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Behaviour is highly flexible, but does this make it special compared to other types of traits? We review how considering indirect genetic effects—the influence of genes expressed by social partners—can inform behavioural ecology research by improving predictions of behavioural optima in different social, evolutionary and ecological contexts. We argue that this framework is ideal for empirically testing behaviour’s proposed, yet heavily debated, unique role in shaping evolutionary patterns and processes. more...

Modifications in female mate choice resulting from social experience can affect male reproductive success, thereby influencing the evolution of male secondary sexual characters. However, there is little information about how social experience affects different stages of female choice, for example, pre- versus postcopulatory choice, and whether social experience exerts parallel or divergent effects. Using field crickets, we tested 1) how prior experience with males of varying attractiveness modifies females' precopulatory and postcopulatory mate choice during subsequent mating encounters and 2) whether socially mediated changes in precopulatory choice reinforce or oppose changes in postcopulatory choice. We manipulated the attractiveness of males that females experienced by surgically silencing them and playing back artificially constructed courtship songs during preliminary mating trials. This experience, mediated solely by acoustic signals, had long-term effects on both pre- and postcopulatory choice during subsequent mating trials. Experience with an attractive male 24 h earlier caused females to mount subsequent males more slowly and retain their spermatophore for less time, whereas experience with an unattractive male caused females to mount subsequent males faster and retain their spermatophores for longer. Prior experience had a parallel effect on pre- and postcopulatory choice. The perceived attractiveness of previously encountered males, mediated by their courtship song, appears to strongly influence the reproductive success of subsequent males via alterations in pre- and postcopulatory female choice, confirming key predictions of theoretical models of sexual selection and mate choice that incorporate social effects. Copyright 2011, Oxford University Press. more...

Sexual signals consist of multiple components, each of which can contribute to mating decisions. Male field crickets use 2 acoustic signals in the context of mating: a calling song that attracts females from a distance and a courtship song that follows once a female makes physical contact with a male. The function of courtship is unclear because females have already chosen and approached a particular male based on his calling song. Using the field cricket Teleogryllus oceanicus, we tested whether females evaluate the attractiveness of males based on their courtship song irrespective of other male qualities. In a tournament-style assay, females chose males based on elements of their courtship song and preferred males with longer courtship songs that had a higher duty cycle (more sound per unit time). Courtship song was also highly repeatable not only within a bout but also between days in the presence of different females. Additionally, we manipulated the attractiveness of males to females by surgically silencing males and broadcasting playbacks of artificially constructed courtship songs. When we broadcast a preferred song model during courtship by previously nonpreferred males, females showed greater attraction, and vice versa. Courtship song may be particularly important in systems with satellite males that do not produce long-range signals because it gives females their only opportunity to evaluate potential mates. Key words: courtship song, mate choice, multiple signals, repeatability, Teleogryllus oceanicus. [Behav Ecol] more...

Female mate choice is a driving force in the evolution of male secondary sexual characters. It can be dissected into several components: discrimination describes the degree to which females distinguish male trait variation, responsiveness indicates the speed or likelihood of females’ reactions to a mate, and preference functions illustrate how the probability of mating relates to male trait variation. Relatively little is known about how these components interact to produce final mating decisions and influence the strength and direction of sexual selection, so I used female field crickets (Teleogryllus oceanicus) to measure interactions between individual preference functions, discrimination, and 2 measures of responsiveness (number of responses and response effort). Preference function shape varied considerably between individual females. Highly discriminating females showed greater numbers of responses to playbacks and were more likely to have stabilizing preference functions. When I constructed 2 population-level preference functions using either response number or response effort, the first yielded a linear, directional function, whereas the second implied a stabilizing function. The clear differences between the 2 imply that different components of female choice can exert contrasting selection pressure on a single male trait. Overall, both response number and discrimination were mutually reinforcing and likely govern the strength of sexual selection in this population. The direction of selection in a wild setting ultimately depends on the relative importance of response number versus response effort, where exogenous factors such as predation risk or density will determine which component of female choice predominates mating decisions. Key words: choosiness, discrimination, mate choice, preference function, sexual selection, Teleogryllus oceanicus. [Behav Ecol] more...

Behavioral preadaptations can provide an accommodating environment in which novel morphological characters may be selected. A very recent morphological mutation, flatwing, has caused the loss of male song in field crickets (Teleogryllus oceanicus) from the Hawaiian island of Kauai. Previous studies in this and related species have shown that females require male courtship song to mount males, but flatwing T. oceanicus males still achieve matings. Females from Kauai may have a relaxed requirement for male courtship song, or flatwing males may compensate for their inability to sing by altering other courtship behaviors. We tested whether male courtship and female responses to male courtship were preadapted in a way that facilitated the spread of the male wing mutation or if parallel changes in male courtship and female responses accompanied the mutation. We performed mating trials in 2 captive-bred populations to assess how mating behavior varied depending on the presence or absence of courtship song playback. The first was an ancestral population from Kauai established prior to the emergence of the flatwing mutation, and the second was derived from Kauai after the mutation became prevalent. Mating behaviors did not differ qualitatively or quantitatively between the ancestral and current populations, and females from both accepted males for mating in the absence of courtship song. Our results provide direct evidence that a mechanism allowing flatwing males to mate with females was in place before the mutation actually arose on Kauai and demonstrate how preexisting behavior facilitated the rapid spread of a novel morphological mutation. Copyright 2008, Oxford University Press. more...