Meeting Abstract

29.5  Wednesday, Jan. 5  Song complexity in the song sparrow (Melospiza melodia) as an indicator of constitutive immune function KUBLI, S.*; MACDOUGALL-SHACKLETON, E.A.; The University of Western Ontario, London, ON; The University of Western Ontario, London, ON skubli@uwo.ca

Indicator models of sexual selection predict that ornaments advertise aspects of male quality, such as disease resistance. However, trade-offs between different components of fitness should prevent investing maximally in both ornamentation and immune function at the same time. In many songbirds, females evaluate mates largely on the basis of song complexity, the costs of which are thought to be paid mainly during early life. This timing may mitigate trade-offs between song learning and adult immune function, making song a highly reliable advertisement of disease resistance. We hypothesized that song sparrows (Melospiza melodia) with larger song repertoires are also better able to allocate toward constitutive immune function as breeding adults. To test this hypothesis, we quantified song complexity (repertoire size) for 34 breeding males and also measured constitutive immune function using a variety of complementary assays. Microbicidal assays were performed to assess whole blood capacity to kill three different microorganisms. In complement to this, we also measured specific individual components of the innate immune system, which included soluble blood proteins (lysozyme, mannan-binding protein, and haptoglobin), natural antibody and complement interactions, and macrophage phagocytic activity. We chose these techniques to inform additionally on investment in constitutive immunity, as well as the physiological state of the individual, including current infection status. The degree to which song complexity advertises constitutive immune function will be discussed.