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

Whether animals breed in the group they are born in influences how they form extended family groups. Whether females stay often depends on properties such as presence of older relatives, including mothers. Using long-term wild house mouse data, we track groups and which group females bred in. Most stayed, but leaving did not reduce breeding success. Presence of mother, who generally stayed, did lead to earlier breeding. This might be a key advantage to remaining to breed. Whether females breed in their natal group is an important factor in the evolution of extended families in animal sociality. Breeding in natal groups comes with costs and benefits, depending on group size and presence of older relatives, including mothers. Studying the consequences of breeding in the natal versus another group provides insight into the decisions and trade-offs governing the formation and structure of family groups. We investigated the family dynamics of a population of free-ranging commensal house mice. Using dynamic community detection on long-term datasets, we determined which females first bred in their natal group. We then looked at how this influenced breeding success. We found most females (77%) exhibited strong philopatry, breeding in their natal groups. Breeding elsewhere was only somewhat predictable at very large and very small group sizes. Despite their philopatric preference, breeding elsewhere made no difference in how quickly and successfully a female bred. However, presence of their mother did lead females to breed sooner when born during high breeding activity, when competition over reproduction is high. Based on these results, potential loss of reproductive success from leaving the natal group does not seem to be the main driver of philopatry in female house mice. The effect of the presence of mothers suggests that benefiting from established social connections promotes breeding in the natal group. Mothers providing benefits also implies a lack of conflict between generations, which will be important for the development of stable social groups.

Automated summary

Whether animals breed in the group they are born in influences the formation of extended family groups. The presence of older relatives, including mothers, determines whether females stay in the group. Breeding in the natal group has both costs and benefits, depending on factors such as group size and presence of older relatives. Studying the consequences of breeding in the natal versus another group provides insights into the decision-making process and trade-offs in family group structure.