Population genetic analysis of the endemic Centaurea spp. in Sardinia

Tyrrhenian Islands are one of Mediterranean hotspots. Within the Mediterranean basin the Sardinian-Corsican system shows one of the highest densities of endemic plant species, therefore it is so original in terms of vegetation cover. Limited information is available on the genetic structure of endemic Mediterranean plant species. Several species are known as palaeo-endemics because the island could have played a significant role during the last glacial maximum, and as schizo-endemics because a great number of endemic species could be evolved after the actual separation of Sardinia from the mainland and from Corsica, ended 20,000 years ago. On 347 endemic species 45.8% are exclusive to Sardinia. Among these, five species of the Centaurea genus are present: C. horrida, C. filiformis, C. corensis, C. ferulacea and C. magistrorum. Microendemic vicariants is a term used for groups of endemic plants whose parentage is obvious and which are specially rather than genetically isolated. In these plants, morphological differentiation is usually weak and the groups are not widely separated geographically. Populations have been fragmented into discrete units, and often the morphological differences between taxa, although small, are constant. As some cases of microendemic, presumably schizo-endemic, species are present within the Centaurea genus in western Mediterranean, we would here assess the genetic variability of Sardinian endemic Centaurea species and their taxonomical relationships.