title: How Ebola impacts social dynamics in gorillas: a multistate modelling approach.
abstract: Emerging infectious diseases can induce rapid changes in population dynamics and threaten population persistence. In socially structured populations, the transfers of individuals between social units, for example, from breeding groups to non-breeding groups, shape population dynamics. We suggest that diseases may affect these crucial transfers. We aimed to determine how disturbance by an emerging disease affects demographic rates of gorillas, especially transfer rates within populations and immigration rates into populations. We compared social dynamics and key demographic parameters in a gorilla population affected by Ebola using a long-term observation data set including pre-, during and post-outbreak periods. We also studied a population of undetermined epidemiological status in order to assess whether this population was affected by the disease. We developed a multistate model that can handle transition between social units while optimizing the number of states. During the Ebola outbreak, social dynamics displayed increased transfers from a breeding to a non-breeding status for both males and females. Six years after the outbreak, demographic and most of social dynamics parameters had returned to their initial rates, suggesting a certain resilience in the response to disruption. The formation of breeding groups increased just after Ebola, indicating that environmental conditions were still attractive. However, population recovery was likely delayed because compensatory immigration was probably impeded by the potential impact of Ebola in the surrounding areas. The population of undetermined epidemiological status behaved similarly to the other population before Ebola. Our results highlight the need to integrate social dynamics in host-population demographic models to better understand the role of social structure in the sensitivity and the response to disease disturbances.
authors.affiliation: UMR 6553, ECOBIO: Ecosystems, Biodiversity, Evolution, CNRS/University of Rennes 1, Station Biologique de Paimpont, 35380, Paimpont, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Genton
authors.affiliation: UMR 6553, ECOBIO: Ecosystems, Biodiversity, Evolution, CNRS/University of Rennes 1, Station Biologique de Paimpont, 35380, Paimpont, France.
authors.forename: Amandine
authors.initials: A
authors.lastname: Pierre
authors.affiliation: UMR 6553, ECOBIO: Ecosystems, Biodiversity, Evolution, CNRS/University of Rennes 1, Station Biologique de Paimpont, 35380, Paimpont, France.|School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, NSW, 2052, Australia.
authors.forename: Romane
authors.initials: R
authors.lastname: Cristescu
authors.affiliation: ENES/CNPS CNRS UMR 8195, Université de Saint-Etienne, Equipe Neuro-Ethologie Sensorielle, 42023, Saint-Etienne, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Lévréro
authors.affiliation: UMR 6553, ECOBIO: Ecosystems, Biodiversity, Evolution, CNRS/University of Rennes 1, Station Biologique de Paimpont, 35380, Paimpont, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Gatti
authors.affiliation: UMR 6553, ECOBIO: Ecosystems, Biodiversity, Evolution, CNRS/University of Rennes 1, Station Biologique de Paimpont, 35380, Paimpont, France.
authors.forename: Jean-Sébastien
authors.initials: JS
authors.lastname: Pierre
authors.affiliation: UMR 6553, ECOBIO: Ecosystems, Biodiversity, Evolution, CNRS/University of Rennes 1, Station Biologique de Paimpont, 35380, Paimpont, France.
authors.forename: Nelly
authors.initials: N
authors.lastname: Ménard
authors.affiliation: UMR 6553, ECOBIO: Ecosystems, Biodiversity, Evolution, CNRS/University of Rennes 1, Station Biologique de Paimpont, 35380, Paimpont, France.
authors.forename: Pascaline
authors.initials: P
authors.lastname: Le Gouar
mesh_terms: D000818:Animals; D018420:Ape Diseases / Q000821:virology*; D003223:Congo; D005260:Female; D006071:Gorilla gorilla; D019142:Hemorrhagic Fever, Ebola / Q000821:virology*; D008297:Male; D008954:Models, Biological; D011157:Population Dynamics; D012919:Social Behavior
keywords: Gorilla gorilla gorilla; capture–recapture; demographic crash; emerging infectious disease; recovery; sociality