Differences in allele effects on fitness within a population are referred to as?

The concept of differences in allele effects on fitness within a population is best encapsulated in the principle of selection. Selection refers to the differential survival and reproduction of individuals due to differences in phenotype, which are often driven by allele variations. When certain alleles provide a better fit to the current environment, individuals carrying those alleles are more likely to survive and reproduce, thereby increasing the frequency of those beneficial alleles in future generations.

In a population, this process results in natural selection, where the alleles that enhance the overall fitness—defined as the ability to survive and reproduce—become more prevalent. This mechanism is fundamental to evolutionary biology, as it explains how populations adapt to their environments over time.

The other options represent different biological processes. Genetic drift refers to random changes in allele frequencies that occur in small populations, while mutation is the process of changing the genetic material, leading to new alleles. Random mating describes a scenario where individuals pair without regard to their genotypes or phenotypes, influencing genetic variation but not directly affecting allele fitness or selection pressures.