Climatic perturbation and speciation of Southern and Eastern African Bulbul/Greenbul species (family Pycnonotidae)

[摘要] ENGLISH ABSTRACT: African greenbuls are an ideal model system with which to explore different hypothesisthat may underlie observed patterns of lineage diversification. Among those few hypothesesamenable to falsification by phylogenetic methods concerning the diversification of thesouthern and east African biota, three can be singled out because of their verifiable predictions:the Plio-Pleistocene refugia, montane speciation and the gradient hypotheses. I usedphylogenetic and population genetics methods to reconstruct the diversification history of threeAfrican greenbul species/species complexes (Pycnonotidae) in southern and east Africa.My study established that most of the greenbul diversification took place in Plio-Pleistocene and the primary mechanism appears to be climatic cycling, yet dispersal andvicarince too have shaped the population genetic structure. The pattern of diversificationobserved in the three study taxa/species complexes differs substantially and can mostly beexplained by the Pleistocene refuge hypothesis. The study did not support the montanespeciation hypothesis as articulated by Roy (1997) for some of the montane Andropadus taxa.Phylogeographic and population genetics analyses on the grey-olive greenbul found aclose association between palaeodrainage systems and swampy areas (seeps) as animportant habitat configuration for diversification of lineages restructured to these patchyhabitats. Historical demographic analysis on Sombre greenbul revealved evidence for putativeeastern and southern coastal forest refugia. Further, this study revealed the complex nature ofEast African biogeography, and two possible routes of dispersal from Albertine Rift refugia tothe Eastern Arc and East African coastal forest in the Yellow-streaked greenbul complex.

[发布机构] Stellenbosch University