Sexual harassment induces a temporary fitness cost but does not constrain the acquisition of environmental information in fruit flies

Across animals, sexual harassment induces fitness costs for females and males. However, little is known about the cognitive costs involved, i.e. whether it constrains learning processes, which could ultimately affect an individual's fitness. Here we evaluate the acquisition of environmental information in groups of fruit flies challenged with various levels of male sexual harassment. We show that, although high sexual harassment induces a temporary fitness cost for females, all fly groups of both sexes exhibit similar levels of learning. This suggests that, in fruit flies, the fitness benefits of acquiring environmental information are not affected by the fitness costs of sexual harassment, and that selection may favour cognition even in unfavourable social contexts. Our study provides novel insights into the relationship between sexual conflicts and cognition and the evolution of female counterstrategies against male sexual harassment.

在动物类群中，性骚扰会对雌性与雄性个体造成适合度成本（fitness cost）。然而目前对其涉及的认知成本尚缺乏深入了解，亦即性骚扰是否会制约学习过程，进而最终影响个体的适合度。本研究以遭受不同强度雄性性骚扰的果蝇群体为研究对象，评估其环境信息获取能力。研究结果显示，尽管高强度性骚扰会使雌性果蝇产生暂时性的适合度成本，但雌雄果蝇的所有群体均表现出相近的学习水平。这一结果提示，在果蝇中，获取环境信息所带来的适合度收益并未受到性骚扰带来的适合度成本的影响；即便处于不利的社会环境中，自然选择仍可能对认知能力产生选择偏好。本研究为性冲突与认知之间的关联，以及雌性对抗雄性性骚扰的反制策略的演化提供了全新的研究视角。