Definition: Characteristics of an organism directly related to its survival and reproduction in a given environment. Example: A bird species lives in an environment recently invaded by a new predator. The birds' feathers are multi-colored to varying degrees. It so happens that the new predator cannot see yellow-colored objects very well. Consequently, over many generations, birds with mostly yellow feathers tend to survive and reproduce, whereas birds with feathers mostly of other colors tend to be caught, not reproduce, and ultimately become extinct. In this environment, an adaptive feature for the bird species is yellow feathers. Note that if, for whatever reasons, the new predator was to leave the environment inhabited by the birds, yellow feathers would no longer be an adaptive feature. Background: Charles Darwin (1809-1882), influenced by Malthus's Essay on the Principle of Population (1798/1914), noted the environment cannot always sustain the reproductive capacity of a species. In such cases, the offspring struggle for survival. Importantly, individuals differ with respect to various traits. The fittest offspring, that is, those possessing adaptive features, prevail and reproduce, whereas less fit individuals extinguish and don't reproduce. In this way the environment naturally selects certain characteristics over others. The process is typically slow, occurring over many eons. Note that adaptive features are not fixed; they are subject to change as the environment changes. Further Reading:
Darwin, C. (1859). On the origin of species by means of natural selection. London: Murray.
Department of Ecology and Evolutionary Biology at Tulane University (1997). Darwin's theory of evolution [On-line] Available: http://www.tulane.edu/~eeob/Courses/Heins/Evolution/lecture3.html
Kimbell, J. W. (2001). Evolution and adaptation [On-line] Available: http://www.ultranet.com/~jkimball/BiologyPages/E/Evolution.html#NaturalSelection
Mayr, E. (1991). One long argument: Charles Darwin and the genesis of modern evolutionary thought. Cambridge Mass.: Harvard University Press.
Related Terms: Darwin, Charles (1809 - 1882)
Malthus, Thomas (1766 - 1834)
Spencer, Herbert (1820 - 1903)
Survival of the fittest
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