September 26 2018

12:00 LSB 2320

Alexander Kirschel
Department of Biological Sciences
University of Cyprus

Factors mediating coexistence and reproductive isolation between related species at contact zones


When related species come into contact their interactions may include competition for resources, territory, even mates. Such interactions can influence species range limits and drive phenotypic evolution. But little is known about the extent of variation in phenotypic traits that may lead to a breakdown in species recognition and assortative mating. We investigated the extent of variation in phenotypic traits across independent contact zones between sister taxa of Pogoniulus tinkerbirds in forest and savanna in sub-Saharan Africa. We also obtained DNA samples across each contact zone representing interactions among different pairs of species or subspecies at each. In forest tinkerbirds, the two species coexisted widely, facilitated by character displacement of song, with the age of interaction best explaining a lack of coexistence and more similar plumage coloration in West Africa. In the savanna tinkerbirds, where greater song similarity may preclude coexistence, the extent to which songs differ mediates the extent of reproductive isolation. Where songs differed more in allopatry, they remained distinct where the two species came into contact. By contrast, where songs were more similar in allopatry, we found convergence in song towards the contact zone; with playback experiments showing only where differences are greater are songs distinguished. Genomic data reveal extensive hybridization at the contact zones where songs converge in spite of over 4 Ma of divergence in mitochondrial DNA, but no evidence of hybridization where songs remain distinct. Our work suggests song plays a vital role in mediating when species interbreed at contact zones, irrespective of the timespan of genetic divergence between them, while the age of the interaction influences the extent of coexistence.

Host: Greg Grether









































































































































































































































































































































































































































































































































































this is idtest: