Abstract
The cold periods of the Pleistocene have had a striking impact on the diversification of most organisms in temperate regions. Phylogeographic patterns and postglacial expansion are poorly understood in the Black Grouse (Tetrao tetrix). This species is widely distributed across Eurasia, and has been divided into a number of subspecies on the basis of morphological differences and geographic isolation. To investigate the evolutionary history of the species, 143 samples from different regions were examined for a mtDNA control region fragment. Overall, analyses of mtDNA gave support for the divergence between Tetrao tetrix tetrix, T. t. ussuriensis and T. t. mongolicus. The analyses reveal the effects of colonisation out of glacial refugia on the genetic diversity and genetic structure of Black Grouse. The phylogeographical results are consistent with a demographic population expansion following a bell-shaped mismatch distribution, a star-shaped phylogeny and low nucleotide diversity. Patterns of postglacial dispersal imply that Black Grouse from southern Europe have been restricted to this area, and did not contribute to the genetic diversity of northern Europe. Instead, Black Grouse spread out to northern Europe from a refugium in the east and a possible one in western Europe, following the retreat of glacial ice sheets, although both refugia remain unidentified. We suggest that T. t. britannicus and T. t. viridanus correspond to northern T. t. tetrix, and that this lineage has diverged from the other subspecies. This division is tentative due to limited sampling, but it will facilitate the management of different evolutionary significant units of the species.
Highlights
The cold periods of the Pleistocene have had a striking impact on most organisms in temperate regions (Hewitt 2000)
We suggest that T. t. britannicus and T. t. viridanus correspond to northern T. t. tetrix, and that this lineage has diverged from the other subspecies
We focus on Black Grouse (Tetrao tetrix) which is a forest bird species distributed across Europe, from Britain to Siberia
Summary
The cold periods of the Pleistocene have had a striking impact on most organisms in temperate regions (Hewitt 2000). With the amelioration of climate, species expanded northwards from one or several refugia and colonised uninhabited areas (Hewitt 1996). The major glacial refugia for many species have been identified in the southern peninsulas of Iberia, Italy and the Balkans, where climatic conditions were less extreme during the Last Glacial Maximum (LGM, 23–18 kya) (Hewitt 1996, 1999, 2000; Taberlet et al 1998). It has been suggested that glacial refugia in Asia and northeastern Europe may have contributed to the colonisation of northern Europe (Bilton et al 1998; Naydenov et al 2007). Few data are available on the contribution of potential easternmost refugia (Taberlet et al 1998)
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