How do populations become reproductively isolated?
Populations can become reproductively isolated in several ways, including:
1. Geographical isolation: When a physical barrier, such as a mountain range or a river, separates a population into two or more groups that cannot interbreed.
2. Temporal isolation: When two or more populations of a species breed at different times of the year, they cannot interbreed.
3. Behavioral isolation: When two populations of a species have different courtship rituals, mating calls or other behaviors, they cannot interbreed.
4. Mechanical isolation: When two populations of a species have physical differences that prevent mating or fertilization, they cannot interbreed.
5. Gametic isolation: When two populations of a species have differences in their reproductive cells (gametes) that prevent fertilization, they cannot interbreed.
Over time, these factors can cause genetic differences to accumulate between the populations, leading to speciation - the formation of new species that are reproductively isolated from each other.