Temporal and genetic variation in female aggression after mating

Abstract

Aggression between individuals of the same sex is almost ubiquitous across the animal kingdom. Winners of intrasexual contests often garner considerable fitness benefits, through greater access to mates, food, or social dominance. In females, aggression is often tightly linked to reproduction, with females displaying increases in aggressive behavior when mated, gestating or lactating, or when protecting dependent offspring. In the fruit fly, Drosophila melanogaster, females spend twice as long fighting over food after mating as when they are virgins. However, it is unknown when this increase in aggression begins or whether it is consistent across genotypes. Here we show that aggression in females increases between 2 to 4 hours after mating and remains elevated for at least a week after a single mating. In addition, this increase in aggression 24 hours after mating is consistent across three diverse genotypes, suggesting this may be a universal response to mating in the species. We also report here the first use of automated tracking and classification software to study female aggression in Drosophila and assess its accuracy for this behavior. Dissecting the genetic diversity and temporal patterns of female aggression assists us in better understanding its generality and adaptive function, and will facilitate the identification of its underlying mechanisms.

Influences of male age, mating history and starvation on female post mating aggression and feeding inDrosophila

“…It is possible that females mated to Old-F males did not receive enough ejaculate to switch on this pathway. The idea of an ‘on-off’ switch is consistent with another study which found that different genotypes of males do not stimulate different levels of post-mating aggression in females, despite potential differences in their ejaculates (Bath et al, 2020).…”

“…Across taxa, female aggression can have substantial fitness consequences, with winners in intrasexual aggressive encounters garnering considerable fitness benefits, in the form of increased access to food, better nesting or oviposition sites, protection of their offspring, or social dominance (Clutton-Brock & Huchard, 2013; Rosvall, 2011). In D. melanogaster , mated females spend twice as much time engaging in aggressive interactions as virgin females when competing over food (Bath, Biscocho, Easton-Calabria, & Wigby, 2020; Bath et al, 2017; Nilsen et al, 2004). Like other post-mating responses (PMRs), increased female aggression after mating is stimulated by components of the male ejaculate in this species - females must receive sperm to maximally increase aggression post-mating, while the Sfp ‘sex peptide’ is also partially responsible for the increase in aggression after mating (Bath et al, 2017).…”

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, 2018 ; Ueda and Kidokoro, 2002 ). Further supporting the close tie between these two social behaviors, we found that nearly a quarter of the synaptic output in the central brain of vpoDN, a descending neuron involved in female receptivity ( Wang et al, 2020b ) goes to pC1d.…”

“…In addition to food availability, the genotype and sex of the target fly influence aggression ( Bath et al, 2020 ; Bath et al, 2018 ; Lim et al, 2014 ; Ueda and Kidokoro, 2002 ; Wohl et al, 2020 ). Our previous neuronal activation experiments demonstrated aggression even in the absence of competition for food ( Figure 1F,G ).…”

“…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).…”