Sexual selection on cuticular hydrocarbons in the Australian field cricket, Teleogryllus oceanicus

Abstract

BackgroundFemales in a wide range of taxa have been shown to base their choice of mates on pheromone signals. However, little research has focussed specifically on the form and intensity of selection that mate choice imposes on the pheromone signal. Using multivariate selection analysis, we characterise directly the form and intensity of sexual selection acting on cuticular hydrocarbons, chemical compounds widely used in the selection of mates in insects. Using the Australian field cricket Teleogryllus oceanicus as a model organism, we use three measures of male attractiveness to estimate fitness; mating success, the duration of courtship required to elicit copulation, and subsequent spermatophore attachment duration.ResultsWe found that all three measures of male attractiveness generated sexual selection on male cuticular hydrocarbons, however there were differences in the form and intensity of selection among these three measures. Mating success was the only measure of attractiveness that imposed both univariate linear and quadratic selection on cuticular hydrocarbons. Although we found that all three attractiveness measures generated nonlinear selection, again only mating success was found to exert statistically significant stabilizing selection.ConclusionThis study shows that sexual selection plays an important role in the evolution of male cuticular hydrocarbon signals.

Sexual selection on cuticular hydrocarbons of male sagebrush crickets in the wild

“…The complex pattern of multivariate nonlinear selection that emerged was characterized primarily by strong stabilizing and disruptive selection on male CHCs, resulting in a saddle-shaped fitness surface. Such a fitness surface seems characteristic of the majority of laboratory studies measuring multivariate sexual selection in male crickets, including male song traits [24], cuticular hydrocarbons [8], morphological characters [42] and the chemical composition of males' nuptial food gifts [43], and a similar pattern has emerged in studies of other insects [44,45]. Many of these sexual signals are known to impose significant energy costs on males, and thus may serve as honest indicators of male quality [46].…”

“…However, a growing body of evidence suggests that male chemical signals in the form of CHCs can have a profound influence on female mating preferences even after pair formation has occurred [7,8,57,58]. Most evidence to date has been based on laboratory observation and the dearth of studies in wild populations is almost certainly a consequence of the difficulty in measuring male mating success under natural conditions.…”

“…More recently, there has been a growing appreciation that the evolution of these compounds may be shaped by sexual selection arising through female mating preferences. The form and intensity of sexual selection on cuticular hydrocarbons (CHCs) have been studied extensively but, with the exception of a single study of field crickets [8], only in Drosophila [9,10] and never in the wild. Little is known about the role of sexual selection in shaping CHC profiles in natural populations.…”

Short-term phenotypic plasticity in long-chain cuticular hydrocarbons

“…Although males cannot force copulations, dominance status does determine a male's ability to attract females via acoustic signals; dominant males will produce calling and/or courtship songs in the presence of subordinate males, whereas subordinate males are suppressed in their courtship song through intermittent attacks by the nearby dominant male [15]. Subordinate males appear to compensate for this disadvantage by displaying a relatively larger proportion of certain cuticular hydrocarbons that have previously been shown to increase male attractiveness to females [16]. Here, we determine if differences in cuticular hydrocarbon profiles between dominant and subordinate T. oceanicus males are fixed, or whether they can display different cuticular hydrocarbon phenotypes depending on the social environment (phenotypic plasticity), in this case a change in social status.…”

Chemically moderated gamete preferences predict offspring fitness in a broadcast spawning invertebrate

“…For example, chemical signals can provide information about the location of prospective mates as well as their intrinsic quality in a manner analogous to auditory or visual displays [3][4][5]. Furthermore, they can be used to communicate information about genetic compatibility [6], allowing selection for mates whose particular genotype is matched to the choosing sex to produce adaptive gene combinations in offspring [7].…”