Immune Defense and Host Life History

Abstract

Recent interest has focused on immune response in an evolutionary context, with particular attention to disease resistance as a life-history trait, subject to trade-offs against other traits such as reproductive effort. Immune defense has several characteristics that complicate this approach, however; for example, because of the risk of autoimmunity, optimal immune defense is not necessarily maximum immune defense. Two important types of cost associated with immunity in the context of life history are resource costs, those related to the allocation of essential but limited resources, such as energy or nutrients, and option costs, those paid not in the currency of resources but in functional or structural components of the organism. Resource and option costs are likely to apply to different aspects of resistance. Recent investigations into possible trade-offs between reproductive effort, particularly sexual displays, and immunity have suggested interesting functional links between the two. Although all organisms balance the costs of immune defense against the requirements of reproduction, this balance works out differently for males than it does for females, creating sex differences in immune response that in turn are related to ecological factors such as the mating system. We conclude that immune response is indeed costly and that future work would do well to include invertebrates, which have sometimes been neglected in studies of the ecology of immune defense.

Costs of Franklin’s ground squirrel (Poliocitellusfranklinii) ectoparasitism reveal adaptive sex allocation

“…Additionally, though body mass can provide an acceptable indicator of body fat in sciurid species (Becker et al 1998;Humphries and Boutin 1996), a more robust estimation of body condition may have revealed an effect of insecticide treatment (Schulte-Hostedde et al 2001). Indeed, costs of parasitism may not be discernible by external metrics given potential disparate effects on different internal systems, or may be detectable only as they accumulate over the long term (Zuk and Stoehr 2002;Kristan 2004;Scantlebury et al 2010). As mass is not the sole measure of juvenile quality, juvenile survival may provide a more informative measure of the influence of parasitism on dam fitness (Arnold and Lichtenstein 1993;Van Vuren 1996;Patterson et al 2013).…”

Subtle effect of Xenos vesparum (Xenidae, Strepsiptera) on the reproductive apparatus of its male host: Parasite or parasitoid?

“…For example, differences in parasite prevalence between males and females are found in a wide range of taxa (see Zuk and McKean, 1996). Intriguingly, males usually show greater parasite prevalence (Klein, 2000;Zuk and Stoehr, 2002;Zuk, 2009;Schmid-Hempel, 2011), due to a trade-off between mating efforts and immunocompetence -and consequently susceptibility to disease: the more resources are spent to procure a mate the less are available for defense against parasites (Schmid-Hempel, 2005). Females, instead, generally do not show this trade-off as they gain reproductive fitness by living longer (i.e.…”

Factors affecting leucocyte profiles in the little auk, a small Arctic seabird

“…However, maintaining or activating immune function in vertebrates can be energetically costly and thus resource dependent (Saino et al 1997(Saino et al , 2003Norris and Evans 2000;Lochmiller and Deerenberg 2000;AlonsoAlvarez and Tella 2001;Martin et al 2002). Therefore, it may compete for nutrient or energy resources with important life-history stages such as reproduction or growth and development (Sheldon and Verhulst 1996;Lochmiller and Deerenberg 2000;Norris and Evans 2000;Zuk and Stoehr 2002;Lee 2006).…”