Electronic Thesis and Dissertation Repository


Master of Science




Dr. Elizabeth A. MacDougall-Shackleton


Parasites vary geographically and dispersing host individuals may encounter different strains and wider varieties than their philopatric counterparts. Previously observed lower parasite counts in philopatric than dispersing birds have been suggested to be the result of local adaptation to parasites, but I suggest an alternative: these patterns may result from differing immune function. I used genetic assignment tests to infer natal philopatry of song sparrows (Melospiza melodia), and tested whether this predicted parasitism and innate and adaptive immune function. I found no relationship between parasitism and philopatry, in contrast to previous findings. In females, philopatry was associated with higher cellular innate immunity and lower humoral innate immunity. I also detected a negative relationship between measures of cellular adaptive immunity and humoral innate immunity. These results suggest a sex-specific, philopatry-mediated immune tradeoff that occurs along the cellular-humoral axis, rather than the innate-adaptive axis traditionally focused on in ecophysiological life history.