Postzygotic barrier

Definition

Postzygotic barriers are mechanisms that reduce the viability or reproductive capacity of hybrid offspring. These barriers occur after fertilization and can prevent hybrids from developing into fertile adults.

5 Must Know Facts For Your Next Test

1. Postzygotic barriers include hybrid inviability, where hybrids fail to develop properly and die early.
2. Hybrid sterility is another example, where hybrids reach maturity but are infertile.
3. Postzygotic barriers contribute to reproductive isolation by preventing gene flow between species.
4. They can result in reduced fitness of hybrid offspring, making them less likely to survive and reproduce.
5. Examples of organisms affected by postzygotic barriers include mules (hybrids of horses and donkeys) which are typically sterile.

Review Questions

• What are two examples of postzygotic barriers?
• How do postzygotic barriers contribute to the formation of new species?
• Why might a mule be considered an example of a postzygotic barrier?

Related terms

Prezygotic Barrier: Mechanisms that prevent mating or fertilization between different species.

Hybrid Inviability: A type of postzygotic barrier where hybrid zygotes fail to develop or reach maturity.

Hybrid Sterility: A type of postzygotic barrier where hybrid offspring are sterile and cannot reproduce.