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

Abstract

The switch point theorem posits that both sexes should exhibit behavioural flexibility, switching between discriminant and indiscriminate mating, as their perceived demographic conditions change. The theorem also predicts that an individual’s mate choice should be more dependent on its own intrinsic characteristics and ecological conditions than on the exaggerated sexually selected traits possessed by potential mates. To test these predictions, we manipulated the operational sex ratio (OSR), a demographic factor, of adult Jamaican field crickets (Gryllus assimilis) under controlled laboratory conditions and evaluated whether the mate choices of females and males were influenced by their social environment, their own body size and the difference in the body size of available potential mates. Body size is under sexual selection in this species, with females preferring larger males and larger males exhibiting repeatable mate choice. We predicted that changes in the OSR should influence the mating behaviour of both sexes, as the OSR determines the probability that an individual will encounter a potential mate. We observed that the OSR affected the flexibility of male, but not female, mate choice. Additionally, the OSR influenced male behaviour, with larger males from the female‐biased OSR taking longer to make a choice than larger males in the male‐biased and even ratio OSR treatments. Mate choice in females was influenced by their intrinsic body size (only large females were choosy) and by the exaggerated traits expressed by potential mates (large females were only choosy when potential mates differed considerably in body size). Collectively, these findings provide partial support for the predictions of the switch point theorem as both sexes exhibited flexible mating decisions, switching from discriminant to indiscriminate mating under varying demographic conditions.

Adult sex ratios affect mating behaviour in the common housefly Musca domestica L. (Diptera; Muscidae)

“…If a male has less time or opportunity to court a female, e.g., due to intra-sexual competition in male-biased sex ratios, females may have fewer opportunities to assess the potential mating partners, which increases the mating latency. In a female-biased sex ratio a male likely suffers less from intra-sexual competition and females have fewer options in terms of mating partners, which may then reduce female choosiness (Souroukis & Murray, 1994;Passos et al, 2014;Villarreal et al, 2018) and the latency to copulation. Lower mating latencies may further increase productivity as less time is lost prior to fertilization and oviposition lowering reproduction time.…”

Farmed cricket (Acheta domesticus, Gryllus assimilis, and Gryllodes sigillatus; Orthoptera) welfare considerations: recommendations for improving global practice

“…A. domesticus (Murtaugh and Denlinger, 1985) G. assimilis (Loranger and Bertram, 2016a) G. sigillatus (Mallard and Barnard, 2004;Sakaluk, 1987) Number of mating partners Multiple Multiple* Multiple A. domesticus (Gray, 1997;Wilson and Walker, 2019) G. assimilis (Masson et al, 2020) G. sigillatus (Sakaluk et al, 2002;Vasanth, 1988 A. domesticus (Alexander, 1961;Gray, 1997;Wilson and Walker, 2019) G. assimilis (Alexander, 1961;Bertram et al, 2017) G. sigillatus (Alexander, 1961;Sakaluk et al, 2019;Vasanth, 1988) (Crocker and Hunter, 2018;Ismail, 1978) G. assimilis (Villarreal et al, 2018) G. sigilatus (Houslay et al, 2015(Houslay et al, ) et al, 2005Gangwere, 1961;Gutiérrez et al, 2020;Hanboonsong et al, 2013). All three species are active yearround (Alexander, 1968;Weissman et al, 2009Weissman et al, , 2012.…”

Sexual display behaviour follows consistent sex-specific reaction norms across latitude in response to operational sex-ratio

“…In the case of short-term fluctuations, OSR theory assumes that individuals plastically adjust their behaviour to the perceived social environment. Empirical work generally supports plastic response of sexual display to OSR (reviewed in de Jong et al 2012, see also : Chuard et al 2016, Weladji et al 2017, Villarreal et al 2018, Munõz-Arroyo et al 2019, Driscoll et al 2022, Chuard et al 2022. However, as pointed out first by de Jong et al (2012), these studies lack a consistent and explicit framework, which makes it difficult to draw comparisons and generalise.…”