treatment of depression-related mood disorders in mammals, particularly humans are disclosed. The methods of the invention include administration of compounds capable of enhancing glutamate transporter activity in the brain of mammals suffering from depression. ATP-sensitive K.sup.+ channel openers and .beta.-lactam antibiotics are used to enhance glutamate transport and to treat depression-related mood disorders and depressive symptoms.
Thomson, Michael; Sharma, Verinder
Postpartum depression is a prevalent disorder affecting many women of reproductive age. Despite increasing public awareness, it is frequently underdiagnosed and undertreated leading to significant maternal morbidity and adverse child outcomes. When identified, postpartum depression is usually treated as major depressive disorder. Many studies have identified the postpartum as a period of high risk for first presentations and relapses of bipolar disorder. Areas covered: This article reviews the acute and prophylactic treatment of postpartum major depressive disorder, bipolar depression and major depressive disorder with mixed features. The safety of antidepressant and mood stabilizing medications in pregnancy and breastfeeding will also be reviewed. Expert commentary: Differentiating postpartum major depressive disorder and postpartum bipolar depression can be difficult given their clinical similarities but accurate identification is vital for initiating proper treatment. Antidepressants are the mainstay of drug treatment for postpartum major depressive disorder, yet randomized controlled trials have shown conflicting results. A paucity of evidence exists for the effectiveness of antidepressant prophylaxis in the prevention of recurrences of major depressive disorder. Mood stabilizing medications reduce the risk of postpartum bipolar depression relapse but no randomized controlled trials have examined their use in the acute or prophylactic treatment of postpartum bipolar depression.
Bubl, E.; Tebartz Van Elst, L.; Ebert, D.
plays a role in major depression we measured contrast sensitivity in patients with major depression and in healthy control subjects. Methods. Twenty-eight patients diagnosed with major depressive disorder were compared to 21 age-matched control subjects on their ability to detect a Gabor target...
... Staying Safe Videos for Educators Search English Español Depression KidsHealth / For Parents / Depression What's in this article? ... Ways to Help Print en español Depresión About Depression It's normal for kids to feel sad, down, ...
Everyone feels blue now and then. It's a part of life. But if your feelings last more than few days and interfere with your normal daily activities, you may be suffering from depression. On this page: Symptoms of depression Who gets depressed and why?
Østergaard, Søren Dinesen; Meyers, B S; Flint, A J
Psychotic depression (PD) is a highly debilitating condition, which needs intensive monitoring. However, there is no established rating scale for evaluating the severity of PD. The aim of this analysis was to assess the psychometric properties of established depression rating scales and a number...... of new composite rating scales, covering both depressive and psychotic symptoms, in relation to PD....
Thapar, Anita; Collishaw, Stephan; Pine, Daniel S; Thapar, Ajay K
Unipolar depressive disorder in adolescence is common worldwide but often unrecognised. The incidence, notably in girls, rises sharply after puberty and, by the end of adolescence, the 1 year prevalence rate exceeds 4%. The burden is highest in low-income and middle-income countries. Depression is associated with sub stantial present and future morbidity, and heightens suicide risk. The strongest risk factors for depression in adolescents are a family history of depression and exposure to psychosocial stress. Inherited risks, developmental factors, sex hormones, and psychosocial adversity interact to increase risk through hormonal factors and associated perturbed neural pathways. Although many similarities between depression in adolescence and depression in adulthood exist, in adolescents the use of antidepressants is of concern and opinions about clinical management are divided. Effective treatments are available, but choices are dependent on depression severity and available resources. Prevention strategies targeted at high-risk groups are promising. PMID:22305766
Wålinder, J; Rutzt, W
Based on the experiences of the Gotland Study that education of general practitioners about depressive illness resulted in a statistically significant reduction in the number of female suicides, leaving the rate of male suicides almost unaffected, we propose the concept of a male depressive syndrome. This syndrome comprises a low stress tolerance, an acting-out behavior, a low impulse control, substance abuse and a hereditary loading of depressive illness, alcoholism and suicide. This notion is supported by data from The Amish study as well as the concept of van Praag of a stress-precipitated, cortisol-induced, serotonin-related and anxiety-driven depressive illness most often seen in males. In order to identify depressed males, the Gotland Male Depression Scale has been developed. Some preliminary data using the scale in a group of alcohol-dependant patients are presented.
In this thesis, I examine the complex experiences of what we call depression in everyday life, the multifaceted and ambiguous experiences of getting a depression diagnosis, and the in-depth processes involved in learning to live under the description of depression. The thesis is based...... on ethnographic fieldwork among adults diagnosed with depression in Denmark, and consists of three articles that provide glimpses into experiences of depression and diagnostic processes. The articles deal with creativity, variability and resistance in diagnostic processes and illustrates how these not are once......-and-for-all-dealt-with matters but rather messy and complicated processes, that involve several actors and multiple relations to the diagnosis. The thesis furthermore challenges the dominant diagnostic understanding depression as a neurobiological, and individual disorder in present-day diagnostic cultures, by arguing...
Davidsen, Annette Sofie; Fosgerau, Christina Fogtmann
The diagnosis of depression is defined by psychiatrists, and guidelines for treatment of patients with depression are created in psychiatry. However, most patients with depression are treated exclusively in general practice. Psychiatrists point out that general practitioners' (GPs') treatment...... of depression is insufficient and a collaborative care (CC) model between general practice and psychiatry has been proposed to overcome this. However, for successful implementation, a CC model demands shared agreement about the concept of depression and the diagnostic process in the two sectors. We aimed...... to explore how depression is understood by GPs and clinical psychiatrists. We carried out qualitative in-depth interviews with 11 psychiatrists and 12 GPs. Analysis was made by Interpretative Phenomenological Analysis. We found that the two groups of physicians differed considerably in their views...
Kemp, Mark A
A high power RF device has an electron beam cavity, a modulator, and a circuit for feed-forward energy recovery from a multi-stage depressed collector to the modulator. The electron beam cavity include a cathode, an anode, and the multi-stage depressed collector, and the modulator is configured to provide pulses to the cathode. Voltages of the electrode stages of the multi-stage depressed collector are allowed to float as determined by fixed impedances seen by the electrode stages. The energy recovery circuit includes a storage capacitor that dynamically biases potentials of the electrode stages of the multi-stage depressed collector and provides recovered energy from the electrode stages of the multi-stage depressed collector to the modulator. The circuit may also include a step-down transformer, where the electrode stages of the multi-stage depressed collector are electrically connected to separate taps on the step-down transformer.
Cancer patients often suffer from major depression or depressive syndromes. Although it is well known that depressive symptoms can appear at any time during the course of an oncological disease, certain periods for instance time after diagnosis carry a higher risk. Reported prevalence rates differ widely (up to 60%), reflecting also diagnostic difficulties. Oncologists recognize depression in their patients only in 15 to 50% and the percentage of patients who receive adequate therapy is even lower. Consequently, this leads to a reduced quality of life. Furthermore, impaired compliance/adherence and consequently a poorer prognosis of the oncological disease are discussed in this context. It should be also emphasized, that concomitant depression increases the risk of suicide in cancer patients. Although the number of clinical trials using either psychotherapy or antidepressant medication for the therapy of depression in cancer patients is limited, good therapeutic options are available.
Wahl, Inka; Löwe, Bernd; Bjørner, Jakob
OBJECTIVES: To provide a standardized metric for the assessment of depression severity to enable comparability among results of established depression measures. STUDY DESIGN AND SETTING: A common metric for 11 depression questionnaires was developed applying item response theory (IRT) methods. Data...... of 33,844 adults were used for secondary analysis including routine assessments of 23,817 in- and outpatients with mental and/or medical conditions (46% with depressive disorders) and a general population sample of 10,027 randomly selected participants from three representative German household surveys....... RESULTS: A standardized metric for depression severity was defined by 143 items, and scores were normed to a general population mean of 50 (standard deviation = 10) for easy interpretability. It covers the entire range of depression severity assessed by established instruments. The metric allows...
Dorval, Bill; Smith, Gregor W.
Interwar macroeconomic history is a natural place to look for evidence on the correlations between (a) deflation and depression and (b) unexpected deflation and depression. We apply time-series methods to measure unexpected deflation or inflation for 26 countries from 1922 to 1939. The results suggest much variation across countries in the degree to which the ongoing deflation of the 1930s was unexpected. There is a significant, positive correlation between deflation and depression for the en...
Full Text Available Group living carries a price: it inherently entails increased competition for resources and reproduction, and may also be associated with mating among relatives, which carries costs of inbreeding. Nonetheless, group living and sociality is found in many animals, and understanding the direct and indirect benefits of cooperation that override the inherent costs remains a challenge in evolutionary ecology. Individuals in groups may benefit from more efficient management of energy or water reserves, for example in the form of reduced water or heat loss from groups of animals huddling, or through reduced energy demands afforded by shared participation in tasks. We investigated the putative benefits of group living in the permanently social spider Stegodyphus dumicola by comparing the effect of group size on standard metabolic rate, lipid/protein content as a body condition measure, feeding efficiency, per capita web investment and weight/water loss and survival during desiccation. Because energetic expenditure is temperature sensitive, some assays were performed under varying temperature conditions. We found that feeding efficiency increased with group size, and the rate of weight loss was higher in solitary individuals than in animals in groups of various sizes during desiccation. Interestingly, this was not translated into differences in survival or in standard metabolic rate. We did not detect any group size effects for other parameters, and group size effects did not co-vary with experimental temperature in a predictive manner. Both feeding efficiency and mass loss during desiccation are relevant ecological factors as the former results in lowered predator exposure time, and the latter benefits social spiders which occupy arid, hot environments.
Undine E. Lang
Full Text Available Several nutrition, food and dietary compounds have been suggested to be involved in the onset and maintenance of depressive disorders and in the severity of depressive symptoms. Nutritional compounds might modulate depression associated biomarkers and parallel the development of depression, obesity and diabetes. In this context, recent studies revealed new mediators of both energy homeostasis and mood changes (i.e. IGF-1, NPY, BDNF, ghrelin, leptin, CCK, GLP-1, AGE, glucose metabolism and microbiota acting in gut brain circuits. In this context several healthy foods such as olive oil, fish, fruits, vegetables, nuts, legumes, poultry, dairy and unprocessed meat have been inversely associated with depression risk and even have been postulated to improve depressive symptoms. In contrast, unhealthy western dietary patterns including the consumption of sweetened beverage, refined food, fried food, processed meat, refined grain, and high fat diary, biscuits, snacking and pastries have been shown to be associated with an increased risk of depression in longitudinal studies. However, it is always difficult to conclude a real prospective causal relationship from these mostly retrospective studies as depressed individuals might also change their eating habits secondarily to their depression. Additionally specific selected nutritional compounds, e.g. calcium, chromium, folate, PUFAs, vitamin D, B12, zinc, magnesium and D-serine have been postulated to be used as ad-on strategies in antidepressant treatment. In this context, dietary and lifestyle interventions may be a desirable, effective, pragmatical and non-stigmatizing prevention and treatment strategy for depression. At last, several medications (pioglitazone, metformin, exenatide, atorvastatin, gram-negative antibiotics, which have traditionally been used to treat metabolic disorders showed a certain potential to treat depression in first randomized controlled clinical trials.
Full Text Available ... few days. It is a serious illness that affects many people. Symptoms can vary, but many depressed ... suffer from depression trying to learn why it affects some people but not others. Treatments for depression ...
Full Text Available ... 3 items) Institute Announcements (24 items) Symptoms and Treatment of Depression February 1, 2010 People with depression ... why it affects some people but not others. Treatments for depression do work. One type of effective ...
Kalfayan, S. H.
Proposed process modification incorporates viscosity depressants to prevent coal from solidifying during liquefaction. Depressants reduce amount of heat needed to liquefy coal. Possible depressants are metallic soaps, such as stearate, and amides, such as stearamide and dimer acid amides.
... Urinary Tract Infections: Indwelling (Foley) Catheter Depression and Spinal Cord Injury [ Download this pamphlet: “Depression and Spinal Cord Injury” (PDF - 477KB)] Depression is a common illness that ...
Teen depression - helping; Teen depression - talk therapy; Teen depression - medicine ... You, your teen, and your health care provider should discuss what might help your teen the most. The most effective treatments ...
... Z Health Topics Depression during and after pregnancy Depression during and after pregnancy > A-Z Health Topics ... To receive Publications email updates Enter email Submit Depression during and after pregnancy When you are pregnant ...
The association between depression and sleep disturbances is perhaps as old as makind. In view of the longstanding experience with this association it is amazing that only some 20 years ago, a few depressed patients attracted attention to the fact that Total Sleep Deprivation (TSD) had
Today there is still considerable symptom overlap between schizophrenia and mood disorders, and the relationship between depression and schizophrenia remains controversial.4. Many patients carry chart diagnoses of both disorders in the clinical setting. Some of the difficulty with the term 'depression' in schizophrenia ...
... Box — Depression, Antidepressants, and the Risk of Suicide. New England Journal of Medicine, 356:2343-2346. xiii http://psychcentral.com/blog/ ... Box — Depression, Antidepressants, and the Risk of Suicide. New England Journal of Medicine, 356:2343-2346.
There is a grooving evidence that dysfunction in circadian rhythm regulation andmelatonergic system function is involved in depression pathogenesis. It is known thatclinically used antidepressants have influence on melatonergic system, probably throughchanged ratio between melatonergic type 1 and 2 receptors. With the clinical use of newcompounds like agomelatine that directly regulates melatonergic system new opportunities in depression treatment emerged
Occurring in about 12 percent of postpartum women, postpartum depression has been focus of considerable research. Variables that have been correlated with postpartum depression range from biological causes, to lack of social support, to relationship with husband, to attributional styles, to psychodynamic explanations. There is need for more…
Full Text Available Androgens have various effects on human body and mood. Testosterone, a hormone mainly secreted from testes and adrenals, is one of the most potent androgens. Multiple studies have found that testosterone plays a role in regulating sexual activity, libido, social behaviors, aggression, cognitive functions, sleep control and well-being in men and women. Testosterone deficiency in hypogonadic or elderly men leads to neuropsychiatric problems, such as fatigue, loss of libido, irritability, insomnia and depressive mood. Testosterone replacement therapy consistently reverses these sequel in men. On the other hand, hyperandrogenic states in women are related to aggression and antisocial behavior, which might lead to depressive mood. Low testosterone levels may also result in depression among oophorectomized women. Because of such effects, a relationship between testosterone and depression has long been an issue of speculation, but yet very few studies have addressed this relation. Along with clinical studies, experimental and epidemiological studies show that testosterone is related to depression in men and women. But studies of testosterone concentrations in depression have yielded inconsistent results reporting low as well as high testosterone levels associated with depression. In this article, the physiological and psychological effects of testosterone and evidence regarding its relationship to depressive disorders and possible gender differences have been reviewed.
... Feelings Expert Answers Q&A Movies & More for Teens Teens site Sitio para adolescentes Body Mind Sexual Health ... for Educators Search English Español Depression KidsHealth / For Teens / Depression What's in this article? Regular Sadness vs. ...
Hemmeter, Ulrich-Michael; Hemmeter-Spernal, Julia; Krieg, Jürgen-Christian
Sleep deprivation (SD) is a powerful antidepressant treatment that shows antidepressant responses within hours in 40-60% of depressed patients. In more than 80% of responders to SD, a relapse into depression occurred after the recovery night. In addition, it serves as an excellent tool to examine the neurobiological disturbance of depression and may profoundly contribute to the development of new specific and more rapidly acting antidepressants. The reason why SD works and relapses occur is still unclear. A key to solve this problem is to include the current knowledge about the neurobiological disturbance of depression in research, with a focus on neurobiological aspects of sleep and SD (sleep EEG, neuroendocrinology, neurochemistry and chronobiology). Based on findings from these different areas, different strategies to stabilize the antidepressant effect of SD have been applied. This article provides an overview of clinical and neurobiological responses related to SD in depression.
Larsen, Karen Kjær
Myocardial infarction (MI) is a severe life event that is accompanied by an increased risk of depression. Mounting evidence suggests that post-MI depression is associated with adverse outcomes, but the underlying mechanisms of this association remain unclear, and no previous studies have examined...... whether the mental burden of MI is so heavy that it increases the risk of suicide. Although post-MI depression is common and burdensome, the condition remains under-recognised and under-treated. The development of new strategies to improve the quality of care for people with post-MI depression requires...... thorough understanding of the mechanisms that influence the prognosis as well as knowledge of the present care provided. The purpose of this PhD thesis is accordingly subdivided into four specific aims: 1. To estimate the prevalence of depression in people with MI after three months, and to estimate...
In this paper, I propose that depression is a political phenomenon insofar as it has political sources and consequences. I then investigate one aspect of this argument—whether depression reduces participation. I hypothesize that individuals with depression lack the motivation and physical capacity to vote and engage in other forms of political participation due to somatic problems and feelings of hopelessness and apathy. Moreover, I examine how depression in adolescence can have downstream consequences for participation in young adulthood. The analyses, using both cross-sectional and longitudinal data, show that voter turnout and other forms of participation decrease as the severity of depressed mood increases. These findings are discussed in light of disability rights and potential efforts to boost participation among this group. PMID:26924857
Full Text Available Estudou-se o efeito da endogamia sobre a maturidade sexual e fecundidade de escargot da espécie Helix aspersa, em três gerações consecutivas de irmãos perfeitos. Os animais foram criados em laboratório com temperatura entre 20 e 25ºC e umidade relativa entre 70 e 90%. O efeito da endogamia foi negativo para as duas características. Quando o valor de F aumentou de 0,25 para 0,50, o percentual de animais sexualmente maduros aos 120 dias diminuiu de 59 para 18% e o número de animais nascidos por postura diminuiu de 94 para 53. Para evitar o efeito negativo, recomenda-se o início de uma criação com pelo menos 100 reprodutores não aparentados, introduzindo-se novas matrizes após a 10ª geração.The effect of inbreeding on two reproductive traits (number of birth per clutch and percentage of sexually mature animals per clutch on three consecutive generations of full sibs of edible snail raised under laboratory conditions (20-25ºC temperature; 70-90% relative humidity was studied. Inbreeding effect was negative for both traits. When F values increased from 0.25 to 0.50, percentages of sexually mature animals after 120 days from birth, decreased from 59 to 18% and the number of birth per clutch decreased from 94 to 53. Population size of at least 100 non related mating snail replaced after 10 generations to avoid inbreeding effect is recommended.
... depression References American Psychiatric Association. Major depressive disorder. Diagnostic and Statistical Manual of Mental Disorders: DSM-5 . 5th ed. Arlington, VA: American Psychiatric Publishing. 2013; ...
Taleb, M; Rouillon, F; Hegerl, U; Hamdani, N; Gorwood, Ph
Depressive disorders represent a major public health concern, regarding their high frequency and their important cost. Depression impair the quality of life more than any other disease, sometimes leading to suicidal ideas or behavior. Indeed, 50% of patients with severe major depression commit suicide. Numerous studies showed that depressive disorders are frequently not recognised, and regularly untreated. In France, where at least 3 millions of inhabitants are concerned, 38% of depressed patients are not using any health system. When they are asking for care, the majority of depressed patients visit their general practitioner (51%), whereas less than 10% visit a psychiatrist. Even when the diagnostic is correct, the treatment prescribed is not systematically relevant. The treatment is, for example, frequently proposed for a too short period, and sometimes the prescribed product does not have proven antidepressive efficacy. Furthermore, as incorrect informations are frequently given to patients, and as there is a general biased judgement about psychotropic drugs in the general population, the compliance is usually poor for antidepressive treatment. Therefore, only a small minority of depressed patients benefits from an adequate care. Public health information methodological asserts. To improve this situation, delivering simple and clear-cut recommendations cannot be considered as sufficiently effective, and public health interventions are required. Different programs improving the recognition of depressive disorders have already been tested in some countries with encouraging results. These programs are based on information campaigns given to the public, and the training of general practitioners about the management of depressive disorders. The "Defeat Depression" campaign in Great-Britain and the "National Depression Screening Day" in the United-States of America may represent informative examples. Restricting these programs to general practitioners only is
The incidence of depression is higher than that of dementia in the elderly. Unlike depression in other age groups, that in the elderly is characterized by frequent physical complaints, irritation, and delusional tendencies. The treatment of depression in the elderly requires the complex incorporation of psychiatric and gerontological viewpoints. Psychiatrically, difficulty in accepting decreases in psychological and physical functions and solitude is important, as a psychological characteristic, inducing the development of depression. Biochemically, there is an underlying decrease in the function of brain monoaminergic nerve activated, such as by serotonin and noradrenalin. Radiologically, damage to the cerebral white matter and a decrease in the frontal lobe function have been frequently reported. Depression is difficult to differentiate from dementia and is also often complicated by dementia. Since a depressive state often precede Alzheimer's disease, evaluation of cognitive function is also necessary in patients with a depressive state. Although apathy is often observed as a symptom of dementia and tends to be confused with a depressive symptom, caution is necessary because of differences in the treatment method. Gerontologically, depression is one of geriatric syndrome and isa frequently observed in the elderly in the later stage and closely associated with a decrease in activities of daily life. Depression is also closely associated with lifestyle-related diseases, and its incidence is high in the presence of cerebrovascular disease, ischemic heart disease, hypertension, and diabetes mellitus, and conversely, depression is often complicated by lifestyle-related disease. Anxiety and depression are frequently observed in the frail elderly, but few studies on the assessment and appropriate approach for psychological matters. Further studies are necessary. The treatment of depression in the elderly could be classified into 3 stages. In the acute stage, the
Fields, Eve S; Meuchel, Jennifer M; Jaffe, Chiara J; Jha, Manish; Payne, Jennifer L
We sought to evaluate the prevalence rate and factors associated with post adoption depression. One hundred and twelve adoptive mothers of infants under 12 months of age were recruited from local and national adoption organizations. A modified Edinburgh Postnatal Depression Scale (EPDS) and a questionnaire collecting medical and psychiatric history, perceived stress, and demographics were administered retrospectively. The rates of significant depressive symptoms (defined as EPDS >or=12) were calculated at three time points post adoption, and associations with specific clinical variables (personal or family psychiatric history, stress, and adjustment difficulty) were assessed. Eighty-six mothers were included. Rates of significant depressive symptoms (EPDS >or=12) were found in 27.9% of subjects at 0-4 weeks, 25.6% at 5-12 weeks, and 12.8% at 13-52 weeks post adoption. Significant depressive symptoms were not associated with personal or family psychiatric history but were associated with stress (p = 0.0011) and adjustment difficulties (p = 0.042) post adoption. Significant depressive symptoms were relatively common in adoptive mothers within the first year after adoption and were associated with environmental stress. Prospective studies are needed to confirm the existence of post adoption depression and the factors associated with it.
Błaszczyk, Barbara; Czuczwar, Stanisław J
Depression episodes in epilepsy is the most common commorbidity, affecting between 11% and 62% of patients with epilepsy. Although researchers have documented a strong association between epilepsy and psychiatric comorbidities, the nature of this relationship is poorly understood. The manifestation of depression in epilepsy is a complex issue having many interacting neurobiological and psychosocial determinants, including clinical features of epilepsy (seizure frequency, type, foci, or lateralization of foci) and neurochemical or iatrogenic mechanisms. Other risk factors are a family history of psychiatric illness, particularly depression, a lack of control over the seizures and iatrogenic causes (pharmacologic and surgical). In addition, treatment with antiepileptic drugs (AEDs) as well as social coping and adaptation skills have also been recognised as risk factors of depression associated with epilepsy. Epilepsy may foster the development of depression through being exposed to chronic stress. The uncertainty and unpredictability of seizures may instigate sadness, loneliness, despair, low self-esteem, and self-reproach in patients with epilepsy and lead to social isolation, stigmatization, or disability. Often, depression is viewed as a reaction to epilepsy's stigma and the associated poor quality of life. Moreover, patients with epilepsy display a 4-5 higher rate of depression and suicide compared with healthy population. Copyright © 2016. Published by Elsevier Urban & Partner Sp. z o.o.
Lesbians are a marginalized group of women living in a heteronormative society. This study describes lesbians’ subjective experiences of depression, and identifies the ways that dominant and alternative discourses shaped their understandings of depression and sexuality. Twelve self-identified lesbians participated in up to three in-depth interviews conducted over a nine month period. Thematic analysis led to themes that explicated their physical and emotional descriptions of depression; identified troubled interpersonal relationships as a primary source of depression; and the means implemented to cope with depression, including taking medication, engagement in therapy, developing social support networks, and discovering their own spirituality. Depression and sexuality were understood within the framework of the dominant discourses of (1) medical model (2) dysfunctional family and (3) organized religion; and the alternative discourses of (1) lesbian identity, (2) alternative families and (3) spirituality. Nurses in clinical practice can assist depressed lesbians clients by bolstering explorations of spirituality and the development of strong support networks within the lesbian and gay communities. Politically, institutionalized heteronormativity must be attacked at every level. PMID:19350435
Pearson, Sue; Schmidt, Mike; Patton, George; Dwyer, Terry; Blizzard, Leigh; Otahal, Petr; Venn, Alison
OBJECTIVE To examine the association between depressive disorder and insulin resistance in a sample of young adults using the Composite International Diagnostic Interview to ascertain depression status. RESEARCH DESIGN AND METHODS Cross-sectional data were collected from 1,732 participants aged between 26 and 36 years. Insulin resistance was derived from blood chemistry measures of fasting insulin and glucose using the homeostasis model assessment method. Those identified with mild, moderate, or severe depression were classified as having depressive disorder. RESULTS The 12-month prevalence of depressive disorder was 5.4% among men and 11.7% among women. In unadjusted models mean insulin resistance was 17.2% (95% CI 0.7–36.0%, P = 0.04) higher in men and 11.4% (1.5–22.0%, P = 0.02) higher in women with depressive disorder. After adjustment for behavioral and dietary factors, the increased level of insulin resistance associated with depressive disorder was 13.2% (−3.1 to 32.3%, P = 0.12) in men and 6.1% (−4.1 to 17.4%, P = 0.25) in women. Waist circumference was identified as a mediator in the relationship between depression and insulin resistance, reducing the β coefficient in the fully adjusted models in men by 38% and in women by 42%. CONCLUSIONS A positive association was found between depressive disorder and insulin resistance in this population-based sample of young adult men and women. The association seemed to be mediated partially by waist circumference. PMID:20185745
Videbech, Poul Bror Hemming; Deleuran, Anette
AIM OF DATABASE: The purpose of the Danish Depression Database (DDD) is to monitor and facilitate the improvement of the quality of the treatment of depression in Denmark. Furthermore, the DDD has been designed to facilitate research. STUDY POPULATION: Inpatients as well as outpatients...... with depression, aged above 18 years, and treated in the public psychiatric hospital system were enrolled. MAIN VARIABLES: Variables include whether the patient has been thoroughly somatically examined and has been interviewed about the psychopathology by a specialist in psychiatry. The Hamilton score as well...
Vinberg, Maj; Levinsen, Mette Frandsen; Kessing, Lars Vedel
Depression is considered resistant when two treatment attempts with antidepressants from different classes fail to produce significant clinical improvement. In cases of treatment-resistant depression, it is recommended to reevaluate the diagnosis, clarify comorbidity, substance abuse and lack...... of compliance. Regarding treatment, evidence is sparse, but switching to a different antidepressant, and combination or augmentation with another agent, admission and treatment with ECT are the options. The choice of treatment must be based on the characteristics of the depression, the severity of treatment...
Mtileni, Bohani; Dzama, Kennedy; Nephawe, Khathutshelo; Rhode, Clint
diversity ascribed to population differences within groups (F SC = 0.106). The results suggest that significant genetic erosion has occurred within the conservation flocks due to inbreeding, pronounced effects of random drift and selection. It might be necessary to introduce new breeding individuals from the respective field populations in order to increase the effective population sizes of the conservation flocks and counter the effects of genetic erosion.
Gade, Anders; Kristoffersen, Marius; Kessing, Lars Vedel
BACKGROUND: The personality trait of neuroticism is strongly related to depression, but depression is etiologically heterogeneous. Late-onset depression (LOD) may be more closely related to vascular factors, and previous studies of neuroticism in LOD versus early-onset depression (EOD) have not b...
... It's designed for treatment-resistant conditions. Interpersonal psychotherapy. Interpersonal psychotherapy focuses on resolving relationship issues that may contribute to your depression. Family or marital therapy. This type of therapy involves family members or ...
... teens change negative patterns of thinking and behaving. Interpersonal therapy focuses on how to develop healthier relationships at home and at school. Medication relieves some symptoms of depression and is often prescribed along with therapy. When ...
... shown to be particularly effective in treating postpartum depression are: Cognitive behavioral therapy (CBT), which helps people recognize and change their negative thoughts and behaviors; and Interpersonal therapy (IPT), which helps people understand and work ...
Wium-Andersen, Marie Kim; Ørsted, David Dynnes; Rode, Line
BACKGROUND: Depression has been cross-sectionally associated with short telomeres as a measure of biological age. However, the direction and nature of the association is currently unclear. AIMS: We examined whether short telomere length is associated with depression cross-sectionally as well...... as prospectively and genetically. METHOD: Telomere length and three polymorphisms, TERT, TERC and OBFC1, were measured in 67 306 individuals aged 20-100 years from the Danish general population and associated with register-based attendance at hospital for depression and purchase of antidepressant medication....... RESULTS: Attendance at hospital for depression was associated with short telomere length cross-sectionally, but not prospectively. Further, purchase of antidepressant medication was not associated with short telomere length cross-sectionally or prospectively. Mean follow-up was 7.6 years (range 0...
Doxepin is used to treat depression and anxiety. Doxepin is in a class of medications called tricyclic antidepressants. It works by increasing the amounts of certain natural substances in the brain ...
American Psychiatric Association. Major depressive disorder. Diagnostic and Statistical Manual of Mental Disorders: DSM-5 . 5th ed. Arlington, VA: American Psychiatric Publishing. 2013;160-168. Bostic JQ, Prince JB, Buxton DC. Child and adolescent psychiatric ...
Full Text Available The treatment guideline draws on several international guidelines: (iPractice Guidelines of the American Psychiatric Association (APAfor the Treatment of Patients with Major Depressive Disorder, SecondEdition;(ii Clinical Guidelines for the Treatment of DepressiveDisorders by the Canadian Psychiatric Association and the CanadianNetwork for Mood and Anxiety Treatments (CANMAT;(iiiNational Institute for Clinical Excellence (NICE guidelines;(iv RoyalAustralian and New Zealand College of Psychiatrists Clinical PracticeGuidelines Team for Depression (RANZCAP;(v Texas MedicationAlgorithm Project (TMAP Guidelines;(vi World Federation ofSocieties of Biological Psychiatry (WFSBP Treatment Guideline forUnipolar Depressive Disorder;and (vii British Association forPsychopharmacology Guidelines.[7
... support, most employees can overcome clinical depression and pick up where they left off. Know The Facts ... www.workplacementalhealth.org/Functional/About-Us/Meet-the-staff.aspx i Greenberg PE, Kessler RC, Birnbaum HG, ...
Hauenstein, Emily J
Major depressive disorder is a common problem for adolescents. It has a wide array of symptoms affecting somatic, cognitive, affective, and social processes. Academic failure, poor peer relationships, behavioral problems, conflict with parents and other authority figures, and substance abuse are some of the consequences of major depressive disorder in this age group. Effective treatments include nontricyclic antidepressants and coping skills training. The nurse is key to depression detection and suicide prevention, especially in primary care settings. Through psychoeducation, nurses can promote recovery from depression by encouraging a healthy lifestyle, enhancing social skills, and assisting the adolescent to identify and use sources of social support. These measures can prevent premature death and promote long-term well-being of the adolescent.
Social media has recently emerged as a premier method to disseminate information online. Through these online networks, tens of millions of individuals communicate their thoughts, personal experiences, and social ideals. We therefore explore the potential of social media to predict, even prior to onset, Major Depressive Disorder (MDD) in online personas. We employ a crowdsourced method to compile a list of Twitter users who profess to being diagnosed with depression. Using up to a year of pri...
Van Assche, E; De Backer, J; Vermote, R
Music therapy is a predominantly non-verbal psychotherapy based on music improvisation, embedded in a therapeutic relationship. This is the reason why music therapy is also used to treat depression. To examine the efficacy of music therapy and to report on the results of recent research into the value of music therapy as a treatment for depression. We reviewed the literature on recent research into music therapy and depression, reporting on the methods used and the results achieved, and we assessed the current position of music therapy for depression in the context of evidence-based scientific research. A wide variety of research methods was used to investigate the effects of using music therapy as a psychotherapy. Most studies focused usually on the added value that music therapy brings to the standard form of psychiatric treatment, when administered with or without psychopharmacological support. Music therapy produced particularly significant and favourable results when used to treat patients with depression. Current research into music therapy and depression points to a significant and persistent reduction in patients' symptoms and to improvements in their quality of life. However, further research is needed with regard to the best methods of illustrating the effects of music therapy.
Ionescu, Dawn F; Niciu, Mark J; Mathews, Daniel C; Richards, Erica M; Zarate, Carlos A
Anxious depression is a common, distinct clinical subtype of major depressive disorder (MDD). This review summarizes current neurobiological knowledge regarding anxious depression. Peer-reviewed articles published January 1970 through September 2012 were identified via PUBMED, EMBASE, and Cochrane Library, using the following key words: anxious depression electroencephalography (EEG), anxious depression functional magnetic resonance imaging (fMRI), anxious depression genetics, anxious depress...
Anees, M.; Barki, H.; Masood, M.
To measure the frequency of depression and its risk factors in patients under going hemodialysis. It is a cross-sectional prospective study conducted at Hemodialysis unit of Shalamar Hospital and Shaikh Zayed Hospital, Lahore from 1/sup st/ January 2006 to 30/sup th/ April 2006. All patients getting regular hemodialysis for more than three months were included. Beck's Depression Inventory- II (BDI-II; adapted in Urdu) was administered on all the patients who were able to read or understand it. Blood sample were drawn at the same time for routine hematological, biochemical parameters and viral markers (Anti HCV and HbsAg). Diagnosis was made as per Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM IV) for correlation of psychological variables with clinical, hematological and biochemical parameters. Eighty nine patients were enrolled which included fifty two (58.4%) were male and seventy seven (86.5%) were married. Major causes of renal failure were diabetes, hypertension and chronic glomerulonephrotis. Duration of dialysis was from 03 to 49 months with mean of 19.64 +- 11.7 months. Severity of depression was categorized in to mild, moderate and severe on the basis of BDI score. Majority of the patients fifty (56.1%) were moderately to severely depressed and there was no gender difference in the prevalence of depression. Majority of patients undergoing hemodialysis were depressed. Major risk factors for depression were marital status, illiteracy, number of children, socioeconomic factors, gender, hypertension and hypoalbuminemia. Patients with anemia, hyponatremia and hyperkalemia had suicidal tendency. Patients with hepatitis C and disturbed liver function have strong correlation with psychological parameters. (author)
Sarris, Jerome; O'Neil, Adrienne; Coulson, Carolyn E; Schweitzer, Isaac; Berk, Michael
The prevalence of depression appears to have increased over the past three decades. While this may be an artefact of diagnostic practices, it is likely that there are factors about modernity that are contributing to this rise. There is now compelling evidence that a range of lifestyle factors are involved in the pathogenesis of depression. Many of these factors can potentially be modified, yet they receive little consideration in the contemporary treatment of depression, where medication and psychological intervention remain the first line treatments. "Lifestyle Medicine" provides a nexus between public health promotion and clinical treatments, involving the application of environmental, behavioural, and psychological principles to enhance physical and mental wellbeing. This may also provide opportunities for general health promotion and potential prevention of depression. In this paper we provide a narrative discussion of the major components of Lifestyle Medicine, consisting of the evidence-based adoption of physical activity or exercise, dietary modification, adequate relaxation/sleep and social interaction, use of mindfulness-based meditation techniques, and the reduction of recreational substances such as nicotine, drugs, and alcohol. We also discuss other potential lifestyle factors that have a more nascent evidence base, such as environmental issues (e.g. urbanisation, and exposure to air, water, noise, and chemical pollution), and the increasing human interface with technology. Clinical considerations are also outlined. While data supports that some of these individual elements are modifiers of overall mental health, and in many cases depression, rigorous research needs to address the long-term application of Lifestyle Medicine for depression prevention and management. Critically, studies exploring lifestyle modification involving multiple lifestyle elements are needed. While the judicious use of medication and psychological techniques are still advocated
ATASSI, NAZEM; COOK, AMANDA; PINEDA, CRISTIANA M. E.; YERRAMILLI-RAO, PADMAJA; PULLEY, DARLENE; CUDKOWICZ, MERIT
Depression is an under-recognized comorbidity associated with amyotrophic lateral sclerosis (ALS). The goals of this study were to prospectively estimate the prevalence of depression and other ALS related symptoms and to study the impact of depression on enrollment in research studies. One hundred and twenty-seven people with ALS completed the ALS Depression Inventory (ADI-12) and answered questions about ALS related symptoms and research study enrollment preferences. Demographics, ALS symptoms, medications, functional status, and research enrollment were compared between depressed and non-depressed patients. Results showed that the prevalence of mild and severe depression was 29% and 6%, respectively. More than one-third of our ALS patients were receiving anti-depressants to treat depression, sialorrhea, and pseudobulbar affect. Depression prevalence was not correlated with disease duration or progression. Except for anxiety, none of the ALS related symptoms predicted depression. The presence of depression did not have an effect on the decision to enroll in research studies. In conclusion, major depression is less common in our ALS cohort than in the general population. The diagnosis of depression can be masked by some ALS related symptoms and it has no impact on enrollment in ALS clinical trials. PMID:21091399
Relationship between heterosis and genetic divergence for phosphorus use efficiency and its components in tropical maize Relação entre heterose e divergência genética para a eficiência no uso do fósforo e seus componentes em milho tropical
Débora Santos Caixeta
Full Text Available The objective of this study was to determine the relationship between heterosis and genetic divergence for phosphorus use efficiency (PUE in tropical maize. It was used two groups of genitors, each consisting of seven lines, contrasting with each other in the nitrogen and phosphorus use efficiency. It was obtained 41 hybrid combinations between these groups, which were evaluated in low phosphorus. Randomized complete block design with two replications was used. For obtaining the components of variance and the breeding values were used REML/BLUP method. In the genotyping of the parental lines were used 80 microsatellite markers. Through the correlation between genetic distance obtained by the markers and specific combining ability it was not possible to determine with accuracy by molecular markers, the crosses that produced hybrids with the highest heterosis for PUE. Thus, is possible to conclude that there is no relationship between genetic divergence and heterosis for phosphorus use efficiency and its components in tropical maize.O objetivo deste estudo foi determinar a relação entre divergência genética e heterose para a eficiência no uso de fósforo (EUP em milho tropical. Utilizaram-se dois grupos de genitores, compostos de sete linhagens cada, contrastantes entre si para as eficiências no uso de nitrogênio e fósforo. Foram obtidas 41 combinações híbridas entre esses grupos, as quais foram avaliadas em baixo fósforo. Usou-se o delineamento em blocos ao acaso com duas repetições. A obtenção dos componentes de variância e valores genéticos foi realizada via REML/BLUP e, para genotipagem das linhagens genitoras, foram utilizados 80 marcadores microssatélites. Através da correlação entre a distância genética obtida pelos marcadores e a capacidade específica de combinação, observou-se não ser possível a determinação com acurácia, via marcadores moleculares, dos cruzamentos que produziram os híbridos com as maiores
Pedersen, Niels C; Liu, Hongwei; Leonard, Angela; Griffioen, Layle
Previous studies documented the problem of inbreeding among Italian Greyhounds (IG) from the USA and its possible role in a multiple autoimmune disease syndrome. The present study is an extension of these earlier experiments and had two objectives: 1) to identify pockets of additional genetic diversity that might still exist among IG from the USA and Continental Europe, and 2) to determine how loss of genetic diversity within the genome and in the dog leukocyte antigen (DLA) complex relates to the problem of autoimmune disease in IG from the USA. Genetic testing was conducted using 33 short tandem repeat (STR) loci across 25 chromosomes and 7 STR loci that associated with specific dog leukocyte antigen (DLA) class I and II haplotypes. Standard genetic assessment tests based on allele frequencies and internal relatedness (IR) were used as measures of breed-wide and individual heterozygosity. The results of these tests demonstrated that IG from the USA and Continental Europe belonged to a single breed but were genetically distinguishable by genomic allele frequencies, DLA class I and II haplotypes, and principal coordinate analysis (PCoA). In the second part of the study, 85 IG from the USA that had suffered various autoimmune disorders (case) and 104 healthy dogs (control) of comparable age were studied for genetic associations with disease. Case dogs were found to be significantly more homozygous in the DLA regions than control dogs. Principal coordinate analysis did not differentiate case from control populations. No specific STR-associated DLA-class I or II haplotype was associated with increased autoimmune disease risks. Reasons for the loss of genetic diversity and increased homozygosity among IG from the USA were studied using registration data and deep pedigrees. The breed in the USA started from a small number of founders from Europe and has remained relatively isolated and small in numbers, limiting breeding choices especially in the period before modern
Morimoto, Sarah Shizuko; Alexopoulos, George S
Inflammatory processes are likely to play a causal role in geriatric depression. Geriatric depression occurs in the context of illnesses in which inflammatory processes are part of the pathogenesis. Both aging and depression are associated with immune responses, and the connectivity among mood-regulating structures may be modulated by inflammatory responses. Geriatric depression exacerbates the symptoms of comorbid disorders. Geriatric depression often occurs in persons exposed to chronic stress, a state precipitating geriatric depression and triggering proinflammatory responses. The successful treatment of comorbid conditions that increase central nervous system inflammatory responses has general health benefits and should be part of clinical practice. Copyright © 2011 Elsevier Inc. All rights reserved.
Kessing, Lars Vedel; Hansen, Hanne Vibe; Demyttenaere, Koen
BACKGROUND: There is increasing evidence that attitudes and beliefs are important in predicting adherence to treatment and medication in depressive and bipolar disorders. However, these attitudes have received little study in patients whose disorders were sufficiently severe to require...... hospitalization. METHOD: The Antidepressant Compliance Questionnaire (ADCQ) was mailed to a large population of patients with depressive or bipolar disorder, representative of patients treated in hospital settings in Denmark. RESULTS: Of the 1005 recipients, 49.9% responded to the letter. A large proportion....... Moreover, their partners agreed on these negative views. Women had a more negative view of the doctor-patient relationship than men, and patients with a depressive disorder had a more negative view of antidepressants than patients with bipolar disorder. The number of psychiatric hospitalizations...
Full Text Available Abstract Background Given that the prevalence of antenatal and postnatal depression is high, with estimates around 13%, and the consequences serious, efforts have been made to identify risk factors to assist in prevention, identification and treatment. Most risk factors associated with postnatal depression have been well researched, whereas predictors of antenatal depression have been less researched. Risk factors associated with early parenting stress have not been widely researched, despite the strong link with depression. The aim of this study was to further elucidate which of some previously identified risk factors are most predictive of three outcome measures: antenatal depression, postnatal depression and parenting stress and to examine the relationship between them. Methods Primipara and multiparae women were recruited antenatally from two major hoitals as part of the beyondblue National Postnatal Depression Program 1. In this subsidiary study, 367 women completed an additional large battery of validated questionnaires to identify risk factors in the antenatal period at 26–32 weeks gestation. A subsample of these women (N = 161 also completed questionnaires at 10–12 weeks postnatally. Depression level was measured by the Beck Depression Inventory (BDI. Results Regression analyses identified significant risk factors for the three outcome measures. (1. Significant predictors for antenatal depression: low self-esteem, antenatal anxiety, low social support, negative cognitive style, major life events, low income and history of abuse. (2. Significant predictors for postnatal depression: antenatal depression and a history of depression while also controlling for concurrent parenting stress, which was a significant variable. Antenatal depression was identified as a mediator between seven of the risk factors and postnatal depression. (3. Postnatal depression was the only significant predictor for parenting stress and also acted as a mediator
Leigh, Bronwyn; Milgrom, Jeannette
Given that the prevalence of antenatal and postnatal depression is high, with estimates around 13%, and the consequences serious, efforts have been made to identify risk factors to assist in prevention, identification and treatment. Most risk factors associated with postnatal depression have been well researched, whereas predictors of antenatal depression have been less researched. Risk factors associated with early parenting stress have not been widely researched, despite the strong link with depression. The aim of this study was to further elucidate which of some previously identified risk factors are most predictive of three outcome measures: antenatal depression, postnatal depression and parenting stress and to examine the relationship between them. Primipara and multiparae women were recruited antenatally from two major hoitals as part of the beyondblue National Postnatal Depression Program 1. In this subsidiary study, 367 women completed an additional large battery of validated questionnaires to identify risk factors in the antenatal period at 26-32 weeks gestation. A subsample of these women (N = 161) also completed questionnaires at 10-12 weeks postnatally. Depression level was measured by the Beck Depression Inventory (BDI). Regression analyses identified significant risk factors for the three outcome measures. (1). Significant predictors for antenatal depression: low self-esteem, antenatal anxiety, low social support, negative cognitive style, major life events, low income and history of abuse. (2). Significant predictors for postnatal depression: antenatal depression and a history of depression while also controlling for concurrent parenting stress, which was a significant variable. Antenatal depression was identified as a mediator between seven of the risk factors and postnatal depression. (3). Postnatal depression was the only significant predictor for parenting stress and also acted as a mediator for other risk factors. Risk factor profiles for
Smith, Caroline A; Armour, Mike; Lee, Myeong Soo; Wang, Li-Qiong; Hay, Phillipa J
Depression is recognised as a major public health problem that has a substantial impact on individuals and on society. People with depression may consider using complementary therapies such as acupuncture, and an increasing body of research has been undertaken to assess the effectiveness of acupuncture for treatment of individuals with depression. This is the second update of this review. To examine the effectiveness and adverse effects of acupuncture for treatment of individuals with depression.To determine:• Whether acupuncture is more effective than treatment as usual/no treatment/wait list control for treating and improving quality of life for individuals with depression.• Whether acupuncture is more effective than control acupuncture for treating and improving quality of life for individuals with depression.• Whether acupuncture is more effective than pharmacological therapies for treating and improving quality of life for individuals with depression.• Whether acupuncture plus pharmacological therapy is more effective than pharmacological therapy alone for treating and improving quality of life for individuals with depression.• Whether acupuncture is more effective than psychological therapies for treating and improving quality of life for individuals with depression.• Adverse effects of acupuncture compared with treatment as usual/no treatment/wait list control, control acupuncture, pharmacological therapies, and psychological therapies for treatment of individuals with depression. We searched the following databases to June 2016: Cochrane Common Mental Disorders Group Controlled Trials Register (CCMD-CTR), Korean Studies Information Service System (KISS), DBPIA (Korean article database website), Korea Institute of Science and Technology Information, Research Information Service System (RISS), Korea Med, Korean Medical Database (KM base), and Oriental Medicine Advanced Searching Integrated System (OASIS), as well as several Korean medical journals
Full Text Available ... items) Autism (13 items) Bipolar Disorder (2 items) Borderline Personality Disorder (3 items) Depression (32 items) Eating ... items) Autism (13 items) Bipolar Disorder (2 items) Borderline Personality Disorder (3 items) Depression (32 items) Eating ...
Full Text Available ... Traumatic Events (3 items) Institute Announcements (24 items) Symptoms and Treatment of Depression February 1, 2010 People ... is a serious illness that affects many people. Symptoms can vary, but many depressed people lose interest ...
Depression and Bipolar Support Alliance Crisis Hotline Information Coping with a Crisis Suicide Prevention Information Psychiatric Hospitalization ... sign-up Education info, training, events Mood Disorders Depression Bipolar Disorder Anxiety Screening Center Co-occurring Illnesses/ ...
Full Text Available ... suffer from depression trying to learn why it affects some people but not others. Treatments for depression do work. One type of effective psychotherapy is called cognitive behavioral therapy or CBT. ...
Full Text Available ... Autism (13 items) Bipolar Disorder (2 items) Borderline Personality Disorder (3 items) Depression (32 items) Eating Disorders (9 ... Autism (13 items) Bipolar Disorder (2 items) Borderline Personality Disorder (3 items) Depression (32 items) Eating Disorders (9 ...
Full Text Available ... and environmental factors that influence depression so that new and better treatments can be developed. RODOLFO : With ... shed light on causes of postpartum depression using new research model More News From the Field... Contact ...
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Kraus, Mary Ann; Redman, E. Scott
Postpartum depression is conceptualized as a predictable developmental, family crisis, which occurs when the natural difficulties of childbirth are benignly mishandled. Tactics are illustrated for interdicting maladaptive interpersonal spirals, including normalizing conflicting complaints; reframing depression as positive but costly; regulating…
Full Text Available ... items) Depression (32 items) Eating Disorders (9 items) Panic Disorder (1 item) Post-Traumatic Stress Disorder (7 ... items) Depression (32 items) Eating Disorders (9 items) Panic Disorder (1 item) Post-Traumatic Stress Disorder (7 ...
Full Text Available ... Institute Announcements (24 items) Symptoms and Treatment of Depression February 1, 2010 People with depression discuss how ... MSC 9663 Bethesda, MD 20892-9663 Follow Us Facebook Twitter YouTube Google Plus NIMH Newsletter NIMH RSS ...
Full Text Available ... Autism (13 items) Bipolar Disorder (2 items) Borderline Personality Disorder (3 items) Depression (32 items) Eating Disorders ( ... Autism (13 items) Bipolar Disorder (2 items) Borderline Personality Disorder (3 items) Depression (32 items) Eating Disorders ( ...
Full Text Available ... continues to study the genetic, biological and environmental factors that influence depression so that new and better ... are the first steps on the road to recovery. Depression treatment can take time to work, so ...
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Full Text Available ... Symptoms and Treatment of Depression February 1, 2010 People with depression discuss how they got help. & ... I felt like I was such an awful person that there was no real reason for me ...