© 1979 by The Society for Integrative and Comparative Biology
Fever in Ectotherms: Evolutionary Implications
Department of Physiology, University of Michigan Medical School Ann Arbor, Michigan 48109
Fever, an elevated thermoregulatory "set-point," occurs in vertebrates from fishes through mammals in response to infection with appropriate pathogens. The long phylogenetic history of fever supports the hypothesis that fever has an adaptive or beneficial role (i.e., fever is a component of the host's immunological defenses). Besides providing insight into determining the role of fever in disease, ectothermic vertebrates have also served as excellent animal models to specifically answer many questions relating to fever and disease. For example, survival studies using goldfishes, lizards, and newborn mammals which are also virtually ectothermic) have shown that an elevated body temperature increases the survival rate of the infected organism. Furthermore, by using ectotherms it has been possible to demonstrate that the reduction in serum iron which accompanies most infections is not directly attributable to an elevation in body temperature. Nevertheless, a rise in body temperature, coupled with a fall in serum iron, appears to constitute a coordinated host defense mechanism in response to at least some bacterial infections in reptiles and mammals, and perhaps other groups of vertebrates.