Which of the following statements best defines speciation?

• A. The extinction of a species due to environmental factors.
• B. The migration of individuals between populations.
• C. The formation of new and distinct species in the course of evolution, often via reproductive isolation.
• D. The adaptation of a population without diverging.

Answer: (C)

Speciation is the process by which new and distinct species arise during evolution, usually because populations become reproductively isolated from one another. When gene flow is reduced or stopped, each group can accumulate genetic differences through mutation, natural selection, and genetic drift. Over time, these differences can create barriers to interbreeding, so even if the populations meet again they can no longer produce viable or fertile offspring. That combination of divergence and reproductive separation is what defines the formation of new species.

Extinction, while related to the fate of species, is not how new species form. Migration between populations increases gene flow rather than promoting divergence, so it typically prevents speciation. Adaptation within a single population without divergence into separate lineages does not produce a new species.