Constitutive innate immunity is a component of the pace-of-life syndrome in tropical birds

Abstract

We studied the relationship between one component of immune function and basal metabolic rate (BMR), an indicator of the 'pace-of-life syndrome', among 12 tropical bird species and among individuals of the tropical house wren (Troglodytes aedon), to gain insights into functional connections between life history and physiology. To assess constitutive innate immunity we introduced a new technique in the field of ecological and evolutionary immunology that quantifies the bactericidal activity of whole blood. This in vitro assay utilises a single blood sample to provide a functional, integrated measure of constitutive innate immunity. We found that the bactericidal activity of whole blood varied considerably among species and among individuals within a species. This variation was not correlated with body mass or whole-organism BMR. However, among species, bacteria killing activity was negatively correlated with mass-adjusted BMR, suggesting that species with a slower pace-of-life have evolved a more robust constitutive innate immune capability. Among individuals of a single species, the house wren, bacteria killing activity was positively correlated with mass-adjusted BMR, pointing to physiological differences in individual quality on which natural selection potentially could act.

Capture Stress and the Bactericidal Competence of Blood and Plasma in Five Species of Tropical Birds

“…Furthermore, a follow-up study that increases the number of species (but measures bacteria-killing using whole blood only) demonstrates that bacteria killing and masscorrected basal metabolic rates are inversely related, again suggesting a slow pace of life is associated with high bacteria-killing abilities. (Tieleman et al 2005).…”

Complex Interplay of Body Condition, Life History, and Prevailing Environment Shapes Immune Defenses of Garter Snakes in the Wild

“…A bias toward measures of innate immune function in studies of free-living organisms is not uncommon due to their ease of sampling under field conditions, especially for animals for which recapture in the wild is difficult (e.g., Tieleman et al 2005;Graham et al 2011;Hegemann et al 2012). Unlike many innate immune measures, most measures of acquired immunity routinely used by ecoimmunologists often necessitate two captures (e.g., in vivo antibody response to a challenge and delayedtype hypersensitivity response).…”

A Theoretical Investigation of the Effect of Latitude on Avian Life Histories

“…Ultimate selection pressures influencing the above-named traits may also have been instrumental in shaping widespread differences in metabolic rate between temperate-zone and tropical birds (Ricklefs 1976;Weathers 1979Weathers , 1997Klaassen and Drent 1991;Klaassen 1994;Tieleman et al 2005). In general, tropical birds have lower metabolic rates, that is, a slower "pace of life" (Wikelski et al 2003;Wiersma et al 2007).…”