Patterns and processes in the phylogeography of Western Europe marine fishes

One of the major concerns in the studies of phylogeography of north-eastern Atlantic fishes has been the location of potential unglaciated refugia, where inshore species could have survived the successive glacial peaks of the Pleistocene. The inshore fish species that now occur in west Europe vary in their thermal tolerance, life-history patterns and biogeographic origin and several distributional and phylogeographic patterns can be observed. Some species present a pattern of high level of genetic diversity in the southern part of the range, with the genetic diversity decreasing to the northern limit of their distribution. Many other do not conform to this pattern, presenting similar depths of genealogies throughout their entire ranges, with no drop of genetic diversity in the extreme north. Differences in thermal tolerances and also in life-history patterns may have an important role in the explanation of a substantial part of the variability in the results but a multi species comparison approach is needed to test these hypotheses. Pleistocenic marine refugia in Western Europe and potential routes of post-glacial re-colonization are also discussed.