The Iberian Peninsula was one of the most important Pleistocene glacial refugia in Europe due to its particular characteristics that favoured survival of species throughout the Ice Ages, such as its high physiographic complexity, with several large mountain ranges primarily oriented in an east-west axis, and its peculiar geographical position. In particular, Southern Iberia is home to a variety of amphibian species showing confined and fragmented distributions, and which distinctiveness was recognized only very recently. These include the Betic midwife toad, Alytes dickhilleni, the Iberian parsley frog, Pelodytes ibericus, the pigmy marbled newt, Triturus pygmaeus, and the fire salamander, Salamandra salamandra longirostris. Recently, several investigations suggest that this region might experience a substantial increase in aridity by the end of this century, making it particularly vulnerable to water stress and desertification. In addition, the analysis of amphibian responses to projected climate change suggests that range contractions will happen mainly in Iberia and essentially affect these organisms. These observations, together with the fact that amphibians are undergoing a major global decline, suggest that they provide a unique model system to properly assess the importance of rear edge populations for biodiversity conservation in Southern Iberia under a scenario of climate change.

In this proposal, we will use precisely the four endemic amphibians mentioned above as model organisms to understand the character and conservation needs of rear edge populations in southern Iberia. More specifically, we will test the predictions that rear-edge populations of these species show i) very distinct genetic compositions and both low levels of genetic diversity and connectivity, ii) a tendency for genetic erosion and even extinction under current scenarios of climate change, and iii) evidence for increased levels of ecological stress. We will do this by combining a molecular characterization of populations at unprecedent levels of resolution using mtDNA, microsatellites and nuclear genealogies with fine-scale bioclimatic modeling and the experimental analysis of ecological performance of amphibian larvae to evaluate the dynamics of rear-edge populations under changing environmental conditions.

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