A tale of the nearly tail-less: the effects of Plio-Pleistocene climate change on the diversification of the African avian genus SylviettaAcademic Article
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Sylvietta is a broadly distributed group of African species inhabiting a wide range of habitats and presents an interesting opportunity to investigate the historic mechanisms that have impacted the biogeography of African avian species. We collected sequence data from 50 individuals and used modelbased phylogenetic methods, molecular divergence estimates and ancestral area estimates to construct a timecalibrated phylogeny and estimation of biogeographic history. We estimate a southern African origin for Sylvietta, with an initial divergence splitting the genus into two clades. The first consists of aridadapted species, with a southern African origin and subsequent diversification north into EthiopiaSomalia. The second clade is estimated as having a Congolian forest origin with an eastward pattern of colonization and diversification as a result of PlioPleistocene forest dynamics. Additionally, two members of the genus Sylvietta display interesting patterns of intraspecific diversification. Sylvietta rufescens is an aridadapted species inhabiting southern Africa, and we recover two subclades with a divergence dating to the Pleistocene, a unique pattern for avian species which may be explained via isolation in arid habitat fragments in the early Pleistocene. Second, Sylvietta virens, a species endemic to Afrotropical forests, is recovered with geographically structured genetic diversification across its broad range, an interesting result given that recent investigations of several avian forest species have found similar and substantial geographically structured genetic diversity relating to PlioPleistocene forest fragmentation. Overall, PlioPleistocene habitat cycling played a significant role in driving diversification in Sylvietta, and this investigation highlights the substantial impact of climatedriven habitat dynamics on the history of subSaharan species.
