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Abstract:

The Pleistocene glaciations were the most significant historical event during the evolutionary lifespan of most extant species. However, little is known about the consequences of the ice ages on the distribution and demography of marine animals of the Northeastern Atlantic. Because of reduced levels of contemporary gene flow, a marine demersal fish, the sand goby (Pomatoschistus minutus; Gobiidae, Teleostei) has been chosen for a phylogeographic study using cytochrome b sequences and eight microsatellites. Because of the absence of a fossil record, only ecological and taxonomical information could be used to calibrate the for gobies typically high evolutionary clock. Reciprocal monophyly occurred between the Mediterranean and Atlantic populations with a divergence dated in the Middle-Pleistocene. The Atlantic Clade contains an Iberian and North Atlantic (NA) Group, from which only the latter did contribute to the most recent postglacial distribution expansion. The historical demography of the Mediterranean Clade was mainly influenced by Middle Pleistocene glaciations in contrast to the two Atlantic ESUs who show for the first time evidence for a recent, most likely post-LGM, expansion.