A complex systems approach to understanding the evolution of animal mating systems Understanding the drivers of diverse animal mating systems remains a key challenge in evolutionary biology. In particular, monogyny, where males mate with a single female during their lifetime, remains an evolutionary puzzle because male animals typically maximise reproductive success by mating with multiple females. Monogynous mating systems consist of multiple life history and behavioural traits, including dramatic adaptations such as the lifelong fusing of tiny male anglerfish to a female or the spontaneous death of a male during mating to form a whole-body mating plug in garden spiders. However, intricate correlations between system elements make it difficult to understand their roles in mating system