Blackwell Publishing

Multi-locus population genetics - What would real adaptive topographies look like?


The shifting balance theory

The shifting balance theory of evolution was an attempt by Wright to model evolution using both drift and selection.

Wright suggested that random drift could play a creative role in overcoming the tendency of natural selection to become stuck at local fitness peaks on an adaptive landscape.

Drift will tend to make the population gene frequencies 'explore' around their present position; the population could, by drift, move from a local peak to explore the valleys of the fitness surface. Once it had explored to the foot of another hill, natural selection could start it climbing uphill on the other side. With the processes of drift and selection, a population would be more likely to reach the global peak than if it was under the exclusive control of natural selection.

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