Preexisting behavior facilitated the loss of a sexual signal in the field cricket Teleogryllus oceanicus

Behavioral preadaptations can provide an accommodating environmentin which novel morphological characters may be selected. A veryrecent morphological mutation, flatwing, has caused the lossof male song in field crickets (Teleogryllus oceanicus) fromthe Hawaiian island of Kauai. Previous studies in this and relatedspecies have shown that females require male courtship songto mount males, but flatwing T. oceanicus males still achievematings. Females from Kauai may have a relaxed requirement formale courtship song, or flatwing males may compensate for theirinability to sing by altering other courtship behaviors. Wetested whether male courtship and female responses to male courtshipwere preadapted in a way that facilitated the spread of themale wing mutation or if parallel changes in male courtshipand female responses accompanied the mutation. We performedmating trials in 2 captive-bred populations to assess how matingbehavior varied depending on the presence or absence of courtshipsong playback. The first was an ancestral population from Kauaiestablished prior to the emergence of the flatwing mutation,and the second was derived from Kauai after the mutation becameprevalent. Mating behaviors did not differ qualitatively orquantitatively between the ancestral and current populations,and females from both accepted males for mating in the absenceof courtship song. Our results provide direct evidence thata mechanism allowing flatwing males to mate with females wasin place before the mutation actually arose on Kauai and demonstratehow preexisting behavior facilitated the rapid spread of a novelmorphological mutation.