The developmental environment modulates mating‐induced aggression and fighting success in adult female Drosophila

Abstract

Competition over access to resources early in life can influence development, and, in turn, affect competitive phenotypes in reproductive adults. Theory predicts that competition between adult females should be especially context‐dependent, because of constraints imposed by high costs of reproduction. However, the potential impact of developmental environments on competition in adult females remains little understood. In Drosophila melanogaster , the developmental environment can strongly influence adult condition, and prime adult competitive behaviour. In this species, female–female aggression is dependent on reproductive state and increases after mating due to the receipt of sperm and seminal fluid components. However, the effects of the developmental environment on adult female aggression, and any potential interactions with mating status, are unknown. To address this problem, we first raised flies at low and high larval density, which altered competition over limited resources, produced large and small adult females, respectively, and potentially primed them for differing levels of adult competition. We then fought the resulting adult females, either as virgins, or after receiving aggression‐stimulating ejaculates at mating, to test for interacting effects. We found, as expected, that mating elevated contest duration. However, this mating‐induced boost in aggression was strongly exacerbated for high density (small) females. Low density (large) females won more contests overall, but were not more successful in fights after mating. In contrast, mating increased the fighting success in females raised in high density environments. Our results suggest that individuals who experience competitive, resource‐limited, rearing conditions are more sensitive to the aggression‐stimulating effects of the male ejaculate. This finding highlights the importance of the developmental environment in mediating adult social interactions and provides support for the theory that female–female aggression should be highly context‐dependent. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13214/suppinfo is available for this article.

Temporal and genetic variation in female aggression after mating

“…The increase in female aggression 2-4 hours after mating also appears to occur in conjunction with the stimulation of ovulation (1.5 hours after mating starts) and potentially also with the beginning of egg laying (~3 hours after the start of mating) [26,60]. We have previously shown that the production of eggs is not necessary for mating-induced female aggression and our results from both the timing and genotype experiments lend support to this idea [11,48].…”

“…There is previous evidence, however, that shows that female aggression can vary in magnitude based on qualities of the male ejaculate. Females raised at different larval densities showed different levels of increase in aggression after mating [48]. Females raised…”

Cell types and neuronal circuitry underlying female aggression in Drosophila

“…Interestingly, Wang et al (2020a) also noted differences in the depolarization of pC1d and pC1e following activation of the sex-peptide abdominal ganglion neuron. While these are not as extensive as seen in pC1a, they may provide a neural basis for the reported effect of mating status on female aggressive behavior (Bath et al, 2020(Bath et al, , 2018Ueda and Kidokoro, 2002).…”

Sex ratio at mating does not modulate age fitness effects in Drosophila melanogaster

“…In D. melanogaster , males have strong intrasexual competition over mating and allocate considerable time and effort to court available females, while females are able to re‐mate with multiple males (Dow & Schilcher, ; Markow, ; Pitnick, ). Although intrasexual competition is mostly observed in males, aggression between females is also present, mainly when food sources are scarce (Bath et al, ; Bath, Morimoto, & Wigby, ; Ueda & Kidokoro, ). Furthermore, both males and females of this species exhibit mate choice but the degree and direction of these choices can differ depending on the population of origin and the social environment (Byrne & Rice, ; Edward & Chapman, , ; Gowaty, Steinichen, & Anderson, ; Monier, Nöbel, Isabel, & Danchin, ).…”