Reinforcement

Definition

Reinforcement is a process in which natural selection strengthens prezygotic barriers to reproduction, thus reducing the likelihood of hybrid offspring. This typically occurs when two populations that have diverged come back into contact and interbreed.

5 Must Know Facts For Your Next Test

1. Reinforcement increases reproductive isolation between diverging populations.
2. It often results in increased differences in mating behaviors or other prezygotic mechanisms.
3. Reinforcement can lead to speciation if it completely prevents gene flow between populations.
4. This process usually occurs when hybrids have lower fitness than purebred offspring.
5. Reinforcement is considered an adaptive response to avoid the production of unfit hybrids.

Review Questions

• What role does reinforcement play in the speciation process?
• How does reinforcement affect reproductive barriers between populations?
• Why might reinforcement be favored by natural selection?

Related terms

Hybrid Zone: A region where members of different species meet and mate, producing at least some offspring of mixed ancestry.

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

Postzygotic Barrier: Mechanisms that reduce the viability or reproductive capacity of hybrid offspring.