How can genetic drift lead to speciation in populations?

Genetic drift is a mechanism of evolution that can lead to speciation by causing populations to diverge genetically over time. When a population is small, random changes in allele frequencies can have a significant impact. These changes may result in certain alleles becoming more or less common purely by chance, rather than through natural selection. As genetic drift continues across generations, especially in isolated populations, the genetic differences between them can accumulate.

When these genetic differences become substantial, they can lead to reproductive isolation, where individuals from these diverged populations may no longer interbreed even if they come into contact again. This process is crucial in the formation of new species, as it is the genetic divergence and subsequent isolation that drive speciation.

Other options, while related to evolution and population dynamics, do not adequately describe the role of genetic drift in speciation. Increasing population size typically reduces the impact of genetic drift rather than promoting divergence, while decreased gene flow can indeed contribute to speciation but is a separate mechanism from genetic drift itself. Enhancing natural selection is more about adaptive evolution rather than the random changes that characterize genetic drift.