Genetic Architecture of Sexual Selection: QTL Mapping of Male Song and Female Receiver Traits in an Acoustic Moth (original) (raw)
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Journal of Evolutionary Biology, 2006
The lek paradox arises when choosy females deplete the genetic variance for male display traits from a population, yet substantial additive genetic variation (V A ) in male traits persists. Thus, the lek paradox can be more generally stated as one of the most fundamental evolutionary questions: What maintains genetic variation in natural populations? One solution to this problem may be found in the condition-dependent nature of many sexually selected traits. Genotype · environment (G · E) interactions can maintain V A under conditions of environmental heterogeneity provided certain restrictions are met, although antagonistic pleiotropy has also been proposed as a mechanism. Here, we provide evidence for G · E interactions and against the role of antagonistic pleiotropy in the maintenance of V A for sexually selected traits. Using inbred lines of the lesser waxmoth Achroia grisella, we measured V A for song attractiveness, condition and development rate under different competitive environments and found that genotypes differed in their plasticity. We argue that variation persists in natural populations because G · E interactions prevent any one variant from producing the optimal phenotype across all environments.
Heredity, 2000
The mating system of Achroia grisella (Lepidoptera: Pyralidae) is characterized by male ultrasonic advertisement signalling to which females orientate. Although males provide no direct, somatic bene®ts to their mates, females prefer males whose signal characters are more exaggerated than the population means. Previous studies showed that the signal characters in¯uencing mate attraction are highly repeatable and heritable. We measured the phenotypic and additive genetic variances (heritability) of female preference in A. grisella, as this additive genetic variance is one of the genetic assumptions of indirect models of sexual selection. We determined the preference index of female A. grisella by repeated phonotaxis trials in which a choice of simulated male signals was presented. These playback experiments showed that female preference indices varied but were repeatable within individuals. Speci®cally, females dier in the relative importance of the several signal characters during mate assessment. A subsequent half-sib breeding design revealed an amount of additive genetic variance for the female preference index (h s 2 0.212, SE 0.1347, P 0.0611; CV A 0.1826). Our study highlights the importance of careful preparation of test signals and experimental design for quantifying individual variation in (female) preference along multiple signal dimensions.
Evolution, 2003
Female response to male advertisement signals in lesser waxmoths showed substantial genetic variation, phenotypic plasticity across rearing environments, and genotype-by-environment interactions resulting in crossing reaction norms. These results represent two previously underemphasized means by which genetic variation may be maintained in sexually selected traits: genetic variation in female response to male traits, and variation in the selection acting on both males and females. Genotype-by-environment interactions and reaction norms that cross indicate that divergent selection may act on male and female sexual traits if the level of environmental change is high. The processes that contribute to the maintenance of genetic variation may thus also contribute to population differentiation.
Naturwissenschaften, 2007
Genetic variability among males is a necessary precondition for the evolution of female choice based on indirect genetic benefits. In addition to mutations and hostparasite cycles, migration of locally adapted individuals offers an explanation for the maintenance of genetic variability. In a previous study, conducting a reciprocal transplant experiment on a grasshopper, Chorthippus biguttulus, we found that environmental conditions significantly influenced not only body condition but also an important trait of male calling song, the amplitude of song. Although not significant, all other analysed physical and courtship song traits and attractiveness were superior in native than in transferred males. Thus, we concluded that local adaptation has a slight but consistent influence on a range of traits in our study populations, including male acoustic attractiveness. In our present study, we scanned male grasshoppers from the same two populations for amplification fragment length polymorphism (AFLP) loci connected with acoustic attractiveness to conspecific females. We found greater differences in allele frequencies between the two populations, for some loci, than are expected from a balance between drift and gene flow. These loci are potentially connected with locally adapted traits. We examined whether these alleles show the proposed genotype environment interaction by having different associations with attractiveness in the two populations. One locus was significantly related to sexual attractiveness; however, this was independent of the males' population affiliation. Future research on the evolution of female choice will benefit from knowledge of the underlying genetic architecture of male traits under intraspecific sexual selection, and the 'population genomics' approach can be a powerful tool for revealing this structure.
Divergent Selection and the Evolution of Signal Traits and Mating Preferences
PLoS Biology, 2005
Mating preferences are common in natural populations, and their divergence among populations is considered an important source of reproductive isolation during speciation. Although mechanisms for the divergence of mating preferences have received substantial theoretical treatment, complementary experimental tests are lacking. We conducted a laboratory evolution experiment, using the fruit fly Drosophila serrata, to explore the role of divergent selection between environments in the evolution of female mating preferences. Replicate populations of D. serrata were derived from a common ancestor and propagated in one of three resource environments: two novel environments and the ancestral laboratory environment. Adaptation to both novel environments involved changes in cuticular hydrocarbons, traits that predict mating success in these populations. Furthermore, female mating preferences for these cuticular hydrocarbons also diverged among populations. A component of this divergence occurred among treatment environments, accounting for at least 17.4% of the among-population divergence in linear mating preferences and 17.2% of the among-population divergence in nonlinear mating preferences. The divergence of mating preferences in correlation with environment is consistent with the classic by-product model of speciation in which premating isolation evolves as a side effect of divergent selection adapting populations to their different environments.
Sexual selection in a moth: effect of symmetry on male mating success in the wild
Behavioral Ecology, 2007
Sexual selection is generally caused by female choice and male-male competition. In female choice process, female preference is favored indirectly and/or directly by sexual selection. In indirect selection, females expressing the preference might gain indirect genetic benefits. In direct selection, females expressing the preference might gain direct benefits or avoid male-imposed costs. The white-tailed zygaenid moth Elcysma westwoodii is monandrous, and males often gather around a female to mate with her, suggesting a high opportunity for sexual selection on male traits. We quantified phenotypic selection on male morphology in this species in the field. The morphological characters analyzed included body weight, antenna length, forewing length, hind wing length, hind wing tail length, genital clasper length, and the fluctuating asymmetry (FA) of these bilateral traits. In E. westwoodii, selection favored males with more symmetric genital claspers, as well as longer and more symmetrical hind wings and antennae. Negative correlations between FA and size were also detected in the clasper and the antenna. Our results suggest that FAs of male traits, in particular the genital clasper, may have indirect and direct influences on mating success. During a copulatory attempt, an E. westwoodii male will try to grasp the female's abdominal tip with his claspers but often fail to do so because of the female's reluctance to mate. The female abdominal tips are smooth and strongly sclerotized and could thus be difficult for males to grasp. We hypothesize that more symmetrical male claspers are more efficient in overcoming female reluctance.
A functional approach to sexual selection
Functional Ecology, 2007
Sexual selection theory is a robust and dynamic field within evolutionary biology, yet despite decades of research, remarkably little is known of the mechanistic bases of mate choice and male competition. 2. Because many aspects of sexual selection involve dynamic movements, and are physically challenging, the limits of sexual selection may be defined by key functional and physiological variables (i.e. the 'functional approach'). 3. We advocate the functional approach for providing mechanistic resolution on the adaptive basis of sexual structures and signals, the nature of mate choice and how males compete, among other issues.
Frequency-Dependent Selection on Female Morphs Driven by Premating Interactions with Males
The American Naturalist, 2015
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Variation in Acoustic Signalling Traits Exhibits Footprints of Sexual Selection
Evolution, 2011
Phenotypic variation is ubiquitous in nature and a precondition for adaptive evolution. However, theory predicts that the extent of phenotypic variation should decrease with increasing strength of selection on a trait. Comparative analyses of trait variability have repeatedly used this expectation to infer the type or strength of selection. Yet, the suggested influence of selection on trait variability has rarely been tested empirically. In the present study, I compare estimates of sexual selection strength and trait variability from published data. I constricted the analysis to acoustic courtship traits in amphibians and insects with known variability and corresponding results of female binary choice experiments on these traits. Trait variability and strength of sexual selection were significantly correlated, and both were correlated with signal duration. Because traits under stronger selection had lower variation even after the effect of signal duration was eliminated, I conclude that traces of the strength of selection can be observed with respect to variation of acoustic signaling traits in insects and amphibians. The analysis also shows that traits under stabilizing selection have significantly lower phenotypic variability than traits under directional selection.