Compare and Contrast Directional natural selection and Stabi

Compare and Contrast

Directional natural selection and Stabilizing natural selection

Solution

When selective pressures select against the two extremes of a trait,the population experiences stabilizing selection.Stabilizing selection results in a decrease of a populations genetic variance when natural selection favors an average phenotype and selects against extreme variations.It acts against both extreme phenotypes.Stabilizing selection occurs when conditions do not favor either of the extreme phenotype variants.This favors and results in a high frequency of the intermediate phenotype.
In directional selection,one extreme of the trait distribution experiences selection against it.The result is that the populations trait distribution shifts toward the other extreme.In such case,the mean of the population graph shifts.In directional selection,a population\'s genetic variance shifts toward a new phenotype when exposed to environmental changes.In this a single phenotype is favored,Causing the allele frequency to continuously shift in one direction.When the environment changes,populations will often undergo directional selection, which selects for phenotypes at one end of the spectrum of existing variation.