INDIRECT METHODS TO ESTIMATE GENE FLOW IN CAVE AND SURFACE POPULATIONS OF ANDRONISCUS DENTIGER (ISOPODA: ONISCIDEA)

We estimateci gene flow among several populations of the troglophilic woodlouse Androniscus dentiger from central Italy using allozyme data. Estimates of gene flow were obtained from G_ST , θ, and the private alleles method, after being tested whether the assumption of the population genetic model and the assumption of neutrality of alleles had been met. Hierarchical analysis of gene flow has been used to investigate the geographic scale at which gene exchange can actually occur. Results showed that, independent of the methods, no ongoing gene flow can be detected among populations, even among geographically proximate ones. Genetic drift is likely the main agent shaping the pattern of genetic divergence among these populations. Patterns of past and ongoing gene flow were considered, as surface populations have become genetically isolated more recently than cave populations. In general, all three methods to estimate gene flow provided Nm estimates of the same magnitude.