What evolutionary mechanisms have the ability to increase or decrease genetic diversity in a population? List and define three.

Answer 1

Four forces of evolution are genetic drift, mutation, migration, and selection.

Genetic drift can occur through inbreeding or random events that alter a population. For inbreeding, alleles can be lost if they are under represented in the inbreeding population. Similarly, when random events, such as isolation or natural disasters, alter a population alleles can become under represented and lost in the population. This type of evolution decreases diversity within a population and increases diversity between populations.

Mutations can be as small as single base changes (point mutations) or the gain or loss of large portions of a chromosome. This type of evolution has the effect of increasing variation within populations, but decreasing variability between populations.

Migration occurs when individuals from one population move into another population. The alleles of the migrating individuals get introduced into the gene pool of the new population. This type of evolution has the effect of increasing variability within the new population as new alleles are introduced, and decreasing variability between populations because the spread of alleles makes the two populations more similar.

Selection occurs when one allele has a greater fitness for survival in a particular environmental background that another. This is often misstated as "survival of the fittest", but should be termed "survival of the fit" because an allele that is beneficial to survival in one environment might not be beneficial in another environment. Depending on the type of selection, this type of evolution can either increase or decrease variability both within and between populations.

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