Genetic differentiation between conspecific populations of Merodon avidus A (Diptera, Syrphidae)

Abstract

Allozyme variability of populations of Merodon avidus A (M i l a n - k o v et al., 2001) from Dubasnica Mountain (Serbia), Morinj Bay (Montenegro) and Pindos Mountain (Greece) was analysed. The influence of gene flow on genetic differentiation among populations from the three biogeographical regions was also investigated. Genetic differentiaiton quantified by the Fst value, which is an inverse function of gene flow between populations, seemed to be correlated to both geographic and genetic distance (D, N e i, 1978), Namely in the population pairs Morinj - Dubasnica (253 km air distance), Morinj - Pindos (390km air distance) genetic differentiation and genetic distance increased with the geographic distance (Fst = 0.133, D = 0.022 and Fst = 0.309, D = 0.052, respectively). The exception was the population pair Dubasnica - Pindos (500 km air distance), where a lower degree of genetic differentiation was observed (Fst = 0.266; D = 0.047) than was expected based solely on the geographic distance. Results of this study suggest that that genetic differentiation among conspecific populations depends not only on the number of migrants (i. e. gene flow), but also on different selection pressure in different habits.