title: Low rates of X-Y recombination, not turnovers, account for homomorphic sex chromosomes in several diploid species of Palearctic green toads (Bufo viridis subgroup).
abstract: Contrasting with birds and mammals, most ectothermic vertebrates present homomorphic sex chromosomes, which might be due either to a high turnover rate or to occasional X-Y recombination. We tested these two hypotheses in a group of Palearctic green toads that diverged some 3.3 million years ago. Using sibship analyses of sex-linked markers, we show that all four species investigated share the same pair of sex chromosomes and a pattern of male heterogamety with drastically reduced X-Y recombination in males. Phylogenetic analyses of sex-linked sequences show that X and Y alleles cluster by species, not by gametolog. We conclude that X-Y homomorphy and fine-scale sequence similarity in these species do not stem from recent sex-chromosome turnovers, but from occasional X-Y recombination.
authors: Department of Ecology and Evolution (DEE), University of Lausanne, Lausanne, Switzerland.
authors: M
authors: M
authors: Stöck
authors: R
authors: R
authors: Savary
authors: C
authors: C
authors: Betto-Colliard
authors: S
authors: S
authors: Biollay
authors: H
authors: H
authors: Jourdan-Pineau
authors: N
authors: N
authors: Perrin
mesh_terms: D000483:Alleles; D000818:Animals; D002025:Bufonidae / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000032:analysis / Q000235:genetics; D004171:Diploidy; D019143:Evolution, Molecular; D005260:Female; D008040:Genetic Linkage; D060005:Genotyping Techniques; D007178:Inbreeding; D008297:Male; D008928:Mitochondria / Q000235:genetics; D010802:Phylogeny; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D013997:Time Factors; D014960:X Chromosome / Q000235:genetics / Q000378:metabolism*; D014998:Y Chromosome / Q000235:genetics / Q000378:metabolism*
chemical_list: D004272:DNA, Mitochondrial