Mitochondrial DNA and nuclear microsatellites reveal high diversity and genetic structure in an avian top predator, the white-tailed sea eagle, in central Europe

We analysed 123 white-tailed sea eagles (Haliaeetus albicilla) from (primarily central) Europe with respect to variability and differentiation based on 499 bp of the mitochondrial control region and genotypes at seven unlinked nuclear microsatellites. Variability was high (overall expected heterozygosity, haplotype and nucleotide diversity being 0.70, 0.764 and 0.00698, respectively) and both marker systems showed a subdivision into two main genetic clusters (microsatellites) or haplogroups (mtDNA). In line with earlier analyses focusing on populations from northern and eastern Europe, as well as from Asia, we found a high level of admixture in Europe and no signs of a bottleneck - despite a severe decline of white-tailed sea eagle populations during the 20th century. Europe is thus a global stronghold for this species not only with respect to the number of breeding pairs but also regarding the proportion of species-wide genetic diversity. Our dense sampling revealed a possibly clinal variation within central Europe from north-west to south-east that was reflected by the distribution of mtDNA haplotypes as well as the two microsatellite-based clusters. This population differentiation in central Europe probably originated from a geographically structured postglacial colonization and was later enhanced by recent demographic fluctuations.