AP Biology · Unit 7: Natural Selection
7.10 Speciation
In short
You must understand that speciation is driven by reproductive isolation. You need to know the biological species concept (populations capable of interbreeding to produce viable, fertile offspring). The topic covers the rates of speciation, specifically contrasting punctuated equilibrium (rapid evolution after long stasis) with gradualism (slow evolution over long periods).
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What else do you need to know about Speciation?
You must differentiate between divergent evolution (including rapid adaptive radiation in new habitats) and convergent evolution (similar adaptations due to similar selective pressures). Furthermore, you must distinguish between sympatric speciation (occurring with geographic overlap) and allopatric speciation (occurring with geographic isolation). Finally, you must understand how various pre-zygotic and post-zygotic mechanisms maintain reproductive isolation and prevent gene flow. Illustrative examples that can be used include Hawaiian Drosophila, Caribbean Anolis, and the Apple maggot Rhagoletis.
Can you do these?
- I can explain that speciation occurs when two populations become reproductively isolated from each other.
- I can define a species using the biological species concept as a group capable of interbreeding and exchanging genetic information to produce viable, fertile offspring.
- I can distinguish between punctuated equilibrium and gradualism as different rates of evolution.
- I can describe how divergent evolution and adaptive radiation lead to rapid speciation when new habitats become available.
- I can explain how convergent evolution results in similar phenotypic adaptations in different populations due to similar selective pressures.
- I can differentiate between sympatric speciation (geographic overlap) and allopatric speciation (geographic isolation).
- I can describe how various pre-zygotic and post-zygotic mechanisms maintain reproductive isolation and prevent gene flow.
How is Speciation tested on the exam?
A common you error on the AP Exam is failing to clearly differentiate the types of reproductive isolating mechanisms that lead to speciation. You should be prepared to work with different models of isolation mechanisms (e.g., visual representations or cartoons) to explain relationships between characteristics of biological models (Skill 2.B) and predict the causes or effects of disruptions in a biological system (Skill 6.E). Free-response questions may require you to explain how genome changes contribute to speciation, specifically how random mutations in organisms exposed to different selective pressures can become fixed and lead to reproductive isolation.
Free practice questions with full explanations, and instant marking of your free-response answers.
Speciation: common questions
What do you need to know about Speciation for AP Biology?
You must understand that speciation is driven by reproductive isolation. You need to know the biological species concept (populations capable of interbreeding to produce viable, fertile offspring). The topic covers the rates of speciation, specifically contrasting punctuated equilibrium (rapid evolution after long stasis) with gradualism (slow evolution over long periods).
How is Speciation tested on the AP Biology exam?
A common you error on the AP Exam is failing to clearly differentiate the types of reproductive isolating mechanisms that lead to speciation.
How do I know I have mastered Speciation?
Check you can do each of these: explain that speciation occurs when two populations become reproductively isolated from each other; define a species using the biological species concept as a group capable of interbreeding and exchanging genetic information to produce viable, fertile offspring; distinguish between punctuated equilibrium and gradualism as different rates of evolution; describe how divergent evolution and adaptive radiation lead to rapid speciation when new habitats become available; explain how convergent evolution results in similar phenotypic adaptations in different populations due to similar selective pressures; differentiate between sympatric speciation (geographic overlap) and allopatric speciation (geographic isolation); describe how various pre-zygotic and post-zygotic mechanisms maintain reproductive isolation and prevent gene flow.
Where does Speciation fit in AP Biology?
Speciation is topic 7.10 in Unit 7: Natural Selection of AP Biology.
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