Growth rates versus immunocompetence in nestling Leach's storm-petrels (Oceanodroma leucorhoa)
LE3 .A278 2011
Bachelor of Science
Life-history theory predicts trade-offs among life-history components. One potential trade-off that I tested for is between growth rate versus immunity in nestling Leach’s storm-petrels, Oceanodroma leucorhoa. The study was done on Bon Portage Island, Nova Scotia. To test immune system strength (immunocompetence), two tests were done: the phytohaemagglutinin skin-test (PHA test), and a bacteria-killing assay. The PHA test assesses adaptive immune responses that involve antibodies tagging invaders for destruction; adaptive immunity can maintain memory of invaders in future infections. The bacteria-killing assay assesses innate immunity that can attack invaders in the blood, primarily through phagocytosis. Growth rates of nestlings were measured by taking four different morphological measurements on a regular basis. There was no significant correlation found between growth rate of tarsus, bill, wing, or mass versus PHA swelling. Likewise there was no significant correlation found between growth rate of tarsus, bill, wing, or mass versus bacteria-killing ability. None of these results was statistically significant (lowest P = 0.11). Thus my results suggest that there is no trade-off between immunocompetence and growth rates in nestling Leach’s storm-petrels. I did find a significant correlation between PHA swelling and mass on day of test, but this relationship was not found for the bacteria-killing assay. Because my study was observational, future work could manipulate nestling nutrition to affect growth rates, and again test for trade-offs with immunocompetence.
The author retains copyright in this thesis. Any substantial copying or any other actions that exceed fair dealing or other exceptions in the Copyright Act require the permission of the author.