Table_1_Sex Matters: Effects of Sex and Mating in the Presence and Absence of a Protective Microbe.pdf

In most animals, female investment in offspring production is greater than for males. Lifetime reproductive success (LRS) is predicted to be optimized in females through extended lifespans to maximize reproductive events by increased investment in immunity. Males, however, maximize lifetime reproductive success by obtaining as many matings as possible. In populations consisting of mainly hermaphrodites, optimization of reproductive success may be primarily influenced by gamete and resource availability. Microbe-mediated protection (MMP) is known to affect both immunity and reproduction, but whether sex influences the response to MMP remains to be explored. Here, we investigated the sex-specific differences in survival, behavior, and timing of offspring production between feminized hermaphrodite (female) and male Caenorhabditis elegans following pathogenic infection with Staphylococcus aureus with or without MMP by Enterococcus faecalis. Overall, female survival decreased with increased mating. With MMP, females increased investment into offspring production, while males displayed higher behavioral activity. MMP was furthermore able to dampen costs that females experience due to mating with males. These results demonstrate that strategies employed under pathogen infection with and without MMP are sex dependent.

在绝大多数动物类群中，雌性在后代生产上的资源投入显著高于雄性。学界预测，雌性可通过延长寿命、增强免疫投入以增加繁殖事件的总量，从而优化终生繁殖成功率（Lifetime Reproductive Success，LRS）；而雄性则通过尽可能多地获取交配机会来最大化自身的终生繁殖成功率。在以雌雄同体个体为主的种群中，繁殖成功率的优化可能主要受配子与资源可获得性的调控。已知微生物介导的保护（Microbe-mediated protection，MMP）可同时影响宿主的免疫与繁殖功能，但性别是否会影响机体对MMP的应答仍有待探究。本研究以粪肠球菌（Enterococcus faecalis）介导或不介导微生物保护的金黄色葡萄球菌（Staphylococcus aureus）感染后的秀丽隐杆线虫（Caenorhabditis elegans）为实验对象，探究了雌性化雌雄同体（雌性）与雄性个体在存活能力、行为模式及后代生产时序上的性别特异性差异。总体而言，雌性的存活寿命随交配频次增加而下降。在存在MMP的情况下，雌性会提升后代生产的资源投入，而雄性则表现出更高的行为活跃度；此外，MMP还能够缓解雌性因与雄性交配而承受的生存代价。本研究结果表明，无论是否存在MMP，病原体感染下的宿主应对策略均存在显著的性别依赖性。