Patterns of Extinction in Prairie Dog Metapopulations: Plague Outbreaks Follow El Nino Events

Abstract

Outbreaks of many vector‐borne human diseases are broadly correlated with climatic variation, but evidence of similar fluctuations in disease in natural host populations is rare. Here, we use 21 years of monitoring of black‐tailed prairie dog (Cynomys ludovicianus) colonies to demonstrate a link between extinctions of colonies attributed to plague (Yersinia pestis) and climatic fluctuations associated with El Ninì Southern Oscillation events that promote the growth of flea vector and rodent host populations. During epizootics, rates of extinction of the largest colonies (>16 ha) were nearly as high (>60%) as for the smallest ones (<3 ha), but only a third of intermediate‐sized colonies were extirpated. The probability of extinction was influenced by the size and fate of adjacent colonies, but there was no predictable relationship between extinction probabilities and intercolony distance, indicating that spatial isolation does not reduce the vulnerability of colonies to plague. By causing sporadic extinctions of colonies, plague creates a metapopulation structure that has altered the dynamics of prairie dog colonies as they respond to a century of human persecution and habitat loss.

Plague outbreaks in prairie dog populations explained by percolation thresholds of alternate host abundance

“…Patterns of prairie dog colony extinctions suggest that colony area and the fate of adjacent colonies are important influences on the likelihood a colony suffering die-offs (8). This pattern suggests that the movement of plague between prairie dog colonies is caused by the movement of infectious animals or animals carrying infectious fleas and that metapopulation dynamics may be important in explaining plague's ecology at the landscape scale (1,8,26,27). Nonetheless, our model and field observations suggest that, if plague arrives at a prairie dog colony, the local grasshopper mouse abundance will be a strong influence on the likelihood of Y. pestis transmission erupting into an outbreak as opposed to smoldering cryptically through the prairie dog population.…”

“…Prairie dogs are social ground squirrels that occupy large towns or colonies on the prairie that can extend for hundreds of hectares and comprise several thousand individuals. Plague-induced prairie dog die-offs occur intermittently, but when they do, nearly 100% of prairie dogs in a colony die from the disease (7,8). Based on observations of prairie dog die-offs, the general consensus suggests that plague outbreaks occur extremely rapidly, such that only a few survivors are observed after 6-8 wk (7,9).…”

Flea Diversity and Infestation Prevalence on Rodents in a Plague-Endemic Region of Uganda

“…In situations where flea loads differed among time periods, they generally increased during the months of early rains or agricultural harvest periods from March through August as the plague season approached. These changes could be driven by climate, as has been suggested for plague activity in this and other geographic regions, 8,[41][42][43][44] and could prime vector-host communities for plague epizootics, if the pathogen is introduced. The onset of heavy rains in late August, which marks the start of the plague season, could drive rats into human dwellings, which may increase the likelihood of human exposure to infected rats or their fleas.…”

Tropical cloud forest climate variability and the demise of the Monteverde golden toad

“…Epidemicdriven extinction may be the result of a series of biotic and abiotic interactions across spatial and temporal scales (11,44). Drought or pluvial conditions associated with strong ENSO events are known to be associated with localized extinction (45,46). In Yellowstone National Park, amphibian declines have been linked to the combination of decreasing precipitation, increasing temperatures, and wetland desiccation, which affects populations by contributing to increasing mortality, decreased migration, and reduced opportunities for wetland colonization (47).…”