TitleDiscordant divergence times among Z-chromosome regions between two ecologically distinct swallowtail butterfly species.
Publication TypeJournal Article
Year of Publication2007
AuthorsPutnam, AS, J Scriber, M, Andolfatto, P
Date Published2007 Apr
KeywordsAnimals, Base Sequence, Bayes Theorem, Butterflies, Chromosomes, Evolution, Molecular, Genes, Insect, Genetic Speciation, Genetics, Population, Models, Genetic, Molecular Sequence Data, Polymorphism, Genetic, Sequence Analysis, DNA, Species Specificity, Time Factors

We investigate multilocus patterns of differentiation between parental populations of two swallowtail butterfly species that differ at a number of ecologically important sex-linked traits. Using a new coalescent-based approach, we show that there is significant heterogeneity in estimated divergence times among five Z-linked markers, rejecting a purely allopatric speciation model. We infer that the Z chromosome is a mosaic of regions that differ in the extent of historical gene flow, potentially due to isolating barriers that prevent the introgression of species-specific traits that result in hybrid incompatibilities. Surprisingly, a candidate region for a strong barrier to introgression, Ldh, does not show a significantly deeper divergence time than other markers on the Z chromosome. Our approach can be used to test alternative models of speciation and can potentially assign chronological order to the appearance of factors contributing to reproductive isolation between species.

Alternate JournalEvolution