Question

which mechanism of evolution is taking place in the following example?
in oregon, captive - bred trout have been introduced into rivers to supplement wild populations. researchers found that the allele frequencies of the wild trout population changed after introduction of the captive - bred fish.
mutation
natural selection
genetic drift
gene flow

Explanation:

Gene flow refers to the transfer of alleles or genes from one population to another. In this case, the introduction of captive - bred trout (which have different allele frequencies) into the wild trout population (causing a change in allele frequencies of the wild population) is an example of gene flow. Mutation is a change in the DNA sequence. Natural selection is the process where organisms better adapted to their environment tend to survive and reproduce. Genetic drift is the change in allele frequencies due to random sampling (e.g., in small populations).

Answer:

gene flow