Deployment cost–benefit selection in physiology


Deployment cost–benefit selection in physiology

Deployment cost–benefit selection in physiology concerns the costs and benefits of physiological process that can be deployed and selected in regard to whether they will increase or not an animal’s survival and biological fitness. Variably deployable physiological processes relate mostly to processes that defend or clear infections as these are optional while also having high costs and circumstance linked benefits. They include immune system responses, fever, antioxidants and the plasma level of iron. Notable determining factors are life history stage, and resource availability.

Contents

Immunity

Activating the immune system has the present and future benefit of clearing infections, but it is also both expensive[1] in regard to present high metabolic energy consumption,[2] and in the risk of resulting in a future immune related disorder. Therefore, an adaptive advantage exists if an animal can control its deployment in regard to actuary-like evaluations of future benefits and costs as to its biological fitness.[3][4] In many circumstances, such trade-off calculations explain why immune responses are suppressed and infections are tolerated.[5][6] Circumstances where immunity are not activated due to lack of an actuarial benefit include:

Fever

Cost benefit trade-off actuary issues apply to the antibacterial and antiviral effects of fever (increased body temperature). Fever has the future benefit of clearing infections since it reduces the replication of bacteria[13] and viruses.[14] But it also has great present metabolic (BMR) cost, and the risk of hyperpyrexia. Where it is achieved internally, each degree raise in blood temperature, raises BMR by 10–15%.[15][16] 90% of the total cost of fighting pneumonia, goes, for example, on energy devoted to raising body temperature.[2] During sepsis, the resulting fever can raise BMR by 55%—and cause a 15% to 30% loss of body mass.[17][18] Circumstances in which fever deployment is not selected or is reduced include:

  • Aged individuals—the burden of tolerating infection will exist for a short time which reduces the actuarial future benefits of clearing an infection compared to the costs of its removal. This change favors reduced or no deployment of fever.[19][20]
  • When internal resources are limited (such as in winter), and the ability to afford high expenditure on increased metabolism is reduced. This increases the risks of activating fever relative to its potential benefit, and animals are less likely to use fever to fight infections.[21]
  • Late Pregnancy[22]

Antioxidants

Antioxidants such as carotenoids, vitamin C, Vitamin E, and enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GPx) can protect against reactive oxygen species that damage DNA, proteins and lipids, and result in cell senescence and death. A cost exists in creating or obtaining these antioxidants. This creates a conflict between the biological fitness benefits of future survival compared with the use of these antioxidants to advantage present reproductive success. In some birds, antioxidants are diverted from maintaining the body to reproduction for this reason with the result that they have accelerated senescence[23] Related to this, birds can show their biological capacity to afford the cost of diverting antioxidants (such as carotenoids) in the form of pigments into plumage as a costly signal.[24][25]

Hypoferremia

Iron is vital to biological processes, not only of a host, but also to bacteria infecting the host. A biological fitness advantage can exist for hosts to reduce the availability of iron within itself to such bacteria (hypoferremia), even though this happens at a cost of the host impairing itself with anemia.[26][27] The potential benefits of such self impairment is illustrated by the paradoxical effect that providing iron supplements to those with iron deficiency (which interferes with its antibacterial action) can result in an individual being cured of anemia but having increased bacterial illness.[28]

See also

Notes

  1. ^ Lochmiller, R. Deerenberg, C. (2000) "Trade-offs in evolutionary immunology: just what is the cost of immunity?" Oikos. 88: 87–98 doi:10.1034/j.1600-0706.2000.880110.x
  2. ^ a b Romanyukha, A. A., Rudnev, S. G. Sidorov, I. A. (2006) "Energy cost of infection burden: an approach to understanding the dynamics of host-pathogen interactions". J Theor Biol. 241: 1–13 PubMed
  3. ^ Read, A. F. Allen, J. E. (2000) "Evolution and immunology. The economics of immunity". Science. 290: 1104–1105 PubMed
  4. ^ van Boven, M. Weissing, F. J. (2004) "The evolutionary economics of immunity". Am Nat. 163: 277–294 PubMed
  5. ^ Hanssen, S. A., Hasselquist, D., Folstad, I. Erikstad, K. E. (2004) "Costs of immunity: immune responsiveness reduces survival in a vertebrate". Proc Biol Sci. 271: 925–930 PubMed
  6. ^ Moret, Y. Schmid-Hempel, P. (2000) "Survival for immunity: the price of immune system activation for bumblebee workers". Science. 290: 1166–1168 PubMed
  7. ^ Lochmiller, R., Vestey, M. Boren, J. (1993) "Relationship between protein nutritional status and immunocompetence in northern Bobwhite chicks". The Auk. 110: 503–510 Ornithological Societies North America JSTOR
  8. ^ Bouree, P. (2003) "Immunity and immunization in elderly". Pathol Biol (Paris). 51: 581–585 PubMed
  9. ^ Prendergast, B. J., Freeman, D. A., Zucker, I. Nelson, R. J. (2002) "Periodic arousal from hibernation is necessary for initiation of immune responses in ground squirrels". Am J Physiol Regul Integr Comp Physiol. 282: R1054-1062 PubMed
  10. ^ Lindstrom, K. M., Foufopoulos, J., Parn, H. Wikelski, M. (2004) "Immunological investments reflect parasite abundance in island populations of Darwin's finches". Proc Biol Sci. 271: 1513–1519 PubMed
  11. ^ Nunn, C. L., Gittleman, J. L. Antonovics, J. (2000) "Promiscuity and the primate immune system". Science. 290: 1168–1170 PubMed
  12. ^ Bilbo, S. D., Drazen, D. L., Quan, N., He, L. Nelson, R. J. (2002) "Short day lengths attenuate the symptoms of infection in Siberian hamsters". Proc Biol Sci. 269: 447–454 PubMed
  13. ^ Bennett, I. L., Jr. Nicastri, A. (1960) "Fever as a mechanism of resistance". Bacteriol Rev. 24: 16–34 PubMed
  14. ^ Herman, P. P. Yatvin, M. B. (1994) "Effect of heat on viral protein production and budding in cultured mammalian cells". Int J Hyperthermia. 10: 627–641 PubMed
  15. ^ Rodriguez, D. J., Sandoval, W. Clevenger, F. W. (1995) "Is measured energy expenditure correlated to injury severity score in major trauma patients?" J Surg Res. 59: 455–459 PubMed
  16. ^ Roe, C. F. Kinney, J. M. (1965) "The Caloric Equivalent of Fever. Ii. Influence of Major Trauma". Ann Surg. 161: 140–147 PubMed
  17. ^ Kreymann, G., Grosser, S., Buggisch, P., Gottschall, C., Matthaei, S. Greten, H. (1993) "Oxygen consumption and resting metabolic rate in sepsis, sepsis syndrome, and septic shock". Crit Care Med. 21: 1012–1019 PubMed
  18. ^ Long, C. L. (1977) "Energy balance and carbohydrate metabolism in infection and sepsis". Am J Clin Nutr. 30: 1301–1310 PubMed
  19. ^ Roghmann, M. C., Warner, J. Mackowiak, P. A. (2001) "The relationship between age and fever magnitude". Am J Med Sci. 322: 68–70 PubMed
  20. ^ Tocco-Bradley, R., Kluger, M. J. Kauffman, C. A. (1985) "Effect of age on fever and acute-phase response of rats to endotoxin and Salmonella typhimurium". Infect Immun. 47: 106–111 PubMed
  21. ^ Bilbo, S. D., Drazen, D. L., Quan, N., He, L. Nelson, R. J. (2002) "Short day lengths attenuate the symptoms of infection in Siberian hamsters". Proc Biol Sci. 269: 447–454 PubMed
  22. ^ Mouihate A, Harré EM, Martin S, Pittman QJ. (2008) Suppression of the febrile response in late gestation: evidence, mechanisms and outcomes. J Neuroendocrinol. 20:508–14.
  23. ^ Wiersma, P., Selman, C., Speakman, J. R. Verhulst, S. (2004) "Birds sacrifice oxidative protection for reproduction". Proc Biol Sci. 271 Suppl 5: S360-363 PubMed
  24. ^ Blount, J. D., Metcalfe, N. B., Birkhead, T. R. Surai, P. F. (2003) "Carotenoid modulation of immune function and sexual attractiveness in zebra finches". Science. 300: 125–127 PubMed
  25. ^ Lozano, G. (1994) "Carotenoids, parasites, and sexual selection". Oikos. 70: 309–311 Blackwell [1]
  26. ^ Kluger, M. J. Rothenburg, B. A. (1979) "Fever and reduced iron: their interaction as a host defense response to bacterial infection". Science. 203: 374–376 PubMed
  27. ^ Weinberg, E. D. (1984) "Iron withholding: a defense against infection and neoplasia". Physiol Rev. 64: 65–102 PubMed
  28. ^ Murray, M. J., Murray, A. B., Murray, M. B. Murray, C. J. (1978) "The adverse effect of iron repletion on the course of certain infections". Br Med J. 2: 1113–1115 PubMed

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