K-selection
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In ecology, K-selection (note : upper case "K") relates to the selection of traits (in organisms) that allow success in stable or predictable environments. Under these circumstances, the ability to compete successfully for limited resources is crucial, and populations of K-selected organisms are typically very constant and close to the maximum that the environment can bear. Traits that are thought to be characteristic of K-selection include : large size; long life span; and the production of fewer offspring that are well cared for. Organisms whose life history is subject to K-selection are often referred to as "K-strategists". Species with K-selected traits include trees, and large animals such as elephants, humans and whales.
The term K-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>K<math> is the carrying capacity of the population (<math>N<math>), and <math>r<math> is its growth rate.
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 r-selection.