Origination and extinction patterns of mammals in three Central Western Mediterranean islands from the Late Miocene to Quaternary.

An overview of the population histories of three insular realms (Gargano palaeo-archipelago, Sardinia–Maritime Tuscany palaeobioprovince and the Sicilian insular complex) during the Late Miocene and Quaternary are here presented. The complexity of biodiversity changes in the islands is analysed to propose an interpretation of origination and extinction patterns. The study highlighted several important aspects of insular faunas. Evolutionary radiations were found to contribute significantly only to the Gargano faunal diversity, likely because the area was an archipelago at the time. Another interesting result is that large and small mammals do not disperse and become extinct all at the same time on each island. In fact, because of their distinct body sizes, large and small mammals have different dispersal ability and therefore different chances to cross-filtering barriers. But distinct body sizes means also different influence on diversity, resistance to environmental changes and likelihood of extinction. Another important point is that large mammalian carnivores at the top of the trophic net are quite more fragile and susceptible to become extinct than other predators. The study finally shows the clear influence that the intense Middle and Late Pleistocene climate-driven environmental changes had on island communities. The reconstruction of the faunal histories of Sardinia and Sicily shows that without exchanges with the mainland the island system represents a rather stable refuge area not too affected by the changes in the ‘‘physical’’ parameters of the environment. In contrast, if the island is frequently connected with the continent, insular faunal assemblages tend to behave as their mainland counterparts.