ISOLATION MECHANISMS IN CLOSELY RELATED GRASSHOPPER SPECIES CHORTHIPPUS ALBOMARGINATUS AND CH.OSCHEI (ORTHOPTERA: ACRIDIDAE)

V.Yu. Vedenina (1), N.K. Kulygina(2) and A.K. Panyutin (1)

1)Institute for Information Transmission Problems, Russian Academy of Sciences, B. Karetnyi per. 19, Moscow 127994, Russia
2)Moscow State University, Faculty of Biology, Moscow, 119899, Russia


Abstract
Two closely related grasshopper species Chorthippus albomarginatus and Ch. oschei are known to hybridize in the narrow contact zone at the territory of Ukraine and Moldova. We studied different isolation mechanisms providing reproductive isolation between the two species. In choice mating experiments, females of the both species demonstrated a strong assortative mating (80-90 % preference for the conspecific males). Comparison of the parental and hybrid viability revealed a reduced hatching and increased larval mortality in F1 and F2 hybrids. In choice mating experiments, the hybrid females mated less assortatively than the parental females. We found asymmetry in both mating preferences and in viability of hybrids. The results demonstrate the existence of pre- and post-mating isolation between Ch. albomarginatus Ch. oschei. A possible fate of the hybrid zone is discussed.