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. Relict Populations and Endemic Clades inSouthern 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.

Molecular phylogenetics and historical biogeography of the west-palearctic common toads (Bufo bufo species complex)

“…The crown age of the family Bufonidae was estimated at approximately 60 Ma (95% HDP = 47.94-75.48 Ma), compatible with previous estimates (Roelants et al, 2007;Van Bocxlaer et al, 2009, 2010 and with the age of the oldest fossil attributable to the family Bufonidae (55 Ma old) (Báez and Nicoli, 2004).…”

“…2 and 3). A similar phylogeographic pattern occurs in the reptile Zamenis longissimus (Joger et al, 2010) and several species of mammals (Randi, 2007;and references therein). The presence of a cool temperate forest has been proposed for a narrow band along the southern shore of the Black Sea 18 ka (Adams and Faure, 1997), supporting the putative role of this region as a glacial refugium.…”

“…The existence of more than one phylogroup in the Italian Peninsula is a very common pattern in other Mediterranean Peninsulas, revealing so-called ''refugia within refugia'' (Gómez and Lunt, 2007). The main phylogeographic feature found in many Italian taxa is the presence of distinctive lineages in the Sicilian-Southern Italian region, as observed for instance in the mammal Sciurus vulgaris (Grill et al, 2009), reptiles Hierophis viridiflavus and Zamenis longissimus/Zamenis lineatus (Joger et al, 2010) and amphibians Bombina pachypus (Canestrelli et al, 2006) and Hyla intermedia (Canestrelli et al, 2007). Our results match this pattern, with a clearly differentiated Southern Italian haplotype group distributed across Sicily and Southern Italy.…”

“…Despite that, the event that separated these two species complexes was probably not the geological origin of the Central Asian Deserts but their emergence as biogeographic barriers, and these two phenomena do not necessarily have to be synchronous. In fact, mineralogical and sedimentological records of the Northern-South China Sea show that the aridification process of Central Asia was not a homogeneous process but encompassed several pulses of accelerated aridification, with two great pulses at approx- nies of this family (Van Bocxlaer et al, 2009, 2010, and all the nodes involving the Bufo bufo species complex were recovered with the highest possible support (posterior probability of 1) (Supplementary material II).…”

“…Four external calibration points were used, all of them already employed in previous studies to calibrate timescales encompassing the whole family Bufonidae (Pramuk et al, 2007;Van Bocxlaer et al, 2009, 2010, see references therein) (Supplementary material II):…”