Selection - Mutation - Drift

Adaptation and the environment

Selection reduces genetic variation

In this simulation, selection and drift remove alleles from the population, thus decreasing gentetic variation. Alleles are lost randomly (drift) or due to low fitness (selection). At the same time, mutation adds alleles and increases variation.

[graphic]

Selection can lead to adaptation

Without drift, the genotypes that reproduce more and increase in frequency are those whose alleles make them more successful in an environment. [prose]

Thus, selection results in adaptation.

Changes in the environment change the selection on phenotypes. prose for "changeable phenotype frequencies" graphic.

[graphic: user sets an environmental parameter -> changes the graphic of worm phenotypes in response.
   E.G., graphic of worms, some hot phenotypes and some cold phenotypes. The user slides a button along a bar, raising the "temperature." -> the graphic changes, now with more "hot" and fewer "cold" phenotypes.

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Selection