Significant Asia-Europe divergence in the middle spotted woodpecker (Aves, Picidae)

Population divergence could be strongly affected by species' ecology and might not be a direct response to climate-driven environmental change. We tested this in the middle spotted woodpecker (Dendrocoptes medius), a non-migratory, low-dispersal habitat specialist associated with old deciduous forests of the Western Palearctic. We present the first phylogeographic study of this species integrating genetic data (three mitochondrial loci, one autosomal and one Z-linked intron) with species distribution modelling. Based on this species' ecology, we predicted that the middle spotted woodpecker could have colonized its current range from multiple Last Glacial Maximum (LGM) refugia and that strongly structured populations could be expected. Indeed, we discovered a strong genetic divergence between Asian and European populations, with a split estimated at around one million of years ago. This was surprising given only slight intraspecific variation in plumage and morphology. Although there was no significant phylogeographic structure within the Asian and European groups, we cannot exclude the possibility of multiple refugia within either group during the LGM. This has to be further investigated with more extensive geographic sampling and larger number of variable independently evolving markers. Future studies should also investigate potential differences in vocalizations and ecology between the two groups. Lineages showing similar level of genetic differentiation including woodpeckers are often treated as species-level taxa. Comparison of our results with the phylogeographic history of other woodpeckers, suggests that sympatric species with similar life-histories might have idiosyncratic phylogeographic patterns probably resulting from different ecological requirements or historic stochasticity.