Written by the Fiveable Content Team โข Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 examโขWritten by the Fiveable Content Team โข Last updated September 2025
Definition
Postzygotic barriers are mechanisms that occur after the formation of a zygote (fertilized egg) between individuals of different species. These barriers reduce the fitness or reproductive success of hybrid offspring.
Related terms
Reduced hybrid viability: Hybrid offspring may have lower survival rates or overall fitness compared to purebred individuals.
Reduced hybrid fertility: Hybrid offspring may be sterile or have reduced fertility, making it difficult for them to produce viable offspring.
Hybrid breakdown: The first-generation hybrids may be viable and fertile, but subsequent generations might experience reduced viability or fertility.