Rapid evolutionary change in a sexual signal: genetic control of the mutation ‘flatwing’ that renders male field crickets (Teleogryllus oceanicus) mute

Abstract

Colonizing events may expose organisms to physical and ecological environments found nowhere else in their range. Novel selection pressures can then influence subsequent rapid evolutionary changes. Here, I investigate the genetics of one such rapid change in the sexual signal of Polynesian field crickets, Teleogryllus oceanicus, that recently colonized the Hawaiian Islands. In Hawaii, T. oceanicus encounter a deadly parasitoid fly found nowhere else in their range. In o20 generations, a wing mutation, flatwing, that eliminates the crickets' song, an important sexual signal, but protects them from the fly, spread to 490% of males on the island of Kauai. I show, using crosses between flatwing males and females from a population that has never contained flatwings, that the song-suppressing mutation is due to a change in a single sex-linked locus. Contemporary evolution of secondary sexual characteristics has only rarely been identified as the result of single-gene changes and never before as a single sex-linked locus, but sex-linked inheritance is thought to facilitate the rapid evolution of these types of traits. Because divergence of sexual signals can influence reproductive isolation, understanding how colonization events and subsequent selection affect signals, and the genetic mechanisms of such change, can shed light on processes likely to play a role in speciation.

Acoustic experience shapes female mate choice in field crickets

“…In fewer than 5 years (approx. 16-20 generations), over 90 per cent of male crickets on Kauai now exhibit a flatwing morphology that renders them mute (Zuk et al 2006;Tinghitella 2008). Lacking the wing structures normally used to produce sound, these males appear to adopt a satellite strategy by intercepting females responding to the few remaining callers (Cade 1980;Zuk et al 2006).…”

Alteration of sex-related developmental modules: A case of "feminized" male wing morphology in Creobroter gemmatus (Mantodea: Hymenopodidae)

“…Such an alteration could be of modular origin, as it occurred independently of other factors (sex in this case) and affected similar areas of different organs (Schlosser & Wagner, 2004b). Comparison with T. oceanicus is relevant, as an alteration at a single locus results in the suppression of a set of structures involved in song production (Tinghitella, 2008), which possibly constitute a single module. Interestingly the hind wing remigium of specimen IWC OB 128 is not altered: it is devoid of the dark pink coloration typical of females.…”

Host behaviour–parasite feedback: an essential link between animal behaviour and disease ecology

“…A few years later, cricket density rebounded, but almost all the males had female-like wings that made them incapable of producing song. Now, silent males compensate for their inability to produce mating calls by showing greater 'satellite' behaviour; they aggregate around the few remaining singing males, which brings them into close proximity of potential mates [39,40]. Recent work also points to parasite-induced selection on other aspects of male mating behaviour, including locomotory behaviours that enhance the encounter rate of silent males with females [41].…”