Males adjust their manipulation of female remating in response to sperm competition risk

Abstract

To reduce the potential for sperm competition, male insects are thought to inhibit the post-mating reproductive behaviour of females through receptivity-inhibiting compounds transferred in the ejaculate. Selection is expected to favour phenotypic plasticity in male post-copulatory expenditure, with males investing strategically in response to their perceived risk of sperm competition. However, the impact that socially cued strategic allocation might have on female post-mating behaviour has rarely been assessed. Here, we varied male perception of sperm competition risk, both prior to and during mating, to determine if a male's competitive environment impacts the extent to which he manipulates female remating behaviour. We found that female Australian field crickets ( Teleogryllus oceanicus ) mated to males that were reared under sperm competition risk emerged from a shelter in search of male song sooner than did females mated to males reared without risk, but only when mating occurred in a risk-free environment. We also found that females reared in a silent environment where potential mates were scarce emerged from the shelter sooner than females exposed to male calls during development. Collectively, our findings suggest complex interacting effects of male and female sociosexual environments on female post-mating sexual receptivity.

Rapid Genomic Evolution Drives the Diversification of Male Reproductive Genes in Dung Beetles

“…Numerous studies across a broad range of taxa implicate sperm competition as a driving force behind the extraordinary diversity in male and female genital morphology, sperm form, seminal plasma biochemistry, as well as in sex-specific physiology and/or behaviours that can impact competitive fertilization success ( Birkhead and Møller 1998 ; Gasparini et al 2020 ; Lüpold et al 2020 ; Simmons and Wedell 2020 ). Females of most insect species not only mate multiply, but they also possess specialized organs for long-term sperm storage, facilitating co-occurrence of sperm from two or more males in the female reproductive tract ( Moschilla et al 2020 ; Simmons et al 2020 ; Wylde et al 2020 ). Hence the internal female reproductive environment acts as the competitive arena for fertilization, and much of postcopulatory sexual selection is in fact shaped by variation in male ejaculate and female interactions that can facilitate rapid diversification ( Yamane et al 2015 ; Lüpold et al 2016 ).…”

Nongenetic inheritance of behavioural variability is context specific and sex specific

“…Variation in the social environment, such as the presence of intraspecific sexual signals, is an important driver of phenotypic plasticity in crickets (Conroy & Roff, 2018;Kasumovic & Brooks, 2011;Rebar, Barbosa, & Greenfield, 2016. In T. oceanicus in particular, exposure to male acoustic sexual signals acts as an effective cue to the risk of sperm competition, generating plasticity in male post-copulatory strategy in the form of differential investment in sperm quality and seminal fluid gene expression (Gray & Simmons, 2013;Moschilla et al, 2020b;Simmons & Lovegrove, 2017;Sloan et al, 2018). We hypothesise that this plasticity in ejaculate expenditure may have consequences for offspring performance (Crean et al, 2013;Gasparini et al, 2018;Immler, 2018;Simmons & Lovegrove, 2019).…”

Sex ratio distorting microbes exacerbate arthropod extinction risk in variable environments

“…Females lay a brood of size $$$ \sigma $$$ at the end of each day on which they have mated. Females can mate with multiple males over the course of their lifetime but, to simulate re‐mating latency such as that driven by sperm competition avoidance (Moschilla et al., 2020; Wedell et al., 2002), females can only mate with one male per day. As such, each individual brood is fathered by a single male.…”