A natural catastrophic turnover event: individual sociality matters despite community resilience in wild house mice

Abstract

Natural disasters can cause rapid demographic changes that disturb the social structure of a population as individuals may lose connections. These changes also have indirect effects as survivors alter their within-group connections or move between groups. As group membership and network position may influence individual fitness, indirect effects may affect how individuals and populations recover from catastrophic events. Here we study changes in the social structure after a large predation event in a population of wild house mice ( Mus musculus domesticus ), when a third of adults were lost. Using social network analysis, we examine how heterogeneity in sociality results in varied responses to losing connections. We then investigate how these differences influence the overall network structure. An individual's reaction to losing associates depended on its sociality prior to the event. Those that were less social before formed more weak connections afterwards, while more social individuals reduced the number of survivors they associated with. Otherwise, the number and size of social groups were highly robust. This indicates that social preferences can drive how individuals adjust their social behaviour after catastrophic turnover events, despite the population's resilience in social structure.

Rhesus macaques build new social connections after a natural disaster

“…In particular, we asked whether individual monkeys increased their number of social partners or strengthened their existing connections (or both), two strategies that potentially provide different benefits after catastrophic events. 7,22,30 Our results confirmed that rhesus macaques engaged more in affiliative interactions after the storm and that this effect was driven by an increase in their number of partners rather than intensifying existing relationships. These findings motivated us to explore the final two of our five questions: (4) because partner selection might provide critical insights into the function of social relationships, [34][35][36] we asked which partners monkeys associated with after the disaster.…”

“…(2) Whether individuals lost members of their pre-hurricane social network (i.e., a pre-storm grooming partner who died within 6 months after the hurricane). 30,31,33 Although the island did not suffer from mass mortality as a result of the storm, the death rate was higher in the month after the hurricane (October 2017) than in this month in previous years (Figure 1B), which might affect probabilities of affiliation beyond what was expected from normal demographic processes. 31 (3) For the grooming probability model only, whether increased grooming reflected increased use of shared space (i.e., proximity to others) after the disaster.…”

“…(2) We investigated inter-individual differences in social responses to the hurricane. Specifically, we asked whether pre-to post-hurricane changes in probabilities of affiliative behaviors were similar for all monkeys and, if not, whether inter-individual differences were predicted by gregariousness prior to the hurricane, 30 the loss of a grooming partner as a result of the storm, 31 or clustering around newly scarce resources like shade. 11,32 In prior studies, gregariousness and loss of a partner influenced individual social responses to a mass predation event in wild mice 30 and female chacma baboons.…”

Long-term overlap of social and genetic structure in free-ranging house mice reveals dynamic seasonal and group size effects

“…2003 ). Predation pressure, however, is unlikely in our system as predators which might be attracted by an aggregation can rarely access the barn (though see: Evans et al. 2020 ).…”

Family dynamics reveal that female house mice preferentially breed in their maternal community

“…Female house mice typically live in social groups with overlapping generations, demic structure and female philopatry (Baker, 1981; Gerlach, 1996; König and Lindholm, 2012; Lewontin and Dunn, 1960). In our study population, groups are relatively stable over time and have proven to be resilient even after a major disturbance (Evans et al, 2020a; Liechti et al, 2020). While there is strong intrasexual female reproductive competition, several females usually breed simultaneously in the same group and even engage in communal offspring care (Ferrari et al, 2019).…”