Meeting Abstract

134.4  Monday, Jan. 7  Delusions of immunocompetence: song complexity, song consistency and immune trade-offs in song sparrows KUBLI, SP; MACDOUGALL-SHACKLETON, EA*; Western University; Western University emacdoug@uwo.ca

In short-lived, migratory songbirds, constitutive innate immunity is an important component of fitness. Females cannot directly assess immune function of potential mates, but condition-dependent ornaments or displays may provide information about the signaler’s past or current condition. We investigated the degree to which song complexity and song consistency, thought to reflect condition over different developmental timescales, predict multiple aspects of constitutive innate immunity in 38 male song sparrows. We also investigated correlations among immune measures. Principal components analysis revealed an overall pattern of opposite loading between protective protein (haptoglobin, lysozyme, natural antibody) versus cellular (microbicidal, phagocytosis) components of immunity. Song complexity, a static trait that does not change during adulthood in this species, was associated with relative investment in protective proteins versus cellular activity: males with large repertoires had higher protective protein titres but lower leukocyte activity relative to males with small repertoires. Song consistency, a dynamic trait that varies throughout the life of the individual, did not predict relative investment in proteins versus cellular defences. Song complexity may reflect individual variation in self-maintenance strategies, rather than overall immune functioning per se. Perhaps most important, these findings illustrate the importance of assessing multiple aspects of immunity rather than attempting to infer “immunocompetence” from a single metric.