Biology, Eighth Edition (Raven)

Chapter 22: The Origin of Species

Learning Outcomes

• Define and differentiate between sympatric and allopatric speciation.
• Be able to describe and give an example of instantaneous speciation and polyploidy.
• Know what is meant by the Biological Species Concept and explain why the controversy of hybrid species surrounds it.
• Distinguish between the Biological Species Concept and the Ecological Species Concept.
• Differentiate between prezygotic and postzygotic isolating mechanisms.
• Distinguish between the three types of postzygotic isolating mechanisms.
• List the six predominant prezygotic isolating mechanisms and give examples of each.
• Give two ideas that may be explanations for the development of reproductive isolating mechanisms.
• Explain how geographical isolation influences allopatric speciation.
• Give examples of how clusters of species reflect rapid evolution through adaptive radiations and character displacement.
• Develop an appreciation for the importance of the Cambrian explosion and mass extinction events as they have led to species diversity.
• Describe how extinctions during the Cretaceous led to increased opportunities for mammal diversity.
• Differentiate between gradualism and punctuated equilibria.
• Be able to speculate on some possible outcomes of the human species evolutionary future.
• Describe how the influences of humans can affect the future of evolution.