A functional perspective on sexual selection: insights and future prospects

A large number of sexual selection studies have focused on examining the morphological and behavioural factors involved in male combat and female choice, such as whether large males achieve higher reproductive success compared with smaller males. However, until recently, the mechanistic reasons why such cues are linked to male dominance or female choice have been elusive. An emerging body of work shows that physiological and whole-organism performance capacities are important in individual reproductive success. Males with high performance or other physiological capacities (e.g. endurance, biting) often enjoy an advantage over males with poorer performance capacities during male–male contests. In contrast, few studies have examined links between performance and female choice. Here, we highlight recent key literature integrating sexual selection, performance and physiology. We also point to areas where a more rigorous investigation of underlying physiological processes may yield insights into sexual selection. In particular, we note that current progress in several important areas may be hampered by an inadequate physiological understanding of condition. We suggest a conceptual approach that may shed light on the physiological factors underlying condition, and we point out several other potentially important avenues for future research.