Patterns of genetic differentiation and gene flow in Central Italian populations of Dinocras cephalotes (CURTIS, 1827) (Insecta, Plecoptera)

Dispersal is a crucial phenomenon which has a strong influence on the ecolo gy and evolution of species, determining the extent of gene flow among cons pecific populations. In this paper, we present data on the degree of geneti c structuring in 11 populations of the stonefly Dinocras cephalotes, focusi ng our attention on three Central Italian rivers: Aniene, Nera and Velino. We studied the genetic variation at 28 enzymatic loci by means of starch ge l electrophoresis: 19 loci were polymorphic in one population at least. The degree of genetic structuring and levels of gene flow were estimated by F- statistics using WEIR & COCKERHAM'S estimators. Relatively high levels of g enetic differentiation were revealed, considerably higher than those obtain ed in other studies of stonefly species. Neighbour-joining analysis provide d a geographic scheme of relationships of the study populations, grouping t hem according to the river of origin. This analysis was supported by bootst rap values. We were not able to detect an unequivocal relationship between gene flow and geographic distances between sites within each river; this le d us to hypothesise that equilibrium has not been reached between genetic d rift and gene flow.