Climatic legacies and sex Chromosomes: Latitudinal patterns of voltinism, diapause, size, and host-plant selection in two species of swallowtail butterflies at their hybrid zone

Abstract

Latitudinal differences in host plant utilization, voltinism, size. Control of these characters by a coadapted gene-complex located on the sex chromosome. This, together with the "Haldane-effect" (the heterogametes suffer most from hybridization) assures that the exchange of these genes is low between Papilio glaucus and P. canadensis over the hybrid zone in Michigan, helping to keep the species distinct.