PATTERNS OF MATING BETWEEN 2 CLOSELY-RELATED GROUND CRICKETS ARE NOT INFLUENCED BY SYMPATRY

Allonemobius fascintus (De Geer) and A. socius (Scudder) (Orthoptera: Gryllidae) are small ground-dwelling crickets that meet and hybridize, to a limited extent, in a mosaic contact zone stretching from New Jer sey to at least as far west as Illinois. To determine whether short-ra nge signals such as visual cues, tactile stimulation, or pheromones ar e important in limiting gene flow between A. fasciatus and A. socius w e carried out a study in the laboratory. A male or a female was placed in a cage with an A. fasciatus and A. socius individual of the opposi te sex and the outcome, a conspecific or a heterospecific mating, was recorded, Overall, conspecific matings occurred more frequently than h eterospecific matings. However, individuals from areas of sympatry wer e no more likely to mate with a conspecific than were individuals from areas of allopatry. Thus, the challenge posed by a related species ha s not resulted in a strengthening of positive assortative mating in th ese crickets.