The founder sociality hypothesis.

James Brooks,Shinya Yamamoto

doi:10.1002/ece3.8143

Abstract

In this review, we propose that the social dynamics of founder populations in novel and newly available environments can have critical effects in shaping species' sociality and can produce long‐lasting changes in social structure and behavior. For founder populations which expand into an underexploited niche separated from the parent population, the necessity of bond formation with strangers, lack of clear territories, and initial abundance of resources can lead to altered initial social dynamics to which subsequent generations adapt. We call this the founder sociality hypothesis. After specifying the theoretical reasoning and mechanism of effect, we focus on three particular cases where the social dynamics of founder populations may have a central role in explaining their modern behavioral ecology. In particular, we develop and review evidence for three predictions of the founder sociality hypothesis in territorial, mixed‐sex group forming species: relatively stronger social bonds in the dispersing sex with relatively weaker bonds in the nondispersing sex, reduced territoriality, and increased social tolerance. We briefly touch on the implications for human evolution given our species' evolutionary history marked by frequent expansion and adaptation to novel environments. We conclude by proposing several experiments and models with testable predictions following from the founder sociality hypothesis.

Highlights

After specifying the theoretical reasoning and mechanism of effect, we focus on three particular cases where the social dynamics of founder populations may have a central role in explaining their modern behavioral ecology
Bonobos clearly differ strongly from chimpanzees esis, the lack of competition with gorillas or greater fruit or herb in their form of intergroup relations and we propose the founder volume in bonobos environments, for which the evidence is unclear sociality hypothesis may be, at least in part, responsible for these (Furuichi, 2009, 2020; Hohmann et al, 2009; Yamakoshi, 2004), is differences
Zanzibar red colobus monkeys living in spice farms have relatively sociality hypothesis predicts a relative increase in the strength of festrong female social bonds and relatively weak male social bonds, inmale social bonds and relative decrease in the strength of male socreased home range overlap, and increased grooming and play comcial bonds

Summary

Funding information

#21J21123 to JB, KAKENHI #19H00629 and #19H05736 to SY and newly available environments can have critical effects in shaping species' socialpopulations which expand into an underexploited niche separated from the parent population, the necessity of bond formation with strangers, lack of clear territories, and initial abundance of resources can lead to altered initial social dynamics to which subsequent generations adapt. Their territories are enced strong initial selection for their ability to form new groups and well defined, and coalitions will engage in border patrols where sevbest exploit -underexploited resources available and that suberal individuals of one community will range at the border of their sequent generations evolved under this novel social environment Under this hypothesis, a more chimpanzee-like common ancestor often aggressive and sometimes lethal (Wilson & Wrangham, 2003). Chimpanzees will engage in lethal aggression even tothe social dynamic predicted by several individual chimpanzees ward members of their group, while bonobos in the wild have never crossing the Congo River and adapting to the novel rich environment been observed to kill a conspecific (Hare & Yamamoto, 2017; Pruetz populated largely by strangers maps neatly onto the observed social et al, 2017) We suggest these differences may be explained in part dynamic in the wild. By the founder sociality hypothesis of early bonobo ancestors upon crossing the Congo River

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