Genetic divergence between populations and species of talitrids from Aegean Islands

Abstract

Allozymic variation was studied in one population of Orchestia gammarellus, five populations of O. montagui, six populations of Talitrus saltator, and one population of Talorchestia deshayesii collected on five small islands around the Aegean Sea. Twenty loci were analyzed. Low levels of genetic variability (H̄(o)) were found with some differences between populations (0.005 < H̄(o) < 0.063). Interspecific values of Nei's genetic distance (D) ranged from 0.594 to 1.791, while the intraspecific measures of D were of a different level within O. montagui and T. saltator (0.001 and 0.042, respectively). In O. montagui and T. saltator, the allozymic data were also used to compare estimates of gene flow (N(m)) obtained by F(ST) parameters calculated with the methods of Nei and Chesser and Weir and Cockerham. The estimates of the two approaches were very similar. Measures of variance for each of these indices were obtained by the two resampling techniques of bootstrapping and jack-knifing. Gene flow levels were generally high (N(m) >> 1) within O. montagui, but were generally low (N(m) < 1) within T. saltator. The estimates of gene flow are discussed with regard to the dispersal capabilities of Talltridae.