Upon infection, animals display a collection of behaviors called "sickness behaviors." Studies of sickness behaviors in seasonally breeding species have shown that the magnitude of an animal's response to infection varies across seasons. Seasonal modulation of sickness behaviors may be a mechanism to avoid over-expending energy or missing a reproductive opportunity, but suppressing the expression of these behaviors may put an organism at greater risk of not being able to clear an infection. Therefore, the degree to which an organism expresses sickness will have profound effects on its survival and reproductive success. When comparing across studies, a clear pattern emerges in that sickness behaviors are attenuated in the season in which an animal has the lowest energy reserves; however, the causative nature of this relationship has not been tested experimentally. The project's working hypothesis is that seasonal variation in sickness behaviors is due to seasonal variation in energy stores. The specific aims of the research are to: 1) determine the contributions of seasonal changes in food availability on sickness behaviors, 2) determine how metabolic hormones influence variation in sickness behaviors, and 3) evaluate the contributions of experimental manipulations of food availability and metabolic hormones on endocrine and immunological factors that directly mediate sickness behavior in seasonally breeding Siberian hamsters. An understanding of the physiological signals that act to modulate the display of sickness behaviors will enhance our knowledge of how environmental conditions affect how an animal responds to an infection. The results of this research will contribute to the current initiatives to understand disease susceptibility as a function of pathogen prevalence (i.e., disease ecology) and host immune function (i.e., ecoimmunology). Additionally, this work has provided opportunities to engage diverse undergraduates in research training and will continue to do so as these projects are completed.
Data will be made available on Research Data Complex (RDC), http://pervasive.iu.edu/hps/rdc
