Natural Selection: The main mechanism of evolutionary change. In a given population of organisms, there are heritable traits that enable some members to contribute a larger number of offspring than others. If these offspring also have a greater reproductive success, then the genetic composition of the population is altered, thus evolution. See also selection pressure.

 

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Natural Selection: The process of differential survival and reproduction of fitter genotypes; can be stabilizing, directional, or disruptive. Better adapted individuals are more likely to survive to reproducti . . . View Full Definition

Directional Selection: A process of natural selection that tends to favor phenotypes at one extreme of the phenotypic range.

Stabilizing Selection: A process of natural selection that tends to favor genotypic combinations that produce an intermediate phenotype; selection against the extremes in variation.

Selection Pressure: A measure of the effectiveness of natural selection in altering the genetic composition of a population. See also natural selection.