Abstracts (first author)
Does “Coyne’s Rule” apply to amphibians? Introgression of sex-linked and autosomal markers across a tree frog hybrid zone
The large role of sex chromosomes in reproductive barriers between recently diverged species is one of the best-supported ideas in speciation research, and has been termed “Coyne’s Rule”. Most of this support, however, comes from studies of organisms with well-differentiated sex chromosomes such as fruit flies, mammals, and birds. In contrast to these groups, many fish and nearly all amphibians have homomorphic sex chromosomes, which contain a small sex-determining region and very large pseudo-autosomal regions. To date, little evidence is available to test how this dramatic difference in sex chromosome structure affects the genetic architecture of reproductive barriers. We genotyped 8 sex-linked and 16 autosomal microsatellites in frogs sampled along two transects across the hybrid zone between Hyla arborea and Hyla orientalis, and estimated cline width and position in order to test for differential introgression. Our results show no significant difference between introgression of sex-linked and autosomal markers, suggesting that the large effect of sex chromosomes on speciation may be limited to species with old and highly divergent sex chromosomes.