Abstract: Aim: to understand the role of climate in fostering diversification, this study reconstructs the historical biogeography of Western Mediterranean vipers

Location: Western Mediterranean Basin

Taxon: Vipera aspis and V. latastei-monticola complex

Methods: phylogeographic analyses were performed over mitochondrial (three genes) and nuclear sequences (two genes), extensively covering species ranges. A total of 4,056 records were assigned to genetic units, using interpolations of genetic data, to test phylogenetic niche conservatism, under a 3D hypervolume approach, and to perform paleoclimatic reconstructions for main lineages that diversified during the Pleistocene.

Results: Bayesian inferences based on mtDNA recovered three Miocene clades and nine Pliocene lineages that distinctly diversified during the Pleistocene. Diversification until late Pliocene was mostly restricted to southern regions of Iberian and Italian Peninsulas, and north-western African mountains, expanding northwards during the Pleistocene. Accordingly, genetic diversity was higher in southern regions. Ecological niche tests support a general mode of allopatric diversification with niche conservatism, although niche shift was found for two divergence events. Paleoclimatic models identified particular requirements for the distribution of main lineages and distinct responses to the cooling and warm events of the Pleistocene. Areas of climatic stability during Pleistocene were identified for main lineages; however, climatic stability was weakly correlated to haplotype diversity.

Main conclusions: our integrative approach enhances the understanding of the evolutionary and ecological dynamics occurred in the Western Mediterranean region, evidencing the paleo-tectonic and -climatic factors driving diversification since the Miocene in this biodiversity hotspot. Comparisons among patterns of diversification, haplotype diversity and climatic stability suggest that southern Iberian and Italian Peninsulas, and North-West African Mountains acted as refugia since the Pliocene, while some northern areas favoured population persistence during the Pleistocene.

Alignments of sequences (in fasta format) for 5 markers, 3 mithocondrial (cytochrome b, Cytb; and NADH dehydrogenase subunits 2, ND2, and 4, ND4) and 2 nuclear (prolactin receptor, PRLR; Neurotoxin-3, NT3). Sequences, and data for each one, are available on GenBank.

Occurrence data for V. aspis (VAS), V. latastei in Iberian Peninsula (VLA_Iberia) and V. latastei in North Africa [V. monticola included] (VLA_North-Africa). Data were retrieved from fieldwork, museum collections, publications and herpetological societies’ databases (including AHE, Spain; SHF, France; info fauna - karch, Switzerland). Occurrence data were processed at 5x5 km resolution in WGS84.