Ecological immunology
Hosts can either resist an infection by eventual clearance, or tolerate the consequences of parasitism, and thus leads to various outcomes in terms of specificity, response delay and strength, or the formation of memory.
Abstract
Infections and parasite loads vary among hosts. Variation results from ecological, genetic, and immunological factors. Immune defences provide benefits as well as costs and are, therefore, a compromise. Costs result from trade-offs with other needs and can be genetically encoded or plastic (i.e. can change depending on circumstances). Costs are physiological (e.g. energy consumption) or based on evolved genetic covariance. Self-damage (immunopathology) is a further, important cost. Natural selection should optimize the costs and benefits of defences and thus leads to various outcomes in terms of specificity, response delay and strength, or the formation of memory. Moreover, hosts can either resist an infection by eventual clearance, or tolerate the consequences of parasitism.