Nuclear-mitochondrial discordance and gene flow in a recent radiation of toads

► Natural hybridization among closely related species could facilitate speciation by introducing novel genetic variation. ► We examined gene flow and nuclear-mitochondrial discordance in a recent radiation of toads using AFLP and mitochondrial DNA markers. ► Phylogenies generated using nuclear and mitochondrial DNA were markedly discordant and gene flow was high between species that occurred in close proximity and shared similar male advertisement calls. ► Species in the Anaxyrus americanus group have experienced high levels of gene flow and hybridization may have played a role in their North American radiation.