Mitochondrial diversity of European pond turtles (Emys orbicularis) in Anatolia and the Ponto-Caspian Region: Multiple old refuges, hotspot of extant diversification and critically endangered endemics

The European pond turtle, Emys orbicularis (Linnaeus, 1758), is one of the world's most widely distributed chelonian species. We investigated its mitochondrial phylogeography and demography using ∼1300 cyt b sequences from the entire range, with a focus on the eastern part, in particular on Turkey, where the species currently suffers massive losses. Coloration data from >1450 turtles were compared with mtDNA differentiation to assess the validity of the currently accepted subspecies from Turkey, the Black Sea Region, the Transcaucasus, and Iran. Our study region harbors considerable part of the mtDNA diversity of Emys, including a newly discovered lineage and 16 new haplotypes. In this area corresponding to approximately one-third of the entire distribution range, six out of the ten mitochondrial lineages and about half of all 72 haplotypes occur. Two mitochondrial lineages (VIII, X) are confined to small ranges along the southern coast of Turkey, another lineage (I) occupies the remainder of Turkey, the entire Black Sea Region, and the north-eastern part of the species’ range. In the south-western corner of the Black Sea and in the Aegean Region, two lineages (II, IV) occur that have their main distribution areas farther west. In the Transcaucasus and northern Iran, another endemic lineage (VII) is found. Lineage I is the largest and most diverse of all lineages and has its greatest diversity in Anatolia. Phylogeographic and demographic data suggest Anatolia as an ancient glacial refuge for turtles harboring mitochondrial lineages I, VIII and X, and that Anatolia and the Black Sea coasts constitute a hotspot for a younger burst of diversification within lineage I. These two regions correspond to the glacial refuge from which lineage I turtles recolonized more northerly parts of the range in the Holocene; lineage II represents an off-shoot of lineage I that became isolated in a westward-located refuge in the south-eastern Balkans during a previous Pleistocene glacial. Our data on coloration indicate that such characters have only limited value for delineating evolutionarily significant units. We propose to reduce the number of subspecies using mtDNA lineages as arbiter, and to recognize three subspecies as valid in Turkey, the Black Sea Region, the Transcaucasus and Iran: Emys orbicularis orbicularis (mtDNA lineage I); E. o. eiselti Fritz et al., 1998 (X); and E. o. persica Eichwald, 1831 (VII). However, the southern Turkish lineage VIII most probably represents an additional undescribed subspecies. Both southern Turkish endemics are critically endangered, with only three surviving populations of fewer than 30 adults each. We recommend establishing sanctuaries for them, and including them in the IUCN Red List.