Winter is coming: Miocene and Quaternary climatic shifts shaped the diversification of Western-Mediterranean Harpactocrates (Araneae, Dysderidae) spiders.

Past climatic shifts have played a major role in generating and shaping biodiversity. Quaternary glacial cycles are the better known examples of dramatic climatic changes endured by ecosystems in temperate regions. Although still a matter of debate, some authors suggest that glaciations promoted speciation. Here we investigate the effect of past climatic changes on the diversification of the ground-dwelling spider genus Harpactocrates, distributed across the major mountain ranges of the western Mediterranean. Concatenated and species-tree analyses of multiple mitochondrial and nuclear loci, combined with the use of fossil and biogeographic calibration points, reveal a Miocene origin of most nominal species, but also unravel several cryptic lineages tracing back to the Pleistocene. We hypothesize that the Miocene Climatic Transition triggered major extinction events in the genus but also promoted its subsequent diversification. Under this scenario, the Iberian mountains acted as an island-like system, providing shelter to Harpactocrates lineages during the climate shifts and favouring isolation between mountain ranges. Quaternary glacial cycles contributed further to the diversification of the group by isolating lineages in peripheral refugia within mountain ranges. In addition, we recovered some unique biogeographic patterns, such as the colonization of the Alps and the Apennines from the Iberian Peninsula.