The direct costs of living in a sexually harassing environment

Abstract

Sexual conflict can lead to individuals evolving behaviours to circumvent preferences of the opposite sex. For example, females have been shown to adjust their behaviours depending on the risk of sexual harassment. In the present study we investigated the effects of sexual harassment in sailfin mollies, Poecilia latipinna, on both females and males depending on the level of male presence to which they were exposed. We exposed females to four levels of male presence (which we assumed to be correlated with intensity of sexual harassment): (1) no harassment (four females); (2) low male presence (one male with three females); (3) moderate male presence (two males with two females); and (4) high male presence (three males with one female). We measured sexual harassment as male sexual behaviours received by the females. The cost of sexual harassment on both males and females was measured as the overall change in body condition after being exposed to a particular treatment. There were three major results. (1) Sexual harassment caused a decrease in male body condition; this is one of the first studies to examine the cost of sexual harassment for males. (2) There are direct negative effects of sexual harassment on female fitness. (3) Male sexual behaviours are not additive, suggesting that there is some nonlinear relationship between the number of males in a population and the degree of harassment females are subjected to. We demonstrate that the social environment can have a direct effect on the body condition of the individuals within that particular environment. 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. Sexual conflict is widespread throughout polygynous sexual organisms (Arnqvist & Rowe 2005). It occurs when individuals of one sex invest less into reproduction and increase their fitness through frequent matings, while individuals of the other sex