Genetic variation among Corsican and continental populations of the Eurasian treecreeper (Aves: Certhia familiaris) reveals the existence of a palaeoendemic mitochondrial lineage

In this study we investigated the phylogenetics of the Eurasian treecreeper (Certhia familiaris), a forest passerine with a wide Palaearctic range including Corsica, using three mitochondrial genes and three nuclear introns, and
its phylogeographic history using the COI gene. Our phylogenetic results, including eight of the ten sub-species currently recognized, support the monophyly of C. familiaris with respect to its Indo-Asian sister species
C. hodgsoni. C. familiaris comprises two lineages that diverged during the mid-Pleistocene (c. 1 Myr): one palaeoendemic lineage has an allopatric range nowadays restricted to the Corsica island and the Caucasus region
whereas the second one, more recent and widespread, is distributed over most of Eurasia and in northern China. The most likely scenario that may explain such a pattern is a double colonization of the western Palaearctic from
the eastern range of the species. During the middle Pleistocene period, a first lineage expanded its range up into Europe but did not persist through glacial cycles except in Corsica and the Caucasus region. Later, during the
upper Pleistocene, a second lineage began to diversify around 0.09 Myr, spreading towards the western Palaearctic from a unique refuge likely located in the eastern Palaearctic [correction added on 6 March 2015 after first online
publication: 0.9 Myr amended to 0.09 Myr]. Apart from C. f. corsa, our results do not suggest any distinct evolutionary history for other sub-species previously described on morphological grounds in Europe. Our study
highlights the important conservation value of the Corsican treecreeper and emphasizes the major role of mature pine forests in the evolution of endemic bird taxa in Corsica.