Meeting Abstract
Male field crickets typically produce a long distance calling song to attract females. In response to selective pressure by an acoustically orienting parasitoid fly, however, a wing mutation has arisen on the islands of Kauai and Oahu that renders >90% and 50% of male Teleogryllus oceanicus silent respectively. Such silent males avoid parasitization but are unable to attract females. We hypothesized that on Kauai pressure to locate females when calling males are rare has selected for males who are phonotactic towards conspecific male song because it increases their likelihood of intercepting females attracted to the calling male. Individuals from Kauai, Oahu, and Mangaia, a Cook Islands population without the silent mutation, either were or were not exposed to calling song during development. Satellite assays showed the males originating from Kauai and reared in silence moved closer to the speaker and spent more time engaged in satellite behavior than did their counterparts reared with calling song. Males from Oahu and Mangaia, however, showed no such effect of acoustic rearing environment on these behaviors. This suggests that there has been directional selection on Kauai for males that respond to reduced calling song in their environment with increased phonotaxis, thus compensating for their lack of song and increasing the chance of intercepting receptive females. We previously found a similar pattern when studying wandering behavior, suggesting that males from Kauai, but not Oahu and Mangaia, that increase their investment in alternative mating tactics when reared in the absence of conspecific song are under positive selection.
