Pattern of gene flow and genetic divergence in the three Italian species of the cave cricket genus Troglophilus (Orthoptera, Rhaphidophoridae): allozyme data

In this paper, we report data on the levels of genetic differentiation among and gene flow within each of the three species of the cave cricket genus Troglophilus living in Italy. We analyzed genetic variation at 18 enzymatic loci in 12 populations of T. cavicola, 6 populations of T. neglectus and 3 populations of T. andreinii. In particular, populations of T. cavicola and T. neglectus were sampled in overlapping geographical areas, from North-Eastern Italy to Slovenia and Croatia. We found a significant isolation by distance pattern for T. cavicola, indicating that the spatial distribution of genetic heterogeneity is best described by a stepping-stone model. The same does not hold for T. neglectus. Within the three species, the pattern of genetic structuring was mainly related to the limestone structure of the area rather than the availability of epigean routes for dispersal. A calibration for gene flow estimates in cave crickets is provided to discriminate between and current gene flow. This supports previous cave cricket data suggesting that detected gene flow is due to historical rather than current connections among populations.