Do sex and age affect immunity in Leach's Storm-Petrels?
LE3 .A278 2009
2009
Shutler, Dave
Acadia University
Bachelor of Science
Honours
Biology
Limited energy means that individuals face tradeoffs among competing demands such as growth, reproductive effort, and self-maintenance. Different priorities reflect different life histories, including differences in mating systems and longevity. Polygamous species can have sex-biased immune responses, but less is known about monogamous species. Compromised immunity may be a consequence of increased demands from sexual selection and/or parental care on one sex. In monogamous species, sexual selection may be similar for each sex, and therefore males and females may exhibit similar immune responses. Age also influences immunocompetence; demands of growth may compromise immune investment. Also, the acquired immune system requires previous exposure to antigens to build immunity. For these reasons, juveniles are predicted to have weaker immune systems than adults. To test these predictions, I measured several components of the immune system in Leach’s storm-petrels (Oceanodroma leucorhoa). Petrels are monomorphic, monogamous, long-lived (>30 yr) seabirds that lay single-egg clutches and exhibit very slow post-natal growth. These attributes make them particularly interesting for investigating effects of sex and age on immunity. For both nestlings and adults, I used a hemolysis-hemagglutination assay that measures strength of natural antibodies and complement-mediated lysis. For nestlings only, I used the phytohaemagglutinin test that measures cell-mediated immune response. I collected data on 97 individuals (54 adults and 43 nestlings) in summer 2008 on Bon Portage Island, Nova Scotia. Results confirm my predictions that immune response is unbiased between sexes, and that immune function strengthens with a
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https://scholar.acadiau.ca/islandora/object/theses:553
