R-selection
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- The title of this article is incorrect because of technical limitations. The correct title is r-selection.
In ecology, r-selection (note: lower case "r") relates to the selection of traits (in organisms) that allow success in unstable or unpredictable environments. Under these circumstances, the ability to reproduce quickly is crucial, and there is little advantage in adaptations that permit successful competition with other organisms (since the environment is likely to change again). Traits that are thought to be characteristic of r-selection include : high fecundity; small size; short generation time; and the ability to disperse offspring widely. Organisms whose life history is subject to r-selection are often referred to as "r-strategists". Species with r-selected traits include bacteria, diatoms, many insects and plants labelled weeds.
The term r-selection itself is derived from standard ecological algebra, as illustrated in the simple Verhulst equation of population dynamics:
- <math>\frac{dN}{dt}=rN(K-N) \qquad \!<math>
Where <math>r<math> is the growth rate of the population (<math>N<math>), and <math>K<math> is its carrying capacity.
It should be noted that, although some organisms are primarily r- or K-strategists, the majority of organisms fall between these two ecological extremes, and may display traits considered characteristic of both ends of the r-K spectrum. For instance, trees have traits such as longevity and strong competitiveness that characterise them as K-strategists. However, in reproduction, trees typically produce thousands of offspring and disperse them widely, traits characteristic of r-strategists.
Contrast with K-selection.