Sociality shapes the life histories of animals along the fast-slow continuum, but does not affect their senescence

Abstract

AbstractThe role of sociality on the demography of animal species has become an intense focus of research in recent decades. However, efforts to understand the sociality-demography nexus have focused on single species or isolated taxonomic groups. Consequently, we lack generality regarding how sociality shapes demographic traits along the Animal Kingdom. Here, I propose a continuum of sociality, from solitary to tightly social, and test whether it predicts key demographic properties of 152 species, from jellyfish to humans. After correction for body mass and phylogenetic relationships, I show that the sociality continuum predicts key life history traits: more social species live longer, postpone maturity, have greater generation time, and greater probability of achieving reproduction than solitary, gregarious, communal, or colonial species. The sociality continuum is positively correlated with the fast-slow continuum. However, contrary to predictions, sociality does not result in more buffered populations: more social species have a lower ability to benefit from disturbances, although display greater resistance than more solitary species. Finally, I also show that sociality does not shape reproductive or actuarial senescence rates. This cross-taxonomic examination of sociality across the demography of 13 taxonomic classes highlights keyways in which individual interactions shape most aspects of animal demography.