BIOCHEMICAL SYSTEMATICS AND PHYLOGEOGRAPHY OF THE PERCUS STRICTUS SUBSPECIES (COLEOPTERA, CARABIDAE), ENDEMIC TO SARDINIA

Allozymic variation at 14 loci was studied in six Sardinian populations of the carabid beetle Percus strictus. These populations represent the four subspecies of P. strictus recognised on morphological grounds in the island. Clustering and multivariate analyses were able to discriminate different subspecies, supporting the morphological evidence. Genetic distance data and F-statistics analysis indicated a certain degree of isolation among subspecies, but not high enough to propose the splitting of the polytypic P. strictus into different species. From molecular clock and geological data, it is inferred that the major differentiation events were due to vicariance and took place at the beginning of the Pliocene, in concomitance with sea introgressions that subdivided the island into different blocks roughly corresponding to the present ranges of the different subspecies.