Standard 8c Preknowledge
8c) Students know the effects of genetic drift on the diversity of organisms in a population.
CALIFORNIA FRAMEWORKS SUMMARY:
If a small random sample of individuals is separated from a larger population, the gene frequencies in the sample may differ significantly from those in the population as a whole. The shifts in frequency depend only on which individuals fall in the sample (and so are themselves random). Because a random shift in gene frequency is not guaranteed to make the next generation better adapted, the shift—or genetic drift—with respect to the original gene pool is not necessarily an adaptive change. The bottleneck effect (i.e., nonselective population reductions due to disasters) and the founder effect (i.e., the colonization of a new habitat by a few individuals) describe situations that can lead to genetic drift of small populations.