List the barriers that prevent interbreeding, and give an example of each.

Key Concepts

Prezygotic Barriers

Prezygotic barriers are reproductive obstacles that occur before fertilization, preventing different species from mating or fertilizing eggs. These barriers can include temporal isolation, where species breed at different times, and behavioral isolation, where differences in mating rituals prevent interbreeding. For example, two species of frogs may live in the same area but breed at different times of the year.

Postzygotic Barriers

Postzygotic barriers occur after fertilization and affect the viability or fertility of the hybrid offspring. These barriers include hybrid inviability, where the hybrid does not develop properly or dies early, and hybrid sterility, where the hybrid is sterile and cannot reproduce. A classic example is the mule, a hybrid of a horse and a donkey, which is typically sterile.

Ecological Isolation

Ecological isolation occurs when two species occupy different habitats within the same area, leading to limited interaction and mating opportunities. Even if they are not physically separated, their preferences for different environments can prevent them from interbreeding. For instance, two species of lizards may live in the same geographic region but prefer different types of vegetation, reducing their chances of encountering each other.