Emerging infectious diseases and animal social systems

Authored by Charles L Nunn, Peter H Thrall, Kelly Stewart, Alexander H Harcourt

Date Published: 2008

DOI: 10.1007/s10682-007-9180-x

Sponsors: Max Planck Society United States National Science Foundation (NSF) Conservation International National Center for Ecological Analysis and Synthesis (NCEAS)

Platforms: MATLAB

Model Documentation: Other Narrative Flow charts

Model Code URLs: Model code not found

Abstract

Emerging infectious diseases threaten a wide diversity of animals, and important questions remain concerning disease emergence in socially structured populations. We developed a spatially explicit simulation model to investigate whether-and under what conditions-disease-related mortality can impact rates of pathogen spread in populations of polygynous groups. Specifically, we investigated whether pathogen-mediated dispersal (PMD) can occur when females disperse after the resident male dies from disease, thus carrying infections to new groups. We also examined the effects of incubation period and virulence, host mortality and rates of background dispersal, and we used the model to investigate the spread of the virus responsible for Ebola hemorrhagic fever, which currently is devastating African ape populations. Output was analyzed using regression trees, which enable exploration of hierarchical and non-linear relationships. Analyses revealed that the incidence of disease in single-male (polygynous) groups was significantly greater for those groups containing an average of more than six females, while the total number of infected hosts in the population was most sensitive to the number of females per group. Thus, as expected, PMD occurs in polygynous groups and its effects increase as harem size (the number of females) increases. Simulation output further indicated that population-level effects of Ebola are likely to differ among multi-male-multi-female chimpanzees and polygynous gorillas, with larger overall numbers of chimpanzees infected, but more gorilla groups becoming infected due to increased dispersal when the resident male dies. Collectively, our results highlight the importance of social system on the spread of disease in wild mammals.

Tags

mountain gorillas Reproductive success Wild chimpanzees Metapopulation models Natural-history Sexually-transmitted-diseases Gorilla-gorilla-gorilla Canine-distemper virus Amphibian population declines Ebola-virus