Messinian Salinity Crisis and Quaternary glacial events shaped genetic diversification in Siculo-Maghrebian blister beetles (Coleoptera: Meloidae)

Three non-phoretic blister-beetle species (Mylabris schreibersi, Actenodia distincta and Cabalia segetum) were investigated to trace their Siculo-Maghrebian biogeographic origins and to understand how Tertiary and Quaternary paleogeographic events (e.g. the ‘Messinian Salinity Crisis’ and the cyclic Quaternary glacio-eustatic marine oscillations) shaped their phylogeographic patterns. Data from CAD and RpP01 nuclear genes highlighted a clear lineage sorting between Sicilian and Maghrebian populations of M. schreibersi, explainable by a vicariance event likely occurred after the ‘Messinian Salinity Crisis’. A less marked – but still noticeable – genetic distinction among Sicilian and Maghrebian populations of A. distincta and C. segetum was observed, which could be more referable to moderately old (during Pliocene or late Quaternary) dispersal events. In addition, the low genetic variability and lack of population structure found in Sicily for the three blister-beetle species suggest some drastic reduction in size of Sicilian populations during Pleistocene glacial phases. In general, our results on Meloidae beetles are consistent with published literature, indicating that vicariance or dispersal scenarios can be both plausible explanations of the Siculo-Maghrebian distribution currently observed in a number of animal and plant species.