DIVERGENCE IN MATE FINDING BEHAVIOR BETWEEN 2 SUBSPECIES OF THE MEADOW GRASSHOPPER CHORTHIPPUS-PARALLELUS (ORTHOPTERA, ACRIDIDAE)

Two parapatric subspecies of the grasshopper Chorthippus parallelus fo rm a hybrid zone in the Pyrenees. Partial assortative mating between s ubspecies must result from differences in elements of the sequence of behaviors that leads to mating. It was already known that the subspeci es differ in the structure of the acoustic mating signal produced by m ales and in the amount of song produced under laboratory conditions. H ere we investigate whether any differences exist in male mating strate gies in the field, concentrating on the prediction that male C. p. ery thropus sing less and compensate for this by active searching (males d ivide their time between singing and moving in search of females). Res ults of field observations show that the two subspecies do in fact all ocate their time differently. C. p. erythropus males spend almost twic e as much time moving around the habitat as C. p. parallelus males Fur thermore, C. p. parallelus males divide their time into long bouts of continuous singing alternating with periods of movement. C. p. erythro pus males, on the other hand, sing in short bursts interspersed with m ovement. The possible reasons for this divergence in male mating behav ior and its consequences are discussed.