Species interactions in Pogoniulus tinkerbirds

Tinkerbirds are small barbets found in Sub-Saharan Africa. They produce simple songs typically consisting of a single tone repeated several times at a constant frequency. We previously found evidence for character displacement in songs and morphology of yellow-rumped tinkerbird (Pogoniulus bilineatus) and yellow-throated tinkerbird (P. subsulphureus) where they coexist in Uganda and Cameroon (Kirschel et al. 2009, PNAS). Since then, we have been exploring interactions between species across the genus in a variety of habitats, investigating the effects of phenotypic and genetic similarity, and habitat preferences on the extent of range overlap, funded by a Marie Curie Reintegration Grant. We are also working on the phylogeny of the genus and the historical biogeography of several species. Our findings from this work show that even when the same pairs of related species interact at different contact zones, those interactions can differ. For instance, red-fronted tinkerbird (P. pusillus, below) and its sister species yellow-fronted tinkerbird (P. chrysoconus) meet at contact zones from North to South in Ethiopia, Kenya and adjacent Uganda, Tanzania and Swaziland and adjacent South Africa. Our studies show that the songs of the two species differ more in the two northern populations, which our evidence suggests aids species recognition, while the songs converge in the two southern populations, potentially leading to species recognition failure and interbreeding. Our analyses of genomic data across contact zones support this hypothesis. Ecological gradients and relative abundances at contact zones may also affect the extent of the interactions between these species.

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