Dispersal is an important individual decision which may influence individual fitness as well as population viability. The social cohesion hypothesis posits more social individuals remain at home, which is supported by prior work across taxa. However, how the sociality and connectivity of the group an individual resides in – their group social structure – relates to dispersal decisions has not been explored. We extend the social cohesion hypothesis to predict individuals residing in more social groups would remain at home, and we quantified the affiliative and agonistic social network structure of female yellow-bellied marmots (Marmota flaviventer), a facultatively social ground-dwelling squirrel, where about half of all females disperse. Using mixed-effects models we found no support for the hypothesis that affiliative group structure explained any variation in a marmot’s decision to disperse. We did find marmots in groups with less agonistic centralization (around one or few individuals) were less likely to disperse. The former finding may result from limited ability to perceive group structure while the latter may reflect individuals in less agonistically centralized groups are less likely to be reproductively suppressed. These results suggest individual dispersal decisions are more impacted by individual sociality and not that of their social group. Thus, the social cohesion hypothesis may not scale to the level of the group. Further work is required to determine whether dispersal decisions in obligately social species are influenced by group social structure.

中文翻译：

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扩展社会凝聚力假说：群体社会结构与黄腹土拨鼠（Marmota flaviventer）的扩散有关吗？

分散是一个重要的个体决定，可能会影响个体的适应性以及种群的生存能力。社会凝聚力假说假设更多的社会个体留在家里，这一点得到了先前跨类群研究的支持。然而，个体所在群体的社会性和连通性（群体社会结构）如何与分散决策相关尚未得到探讨。我们扩展了社会凝聚力假说来预测居住在更多社会群体中的个体将留在家中，并且我们量化了雌性黄腹土拨鼠（Marmota flaviventer）的亲和性和对抗性社交网络结构，黄腹土拨鼠是一种兼性社会性的地栖松鼠，其中大约一半的女性散去。使用混合效应模型，我们发现没有证据支持这样的假设：隶属群体结构可以解释土拨鼠分散决策的任何变化。我们确实发现土拨鼠在竞争集中度较低的群体中（围绕一个或几个个体）不太可能分散。前一个发现可能是由于感知群体结构的能力有限，而后者可能反映了竞争性集中程度较低的群体中的个体不太可能受到生殖抑制。这些结果表明，个人驱散决策更多地受到个人社会性的影响，而不是其社会群体的影响。因此，社会凝聚力假说可能无法扩展到群体的水平。需要进一步的工作来确定专性社会物种的扩散决策是否受到群体社会结构的影响。