In genetics, what encompasses the changes in gene frequencies due to each individual in a population surviving randomly?

The correct choice is the concept of genetic drift, which refers to the random changes in gene frequencies within a population over time, particularly in small populations. This process occurs due to chance events that affect which individuals survive and reproduce, thereby passing on their genes to the next generation. Unlike natural selection, where environmental factors influence which traits are favorable, genetic drift operates independently of those factors.

Over generations, genetic drift can lead to significant shifts in allele frequencies, potentially resulting in the loss of genetic variation and making some traits more common simply due to random sampling of alleles. This is particularly evident in small populations, where the effects of random events can have a more pronounced impact compared to larger populations where these random fluctuations are averaged out. Understanding genetic drift is fundamental to studying population genetics and evolutionary biology, as it illustrates one way in which evolution can occur outside the context of adaptive change.