Prezygotic is before the union of the gametes, and postzygotic is after the union of the gametes. The first prezygotic isolating mechanism is called temporal isolation. Temporal isolation prevents fertilization because the two different species reproduce at different times. The time periods could differ simply by hours, or by seasons. If one species reproduces in the spring, while the other reproduces in the fall, the two species aren t able to breed.
Behavioral isolation is another isolating mechanism.
This mechanism operates through courtship behavioral patterns. If one species displays a certain courtship pattern, it won t be recognized by those of the other species. This is the mechanism which separates wolfs from dogs, their courtship patterns are different in the wild. Mechanical isolation deals with the actual mechanics of the reproductive organs. Mechanical isolation acts a prezygotic barrier by preventing sexual intercourse between two different species.