Testing the fisherian mechanism: examining the genetic correlation between male song and female response in waxmoths

Abstract

International audienceModels of indirect (genetic) benefits sexual selection predict linkage disequi-libria between genes that influence male traits and female preferences, owing to either non-random mate choice or physical linkage. Such linkage disequilibria, a genetic correlation, can accelerate the evolution of male traits and female preferences to exaggerated levels. But relatively few empirical studies have measured the genetic correlation between male traits and female responses in natural populations, and the findings of those few are mixed: often, genetic correlations are not found. We tested the above prediction in an acoustic pyralid moth, Achroia grisella, in which males attract females with a rhythmic train of sound pulses, and females respond only to song that exceeds a minimum pulse rhythm. Both male song rhythm and female threshold response are repeatable and heritable characters. Because female choice in A. grisella is based largely on male song, and males do not appear to provide direct benefits at mating, genetic correlation between male song rhythm and female response is expected. We studied 2 A. grisella populations, bred them according to a full-sib/half-sib design, split the progeny among 4 different environmental conditions, and measured the male song/female response genetic correlation in each of the 8 resulting groups. While song rhythm and response threshold were generally heritable, we found no evidence of significant genetic correlation between these traits. We suggest that the complexity of the various male song characters, of female response to male song, and of correlations between male song characters and between aspects of female response have mitigated the evolution of strong genetic correlation between song and response. Thus,exaggerated levels of trait development may be tempered

Genotype-by-Environment Interactions for Female Mate Choice of Male Cuticular Hydrocarbons in Drosophila simulans

“…None of the genetic correlations measured between female preference and male CHC attractiveness were significant across any combination of temperatures, although they were consistently positive, as would be predicted under a Fisherian process. Similar results were also found in a study of the cross-environment genetic covariance between female preference and a male sexual signal in A. grisella [45]. At first glance, this is highly unexpected.…”

Bias in the heritability of preference and its potential impact on the evolution of mate choice

“…To set the variance, we extracted data from the literature on the relative phenotypic variance of preference to the preferred trait. The ratios for the four species for which such data are available (Gryllus texensis, Achroia grisella, Colias eurythem and Ficedula albicollis) were 1.2, 1.63, 0.8 and 1.0, respectively (sources: Gray and Cade, 1999;Zhou et al, 2011;Sappington and Taylor, 1990;Qvarnström et al, 2006). Thus for these four species the phenotypic variance in preference is similar to the variance in the preferred trait.…”

Hemiclonal analysis of interacting phenotypes in male and female Drosophila melanogaster

“…According to predictions of the Fisherian model of sexual selection, a positive genetic correlation between male attractiveness and female choosiness would result in both attractive males and choosey females [2,3,8,12]. While previous empirical tests of genetic correlations between male attractiveness and female choosiness have yielded mixed results (see [6,7,15,34,66]), this is, to the best of our knowledge, the first instance where a negative correlation has been reported. Instead our results show that the production of choosey female genotypes also yields unattractive male genotypes, and vice versa, consistent with sexual conflict theory [40,42,67].…”

“…To our knowledge, no previous study has examined female choosiness (the degree to which females discriminate among potential mates), female responsiveness (the likelihood a female will respond to a potential mate), and maternal investment patterns while simultaneously varying both male and female genetic identity. Additionally, studies examining the genetic covariance between female choosiness and male attractiveness are mixed; some have found a transient positive correlation that disappears after one generation of random mating [6,13,32], others have found no correlation at all [15,33,34]. While the prediction of a positive genetic correlation between male attractiveness and female choosiness is a central element of Fisherian runaway selection [10] it is not essential to other models of sexual selection.…”