LEE, Kelly A.; MARTIN, Lynn B.; WIKELSKI, Martin C.; Princeton University; The Ohio State University; Princeton University: Do immune defense strategies differ between invasive New World populations of the House Sparrow and their Old World ancestors?

When introduced into new regions, invading organisms leave many native pathogens behind but also encounter evolutionarily novel disease threats. In the presence of predominantly novel pathogens that have not co-evolved to avoid inducing a strong host immune response, costly and potentially dangerous defences such as the systemic inflammatory response could become more harmful than protective to the host. Therefore we hypothesized that successful invaders should exhibit downregulated systemic inflammatory responses relative to their native ancestral populations. To test this hypothesis we conducted a series of experiments comparing behavioural and physiological responses to an inflammatory agent in native and introduced populations of the highly successful avian invader, the House Sparrow(Passer domesticus ). Here we present comparative data from three New World and 2 Old World populations.