Early and adult social environments have independent effects on individual fitness in a social vertebrate

Abstract

Evidence that the social environment at critical stages of life-history shapes individual trajectories is accumulating. Previous studies have identified either current or delayed effects of social environments on fitness components, but no study has yet analysed fitness consequences of social environments at different life stages simultaneously. To fill the gap, we use an extensive dataset collected during a 24-year intensive monitoring of a population of Alpine marmots (Marmota marmota), a long-lived social rodent. We test whether the number of helpers in early life and over the dominance tenure length has an impact on litter size at weaning, juvenile survival, longevity and lifetime reproductive success (LRS) of dominant females. Dominant females, who were born into a group containing many helpers and experiencing a high number of accumulated helpers over dominance tenure length showed an increased LRS through an increased longevity. We provide evidence that in a wild vertebrate, both early and adult social environments influence individual fitness, acting additionally and independently. These findings demonstrate that helpers have both short-and long-term effects on dominant female Alpine marmots and that the social environment at the time of birth can play a key role in shaping individual fitness in social vertebrates.

Individual heterogeneity and capture–recapture models: what, why and how?

“…Between-individual differences in phenotypic attributes such as age (Caughley 1966, Emlen 1970, sex (Short and Balaban 1994), body mass (Sauer and Slade 1987), or personality (Dingemanse and Dochtermann 2013), in genotype (Coulson et al 2011), in habitat use or habitat selection such as home range size or quality (Mcloughlin et al 2007), or in prey selection (Estes et al 2003) have all been reported to affect most life history traits. More recently, both current and early-life environmental conditions encountered by individuals throughout their lives have been shown to generate individual differences in life history traits (Douhard et al 2014, Berger et al 2015.…”

Sibship effects on dispersal behaviour in a pre‐industrial human population

“…However, such multivariate analysis is essential for a comprehensive understanding of dispersal and its determinants in family-living species. Previous studies on the effects of kin structure on dispersal have rarely addressed these questions against predictions derived from the effects of kin on other life-history traits, although at least in some species, the effects of kin on traits such as breeding probability and reproductive success can be sex-specific (Nitsch et al, 2013;Scandolara et al, 2014a) or vary across different life-history stages (Sparkman et al, 2011;Nitsch et al, 2013;Berger et al, 2015). Therefore, it is likely that dispersal decisions are most fruitfully examined with an integrative approach that considers effects on all such traits simultaneously.…”

Individual size, sex, and rearing environment impact on aggression in newly weaned seals

“…, Takahashi ) and reproductive success (Berger et al . ). However, the source of this variation may also be genetic, as high density sites on breeding colonies are frequently occupied by aggressive, dominant males (Boness et al .…”

“…There has been a long history of studies investigating the impacts of early social environment on an infant's subsequent behavior in a wide range of animal species, from ants to nonhuman primates (reviewed in Scott 1962). The social environment in which an individual is raised has been shown to exert lifelong effects on adult behavior (Crawley et al 1975, Takahashi 1986) and reproductive success (Berger et al 2015). However, the source of this variation may also be genetic, as high density sites on breeding colonies are frequently occupied by aggressive, dominant males (Boness et al 1982) and females (Pomeroy et al 2000).…”