How does individual variation in sociality influence fitness in prairie voles?

Abstract

Comparative studies aid in our understanding of specific conditions favoring the initial evolution of different types of social behaviors, yet there is much unexplained intraspecific variation in the expression of social behavior that comparative studies have not yet addressed. The proximate causes of this individual variation in social behavior within a species have been examined in some species but its fitness consequences have been less frequently investigated. In this study, we quantified the fitness consequences of variation in the sociality of prairie voles (Microtus ochrogaster). We characterized sociality of voles in semi-natural enclosures using an automated behavioral tracking system paired with social network analyses to quantify the degree of spatial and temporal co-occurrence of different voles. We then assessed the relationship between sociality with mating success (number of different conspecifics with which an individual produced offspring) and reproductive success (total number of offspring surviving to first capture). We measured the number of social connections each individual had with all voles and only with opposite-sex voles by calculating unweighted degree through social network analyses.Both female and male voles varied in the number of social connections they had with all conspecifics and with opposite-sex conspecifics. Voles with an intermediate number of social connections with voles of both sexes had higher mating success overall. In our analyses that considered all social connections with voles of both sexes, voles with an intermediate number of social connections produced more offspring. Males with a very high or low number of social connections also had the lowest average body mass. Overall, our results suggest some limit on the fitness benefits of sociality. Although there was substantial individual-variation in our measure of vole social behavior, intermediate levels of social connections may be most favorable.

Higher sociability leads to lower reproductive success in female kangaroos

“…Observations of 'adoptions' in kangaroos suggest that mother-young recognition may not be well developed [70]. Second, the time and cognitive effort needed by females with more differentiated social relationships to keep track of interactions with others could also reduce those mothers' time available for activities such as maintaining contact with young and anti-predator vigilance, as suggested by Montero et al [33] for yellow-bellied marmots and Sabol et al [71] for prairie voles (Microtus ochrogaster).…”

Social network position predicts male mating success in a small passerine

“…However, we additionally repeated our main analyses removing 5% and 10% of weakest edges (see Supplementary Tables S1–S8 ). We chose these four metrics because previous studies showed that they influence mating in other systems (e.g., number of associates: Sabol et al 2020 , betweenness centrality: Oh and Badyaev 2010 , sex ratio: Grant and Grant 2019 ) and because we can make meaningful predictions of how they may influence mating outcomes in blue tits (see Introduction).…”

“…These studies show that not only the focal male’s phenotype but also the composition of the social environment (i.e., the other males’ phenotypes) influence its future success in acquiring a territory ( Farine and Sheldon 2015 ) or in gaining copulations ( Formica et al 2011 ; Wey et al 2015 ; Fisher et al 2016 ; Ziv et al 2016 ). Furthermore, it has been shown that more central or active individuals (in males: Formica et al 2012 ; Sih et al 2014 ; in females: Ziv et al 2016 ) and those with a higher number of social connections (both sexes: Sabol et al 2020 ) gain more copulations. However, many of these studies focused on nonmonogamous mating systems ( Formica et al 2011 , 2012 ; Sih et al 2014 ; Wey et al 2015 ; Ziv et al 2016 ) or examined mating success indirectly through the acquistion of nest sites ( Farine and Sheldon 2015 ).…”

“…In addition to phenotypic characteristics, the social network position could affect the likelihood to acquire a social and extrapair partner. For instance, individuals connected to more conspecifics of the opposite sex and relatively fewer same-sex conspecifics may experience higher mate availability and less competition ( Sabol et al 2020 ), and thus may be more likely to find social and extrapair mates. Further, individuals moving more frequently between social groups (i.e., that are more central) may have more opportunities to encounter suitable mates (sensu Ihle et al 2015 ) and thus may be more likely to acquire a social partner ( Oh and Badyaev 2010 ) and extrapair mates.…”

Non-random Co-occurrence of Juvenile White Sharks (Carcharodon carcharias) at Seasonal Aggregation Sites in Southern California

“…Sociality, or the propensity of individuals to form social groups (Merriam-Webster., 2021), is a trait exhibited across taxa and varies between loose temporary aggregations to life-long associations (Alexander, 1974;Sabol et al, 2020). Social interactions have been shown to reduce predation risk and increase foraging efficiency, navigational capability, and reproductive opportunities Berdahl et al, 2018;Campbell et al, 2018;Diaz-Aguirre et al, 2019).…”