Receptive females mitigate costs of sexual conflict

Abstract

Males typically gain fitness from multiple mating, whereas females often lose fitness from numerous mating, potentially leading to sexual conflict over mating. This conflict is expected to favour the evolution of female resistance to mating. However, females may incur male harassment if they refuse to copulate; thus, greater female resistance may increase costs imposed by males. Here, I show that the evolution of resistance to mating raises fitness disadvantages of interacting with males when mating is harmful in female adzuki bean beetles, Callosobruchus chinensis. Females that were artificially selected for higher and lower remating propensity evolved to accept and resist remating, respectively. Compared with females that evolved to accept remating, females that evolved to resist it suffered higher fitness costs from continuous exposure to males. The costs of a single mating measured by the effect on longevity did not differ among selection line females. This study indicates that receptive rather than resistant females mitigate the fitness loss resulting from sexual conflict, suggesting that even though mating is harmful, females can evolve to accept additional mating.

Sexual Success after Stress? Imidacloprid-Induced Hormesis in Males of the Neotropical Stink Bug Euschistus heros

“…heros males by increasing their mating frequency, which resulted in higher reproductive outputs of their unexposed female partners. Males are known to typically increase their fitness by increasing their mating frequency, whereas females often suffer reduced fitness from multiple matings, potentially leading to sexual conflict over mating [ 21 – 24 ]. Such gains in male fitness success may favor the evolution of male traits that entice females to mate multiply, thereby increasing the probability that males will sire offspring [ 21 – 25 ].…”

“…Males are known to typically increase their fitness by increasing their mating frequency, whereas females often suffer reduced fitness from multiple matings, potentially leading to sexual conflict over mating [ 21 – 24 ]. Such gains in male fitness success may favor the evolution of male traits that entice females to mate multiply, thereby increasing the probability that males will sire offspring [ 21 – 25 ]. However, additional study is required to evaluate precisely what property of sublethal exposure to imidacloprid is responsible for the responses of males.…”

“…Imidacloprid-exposed females possibly attempted to increase their reproductive performance by mating multiply with unexposed males, which may potentially compensate for the shortened duration of mating events recorded for these couples. Although controversial, by increasing their mating frequency, multiply mated females may increase their fitness by receiving more male-contributed materials [ 21 , 22 , 24 ]. However, these multiply mated females may also suffer reduced fitness because multiple matings have costs, such as increased time and energy expenditures, increased risk of predation and increased risk of being intoxicated by undesirable male materials [ 21 , 22 , 24 ].…”

“…Curiously, the contribution of males to insecticide-induced hormetic responses on the insect sexual success has been largely ignored. Male insects sublethally exposed to insecticides may alter their abilities of enticing or coercing the females for multiple matings and, therefore, increase the probability of siring offspring [ 21 – 25 ]. Furthermore, by increasing locomotory activities, males may increase their sexual success due to increases in the rate of encounters between mating partners [ 26 ].…”

Sexual selection, phenotypic plasticity and female reproductive output

“…Mating with males who are more sexually competitive can still increase a female's fitness even if it lowers her LRS if the costs of mating resistance are higher than accepting such males as mates. However, selection on females could lead to the evolution of the ability of females to reduce mating costs [154]. The net effect is that sexual selection on males can lower mean female LRS.…”