Final answer:
Over a long period, two populations may become so distinct through reproductive isolation and evolutionary forces that they are considered different species. Speciation occurs at the species level and does not affect larger taxonomic groups.
Step-by-step explanation:
Over the course of a long period of time, two populations may diverge to such a degree that they would be referred to as different species. When two populations become reproductively isolated from each other through mechanisms like habitat isolation, they cease to reproduce with their parent species, and over time, they become genetically independent.
Evolutionary forces such as natural selection, mutation, and genetic drift contribute to this divergence, ultimately leading to speciation. Speciation is the process by which new biological species arise. It's important to note that divergence due to speciation occurs at the species level and does not affect larger taxa like orders, genera, or families. A species is defined as a group of organisms that are genetically related and capable of breeding to produce fertile offspring.