The history of the Caatinga: mapping genetic patterns and evolutionary processes in an endemic species using rapid evolution markers

Abstract

The Caatinga is the least studied and protected biome in Brazil. Its most striking feature is the water deficit caused by long and intense dry seasons, for which the biota is highly adapted. Despite this general condition of dryness, abiotic factors vary regionally and associations between environmental conditions and distribution patterns of diversity suggest historic relationships and a role in diversification. Information on the history of the biome are scarce and local, but suggest interactions with adjacent biomes related to past climate changes. Paleoindicators indicate partial replacement of the Caatinga by rain forests in the Pleistocene, while niche palaeomodeling supports a fairly stable Caatinga for the same period. Phylogeographic studies with endemic species will be needed to investigate these broad scale hypotheses of diversification, while the development of new hypotheses at a finer scale depends on inference based on powerful genetic markers. In this study we propose to explore fine patterns of distribution of genetic diversity in Pleurodema diplolister, a species of frog endemic to the Caatinga but distributed throughout the biome. We will use rapidly evolving markers (microsatellites) to identify and map evolutionary processes. Our aim is to perform a first evaluation on the applicability of the abovementioned hypotheses (historical correlation with abiotic factors, habitat stability and past climate changes), and to propose more detailed scenarios to be tested in the context of the original research project. (AU)