Meeting Abstract

S6.9  Wednesday, Jan. 5  Individual heterogeneity in house finch immunity and disease resistance: what can physiology tell us about epidemiology? HAWLEY, DM; Virginia Tech hawleyd@vt.edu

Individual heterogeneity in disease susceptibility is largely the rule for natural populations, with striking consequences for population-level disease dynamics. However, surprisingly few studies have characterized the ecological and social factors mediating vertebrate immunity and disease resistance over space and time. Here I summarize my research to date on house finches, Carpodacus mexicanus, a common North American songbird species which was colonized by the bacterial pathogen Mycoplasma gallisepticum in the early 1990s. Because house finch infection with M. gallisepticum occurs exclusively in a social context, I use this system to explore how social behavior, genetics, immunity, and endocrinology interact to mediate individual variation in resistance and exposure to M. gallisepticum. I present evidence that individual immunity and disease resistance are mediated by social status in house finches, but the nature and extent of these effects are largely dependent on social context. In male house finches, social competition for food resources directly mediates both the ability to resist M. gallisepticum and the potential for secondary transmission to susceptible conspecifics, making aggression levels a particularly interesting mediator of disease dynamics in this system. I discuss how context-dependent variation in susceptibility and exposure in house finches may scale up to mediate population-level disease dynamics, including the continued persistence of M. gallisepticum epidemics in North American house finch populations.