Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment

A recent study on bush frogs in the Western Ghats Escarpment reveals that more than 60 distinct lineages have diversified in situ, with deep geographical and clade-level endemism shaped by both geological processes and ecological gradients. The research highlights the biogeographic significance of the Palghat Gap, an ancient valley, which separates two deeply divergent sister clades—North and South. The study found that range stasis and allopatric speciation driven by geological processes dominate lineage isolation on adjacent massifs. Additionally, diversification events in montane zones (above 1800 m) suggest a role for climate-mediated forest-grassland persistence, while independent transitions along elevational gradients during the Miocene indicate diversification along these gradients. High elevations act as centers of lineage diversification, whereas low- and mid-elevations in southern regions serve as 'museums' for deeply divergent lineages.

Vijayakumar, S. P., Menezes, R. C., Jayarajan, A., & Shanker, K. (2016). Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment. Proceedings of the Royal Society B: Biological Sciences, 283(1836), 20161011. https://doi.org/10.1098/rspb.2016.1011