Extreme Male Mating Behaviours: Anecdotes in a Nuptial Gift-Giving Spider

Abstract

Summary Nuptial gifts may serve to increase male mating success, copulation duration, and fertilization success, as is known for the nuptial feeding spider Pisaura mirabilis Clerck, 1757. In this species, strong sexual selection for the gift-giving trait may lead to male strategies, such as gift enlargement or thanatosis behaviour (death feigning), which ultimately maximize male fitness. In laboratory trials, we observed male gift enlargement by inclusion of an autosomal (self-amputated) limb, female consumption of male soma during copulation, and high-injury risk thanatosis in which a male feigned death while still in copula and only attached to the female with his pedipalp, instead of hanging onto the gift with the chelicerae as is performed in a typical thanatosis. Although the observations are anecdotal, we propose functional hypotheses for these traits in the context of extreme male mating effort and cannibalism avoidance, which are characteristics of the mating system of this species. Sexual selecti...