Arizona State University (ASU) BIO345 Evolution Exam 1 Practice

Genetic drift is a mechanism of evolution that describes random changes in allele frequencies within a population, particularly pronounced in small populations. This randomness arises because, in smaller groups, chance events can have a more significant impact on which individuals contribute to the next generation's gene pool. Unlike natural selection, which is a non-random process favoring certain traits, genetic drift can lead to the loss of alleles (reducing genetic diversity) or the fixation of alleles (where a particular allele becomes the only variant in the population).

For instance, if a few individuals with a specific allele fail to reproduce due to chance, that allele could disappear entirely from the population. Conversely, a different allele might become fixed simply by chance, not because it provides any advantage. This process highlights the unpredictable nature of genetic drift and its role in shaping genetic variation in small populations, influencing evolutionary trajectories in ways that may not occur in larger populations where allele frequencies are more stable over time.