---
title: "Prezygotic Isolation — AP Bio Definition & Exam Guide"
description: "Prezygotic isolation blocks two species from mating or fertilizing before a zygote forms, maintaining reproductive isolation and driving speciation in Unit 7."
canonical: "https://fiveable.me/ap-bio/key-terms/prezygotic-isolation"
type: "key-term"
subject: "AP Biology"
---

# Prezygotic Isolation — AP Bio Definition & Exam Guide

## Definition

Prezygotic isolation is a mechanism that prevents different species from interbreeding and producing hybrid offspring. This occurs before the fertilization of eggs.

## Related Study Guides

- [7.10 Speciation](/ap-bio/unit-7/speciation/study-guide/EvkCBpDW4LggHrVIepHo)

## Review

### Related Terms

- Behavioral Isolation: A type of prezygotic barrier where two allopatric species do not mate because of differences in courtship behavior.
- Temporal Isolation: A form of prezygotic barrier where two or more species reproduces at different times, thus preventing them from mating.
- Mechanical Isolation: Another form of prezygotic barrier where mating is prevented due to physical incompatibility of reproductive parts.