Sexual interactions have a potent influence on health in several species, including mammals. Previous work in C. elegans identified strategies used by males to accelerate the demise of the opposite sex (hermaphrodites). But whether hermaphrodites evolved counter-strategies against males remains unknown. Here we discover that young C. elegans hermaphrodites are remarkably resistant to brief sexual encounters with males, whereas older hermaphrodites succumb prematurely. Surprisingly, it is not their youthfulness that protects young hermaphrodites, but the fact that they have self-sperm. The beneficial effect of self-sperm is mediated by a sperm-sensing pathway acting on the soma rather than by fertilization. Activation of this pathway in females triggers protection from the negative impact of males. Interestingly, the role of self-sperm in protecting against the detrimental effects of males evolved independently in hermaphroditic nematodes. Endogenous strategies to delay the negative effect of mating may represent a key evolutionary innovation to maximize reproductive success.

Interactions between the sexes negatively impact health in many species. In Caenorhabditis, males shorten the lifespan of the opposite sex—hermaphrodites or females. Here we use transcriptomic profiling and targeted screens to systematically uncover conserved genes involved in male-induced demise in C. elegans. Some genes (for example, delm-2, acbp-3), when knocked down, are specifically protective against male-induced demise. Others (for example, sri-40), when knocked down, extend lifespan with and without males, suggesting general mechanisms of protection. In contrast, many classical long-lived mutants are impacted more negatively than wild type by the presence of males, highlighting the importance of sexual environment for longevity. Interestingly, genes induced by males are triggered by specific male components (seminal fluid, sperm and pheromone), and manipulating these genes in combination in hermaphrodites induces stronger protection. One of these genes, the conserved ion channel delm-2, acts in the nervous system and intestine to regulate lipid metabolism. Our analysis reveals striking differences in longevity in single sex versus mixed sex environments and uncovers elaborate strategies elicited by sexual interactions that could extend to other species.

AbstractInteractions between the sexes negatively impact health in many species, including mammals1–9. In mice, sexual interactions induce weight gain and shorten lifespan in females, independent of fertilization6,9. In Caenorhabditis, males shorten the lifespan of the opposite sex (females or hermaphrodites)1–3,8. However, the mechanisms underlying the negative influence of males on lifespan – and their overlap with known longevity pathways – are still largely unknown. Here, we use transcriptomic profiling and targeted screens to systematically uncover new conserved genes involved in male-induced demise. Interestingly, deficiency of these genes individually, and especially in combination, induces strong protection, highlighting the benefit of combining interventions to extend lifespan. Some genes (e.g. acbp-3, col-43) only extend hermaphrodite lifespan when knocked-down in the presence of males, suggesting specific protective mechanisms against male-induced demise. However, we also uncover two previously unknown longevity genes (sri-40 and delm-2) that, when knocked-down, extend hermaphrodite lifespan both with and without males, which points to new broad mechanisms of resistance. In sharp contrast, many classical long-lived mutants are actually short-lived in the presence of males, suggesting that males hijack and suppress known longevity pathways. This systematic analysis reveals striking differences in longevity in single sex versus mixed sex environments and uncovers the elaborate network of functional regulation elicited by sexual interactions, which could extend to other species.

No abstract