What mechanism can lead to changes in a population's genetic makeup over time?

Changes in a population's genetic makeup over time can occur through multiple mechanisms, each contributing to evolutionary processes.

Gene flow refers to the transfer of genetic material between populations. This exchange can introduce new alleles into a population, increasing genetic diversity and potentially altering the frequency of certain traits. When individuals migrate into or out of a population, their genes come with them, which can have significant impacts on the genetic structure of both the source and recipient populations.

Genetic drift is another mechanism that influences genetic variation through random sampling effects. In smaller populations, genetic drift can result in significant changes over time due to chance events that affect which individuals reproduce. Certain alleles may become more common or completely disappear, not necessarily due to their adaptive value but rather due to random fluctuations.

Natural selection is the process where individuals with advantageous traits survive and reproduce more successfully than others. Over generations, this can lead to a change in the allele frequencies within a population, as beneficial traits become more common and harmful ones diminish.

Given that all of these mechanisms—gene flow, genetic drift, and natural selection—can independently and collectively shape the genetic makeup of populations, the comprehensive option that includes all three is the correct choice. Each mechanism contributes uniquely to how genetic variation can change within