A metapopulation model of social group dynamics and disease applied to Yellowstone wolves

Abstract

The population structure of social species has important consequences for both their demography and transmission of their pathogens. We develop a metapopulation model that tracks two key components of a species’ social system: average group size and number of groups within a population. While the model is general, we parameterize it to mimic the dynamics of the Yellowstone wolf population and two associated pathogens: sarcoptic mange and canine distemper. In the initial absence of disease, we show that group size is mainly determined by the birth and death rates and the rates at which groups fission to form new groups. The total number of groups is determined by rates of fission and fusion, as well as environmental resources and rates of intergroup aggression. Incorporating pathogens into the models reduces the size of the host population, predominantly by reducing the number of social groups. Average group size responds in more subtle ways: infected groups decrease in size, but uninfected groups may increase when disease reduces the number of groups and thereby reduces intraspecific aggression. Our modeling approach allows for easy calculation of prevalence at multiple scales (within group, across groups, and population level), illustrating that aggregate population-level prevalence can be misleading for group-living species. The model structure is general, can be applied to other social species, and allows for a dynamic assessment of how pathogens can affect social structure and vice versa.

Higher temperature extremes exacerbate negative disease effects in a social mammal

“…Disease outbreaks can directly cause mass mortality in social groups 16,17 ; or they may decrease group size, by reducing individual survival and fecundity, and thus make groups more vulnerable to adverse climatic conditions 18,19 . Assessing these complex pathways through which climate change may affect groups therefore requires quantifying the demographic responses (e.g., survival, reproduction, dispersal) to climate-disease interactions 20 . Here, we use 22 years of detailed individual growth and life-history data from 85 groups of meerkats (Suricata suricatta) 21 , a common species in the Kalahari, to quantify how variation in climate interacts with disease dynamics to affect individual traits, demography, and, ultimately, group persistence.…”

Investigating tritrophic interactions using bioenergetic demographic models

“…We chose to perturb the system in March because it is the month before the wolf and the elk reproduce (in April and May, respectively). These perturbations can yield important insights on the system because they could mimic the impact of diseases, such as canine distemper and sarcoptic mange in wolves and chronic wasting disease in elk (Brandell et al, 2021(Brandell et al, , 2022.…”

La ecología de los parásitos zoonóticos en Carnivora

“…La sociabilidad o la vida en grupo, también afectarán la transmisión exitosa y la dinámica de los parásitos que se propagan a través del contacto cercano (p. ej., lobos, [24,27]). Por el contrario, la mayoría de los úrsidos (osos) y mustélidos, son asociales y relativamente solitarios, excepto durante el apareamiento y el cortejo [28].…”