Male aggressiveness does not explain the frequency of reversed sexual cannibalism

In a few species, males often face a choice between mating and/or cannibalizing females. Various factors influence this decision, making it essential to decipher the role of male behavioural variation. In particular, aggressiveness has been proposed to face sexual selection and increase the incidence of cannibalism in such systems. In this study, we investigated the role of male aggressiveness in the likelihood of reversed sexual cannibalism occurring in the female-cannibalistic ground spider Micaria sociabilis . We conducted behavioural experiments to measure male aggressiveness level, and to assess male mating behaviour, along with potential seasonal (spring and summer) and morphological traits (body size, female size). We found that male aggressiveness was a repeatable trait. However, it was not significantly linked to the likelihood of reversed cannibalism or to the likelihood of copulation. Similarly, aggressiveness did not affect the size of a mating plug. Seasonal variation significantly affected reversed cannibalism, with males more likely to engage in cannibalism during summer, while copulation frequency remained consistent between seasons. Additionally, while aggressiveness was not related to male attacks on females, seasonality had a notable impact, with males attacking females more frequently in summer, while females attacked males more in spring. These findings highlight the complexity of mating dynamics in M. sociabilis , pointing to a multifaceted interaction between intrinsic personality traits and extrinsic factors, such as ecological pressures and female condition. Significant statement In some species, males must navigate a trade-off between mating and cannibalizing their female partners. Our study presents surprising results on the complexities behind that choice in Micaria sociabilis spider. While male aggressiveness is often thought to increase the likelihood of cannibalism or mating success, our findings reveal it plays a less decisive role. Instead, seasonal shifts were stronger influences, with males behaving in a choosy way and being more prone to cannibalize in summer, while in spring females were choosier, likely due to high sexual receptivity, a consequence of what was zero reversed cannibalism. These insights challenge traditional views of male aggressiveness and highlight how external factors and mate quality, rather than personality traits, shape mating and cannibalism dynamics. This research offers a fresh perspective on how behavior and ecology intertwine in cannibalistic species.