Life history theory

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The functional differentiation of life expenditure.

The life-history theory ( Engl. Life history theory ), more rarely, theory of life history known as postulated , is that organisms limited resources such as energy , food and time , vital to several competing processes such as growth , health and reproduction have to split up. This creates a problem of distributing the scarce resources for the organism. Every investment in one of the processes reduces the resources available for other processes.

Through natural selection organisms have in their evolutionary history ( phylogeny different) strategies of growth and differentiation processes designed to store operations to maintain their vital functions and reproduction throughout their lives: the so-called life-cycle strategy ( life-history strategy ). Organisms adapt their phenology and life cycle strategy to the amount and distribution of available resources in their habitat . There is a large variety of life cycle strategies.

description

Each organism has only a limited amount of the resources it needs at its disposal. These are essentially: energy, food (including energy stores like fat reserves ) and time. For his survival and the success of his kind he has to share these resources:

  • on his own growth,
  • on the maintenance of its basic functions (e.g. immune system and repair mechanisms)
  • and on reproduction (for example, finding a partner, mating , caring for the offspring).

This results in an allocation problem , that is, a problem of distributing scarce resources. There are trade-offs in the choice of certain behavior patterns or resources . H. to balance for the more favorable aspect in terms of survival and reproduction.

Certain traits directly influence the likelihood of survival and preservation of the species. The most important characteristics are the size at birth, the duration and the speed of the growth phase, the age and the size at the first reproduction, the number and size of the offspring, the frequency of reproduction and the life expectancy of the organism. Other characteristics are, for example, the gender ratio, as well as the care of the offspring ( parental effort ) and their duration. The characteristics are shaped by natural selection and can vary greatly from species to species. Differences between populations can also arise within a species due to different habitats . The ultimate goal of adaptation is to ensure the greatest possible number of surviving, reproductive offspring for the organism. The life cycle strategy is an adaptation to the habitat.

The theory of life history looks for factors and explanations for the diversity of life cycle strategies between species and within species.

An organism with unlimited resources would be a Darwinian demon . In this thought experiment all parameters of the fitness of an organism would be maximized. He would have an infinite life expectancy and unlimited fertility . He would start reproducing immediately after his birth and would have the highest possible rate of reproduction with a large number of offspring during his infinitely long life . He would have the ability to spread indefinitely and find partners for mating anywhere and anytime.

The theory of life history was developed on the basis of Ronald Aylmer Fisher's work in the 1970s and 1980s. Major contributions to this were made by Brian Charlesworth , Lamont C. Cole and Eric Charnov .

See also

further reading

Individual evidence

  1. ↑ E. Voland: Aging and the life course - an evolutionary biological outline. In: Generations H. Künemund and M. Szydlik (editors), Vs Verlag, ISBN 3-531-15413-3 , p. 26. Restricted preview in the Google book search
  2. ↑ There is no adequate translation of the English term. See: W. Henke and H. Rothe: Stammesgeschichte des Menschen: An introduction. Verlag Springer, 1998, ISBN 3-540-64831-3 , p. 53. Restricted preview in the Google book search
  3. ^ H. Caswell: Life-history strategies. In: Ecological concepts: The contribution of ecology to an understanding of the natural world. JM Cherrett (Editor), Blackwell Scientific Publications, Oxford, 1989, pp. 285-307. ISBN 0-632-02569-7
  4. ^ CR Townsend et al. a .: ecology. Verlag Springer, 1993, ISBN 3-540-00674-5 , p. 190f limited preview in the Google book search
  5. ↑ F. Dziock: Survival strategies and food specialization in predatory hover flies (Diptera, Syrphidae). ( Memento from January 18, 2004 in the Internet Archive ) Dissertation, University of Osnabrück, 2002
  6. ↑ a b P. M. Kappeler: Behavioral biology. Verlag Springer, 2005, ISBN 3-540-24056-X , p. 41f limited preview in the Google book search
  7. ↑ JA Encarnação: Phenology and life cycle strategy of male water bats (Myotis daubentonii, Chiroptera: Vespertilionidae). Dissertation, Justus Liebig University Gießen, 2005, p. 9.
  8. ↑ DA Roff: Contributions of genomics to life-history theory. In: Nat Rev Genet 8, 2007, pp. 116-125. PMID 17230198 (Review)
  9. ^ R. Law: Optimal Life Histories under age-specific Predation: In: The American Naturalist 114, 1979, pp. 399-417.
  10. ^ B. Charlesworth: Evolution in Age-Structured Populations. Cambridge University Press, Cambridge, (here 2nd edition, first edition 1980) 1994, ISBN 0-521-45967-2
  11. ^ LC Cole: The population consequences of life history phenomena. In: Q Rev Biol 29, 1954, pp. 103-137. PMID 13177850
  12. ↑ EL Charnov: The Theory of Sex Allocation. Princeton University Press, Princeton, 1982, ISBN 0-691-08312-6 Limited preview in Google Book Search
  13. ^ JH Brown: Life-history evolution under a production constraint. In: PNAS 103, 2006, pp. 17595-17599. doi : 10.1073 / pnas.0608522103 PMID 17090668