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Breeding populations of southern dunlin Calidris alpina schinzii in South Fennoscandia and the Baltic are severely fragmented and declining dramatically. Information on the genetic structure and diversity is therefore of importance for the conservation and management of these populations. Here we present the results of comparative genetic analyses of these populations with other populations of the schinzii, alpina and arctica subspecies in northern Europe. We sequenced the mitochondrial DNA control region and the Z-chromosome intron VLDLR-9, and analyzed microsatellites and AFLPs, for analyses of within-population genetic diversity. We also extended previous analyses of the phylogeographic structure of dunlins in northern Europe with a larger sample of individuals and populations. Our results revealed no evidence of reduced genetic diversity or increased levels of inbreeding in the small and fragmented populations around the Baltic Sea as compared to the more vital and larger populations elsewhere. Nevertheless, their small population sizes and presumably high degree of isolation may lead to local extinctions, indicating that demographic and ecological factors may pose a greater threat to the survival of these populations than purely genetic factors. Phylogeographically, the schinzii populations in Scandinavia and the Baltic do not form a separate genetic clade, but are part of larger cline of genetic variation encompassing several recognized subspecies of dunlins in the western Palearctic region. Only the Icelandic population showed some distinctiveness in genetic structure and might therefore be considered a separate management unit. Our study highlights the general problem of lack of genetic support for subspecies in avian taxonomy and conservation genetics. [ABSTRACT FROM AUTHOR]