Comparative phylogeography reveals distinct colonization patterns of C retan snakes

Aim We assessed genetic relationships among populations for each of the four snake species found on C rete ( Z amenis situla , H ierophis gemonensis , T elescopus fallax and N atrix tessellata ), including conspecific populations from the A egean area. Our aim was to reconstruct their phylogeographical histories, especially regarding their occurrence on C rete. Location Crete, A egean S ea and eastern M editerranean. Methods Genetic diversity and relationships were based on sequences of the mitochondrial marker cytochrome b , applying phylogenetic analyses (maximum likelihood, B ayesian inference and neighbour‐joining), a median‐joining network analysis and a molecular dating analysis. Results The Z . situla phylogeny includes a clade with specimens from C rete, the P eloponnese and T hera, while specimens from T urkey, northern G reece and the eastern A egean islands form a separate clade. The H . gemonensis tree also presents two clades: one comprising specimens from C rete and K ythera, and another representing the continental part of the species' distribution. For N . tessellata , C retan populations are found as the sister clade to populations from E urope and western T urkey. A more complex genetic structure is found in T . fallax : specimens from C rete, T hera and A ntikythera form a clade, which itself forms part of a ‘western’ clade, and an ‘eastern’ clade includes specimens from T urkey, the eastern A egean islands and C yprus. The splits resulting in the C retan clades for T . fallax and N . tessellata occurred at the end of the M iocene and the P liocene/ P leistocene boundary, respectively. The C retan lineages of H . gemonensis and Z . situla diversified during the P leistocene. Main conclusions Zamenis situla and H . gemonensis exhibit a phylogeographical pattern that involves a transmarine dispersal from southern continental G reece to C rete (possibly by humans in the case of Z . situla ). The occurrence of T . fallax on C rete is explained by a natural dispersal from the west and isolation by vicariance. Although these two patterns have also been inferred for other studied herptiles of C rete, the pattern in N . tessellata is unique and involves a transmarine dispersal from south‐western T urkey to C rete.