The increase in diversity of dog breeds is most closely associated with selective breeding. This process involves humans intentionally mating dogs with specific traits to produce offspring that exhibit desired characteristics. Over generations, selective breeding has allowed for the proliferation of a vast array of dog breeds, each with unique physical and behavioral traits, tailored for specific purposes such as herding, companionship, or working traits.
Selective breeding enables breeders to emphasize particular attributes, like coat color, size, or temperament, leading to the wide variety of breeds we see today. This differs from natural selection, which relies on environmental pressures and survival advantages rather than human choice. Random mutation contributes to genetic variations but does not directly establish the intentional diversification seen in dog breeds. Environmental adaptation also plays a role in how certain breeds may perform better in specific climates or tasks, but it does not drive the purposeful creation of new breeds.