"Little is known about the evolutionary response of species to climate changes because time scales are too long to be directly studied; however recent phylogenetic studies on ancient lakes taxa suggest that climate- and/or geological-induced environmental changes can be reconstructed by analyzing genetic patterns within and among species. Lake Baikal is the most voluminous and deepest freshwater lake in the world. Therefore population genetics patterns can be compared between populations over a latitudinal range from the northern to the Southern basin (650 km) but as well over a large bathymetric range (1600m). Very little population genetics researches have been conducted on endemic Baikal species probably due to geopolitics and sampling difficulties. The endemic cottoid fishes flock contains only 33 described species. Our project attempts to combine population genetics, demographic and paleoclimatic data to investigate the effects of major climatic and geological changes on the Baikal endemic ichtyofauna given the various cottoid fishes habitats (e.g. benthic/pelagic species, shallow water/deep water species, latitudinal differences). We will genotype populations of 6 target sculpin species from different habitat types using 15 microsatellites. For the analytic part of the project we will use the Approximate Bayesian Computation methods, recent model-based methods used in very diverse fields. To reconstruct the recent evolutionary history of species or populations these methods use genetic data to test alternative models of speciation and genetic divergence. One of the main advantages of these methods is their flexibility; there is indeed no a priori limitation on the demographic models that can be built in terms of number of species involved, population structure, and demographic events. Our project will help elucidating the effects of global climatic changes on the general dynamics of diversification, loss of variation, adaptive radiations and speciation events."