Arizona State University (ASU) BIO345 Evolution Exam 1 Practice

The correct choice highlights the fundamental roles of mutation and genetic drift in the evolutionary process. Mutation introduces new genetic variations into a population's gene pool by creating new alleles, which are the different versions of a gene. This increase in heritable variation serves as the raw material for natural selection and can drive evolutionary change.

On the other hand, genetic drift is a stochastic (random) process that can lead to changes in allele frequencies due to chance events, particularly in small populations. As a result, genetic drift can cause the loss of alleles, including beneficial ones, and thereby decreases genetic diversity over time. Thus, while mutation adds new genetic variation, genetic drift can eliminate it, creating an interesting dynamic where one process increases variability and the other may reduce it. This interplay shows how these two mechanisms function as opposing forces in evolution.