Defining species and pre-zygotic and post-zygotic isolating mechanisms

What this note covers

1. Species definitions use different kinds of evidence
2. Species, populations and gene pools are distinct levels
3. Pre-zygotic barriers prevent zygote formation
4. Post-zygotic barriers prevent fertile hybrid descendants
5. Isolation maintains distinct gene pools
6. Worked classifications depend on the causal stage
7. Classifying reproductive barriers from the stage at which reproduction fails
8. Comparing species concepts when different evidence points in different directions

8 sections · 10 key terms & formulas · 6 common mistakes