Inbreeding and Advertisement Calling in the Cricket Teleogryllus Commodus: Laboratory and Field Experiments

Abstract

If sexually selected traits reveal a male's heterozygosity or condition to females, then such traits should exhibit declines with inbreeding. We tested this by examining the effect of inbreeding on advertisement calling in male crickets Teleogryllus commodus.We investigated the effect of one generation of full-sibling mating on calling effort and fine-scale call structure. Inbreeding reduced calling effort but had no effect on call structure. We then compared the attractiveness of inbred and outbred calls in the field by monitoring how many wild females were attracted to each call type. From the field data, we conducted a selection analysis to identify the major axes of linear and nonlinear multivariate sexual selection on call structure. A comparison of multivariate attractiveness of inbred and outbred calls along each major axis of selection revealed no difference in attractiveness. Our results suggest that inbred male calls have a fine-scale structure that is no less attractive to females than that of outbred calls. However, because inbred males call less often, and female T. commodus prefer males with a higher calling effort, inbred males will suffer reductions in mating success. Females who base mate choice on call rate are therefore using a signal correlated with male heterozygosity and/or condition. K E Y W O R D S :Call structure, calling effort, heterozygosity, male attractiveness, selection analysis, sexual selection.

Inbreeding affects sexual signalling in males but not females of Tenebrio molitor

“…In contrast to vertebrates, experimental tests of the effect of inbreeding and heterozygosity on sexual signalling in insects are scarce. However, Drayton et al [17] found that inbreeding reduced the calling effort of the cricket, Teleogryllus commodus, affecting the mating success of inbred males negatively. Similarly, inbreeding in Drosophila montana decreased the frequency of courtship song frequency associated with male's courtship success [18].…”

Sexual Signaling and Immune Function in the Black Field Cricket Teleogryllus commodus

“…Males who call more are more attractive to females [36]. Finally, we have already shown that inbreeding between full siblings affects both immune function [49] and male calling [39], [40], [44]. Inbreeding might therefore decrease the reliability of male calling as a signal of immune function by, for example, disrupting the usual proximate mechanism that determines the appropriate allocation of resources to calling and immune function.…”

“…Furthermore, dietary manipulation has shown that advertisement calling effort is affected by nutrition [37], [38]. Importantly, inbreeding reduces advertisement calling effort [39] and alters fine scale advertisement call structure [40], indicating that both call effort and call structure might signal male fitness (given that inbreeding lowers fitness). It is therefore possible that advertisement calls signal key fitness components such as disease resistance.…”

The scent of inbreeding: a male sex pheromone betrays inbred males

“…In this regard, females of the cricket Teleogryllus commodus detect and reject inbred males based on the reduced acoustic signals that they produce compared with outbred males [16,17]. In other case studies, females detect the genetic quality [18 -21] or the heterozygosity level [22] of their potential mating partners through the assessment of their olfactory cues.…”