Abstract

Increased risk of pathogen transmission through proximity and contact is a well-documented cost of sociality. Affiliative social contact, however, is an integral part of primate group life and can benefit health. Despite its importance to the evolution and maintenance of sociality, the tradeoff between costs and benefits of social contact for group-living primate species remains poorly understood. To improve our understanding of this interplay, we used social network analysis to investigate whether contact via association in the same space and/or physical contact measured through grooming were associated with helminth parasite species richness in a community of wild chimpanzees (Pan troglodytes schweinfurthii). We identified parasite taxa in 381 fecal samples from 36 individuals from the Kasekela community of chimpanzees in Gombe National Park, Tanzania, from November 1, 2006, to October 31, 2012. Over the study period, eight environmentally transmitted helminth taxa were identified. We quantified three network metrics for association and grooming contact, including degree strength, betweenness, and closeness. Our findings suggest that more gregarious individuals—those who spent more time with more individuals in the same space—had higher parasite richness, while the connections in the grooming network were not related to parasite richness. The expected parasite richness in individuals increased by 1.13 taxa (CI: 1.04, 1.22; p = 0.02) per one standard deviation increase in degree strength of association contact. The results of this study add to the understanding of the role that different types of social contact play in the parasite richness of group-living social primates.

Significance statement

Parasite infections reveal costs of group living among wild animal populations. We studied the relationship between sociality and parasite transmission by assessing whether variation in social behavior among wild chimpanzees is associated with the number of unique helminth parasites detected in individual fecal samples. Our findings revealed that associating in the same shared space, but not grooming contact, is related to higher parasite richness. These findings improve our understanding of the complex interplay of parasitism and sociality with important implications for parasite transmission patterns in host species with flexible grouping patterns.

中文翻译：

---

合群性与野生黑猩猩群落中的寄生虫物种丰富度有关

摘要

通过接近和接触传播病原体的风险增加是有据可查的社交成本。然而，亲和的社会接触是灵长类动物群体生活的一个组成部分，可以有益于健康。尽管它对社会性的进化和维持很重要，但对于群居灵长类物种社会接触的成本和收益之间的权衡仍然知之甚少。为了提高我们对这种相互作用的理解，我们使用社交网络分析来调查在同一空间内通过关联进行的接触和/或通过梳理毛发测量的身体接触是否与野生黑猩猩群落中的蠕虫寄生虫物种丰富度有关（Pan troglodytes schweinfurthii）。从 2006 年 11 月 1 日到 2012 年 10 月 31 日，我们在来自坦桑尼亚贡贝国家公园 Kasekela 黑猩猩社区的 36 个人的 381 个粪便样本中鉴定了寄生虫分类群。在研究期间，鉴定了八种环境传播的蠕虫分类群。我们量化了关联和修饰接触的三个网络指标，包括度数强度、介数和亲密度。我们的研究结果表明，更合群的个体——那些在同一空间与更多个体共度更多时间的个体——具有更高的寄生虫丰富度，而梳理网络中的连接与寄生虫丰富度无关。个体的预期寄生虫丰富度增加了 1.13 个类群（CI：1.04，1.22；p = 0.02) 每增加一个标准差，关联联系的强度就会增加。这项研究的结果增加了对不同类型的社会接触在群居社会灵长类动物的寄生虫丰富度中所起的作用的理解。

意义陈述

寄生虫感染揭示了在野生动物种群中集体生活的成本。我们通过评估野生黑猩猩社会行为的变化是否与在个体粪便样本中检测到的独特蠕虫寄生虫的数量相关，研究了社会性和寄生虫传播之间的关系。我们的研究结果表明，在同一个共享空间中进行关联，而不是修饰接触，与更高的寄生虫丰富度有关。这些发现提高了我们对寄生和社会性之间复杂相互作用的理解，这对具有灵活分组模式的宿主物种的寄生虫传播模式具有重要意义。