Individual and environmental determinants of parasitism in a wild rodent population

Poster session
Partie de:
11:30, vendredi 20 déc. 2019 (1 heure)
Dîner   12:30 PM à 01:30 PM (1 heure)
Salle ABCD

Understanding the interactions between parasites, hosts, and their shared environment is central to ecology and evolution. Variation in parasite prevalence may be resulting from environmental and population characteristics; however, it may also depend on individual factors that influence exposure and susceptibility to parasites. Using 12 years of data from a population of wild eastern chipmunks (Tamias striatus) relying on pulsed food resources, we investigated the determinants of bot fly parasitism at both the population and individual level. We assessed the relationship between infestation prevalence and weather conditions, population size and food abundance. Then, we assessed the relationship between infestation intensity and chipmunk behavior, sex, age, body mass and food abundance. Precipitation, temperature and population size were positively related to infestation prevalence, while masting cycles of beech trees were negatively related to infestation prevalence, highlighting the importance of local environmental conditions on hosts and parasites. We also found that the influence of activity on infestation intensity varied according to sex in adults. More active males had more parasites compared to females, suggesting that reproductive behaviors may influence parasite exposure. For juveniles, levels of parasitism were greater when juveniles emerged in the spring as opposed to the fall, possibly because spring emergence is synchronized with the peak of bot fly eggs in the environment, low food availability and a longer activity period. Our results suggest that the environmental, population and host characteristics that are advantageous for reproduction and resource acquisition may come at the cost of increasing parasitism in host populations.

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