A prezygotic barrier is a reproductive barrier that occurs before fertilization, preventing different species from mating or fertilizing each other's eggs. These barriers can take various forms, including behavioral differences (such as mating calls), temporal isolation (different mating seasons), ecological separation (different habitats), mechanical incompatibility (differences in reproductive structures), and gametic isolation (sperm and egg incompatibility). In contrast, postzygotic barriers occur after fertilization and can lead to hybrid inviability or infertility.