Pattern of genetic differentiation in two Isophya species (Orthoptera: Tettigonoidea) in north-east Hungary

Allozyme polymorphism was studied in two populations of Isophya kraussi and Isophya stysi. Both species are flightless and have low dispersal ability. As a consequence, we expected high level of genetic differentiation among their local populations. Samples were collected in three regions of Hungary. Enzyme polymorphism was investigated at 10 loci (Aldox, Est, Got, Gpdh, Hk, Idh, Mdh, Me, Pgi and Pgm) in both species. High levels of polymorphism were detected in all samples. Gpdh proved to be diagnostic as there were no common alleles in the two species. At four further loci (Got, Hk, Mdh and Me), the two species had one common allele together with one or more differentiating alleles. We detected high F_IT values implying a high level of genetic variation. The positive F_IS values suggested a tendency of heterozygote deficiency in both species. The highly significant overall F_ST values indicated clear genetic differentiation among the local populations. Thus our results confirmed the taxonomic status of these two species. The dendrogram constructed on the basis of Nei's genetic distances and the results of the PCA analyses fully confirmed those obtained by F-statistics.