Molecular phylogeny and the historical biogeography of the warblers of the genus Sylvia (Aves)

A molecular phylogeny based on DNA/DNA hybridization revealed that the Sylvia-Parisoma complex is monophyletic and includes three main groups of species, the ''mid-European'' warblers, the genus Parisoma, and the ''eu-Mediterranean'' Sylvia species sensu stricto. The latter can be assigned to three main clusters, a ''West-Mediterranean'' group, a ''Central-Mediterranean group'', and an ''East-Mediterranean'' group. The radiation of the whole complex is much more ancient than formerly believed. It started ca 12-13 Ma ago and the ancestors of the main extant groups differentiated during the Pliocene. Only speciation events within the ''eu-Mediterranean'' lineages occurred during the Pleistocene. The paleoclimatical and paleoecological history of the Mediterranean region is too complicated to provide any evidence for direct relationships between past events and evolutionary steps of these taxa which did not leave any reliable fossil record. However, some major speciation events may be related to well documented climatical crises as well as paleobotanical data. The largely man-induced extension of matorrals over several millenia presumably extended the range of several species that were formerly much more restricted, which complicates reconstruction of the spatio-temporal course of speciation.