Fitness consequences of immune responses: strengthening the empirical framework for ecoimmunology

Abstract

Summary 1.Ecoimmunologists aim to understand the costs, benefits, and net fitness consequences of different strategies for immune defense. 2. Measuring the fitness consequences of immune responses is difficult, partly because of complex relationships between host fitness and the within-host density of parasites and immunological cells or molecules. In particular, neither the strongest immune responses nor the lowest parasite densities necessarily maximize host fitness. 3. Here, we propose that ecoimmunologists should routinely endeavour to measure three intertwined parameters: host fitness, parasite density, and relevant immune responses. We further propose that analyses of relationships among these traits would benefit from the statistical machinery used for analyses of phenotypic plasticity and ⁄ or methods that are robust to the bi-directional causation inherent in host-parasite relationships. For example, analyses of how host fitness depends upon parasite density, which is an evolutionary ecological definition of tolerance, would benefit from these more robust methods. 4. Together, these steps promote rigorous quantification of the fitness consequences of immune responses. Such quantification is essential if ecoimmunologists are to decipher causes of immune polymorphism in nature and predict trajectories of natural selection on immune defense.

Dietary Supplementation of <i>Ocimum Gratissimum </i>Improves Immune Response without Affecting the Growth Performance and Blood Characteristics in Taiwan Country Chicken

“…As emphasized in several recent articles, higher immunological response does not necessarily indicate a better parasite resistance or even better lifetime health (Owen and Clayton, 2007;Graham et al, 2011). On the contrary, higher immune response may even indicate ineffective antiparasite protection or immunopathology (Graham et al, 2005).…”

Variations of transcript profiles between sea otters Enhydra lutris from Prince William Sound, Alaska, and clinically normal reference otters

“…Consistent with our findings of relatively normal transcription of AHR, Bodkin et al (2012) indicated that average annual oil encounter rates ranged from 2 to 24 times yr −1 for females, and 2 to 4 times yr −1 for males. Mitigation of detrimental effects imposes demands on animals above those normally required to sustain life and may result in reduction of fitness evidenced by decreased reproductive capability, increased susceptibility to disease, or disadvantageous behavioral changes (Graham et al 2010, Martin et al 2010. Such effects may ultimately be manifested in reduced survival rates , Monson et al 2011) that contributed to the delayed recovery of sea otters observed in areas of PWS initially oiled in 1989 (Bodkin et al 2002).…”

“…Chronic transcription of genes responsible for immunologic function, including detoxification, can be physiologically costly (Graham et al 2010). Perhaps the largest cost is the reallocation of nutrients and energy from one portion of an individual's resource budget to other functions.…”

Does immune suppression during stress occur to promote physical performance?

“…House sparrows appear prone to hyper-inflammation over long periods in captivity ( enhancements might be interpreted as protective, these elevations are more likely indicative of immune disregulation with subsequent, strong negative impacts (i.e. immunopathology) on hosts (Graham et al, 2011). In the present study, we examined captivity effects on two innate immune measures: BKA (Millet et al, 2007) and oxidative burst (Sepp et al, 2010;Sild and Horak, 2010).…”

“…immunopathology) on hosts (Graham et al, 2011). In the present study, we examined captivity effects on two innate immune measures: BKA (Millet et al, 2007) and oxidative burst (Sepp et al, 2010;Sild and Horak, 2010).…”