What is meant by genetic drift?

Genetic drift refers to the random fluctuations in the frequencies of alleles (variations of a gene) within a population, which can occur over time due to chance events. Unlike natural selection, where traits that confer an advantage are more likely to be passed on to future generations, genetic drift happens independently of the traits' effects on survival or reproduction.

In small populations, genetic drift can have a significant impact, leading to the loss or fixation of alleles, which alters the genetic makeup of the population randomly. An example of genetic drift is the bottleneck effect, where a significant reduction in population size results in a loss of genetic variation. Over time, this randomness can lead to populations that are genetically distinct from one another, even if they originally shared a common gene pool.

The other options describe different processes related to genetic change in populations. Intentional selection focuses on human influence in breeding practices, while natural selection is based on the survival advantages of certain traits. Systematic changes due to environmental factors refer to adaptations rather than the random nature of genetic drift.