What form of reproductive isolation occurs when two populations reproduce at different times?

Temporal isolation is a form of reproductive isolation that occurs when two populations are unable to mate because they reproduce at different times. This can happen due to differences in mating seasons, time of day, or even annual cycles. For example, one population might breed in the spring while another breeds in the fall, preventing any opportunities for interbreeding. This mechanism plays a crucial role in speciation as it helps maintain distinct species by restricting gene flow between them.

In contrast, mechanical isolation refers to physical differences in reproductive structures that prevent mating, behavioral isolation involves differences in mating rituals or behaviors that deter individuals from mating, and gametic isolation occurs when sperm and egg are incompatible, preventing fertilization even if mating occurs. While all these mechanisms serve to reduce the likelihood of interbreeding, temporal isolation specifically focuses on the timing of reproduction as its defining characteristic.