Received: 21 March 2018 | Revised: 22 June 2018 | Accepted: 1 July 2018 DOI: 10.1002/ajp.22898 RESEARCH ARTICLE Long-term group membership and dynamics in a wild western lowland gorilla population (Gorilla gorilla gorilla) inferred using non-invasive genetics Laura Hagemann | Christophe Boesch | Martha M. Robbins | Mimi Arandjelovic | Tobias Deschner | Matthew Lewis* | Graden Froese† | Linda Vigilant Department of Primatology, Max Planck Institute for Evolutionary Anthropology, The social organization of a group-living animal is defined by a balance between Leipzig, Germany group dynamic events such as group formation, group dissolution, and dispersal Correspondence events and group stability in membership and over time. Understanding these Laura Hagemann, Department of Primatology, processes, which are relevant for questions ranging from disease transmission Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 patterns to the evolution of polygyny, requires long-term monitoring of multiple Leipzig, Germany. social units over time. Because all great ape species are long-lived and elusive, the Email:
[email protected] number of studies on these key aspects of social organization are limited, especially Funding information for western lowland gorillas (Gorilla gorilla gorilla). In this study, we used non- Max Planck Society; Tusk Trust; Berggorilla 2 und Regenwald Direkthilfe e. V.; United invasive genetic samples collected within an approximately 100 km area of Loango States Fish and Wildlife Service Great Ape National Park, Gabon to reconstruct group compositions and changes in Conservation Fund composition over more than a decade. We identified 98 gorillas and 11 mixed sex groups sampled during 2014–2017. Using published data from 85 individuals and 12 groups surveyed between 2005 and 2009 at the same locality, we tracked groups and individuals back in time.