Doctoral Dissertation Research: Investigating Western Lowland Gorilla Social Dynamics and Genetic Variability Using DNA from Feces and Hair

通过Dian Fossey和同事的开创性工作，野生山地大猩猩的行为已经得到了很好的记录。 然而，其他大猩猩亚种（西部低地大猩猩和东部低地大猩猩）的行为在很大程度上仍然未知。直到最近，人们还认为山地大猩猩的行为是大猩猩的一般行为的代表。然而，研究人员现在发现，西部低地大猩猩在生态上与山地大猩猩大不相同。山地大猩猩主要吃树叶，而西部低地大猩猩则在饮食中加入大量水果。 虽然我们知道这两个亚种的饮食不同，但它们在社会行为和社会组成上的差异程度是不确定的。这在很大程度上是因为还没有一群西部低地大猩猩习惯于人类研究人员的存在。 由于这一限制，我们还没有回答一些关于西部低地大猩猩社会组织的最基本的问题：一个单一的占主导地位的银背大猩猩是否有排他性的交配机会，就像人们认为的山地大猩猩一样？一个群体中的个体之间的关系有多密切？雌性是留在它们出生的群体中，还是在成年后分散到邻近的群体中？ 本计画将透过遗传分析来探讨西部低地大猩猩社会结构的问题。这项研究将通过分析野外采集的毛发样本的DNA来调查西部低地大猩猩的社会组成。每个样本都会产生一个独特的模式或遗传图谱，可以用来确定一个群体中个体的数量和性别以及家庭关系。 因此，即使没有直接的观察，也可以看出社会动态的各个方面。1998年6月至8月和1999年2月至4月，在中非共和国Mondika研究中心从野生大猩猩的巢穴中采集了毛发样本。 收集的样本来自9个不同大猩猩群体的大约75个个体。 现在将通过开发遗传图谱来分析这些样本，类似于DNA指纹，每个大猩猩个体都是独一无二的。遗传图谱将用于确定大猩猩社会动力学的几个关键方面：首先，这些图谱将通过提供有关哪些银背猩猩是哪些婴儿的父亲的信息，深入了解大猩猩的交配系统和生殖行为。 是一个单一的男性父亲在组中的所有后代（一个男性与女性的后宫）或多个男性父亲的后代（多男性/多女性交配系统）？其次，DNA图谱将确定群体成员之间的遗传关系，并将确定每个群体中的雌性是否属于同一母系，（即，雌性一直与母亲和姐妹呆在同一个群体中，而不是分散到其他群体中）。 这项研究将为野生西部低地大猩猩的家庭关系和社会结构提供重要信息。 这个项目的结果将有助于了解西部低地大猩猩的社会动态和行为，并将有助于大猩猩保护和圈养管理的努力，增加我们的大猩猩种群结构和遗传变异的知识。 研究大猩猩的饮食和行为之间的联系将有助于更好地理解生态因素如何影响动物的社会性。

The behavior of wild mountain gorillas has been well documented through the pioneering work of Dian Fossey and colleagues. However, the behavior of the other gorilla subspecies (the western lowland gorillas and the eastern lowland gorillas) remains largely unknown. Until recently, it was assumed that the behavior of mountain gorillas was representative of that of gorillas in general. However, researchers have now discovered that western lowland gorillas are ecologically quite different from mountain gorillas. While mountain gorillas eat primarily leaves, western lowland gorillas incorporate large amounts of fruit into their diet. Although we know that the diets of these two subspecies differ, the degree to which they differ in social behavior and socialcomposition is uncertain. This is largely due to the fact that there are not yet groups of western lowland gorillas habituated to the presence of human researchers. Because of this limitation, we have yet to answer some of the most fundament questions about western lowland gorilla social organization: Does a single dominant silverback have exclusive mating access to all of the females in the group, as is thought to be the case for mountain gorillas? How closely related are individuals within a group? Are females remaining in the group into which they are born, or do they disperse to neighboring groups upon reaching adulthood? This project will address these questions about western lowland gorilla social structure through genetic analysis. This study will investigate the social composition of western lowland gorillas by analyzing the DNA from hair samples collected in the wild. Each sample yields a unique pattern, or genetic profile, that can be used to determine the number and sex of individuals in a group as well as family relationships. Thus, aspects of social dynamics can be discerned even without direct observation. Between June and August 1998 and February and April 1999 hair samples were collected from the nests of wild gorillas at Mondika Research Center in the Central African Republic. The collected samples are from approximately 75 individuals belonging to 9 different gorilla groups. These samples will now be analyzed by developing genetic profiles, similar to DNA fingerprints, unique to each gorilla individual. The genetic profiles will be used to determine several key aspects of gorilla social dynamics: First, these profiles will give insight into the mating system and reproductive behavior of gorillas by providing information about which silverbacks fathered which infants. Is a single male fathering all of the offspring in the group (one-male with a harem of females) or do multiple males father offspring (multiple-male /multiple-female mating system)? Second, the DNA profiles will identify the genetic relationships between group members, and it will be determined whether or not the females in each group are part of the same matriline, (i.e., the females have remained in the same group as their mother and sisters rather than dispersing to other groups). This study will provide important information on the family relationships, and therefore the social structure, of western lowland gorillas in the wild. The results of this project will aid in understanding western lowland gorilla social dynamics and behavior, and will contribute to gorilla conservation and captive management efforts by increasing our knowledge of gorilla population structure and genetic variability. Investigating the links between gorilla diet and behavior will lead to a greater understanding of how ecological factors influence sociality in animals.