Preliminary genetic characterisation of Southern Smooth Snake Coronella girondica (Serpentes, Colubridae) populations in Italy, with some considerations on their alpine distribution

Abstract

The Southern smooth snake, Coronella girondica, is a small-sized colubrid found in Northwest Africa and Southwest Europe. Mitochondrial DNA-based studies showed that the species can be split into five clades: two from Northwest Africa (one Moroccan and one Tunisian-Algerian) and three from Europe (one in the south-west of the Iberian Peninsula, one in the south-east of Spain and one in the rest of the European range). With regards to Italy, to date, only two samples have been analysed both from the Province of Pisa, Tuscany, pointing at that fact that genetic characterisation of Italian populations is still lacking. Accordingly, we have increased the sampling coverage with 19 new samples from northern and central regions of Italy, including two populations, apparently disconnected from the rest of the known range, and analysed their phylogenetic relationships using a portion of the mitochondrial cytochrome b gene. Our results confirm the general phylogenetic arrangement detected in previous studies; specifically for Italian populations, no variability emerged from the Apennine populations, and a slight differentiation could be shown for the Alpine and subalpine ones. This pattern can be explained assuming past spread and recent isolation of C. girondica relict populations in the Alpine region, likely during the Last Glacial Maximum. Later, during the Holocene, the Italian Alps and the Po Plain went through various climatic variations and high anthropization which may have influenced C. girondica distribution through expansion and contraction processes.