The tropical rivers of Asia are hotspots of freshwater fish biodiversity, yet little scientific attention has been devoted to understanding this diversity in a regional biogeographical context. One major unresolved question is the nature of the freshwater faunal break between Indian and Southeast Asian zoogeographical realms and the evolutionary relationship of species that occur in the transition zone (Myanmar) to species with more westerly and easterly geographical distributions.This project will examine the evolutionary diversification of key groups of Asian fishes with a focus on Myanmar, where recent easing of political tensions has enabled thorough ichthyological exploration for the first time. Four groups have been specifically chosen as representative components of South Asian ichthyofauna, and include economically important, ecologically specialised, taxonomically difficult, and relatively unknown species.A robust phylogenetic framework is essential to test hypotheses about the origin of regional zoogeographical barriers and formation of freshwater biodiversity hotspots. Molecular genetic data will be used to determine evolutionary relationships for four key fish groups. The latest methods of dating species divergences using fossil and molecular data will be used to calibrate the phylogenies in time. Results will be interpreted alongside information on historical river geomorphology and climatic data to identify the processes that have promoted diversification and led to the formation of Myanmar fish biodiversity hotspots.The project will utilise state-of-the-art genetic techniques. It will bring together one of the worlds foremost Myanmar fish taxonomists and an experienced molecular phylogeneticist specialising in Asian ichthyology. It will provide information on evolution, relevant to the conservation of biological diversity in threatened ecosystems in a developing Asian country.