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

Behavioral preadaptations can provide an accommodating environment in which novel morphological characters may be selected. A very recent morphological mutation, flatwing, has caused the loss of male song in field crickets (Teleogryllus oceanicus) from the Hawaiian island of Kauai. Previous studies in this and related species have shown that females require male courtship song to mount males, but flatwing T. oceanicus males still achieve matings. Females from Kauai may have a relaxed requirement for male courtship song, or flatwing males may compensate for their inability to sing by altering other courtship behaviors. We tested whether male courtship and female responses to male courtship were preadapted in a way that facilitated the spread of the male wing mutation or if parallel changes in male courtship and female responses accompanied the mutation. We performed mating trials in 2 captive-bred populations to assess how mating behavior varied depending on the presence or absence of courtship song playback. The first was an ancestral population from Kauai established prior to the emergence of the flatwing mutation, and the second was derived from Kauai after the mutation became prevalent. Mating behaviors did not differ qualitatively or quantitatively between the ancestral and current populations, and females from both accepted males for mating in the absence of courtship song. Our results provide direct evidence that a mechanism allowing flatwing males to mate with females was in place before the mutation actually arose on Kauai and demonstrate how preexisting behavior facilitated the rapid spread of a novel morphological mutation.