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Juha Merilä - One of the best experts on this subject based on the ideXlab platform.
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the role of golf courses in maintaining genetic connectivity between Common Frog rana temporaria populations in an urban setting
Conservation Genetics, 2013Co-Authors: Jarmo Saarikivi, A Granroth, Theresa Knopp, Juha MeriläAbstract:We studied population size, genetic diversity and differentiation of Common Frog (Rana temporaria) populations at urban golf courses and reference natural ponds in the greater Helsinki region, southern Finland. A total of 248 tadpoles from 12 locations (six golf courses, six reference sites) were genotyped with 13 polymorphic microsatellite markers. The most urban populations, situated in northern Helsinki, were the largest breeding sites having >120 (golf courses) and >200 (reference sites) spawn clumps at the time of sampling. On average, there was no difference in the number of spawns between the anthropogenic ponds at golf courses and the natural water bodies. Genetic variation within populations was substantial (HO = 0.68) while genetic differentiation between populations was low (FST = 0.016; average distance = 17.6 km). The golf course populations did not differ from natural populations in terms of genetic variability or differentiation. Hence, our results suggest that golf courses contribute positively to urban amphibian populations by providing suitable water bodies for reproduction and green corridors for dispersal, thus preventing isolation and loss of genetic variability within populations.
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potential effects of climate change on the distribution of the Common Frog rana temporaria at its northern range margin
Israel Journal of Ecology & Evolution, 2013Co-Authors: Lior Blank, Miska Luoto, Juha MeriläAbstract:Climate change is projected to be particularly strong in northern latitudes, and subarctic species are thus likely to be especially susceptible to the effects of climate warming. We forecast potential effects of climate change on the extent of the suitable habitat of the Common Frog, Rana temporaria, at the margin of its northern range. We investigated 179 potential breeding sites in subarctic Finland and subjected the data to detailed bioclimate envelope modelling using three state-of-the-art techniques: generalized additive models, maximum entropy and generalized boosting methods. Moreover, we included local environmental factors in the models to investigate whether they improve model performance. Under all tested climate change projections and irrespective of the modelling method, the suitable habitat for R. temporaria increased in warming climate. The inclusion of local abiotic variables significantly improved the performance of the models. However, June temperature appeared to be the most informative...
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effects of predator exposure on hsp70 expression and survival in tadpoles of the Common Frog rana temporaria
Canadian Journal of Zoology, 2011Co-Authors: Jesper Givskov Sorensen, Juha Merilä, Volker Loeschcke, Anssi LaurilaAbstract:Predator-induced changes in prey behavior and morphology are widespread, but little is known about physiological and cellular-level responses in prey in response to predation risk. We investigated whether predator (larvae of the dragonfly Aeshna Fabricius, 1775) presence elevated the expression level of heat-shock protein 70 (Hsp70)—a Commonly found response to stress—in tadpoles of the Common Frog (Rana temporaria L., 1758). In another experiment, we tested the survival of tadpoles in the presence of a free-ranging predator. Prior to this encounter, the tadpoles were exposed to either an Hsp-inducing environmental stress in the form of heat (31 °C) or to predator cues from a caged predator. We found no evidence for increased Hsp70 expression in tadpoles either in the presence of fed or starved predators. We did not find any effects of prior exposure to neither heat nor predator presence on survival at the end of experiment. Our results do not point to either Hsp70-mediated effect of predator-induced resp...
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First-generation linkage map for the Common Frog Rana temporaria reveals sex-linkage group.
Heredity, 2011Co-Authors: Jose M. Cano, Anssi Laurila, Johanna Vilkki, Juha MeriläAbstract:The Common Frog (Rana temporaria) has become a model species in the fields of ecology and evolutionary biology. However, lack of genomic resources has been limiting utility of this species for detailed evolutionary genetic studies. Using a set of 107 informative microsatellite markers genotyped in a large full-sib family (800 F1 offspring), we created the first linkage map for this species. This partial map—distributed over 15 linkage groups—has a total length of 1698.8 cM. In line with the fact that males are the heterogametic sex in this species and a reduction of recombination is expected, we observed a lower recombination rate in the males (map length: 1371.5 cM) as compared with females (2089.8 cM). Furthermore, three loci previously documented to be sex-linked (that is, carrying male-specific alleles) in adults from the wild mapped to the same linkage group. The linkage map described in this study is one of the densest ones available for amphibians. The discovery of a sex linkage group in Rana temporaria, as well as other regions with strongly reduced male recombination rates, should help to uncover the genetic underpinnings of the sex-determination system in this species. As the number of linkage groups found (n=15) is quite close to the actual number of chromosomes (n=13), the map should provide a useful resource for further evolutionary, ecological and conservation genetic work in this and other closely related species.
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allen s rule revisited quantitative genetics of extremity length in the Common Frog along a latitudinal gradient
Journal of Evolutionary Biology, 2011Co-Authors: Jussi Alho, Anssi Laurila, Ane T Laugen, Gábor Herczeg, Katja Rasanen, Juha MeriläAbstract:Ecogeographical rules linking climate to morphology have gained renewed interest because of climate change. Yet few studies have evaluated to what extent geographical trends ascribed to these rules have a genetic, rather than environmentally determined, basis. This applies especially to Allen's rule, which states that the relative extremity length decreases with increasing latitude. We studied leg length in the Common Frog (Rana temporaria) along a 1500 km latitudinal gradient utilizing wild and Common garden data. In the wild, the body size-corrected femur and tibia lengths did not conform to Allen's rule but peaked at mid-latitudes. However, the ratio of femur to tibia length increased in the north, and the Common garden data revealed a genetic cline consistent with Allen's rule in some trait and treatment combinations. While selection may have shortened the leg length in the north, the genetic trend seems to be partially masked by environmental effects.
Anssi Laurila - One of the best experts on this subject based on the ideXlab platform.
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effects of predator exposure on hsp70 expression and survival in tadpoles of the Common Frog rana temporaria
Canadian Journal of Zoology, 2011Co-Authors: Jesper Givskov Sorensen, Juha Merilä, Volker Loeschcke, Anssi LaurilaAbstract:Predator-induced changes in prey behavior and morphology are widespread, but little is known about physiological and cellular-level responses in prey in response to predation risk. We investigated whether predator (larvae of the dragonfly Aeshna Fabricius, 1775) presence elevated the expression level of heat-shock protein 70 (Hsp70)—a Commonly found response to stress—in tadpoles of the Common Frog (Rana temporaria L., 1758). In another experiment, we tested the survival of tadpoles in the presence of a free-ranging predator. Prior to this encounter, the tadpoles were exposed to either an Hsp-inducing environmental stress in the form of heat (31 °C) or to predator cues from a caged predator. We found no evidence for increased Hsp70 expression in tadpoles either in the presence of fed or starved predators. We did not find any effects of prior exposure to neither heat nor predator presence on survival at the end of experiment. Our results do not point to either Hsp70-mediated effect of predator-induced resp...
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First-generation linkage map for the Common Frog Rana temporaria reveals sex-linkage group.
Heredity, 2011Co-Authors: Jose M. Cano, Anssi Laurila, Johanna Vilkki, Juha MeriläAbstract:The Common Frog (Rana temporaria) has become a model species in the fields of ecology and evolutionary biology. However, lack of genomic resources has been limiting utility of this species for detailed evolutionary genetic studies. Using a set of 107 informative microsatellite markers genotyped in a large full-sib family (800 F1 offspring), we created the first linkage map for this species. This partial map—distributed over 15 linkage groups—has a total length of 1698.8 cM. In line with the fact that males are the heterogametic sex in this species and a reduction of recombination is expected, we observed a lower recombination rate in the males (map length: 1371.5 cM) as compared with females (2089.8 cM). Furthermore, three loci previously documented to be sex-linked (that is, carrying male-specific alleles) in adults from the wild mapped to the same linkage group. The linkage map described in this study is one of the densest ones available for amphibians. The discovery of a sex linkage group in Rana temporaria, as well as other regions with strongly reduced male recombination rates, should help to uncover the genetic underpinnings of the sex-determination system in this species. As the number of linkage groups found (n=15) is quite close to the actual number of chromosomes (n=13), the map should provide a useful resource for further evolutionary, ecological and conservation genetic work in this and other closely related species.
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allen s rule revisited quantitative genetics of extremity length in the Common Frog along a latitudinal gradient
Journal of Evolutionary Biology, 2011Co-Authors: Jussi Alho, Anssi Laurila, Ane T Laugen, Gábor Herczeg, Katja Rasanen, Juha MeriläAbstract:Ecogeographical rules linking climate to morphology have gained renewed interest because of climate change. Yet few studies have evaluated to what extent geographical trends ascribed to these rules have a genetic, rather than environmentally determined, basis. This applies especially to Allen's rule, which states that the relative extremity length decreases with increasing latitude. We studied leg length in the Common Frog (Rana temporaria) along a 1500 km latitudinal gradient utilizing wild and Common garden data. In the wild, the body size-corrected femur and tibia lengths did not conform to Allen's rule but peaked at mid-latitudes. However, the ratio of femur to tibia length increased in the north, and the Common garden data revealed a genetic cline consistent with Allen's rule in some trait and treatment combinations. While selection may have shortened the leg length in the north, the genetic trend seems to be partially masked by environmental effects.
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does testis weight decline towards the subarctic a case study on the Common Frog rana temporaria
Naturwissenschaften, 2005Co-Authors: Anssi Laurila, Ingemar K Jonsson, Gábor Herczeg, Tibor Kovács, Juha MeriläAbstract:Interpopulation comparisons of variation in resource availability and in allocation patterns along altitudinal and latitudinal gradients allow insights into the mechanisms shaping the life history of animals. Patterns of between-population differences in female life history traits have been studied intensively across a wide range of taxa, but similar investigations in males have remained scarce. To study if testis weight—a measure of reproductive investment—varies on a geographical scale in anurans, we focussed on the variation in relative testis weight (RelTW) and asymmetry in 22 populations of the Common Frog Rana temporaria along a 1,600-km latitudinal transect across the Scandinavian peninsula. We found that RelTW decreased towards the north. Body mass and body length both had independent positive effects on testes mass. We found evidence for directional asymmetry (DA) in testis weight with the right testis being larger than the left. The level of DA in testis weight was not related to latitude, but both body mass and testes mass had independent positive effects on asymmetry. We discuss the northwards decrease in RelTW in terms of a decreased reproductive investment as a possible consequence of harsher environmental conditions, and perhaps also, weaker sexual selection in the north than in the south.
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latitudinal divergence of Common Frog rana temporaria life history traits by natural selection evidence from a comparison of molecular and quantitative genetic data
Molecular Ecology, 2003Co-Authors: Jukka U Palo, Anssi Laurila, Ane T Laugen, Craig R Primmer, Robert B Ohara, Juha MeriläAbstract:The main aim of this work was to identify local adaptation processes in amphibian populations, thereby improving the general understanding of genetics and mechanisms behind the evolution and maintenance of biological diversity. Phenotypic and genetic variation in life-history traits was studied within and between populations Common Frog (Rana temporaria) populations along a 1600 km transect from southern Sweden to northern Finland.Embryonic and larval development and growth was investigated both under field and laboratory conditions. The results suggest ample genetic diversity in larval life-history traits among Fennoscandian Common Frog populations. Larval developmental rate along the gradient has evolved a countergradient variation pattern of genotypes and phenotypes as indicated by the positive relationship between developmental rate and latitude under laboratory conditions and the lack of such a relationship in the field. The data suggest that this pattern has evolved because of time constraints due to decreasing length of growth season with latitude. Neither field-caught adults nor laboratory raised larvae displayed a linear latitudinal size cline as expected from the so called Bergmanns rule. Rather, size increased towards the mid-latitude populations and decreased thereafter, indicating that body size is a product of direct environmental induction or a trade-off with other life-history characters. Age and size at hatching showed no consistent latitudinal pattern, indicating that the embryonic stage is not as time constrained as the larval stage.A large part of the variation in age and size at metamorphosis among populations was due to additive genetic effects. However, small, but significant maternal effects, mostly due to variation in egg size and non-additive genetic effects also contributed to among population variation. A comparison of divergence in presumably neutral molecular genetic markers (FST) and quantitative characters (QST) revealed that although both estimates of divergence were relatively high, estimates of QST was generally higher than those of FST, indicating that the genetic variation observed in larval traits is primarily a result of natural selection rather than genetic drift. Hence, our results reinforce the conclusion that intraspecific genetic heterogeneity in the young northern European ecosystems may be more widespread than previously anticipated
Melissa A Toups - One of the best experts on this subject based on the ideXlab platform.
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A reciprocal translocation radically reshapes sex‐linked inheritance in the Common Frog
Molecular Ecology, 2019Co-Authors: Melissa A Toups, Nicolas Rodrigues, Mark KirkpatrickAbstract:X and Y chromosomes can diverge when rearrangements block recombination between them. Here we present the first genomic view of a reciprocal translocation that causes two physically unconnected pairs of chromosomes to be coinherited as sex chromosomes. In a population of the Common Frog (Rana temporaria), both pairs of X and Y chromosomes show extensive sequence differentiation, but not degeneration of the Y chromosomes. A new method based on gene trees shows both chromosomes are sex‐linked. Furthermore, the gene trees from the two Y chromosomes have identical topologies, showing they have been coinherited since the reciprocal translocation occurred. Reciprocal translocations can thus reshape sex linkage on a much greater scale compared with inversions, the type of rearrangement that is much better known in sex chromosome evolution, and they can greatly amplify the power of sexually antagonistic selection to drive genomic rearrangement. Two more populations show evidence of other rearrangements, suggesting that this species has unprecedented structural polymorphism in its sex chromosomes.
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a reciprocal translocation radically reshapes sex linked inheritance in the Common Frog
Molecular Ecology, 2019Co-Authors: Melissa A Toups, Nicolas Rodrigues, Mark KirkpatrickAbstract:X and Y chromosomes can diverge when rearrangements block recombination between them. Here we present the first genomic view of a reciprocal translocation that causes two physically unconnected pairs of chromosomes to be coinherited as sex chromosomes. In a population of the Common Frog (Rana temporaria), both pairs of X and Y chromosomes show extensive sequence differentiation, but not degeneration of the Y chromosomes. A new method based on gene trees shows both chromosomes are sex‐linked. Furthermore, the gene trees from the two Y chromosomes have identical topologies, showing they have been coinherited since the reciprocal translocation occurred. Reciprocal translocations can thus reshape sex linkage on a much greater scale compared with inversions, the type of rearrangement that is much better known in sex chromosome evolution, and they can greatly amplify the power of sexually antagonistic selection to drive genomic rearrangement. Two more populations show evidence of other rearrangements, suggesting that this species has unprecedented structural polymorphism in its sex chromosomes.
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tissue specificity and dynamics of sex biased gene expression in a Common Frog population with differentiated yet homomorphic sex chromosomes
Genes, 2018Co-Authors: Paris Veltsos, Melissa A Toups, Nicolas Rodrigues, Roberto Sermier, Daniel L Jeffries, Nicolas PerrinAbstract:Sex-biased genes are central to the study of sexual selection, sexual antagonism, and sex chromosome evolution. We describe a comprehensive de novo assembled transcriptome in the Common Frog Rana temporaria based on five developmental stages and three adult tissues from both sexes, obtained from a population with karyotypically homomorphic but genetically differentiated sex chromosomes. This allows the study of sex-biased gene expression throughout development, and its effect on the rate of gene evolution while accounting for pleiotropic expression, which is known to negatively correlate with the evolutionary rate. Overall, sex-biased genes had little overlap among developmental stages and adult tissues. Late developmental stages and gonad tissues had the highest numbers of stage- or tissue-specific genes. We find that pleiotropic gene expression is a better predictor than sex bias for the evolutionary rate of genes, though it often interacts with sex bias. Although genetically differentiated, the sex chromosomes were not enriched in sex-biased genes, possibly due to a very recent arrest of XY recombination. These results extend our understanding of the developmental dynamics, tissue specificity, and genomic localization of sex-biased genes.
Mark Kirkpatrick - One of the best experts on this subject based on the ideXlab platform.
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A reciprocal translocation radically reshapes sex‐linked inheritance in the Common Frog
Molecular Ecology, 2019Co-Authors: Melissa A Toups, Nicolas Rodrigues, Mark KirkpatrickAbstract:X and Y chromosomes can diverge when rearrangements block recombination between them. Here we present the first genomic view of a reciprocal translocation that causes two physically unconnected pairs of chromosomes to be coinherited as sex chromosomes. In a population of the Common Frog (Rana temporaria), both pairs of X and Y chromosomes show extensive sequence differentiation, but not degeneration of the Y chromosomes. A new method based on gene trees shows both chromosomes are sex‐linked. Furthermore, the gene trees from the two Y chromosomes have identical topologies, showing they have been coinherited since the reciprocal translocation occurred. Reciprocal translocations can thus reshape sex linkage on a much greater scale compared with inversions, the type of rearrangement that is much better known in sex chromosome evolution, and they can greatly amplify the power of sexually antagonistic selection to drive genomic rearrangement. Two more populations show evidence of other rearrangements, suggesting that this species has unprecedented structural polymorphism in its sex chromosomes.
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a reciprocal translocation radically reshapes sex linked inheritance in the Common Frog
Molecular Ecology, 2019Co-Authors: Melissa A Toups, Nicolas Rodrigues, Mark KirkpatrickAbstract:X and Y chromosomes can diverge when rearrangements block recombination between them. Here we present the first genomic view of a reciprocal translocation that causes two physically unconnected pairs of chromosomes to be coinherited as sex chromosomes. In a population of the Common Frog (Rana temporaria), both pairs of X and Y chromosomes show extensive sequence differentiation, but not degeneration of the Y chromosomes. A new method based on gene trees shows both chromosomes are sex‐linked. Furthermore, the gene trees from the two Y chromosomes have identical topologies, showing they have been coinherited since the reciprocal translocation occurred. Reciprocal translocations can thus reshape sex linkage on a much greater scale compared with inversions, the type of rearrangement that is much better known in sex chromosome evolution, and they can greatly amplify the power of sexually antagonistic selection to drive genomic rearrangement. Two more populations show evidence of other rearrangements, suggesting that this species has unprecedented structural polymorphism in its sex chromosomes.
Nicolas Rodrigues - One of the best experts on this subject based on the ideXlab platform.
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phylogeography more than elevation accounts for sex chromosome differentiation in swiss populations of the Common Frog rana temporaria
Evolution, 2020Co-Authors: Barret C Phillips, Nicolas Rodrigues, Alexandra Jansen Van Rensburg, Nicolas PerrinAbstract:Sex chromosomes in vertebrates range from highly heteromorphic (as in most birds and mammals) to strictly homomorphic (as in many fishes, amphibians, and nonavian reptiles). Reasons for these contrasted evolutionary trajectories remain unclear, but species such as Common Frogs with polymorphism in the extent of sex chromosome differentiation may potentially deliver important clues. By investigating 92 Common Frog populations from a wide range of elevations throughout Switzerland, we show that sex chromosome differentiation strongly correlates with alleles at the candidate sex-determining gene Dmrt1. Y-specific Dmrt1 haplotypes cluster into two main haplogroups, YA and YB , with a phylogeographic signal that parallels mtDNA haplotypes: YA populations, with mostly well-differentiated sex chromosomes, occur primarily south of the main alpine ridge that bisects Switzerland, whereas YB populations, with mostly undifferentiated (proto-)sex chromosomes, occur north of this ridge. Elevation has only a marginal effect, opposing previous suggestions of a major role for climate on sex chromosome differentiation. The Y-haplotype effect might result from differences in the penetrance of alleles at the sex-determining locus (such that sex reversal and ensuing X-Y recombination are more frequent in YB populations), and/or fixation of an inversion on YA (as supported by the empirical observation that YA haplotypes might not recombine in XYA females).
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A reciprocal translocation radically reshapes sex‐linked inheritance in the Common Frog
Molecular Ecology, 2019Co-Authors: Melissa A Toups, Nicolas Rodrigues, Mark KirkpatrickAbstract:X and Y chromosomes can diverge when rearrangements block recombination between them. Here we present the first genomic view of a reciprocal translocation that causes two physically unconnected pairs of chromosomes to be coinherited as sex chromosomes. In a population of the Common Frog (Rana temporaria), both pairs of X and Y chromosomes show extensive sequence differentiation, but not degeneration of the Y chromosomes. A new method based on gene trees shows both chromosomes are sex‐linked. Furthermore, the gene trees from the two Y chromosomes have identical topologies, showing they have been coinherited since the reciprocal translocation occurred. Reciprocal translocations can thus reshape sex linkage on a much greater scale compared with inversions, the type of rearrangement that is much better known in sex chromosome evolution, and they can greatly amplify the power of sexually antagonistic selection to drive genomic rearrangement. Two more populations show evidence of other rearrangements, suggesting that this species has unprecedented structural polymorphism in its sex chromosomes.
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a reciprocal translocation radically reshapes sex linked inheritance in the Common Frog
Molecular Ecology, 2019Co-Authors: Melissa A Toups, Nicolas Rodrigues, Mark KirkpatrickAbstract:X and Y chromosomes can diverge when rearrangements block recombination between them. Here we present the first genomic view of a reciprocal translocation that causes two physically unconnected pairs of chromosomes to be coinherited as sex chromosomes. In a population of the Common Frog (Rana temporaria), both pairs of X and Y chromosomes show extensive sequence differentiation, but not degeneration of the Y chromosomes. A new method based on gene trees shows both chromosomes are sex‐linked. Furthermore, the gene trees from the two Y chromosomes have identical topologies, showing they have been coinherited since the reciprocal translocation occurred. Reciprocal translocations can thus reshape sex linkage on a much greater scale compared with inversions, the type of rearrangement that is much better known in sex chromosome evolution, and they can greatly amplify the power of sexually antagonistic selection to drive genomic rearrangement. Two more populations show evidence of other rearrangements, suggesting that this species has unprecedented structural polymorphism in its sex chromosomes.
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tissue specificity and dynamics of sex biased gene expression in a Common Frog population with differentiated yet homomorphic sex chromosomes
Genes, 2018Co-Authors: Paris Veltsos, Melissa A Toups, Nicolas Rodrigues, Roberto Sermier, Daniel L Jeffries, Nicolas PerrinAbstract:Sex-biased genes are central to the study of sexual selection, sexual antagonism, and sex chromosome evolution. We describe a comprehensive de novo assembled transcriptome in the Common Frog Rana temporaria based on five developmental stages and three adult tissues from both sexes, obtained from a population with karyotypically homomorphic but genetically differentiated sex chromosomes. This allows the study of sex-biased gene expression throughout development, and its effect on the rate of gene evolution while accounting for pleiotropic expression, which is known to negatively correlate with the evolutionary rate. Overall, sex-biased genes had little overlap among developmental stages and adult tissues. Late developmental stages and gonad tissues had the highest numbers of stage- or tissue-specific genes. We find that pleiotropic gene expression is a better predictor than sex bias for the evolutionary rate of genes, though it often interacts with sex bias. Although genetically differentiated, the sex chromosomes were not enriched in sex-biased genes, possibly due to a very recent arrest of XY recombination. These results extend our understanding of the developmental dynamics, tissue specificity, and genomic localization of sex-biased genes.
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sex chromosome differentiation and sex races in the Common Frog rana temporaria
Proceedings of The Royal Society B: Biological Sciences, 2015Co-Authors: Nicolas Rodrigues, Jon Loman, Yvan Vuille, Nicolas PerrinAbstract:Sex-chromosome differentiation was recently shown to vary among Common Frog populations in Fennoscandia, suggesting a trend of increased differentiation with latitude. By rearing families from two contrasted populations (respectively, from northern and southern Sweden), we show this disparity to stem from differences in sex-determination mechanisms rather than in XY-recombination patterns. Offspring from the northern population display equal sex ratios at metamorphosis, with phenotypic sexes that correlate strongly with paternal LG 2 haplotypes (the sex chromosome); accordingly, Y haplotypes are markedly differentiated, with male-specific alleles and depressed diversity testifying to their smaller effective population size. In the southern population, by contrast, a majority of juveniles present ovaries at metamorphosis; only later in development do sex ratios return to equilibrium. Even at these later stages, phenotypic sexes correlate only mildly with paternal LG 2 haplotypes; accordingly, there are no recognizable Y haplotypes. These distinct patterns of gonadal development fit the concept of ‘sex races’ proposed in the 1930s, with our two populations assigned to the ‘differentiated’ and ‘semi-differentiated’ races, respectively. Our results support the suggestion that ‘sex races’ differ in the genetic versus epigenetic components of sex determination. Analysing populations from the ‘undifferentiated race’ with high-density genetic maps should help to further test this hypothesis.