異性間の付き合いは年間の体力と連動するが、社会性は生涯にわたって安定する Opposite-sex associations are linked with annual fitness, but sociality is stable over lifetime
Jamie Dunning, Terry Burke, Alex Hoi Hang Chan, Heung Ying Janet Chik, Tim Evans, Julia Schroeder
Behavioral Ecology Published:08 March 2023
Animal sociality, an individual’s propensity to associate with others, has fitness consequences through mate choice, for example, directly, by increasing the pool of prospective partners, and indirectly through increased survival, and individuals benefit from both. Annually, fitness consequences are realized through increased mating success and subsequent fecundity. However, it remains unknown whether these consequences translate to lifetime fitness. Here, we quantified social associations and their link to fitness annually and over lifetime, using a multi-generational, genetic pedigree. We used social network analysis to calculate variables representing different aspects of an individual’s sociality. Sociality showed high within-individual repeatability. We found that birds with more opposite-sex associates had higher annual fitness than those with fewer, but this did not translate to lifetime fitness. Instead, for lifetime fitness, we found evidence for stabilizing selection on opposite-sex sociality, and sociality in general, suggesting that reported benefits are only short-lived in a wild population, and that selection favors an average sociality.