Biotic vs abiotic factors promoting the diversification of caenophidian snakes.

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It is widely believed that the evolutionary diversification of advanced snakes (Caenophidia) experienced a major burst in the Neogene, but the causes for this increase in diversification remain poorly understood. Several causal hypotheses have been suggested, ranging from predator-prey coevolutionary scenarios to Cenozoic climate change. In the here proposed project we wish to test these hypotheses using an integrative approach comprising both fossil and molecular information: a) We will comprise a comprehensive data set of fossil caenophidian snake occurrences, which we use in conjunction with molecular divergence estimates to calculate rates of speciation and extinction through the Cenozoic; b) using the same approach, we will test for correlations with prey taxa by comparing our results with diversification patterns in mammals, birds, amphibians, and squamates; c) using advanced bioinformatic approaches we will test if caenophidian snake diversification is the result of a key innovation; d) using C4 grasses as a proxy, we will compare Caenophidian diversification rates to Cenozoic climate history. This comprehensive approach will finally allow us to determine the most likely causes for the impressive evolutionary success of Caenophidian snakes.