Unravelling Evolutionary Dynamics of Female Sexual Cannibalism and Male Reproductive Strategies in Spiders.

Sexual cannibalism, a behavioral syndrome where one mating partner consumes the other before, during, or after copulation, is particularly widespread among spiders and often exemplifies sexual conflict. Female sexual cannibalism has driven the evolution of numerous male counter-adaptations. Here we review sexual cannibalism in spiders, evaluate five broad hypotheses explaining its evolution, and provide possible explanations for numerous male reproductive strategies associated with this behavior. These male strategies include mating with immature females, opportunistic mating with molting or feeding females, coercive mating, nuptial gifts, inducing female quiescence, thanatosis, mate binding, sperm transfer adjustments, catapulting, and remote copulation. We emphasize the importance of clearly defining these behaviors and advocate for greater experimental repeatability in future experimental and comparative research. The evolutionary dynamics of these strategies are discussed within the frameworks of sexual conflict, sexually antagonistic coevolution, sperm competition, and cryptic female choice. We call for future research to expand taxonomic sampling, standardize methodologies, integrate field-based observations/experiments, and quantify the costs and benefits for each sex. Such efforts are essential to contextualize sexual cannibalism within broader ecological and evolutionary paradigms.