Is degree of sociality associated with reproductive senescence? A comparative analysis across birds and mammals

Abstract

Our understanding on how widespread reproductive senescence is in the wild and how the onset and rate of reproductive senescence vary among species in relation to life histories and lifestyles is currently limited. More specifically, whether the species-specific degree of sociality is linked to the occurrence, onset and rate of reproductive senescence remains unknown. Here, we investigate these questions using phylogenetic comparative analyses across 36 bird and 101 mammal species encompassing a wide array of life histories, lifestyles and social traits. We found that female reproductive senescence (1) is widespread and occurs with similar frequency (about two thirds) in birds and mammals; (2) occurs later in life and is slower in birds than in similar-sized mammals; (3) occurs later in life and is slower with an increasingly slower pace of life in both vertebrate classes; and (4) is only weakly associated, if any, with the degree of sociality in both classes after accounting for the effect of body size and pace of life. However, when allowing for species differences in pace of life, a higher degree of sociality was associated with later and weaker reproductive senescence in females, which suggests that degree of sociality is indirectly related to reproductive senescence via the pace of life.Subject Areasecology, evolution

Social capital: an independent dimension of healthy ageing

“…mortality) and reproductive senescence, as shown by the huge variations we observed between individuals 49 . These investigations will likely extend our knowledge of how evolution has co-selected sociality and longevity 5,41 . Furthermore, these new findings could subsequently be leveraged to promote healthy ageing.…”

“…For instance, such studies may delineate how social capital modulates life period trade-offs (i.e. early-life growth and subsequent young and adult survival, reproductive success) and how adult social capital may have co-evolved with post-reproductive lifespan 41 . For example, female killer whales (Orcinus orca) live twice as long as males, and post-reproductive females have greater knowledge and lead the group, thus enhancing the survival of their grand-offspring 6 .…”

Senescence: why and where selection gradients might not decline with age

“…Adding further complexity to quantifying reproductive senescence is the variety of shapes age-specific reproductive trajectories can take. Across birds and mammals, increases in a component of reproduction followed by decline from a peak are common [56–58], but indefinite increases with age can also occur across taxa [24] (electronic supplementary material, figure S3). In plants, vegetative dormancy [59] and seed banks [60] add remarkable extra layers of complexity [61,62].…”

“…Sociality appears to be correlated to some extent with longer lifespan [58,80,81]. Extreme sociality is associated with a 100-fold increase in lifespan in social insects [80]; cooperative breeding birds live longer on average than non-cooperative birds [81] and a recent comparative review of reproductive senescence in birds and mammals reveals a relationship between proxies of sociality and a slower pace of life [58]. However, current evidence suggests that this relationship is likely to be due to longer lifespan first being driven by a reduced threat of extrinsic mortality [81].…”

Social capital: an independent dimension of healthy ageing

“…For instance, such studies may delineate how social capital modulates life period trade-offs (i.e,. early-life growth and subsequent young and adult survival, and reproductive success) and how adult social capital may have co-evolved with post-reproductive lifespan (Vágási et al 2020). For example, female killer whales (Orcinus orca) live twice longer than males, and post-reproductive females have greater knowledge and lead the group, thus enhancing the survival of their grand-offspring (Nattrass et al 2019).…”