From the Bosporus to Kopet Dagh: morphological, genetic and bioacoustic variation in the Chiffchaff in Turkey, the Caucasus and western Turkmenistan

The Chiffchaff superspecies complex occupies almost the entire Palearctic and includes many taxa of different ranks. It is traditionally considered to be one of the most complex problems in the taxonomy of Palearctic birds. We present new data on the genetics, morphology and bioacoustics of the Chiffchaff taxa found in Turkey, the Caucasus, Transcaucasia and Kopet Dagh: 'greenish' brevirostris, caucasicus, menzbieri and 'brownish' lorenzii. In southern Turkey, two Chiff chaffs were identified which carried a novel haplotype, recently discovered in Northern Israel. Both individuals from Turkey looked somewhat brighter and more yellowish than typical brevirostris, but their song clearly corresponded to the brevirostris dialect. The form brevirostris, inhabiting the western and central regions of Northern Turkey, was found to be the most distinct among all 'greenish' taxa, due to its small body size, wing formula and distinct vocal dialect. Paradoxically, the mitochondrial DNA of brevirostris is almost identical with caucasicus, whereas, in this respect, menzbieri is different from both. We believe that this paradox can be explained if we suppose that caucasicus originated during the ancient hybridization of brevirostris and menzbieri. The relationships between brevirostris and lorenzii, in the mountainous regions of eastern Turkey, show the mismatch between phenotypic and genotypic traits in some individuals that could also be a result of hybridization.