A conceptual review of mate choice: stochastic demography, within‐sex phenotypic plasticity, and individual flexibility

Abstract

Mate choice hypotheses usually focus on trait variation of chosen individuals. Recently, mate choice studies have increasingly attended to the environmental circumstances affecting variation in choosers' behavior and choosers' traits. We reviewed the literature on phenotypic plasticity in mate choice with the goal of exploring whether phenotypic plasticity can be interpreted as individual flexibility in the context of the switch point theorem, SPT (Gowaty and Hubbell 2009). We found >3000 studies; 198 were empirical studies of within‐sex phenotypic plasticity, and sixteen showed no evidence of mate choice plasticity. Most studies reported changes from choosy to indiscriminate behavior of subjects. Investigators attributed changes to one or more causes including operational sex ratio, adult sex ratio, potential reproductive rate, predation risk, disease risk, chooser's mating experience, chooser's age, chooser's condition, or chooser's resources. The studies together indicate that “choosiness” of potential mates is environmentally and socially labile, that is, induced – not fixed – in “the choosy sex” with results consistent with choosers' intrinsic characteristics or their ecological circumstances mattering more to mate choice than the traits of potential mates. We show that plasticity‐associated variables factor into the simpler SPT variables. We propose that it is time to complete the move from questions about within‐sex plasticity in the choosy sex to between‐ and within‐individual flexibility in reproductive decision‐making of both sexes simultaneously. Currently, unanswered empirical questions are about the force of alternative constraints and opportunities as inducers of individual flexibility in reproductive decision‐making, and the ecological, social, and developmental sources of similarities and differences between individuals. To make progress, we need studies (1) of simultaneous and symmetric attention to individual mate preferences and subsequent behavior in both sexes, (2) controlled for within‐individual variation in choice behavior as demography changes, and which (3) report effects on fitness from movement of individual's switch points.

What is driving male mate preference evolution in Jamaican field crickets?

“…Smaller females may be more willing to oviposit their eggs when they are not allowed to choose their mate, while larger females may limit their egg oviposition while they await future mating opportunities. This negative trend that smaller G. assimilis females oviposit more eggs than larger females also supports the argument that variation in reproductive decisions depends on intrinsic variation of female crickets' social and ecological situation (reviewed in Ah‐King & Gowaty, ).…”

Causes and Consequences of Behavioral Interference between Species

“…While costly interspecific interactions favor innate recognition mechanisms [96] and greater variation in the frequency or intensity of interactions favor learning [97], most recognition systems likely comprise varying degrees of both components [88]. Finally, learning that increases assortative mating between partially diverged populations can contribute to speciation [90,93,96,98], whereas learning that contributes to stochasticity in mate choice would erode assortative mating and promote gene flow that could limit adaptive divergence and speciation, such as might occur when mate choice is flexible [99]. [1,8].…”

Influence of the operational sex ratio on mutual mate choice in the Jamaican field cricket (Gryllus assimilis): Testing the predictions of the switch point theorem

“…In a recent review of the switch point theorem, Ah‐King and Gowaty () tested its predictions by assessing whether individuals exhibit static or flexible mating behaviour under demographic stochasticity. Their findings reveal that animals generally exhibit adaptively flexible mating behaviour, as 92% (182/198) of the reviewed studies that incorporated demographic changes in conditions (e.g., OSR, predation risk, disease exposure, potential reproductive rate, mating experience, age, condition or resources) reported flexible mating behaviour (Ah‐King & Gowaty, ). Ah‐King and Gowaty’s () review concludes that an individual’s mate choice behaviour is more dependent on its own intrinsic characteristics and its ecological circumstances than on the exaggerated sexually selected traits of potential mates.…”

“…Their findings reveal that animals generally exhibit adaptively flexible mating behaviour, as 92% (182/198) of the reviewed studies that incorporated demographic changes in conditions (e.g., OSR, predation risk, disease exposure, potential reproductive rate, mating experience, age, condition or resources) reported flexible mating behaviour (Ah‐King & Gowaty, ). Ah‐King and Gowaty’s () review concludes that an individual’s mate choice behaviour is more dependent on its own intrinsic characteristics and its ecological circumstances than on the exaggerated sexually selected traits of potential mates. Here, the intrinsic characteristics of individuals that influenced whether they exhibited static or flexible mating behaviour included their age, size, condition, diet, parasite load, predation risk, previous mating experience and sexual attractiveness (see Table in Ah‐King and Gowaty, for detailed examples).…”

“…Ah‐King and Gowaty’s () review concludes that an individual’s mate choice behaviour is more dependent on its own intrinsic characteristics and its ecological circumstances than on the exaggerated sexually selected traits of potential mates. Here, the intrinsic characteristics of individuals that influenced whether they exhibited static or flexible mating behaviour included their age, size, condition, diet, parasite load, predation risk, previous mating experience and sexual attractiveness (see Table in Ah‐King and Gowaty, for detailed examples). Unfortunately, Ah‐King and Gowaty () were only able to confidently reach conclusions about the sex that typically displays discriminate mating behaviour, as far less research has been completed on the sex that typically displays indiscriminate mating behaviour.…”