Glossary of Evolution (2nd ed.) by Futuyma (2009)
- A process of genetic change in a population whereby, as a result of natural selection, the average state of a character becomes improved with reference to a specific function, or whereby a population is thought to have become better suited to some feature of its environment. Also, an adaptation: a feature that has become prevalent in a population because of a selective advantage conveyed by that feature in the improvement in some function.
Glossary of Ecology (6th ed.) by Krebs (2009)
- any alteration in the structure or function of an organism by which the organism becomes better able to survive and multiply in its environment.
Glossary of Plant Systematics (1st ed.) by Simpson (2006)
- A structure or feature that performs a particular function and which results in increased survival or reproduction.
- Futuyma, D. J. 2009. Evolution, 2nd ed. -xviii + 633 pp. Sinauer Associates, Inc., Sunderland.
- Krebs, C. J. 2009. Ecology, 6th ed. -xvi + 655 pp. Pearson Benjamin Cummings, San Francisco.
- Simpson, M. G. 2006. Plant Systematics. -xi + 590 pp. Elsevier Academic Press, Oxford.