Sex-specific inbreeding depression depends on the strength of male-male competition

Inbreeding depression has become a central theme in evolutionary biology and is considered to be a driving force for the evolution of reproductive morphology, physiology, behavior, and mating systems. Despite the overwhelming body of empirical work on the reproductive consequences of inbreeding, relatively little is known on whether inbreeding depresses male and female fitness to the same extent. However, sex-specific inbreeding depression has been argued to affect the evolution of selfing rates in simultaneous hermaphrodites and provides a powerful approach to test whether selection is stronger in males than in females, which is predicted to be the consequence of sexual selection. We tested for sex-specific inbreeding depression in the simultaneously hermaphroditic freshwater snail Physa acuta by comparing the reproductive performance of both sex functions between selfed and outcrossed focal individuals under different levels of male–male competition. We found that inbreeding impaired ...

近交衰退（inbreeding depression）现已成为进化生物学的核心议题之一，被认为是驱动生殖形态、生理、行为及交配系统演化的关键动力。尽管已有大量关于近交衰退生殖后果的实证研究，但学界对近交是否会对雄性和雌性适合度（fitness）产生同等程度的抑制作用仍知之甚少。不过，有观点认为性别特异性近交衰退会影响同步雌雄同体（simultaneous hermaphrodites）的自交率演化，同时也为检验雄性是否比雌性承受更强选择压力提供了有力途径——这一推论正是性选择的预期结果。本研究以同步雌雄同体的淡水螺类尖膀胱螺（Physa acuta）为研究对象，在不同程度的雄性间竞争（male–male competition）条件下，比较自交与异交焦点个体的两种性别功能的生殖表现，以此检验其性别特异性近交衰退情况。研究发现近交衰退会损害……