Mitochondrial phylogeography, contact zones and taxonomy of grass snakes (Natrix natrix,N. megalocephala)

Abstract

Grass snakes (Natrix natrix) represent one of the most widely distributed snake species of the Palaearctic region, ranging from the North African Maghreb region and the Iberian Peninsula through most of Europe and western Asia eastward to the region of Lake Baikal in Central Asia. Within N. natrix, up to 14 distinct subspecies are regarded as valid. In addition, some authors recognize big‐headed grass snakes from western Transcaucasia as a distinct species, N. megalocephala. Based on phylogenetic analyses of a 1984‐bp‐long alignment of mtDNA sequences (ND4+tRNAs, cyt b) of 410 grass snakes, a nearly range‐wide phylogeography is presented for both species. Within N. natrix, 16 terminal mitochondrial clades were identified, most of which conflict with morphologically defined subspecies. These 16 clades correspond to three more inclusive clades from (i) the Iberian Peninsula plus North Africa, (ii) East Europe and Asia and (iii) West Europe including Corso‐Sardinia, the Apennine Peninsula and Sicily. Hypotheses regarding glacial refugia and postglacial range expansions are presented. Refugia were most likely located in each of the southern European peninsulas, Corso‐Sardinia, North Africa, Anatolia and the neighbouring Near and Middle East, where the greatest extant genetic diversity occurs. Multiple distinct microrefugia are inferred for continental Italy plus Sicily, the Balkan Peninsula, Anatolia and the Near and Middle East. Holocene range expansions led to the colonization of more northerly regions and the formation of secondary contact zones. Western Europe was invaded from a refuge within southern France, while Central Europe was reached by two distinct range expansions from the Balkan Peninsula. In Central Europe, there are two contact zones of three distinct mitochondrial clades, and one of these contact zones was theretofore completely unknown. Another contact zone is hypothesized for Eastern Europe, which was colonized, like north‐western Asia, from the Caucasus region. Further contact zones were identified for southern Italy, the Balkans and Transcaucasia. In agreement with previous studies using morphological characters and allozymes, there is no evidence for the distinctiveness of N. megalocephala. Therefore, N. megalocephala is synonymized with N. natrix.

Trapped by climate: interglacial refuge and recent population expansion in the endemic Iberian adder Vipera seoanei

“…While thermophilic species retreated and lost habitat during glacial periods (e.g. Hewitt, 1999;Garcia-Porta et al, 2012;Kindler et al, 2013), cold temperate species expanded their distributional ranges, potentially connecting populations with the increase of suitable habitats (e.g. Fedorov et al, 2003;Kropf et al, 2003;Bannikova et al, 2010;Velo-Ant on et al, 2013).…”

Distribution and hybridization of Anguis fragilis and A. colchica in Hungary

“…This hybrid zone lies at the meeting point of the two taxa with long independent evolutionary history recolonizing Europe from different glacial refugia. Anguis fragilis might have expanded to western Europe from a glacial refugium located in the north-western Balkans (Gvozdik et al, 2010) similarly to Natrix natrix lineage 3 (Kindler et al, 2013), while A. colchica populations most probably survived the last glaciations in southern Caspian, Caucasian, and presumably Carpathian refugia, recolonizing Eastern and Northern Europe (Gvozdik et al, 2010). This pattem is similar to expansion of Emys orbicularis lineage II presented by Fritz et al (2007).…”

Phylogeography of grass snakes (Natrix natrix) all around the Baltic Sea: implications for the Holocene colonization of Fennoscandia

“…1). Using mito chondrial DNA sequences, Kindler et al (2013) demonstrated that grass snakes are genetically much differentiated. However, the current sub species classification does not match genetic differentiation and needs revision.…”