Relict populations and endemic clades in palearctic reptiles: Evolutionary history and implications for conservation

Abstract

The phylogeographic history of eight species complexes of West Palearctic reptiles was reconstructed using mitochondrial and nuclear markers. Cryptic endemic taxa were detected in the Southern European peninsulas (Iberia, Southern Italy/Sicily, and Greece) as well as in North Africa, Anatolia, Iran, and the Caucasus. These endemics are mainly of Tertiary or early Pleistocene age. Only part of them can be categorized as relicts of a former, more widely distributed taxon, having survived in ice age refugia; others have probably always remained in a restricted area, close to their origin. Typical Pleistocene relict populations are phylogenetically related to larger conspecific populations elsewhere. They may be restricted to mountain habitats like Vipera berus in the Alps and in Greek mountains, or to islands like Lacerta bilineata on Cres and Natrix tessellata in Crete. Holocene relict populations stem from a postPleistocene range expansion (usually in Southeast-Northwest direction). They reached their largest distribution during the Holocene climatic optimum and were later restricted to small areas in the climatically most favorable regions. Examples are N. tessellata, Zamenis longissimus, L. bilineata, L. viridis, and Emys orbicularis in Germany. These populations are only poorly differentiated genetically; hence the risk of losing genetic diversity is not an appropriate argument for their protection. They may react to global warming by a range expansion. Southern European, North African, and Middle Eastern relicts may, on the contrary, be threatened by global warming. These populations are in need of more studies, and should be brought to the attention of national and international conservation agencies.