What does allele frequency refer to?

Allele frequency specifically refers to the proportion of a particular allele at a given gene locus among all alleles present in the gene pool of a population. This measurement is crucial in population genetics as it provides insight into the genetic diversity of a population and how it may change over time due to factors such as selection, genetic drift, and mutation. By assessing allele frequency, researchers can understand evolutionary processes and the potential adaptability of a population.

The other options do not accurately capture the concept of allele frequency. For instance, the total number of different alleles in a species pertains more to genetic diversity or variation rather than frequency. The rate of mutations in a population relates to how often new alleles are introduced but does not define what allele frequency is. Similarly, while the variety of alleles in an organism is related to genetic diversity, it does not address the proportionate aspect crucial in defining allele frequency. Thus, the accurate understanding of allele frequency is fundamental to studying population genetics and evolution.