Evolutionary diversification in an endangered biodiversity hotspot: the Southeast Asian peat swamp forest fish fauna

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A central theme in evolutionary biology is the understanding of the processes that contribute to the origin and maintenance of biodiversity. The diversity of recent species is not equally distributed among taxonomic groups and across the globe - a small number of clades accounts for a large part of the world's diversity and a number of relatively small areas with high levels of endemism are populated by unusually large numbers of species. These biodiversity hotspots comprise important systems for investigating the processes of evolutionary diversification; a prerequisite to document, explain, and conserve the diversity of life we observe today. The Southeast Asian peat swamp forests (PSF), found in the Sundaland biodiversity hotspot, are waterlogged forests that grow on a layer of dead plant material. Although PSF are one of the most threatened ecosystem, virtually nothing is known about the patterns and processes of evolutionary diversification of its endemic fauna and flora. PSF are characterized by a unique, vastly stenotopic freshwater fish community, which is adapted to highly acidic (pH as low as 3) black waters and comprises many miniature taxa and narrow range endemics many of which have only been discovered in recent years. We will use a multigene, molecular systematic approach to investigate the biogeography, phylogeography and demographic history of selected stenotopic PSF fish clades. Our project will for the first time provide an evolutionary perspective to global PSF conservation efforts. The specific aims are to, (1) reconstruct the time frame for the peat swamp forest fish diversification and test alternative biogeographic hypotheses that have long been contentious - Miocene-Pliocene vicariance vs Pleistocene dispersal among the landmasses of Sundaland, (2) identify past demographic expansions and their taxonomic, geographic and temporal correlates and thus infer the areas that might have been refugia or centres of diversification as opposed to recently colonized areas, and (3) identify regions of elevated taxonomic and genetic diversity that contribute most to the evolutionary legacy of this unique ecosystem. Anticipated results will have an immense impact on our understanding of PSF evolution and will provide an understanding of a key PSF community component, the stenotopic acidophilic freshwater fish fauna. Placing the PSF fish fauna in a historic context will positively contribute to research efforts focussing on palaeoclimate and palaeoecosystem reconstruction of Southeast Asia. The molecular phylogenetic data generated in our project will allow this unique fauna to be better used as model group for Southeast Asian peat swamp forest diversification and conservation. Our findings promise to have a major bearing on several wider issues concerning evolutionary patterns and processes, namely: (1) the effect of past geological event and climate induced changes on diversification patterns (2) the role of Pleistocene refuges in tropical biodiversity hotspots (3) the relationship between species diversity and phylogenetic diversity in hotspots (4) predictive ecological modelling and community assembly.