Meeting Abstract
In order to assess the influence of geomorphology and climatic shifts on species diversification in sub-Saharan Africa, I reconstructed the pattern and timing of phylogenetic relationships of rain frogs (Brevicipitidae: Breviceps). I generated multi-locus sequence data and then reconstructed phylogenetic relationships and locus-specific networks, inferred dates of divergence among ingroup lineages, and finally used niche modeling to identify possible adaptive divergence. I found that Breviceps is monophyletic and comprised of two major, largely allopatric subclades. Diversity within each subclade is concentrated in two areas with contrasting geologic and climatic histories: the arid/semiarid winter rainfall zone in the southwestern Cape, and the semitropical East Coast that receives predominantly summer rainfall. Recognized species diversity in the Cape (based on phenotypic variation) is consistent with observed genetic patterns, whereas the East Coast is shown to harbor unexpectedly high genetic diversity and up to seven putative, cryptic species. Niche models show significant overlap between closely related species. Dating analyses indicate that diversification of Breviceps occurred rapidly within the Miocene, with only a moderate decline over the Plio-Pleistocene, suggesting that this process might be slowed but ongoing. I suggest that a combination of two models, a landscape barrier model and climate fluctuation model, can explain patterns of diversification in Breviceps, and Miocene epeirogenic events and climatic shifts may have had a considerable influence on contemporary patterns of biodiversity. Topographic complexity and relative geoclimatic stability in the East have promoted cryptic diversification in allopatry, and this area clearly harbors numerous undescribed taxa and is in need of more detailed biotic investigation.
