BIOCHEMICAL SYSTEMATICS AND EVOLUTIONARY RELATIONSHIPS IN THE TRICHONISCUS-PUSILLUS COMPLEX (CRUSTACEA, ISOPODA, ONISCIDEA)

In order to clarify taxonomic and phylogenetic relationships among Tri choniscus pusillus (Isopoda, Oniscidea) populations, allozyme variatio n was studied by means of starch gel electrophoresis. The genetic stru cture of several populations belonging to different subspecies (diploi d bisexual, triploid parthenogenetic; epigean, troglophilic and troglo bitic) was assessed by investigating 10 enzymatic systems correspondin g to 15 putative loci. F-statistics and clustering analysis indicated a high degree of genetic differentiation, corresponding to low levels of gene flow among populations, both epigean and hypogean, still consi dered to be conspecific. Estimates of divergence times calculated from genetic distance data suggest that the pattern of differentiation and the colonization of cave environments may be related to the palaeocli matic change of the Messinian and Plio-Pleistocene glaciations.