Phylogenetic relationships of endemic bunting species (Aves, Passeriformes, Emberizidae, Emberiza koslowi) from the eastern Qinghai-Tibet Plateau

Abstract

In this study we reconstructed the phylogenetic relationships of a narrow-range Tibetan endemic, Emberiza koslowi, to its congeners and shed some light on intraspecific lineage separation of further bunting species from Far East Asia and along the eastern margin of the Tibetan Plateau in China. The onset of the Old World bunting radiation was dated to the mid Miocene and gave rise to four major clades: i) one group comprising mainly Western Palearctic species and all high-alpine endemics of the Tibetan Plateau; ii) a clade including E. lathami, E. bruniceps and E. melanocephala; iii) one group comprising mainly Eastern Palearctic species and all insular endemics from Japan and Sakhalin; iv) an exclusively Afrotropic clade that comprised all African species except E. affinis, whose phylogenetic relationships were ambiguous and only poorly supported in all reconstructions. The Tibetan bunting, E. koslowi, turned out as an early offshoot of the Western Palearctic-Tibetan clade 1 and thus represents an ancient relic lineage that dates back to a mid Miocene colonization event of its ancestors to the alpine plateau habitats. This temporal scenario of an early Miocene origin of alpine Tibetan endemics coincides with recent results for two further species, the Tibetan ground tit, Pseudopodoces humilis, and the Tibetan rosefinch, Carpodacus roborowskii. The origin of extant intraspecific phylogeographic patterns and splits among sister species in Eastern Asia were dated back to the Pleistocene with earliest lineage splits occurring among taxa from the Japanese Archipelago including Sakhalin and their mainland counterparts. A similarly ancient split separated a southern clade of E. godlewskii yunnanensis from S Sichuan and Yunnan from a northern clade including populations from central and northeastern China, Mongolia and S Siberia. Ecological segregation among breeding habitats of southern E. g. yunnanensis at lower elevations and those of other conspecifics at high-alpine habitats might have played a key role in the spatial genetic diversification of this species.