Name _______________________________
Date __________________
Ch 22 reading guide – Biology in Focus
(Adapted from Fred and Theresa Holtzclaw’s reading guides)
(www.bozemanscience videos that go with this chapter 003 – genetic drift, 009 Evolution Continues)
Overview:
1. What was Darwin’s “mystery of mysteries”?
Concept 22.1 The biological species concept emphasizes reproductive isolation.
2. What is a species based on the biological species concept?
3. Explain how reproductive isolation can lead to new species.
4. Define hybrid.
5. Explain the difference between prezygotic and postzygotic barriers.
6. The following charts summarize the various ways that reproductive isolation is maintained.
Explain and give an example of each type of isolating mechanism.
Prezygotic
Barriers
Reproductive Explanation
Habitat Isolation
Temporal isolation
Example
Behavioral Isolation
Mechanical Isolation
Gametic Isolation
Postzygotic
Barriers
Reproductive Explanation
Example
Reduced hybrid viability
Reduced hybrid fertility
Hybrid breakdown
7. What are the limitations of the Biological Species Concept?
Concept 22.2 Speciation can take place with or without geographic speciation.
8. Explain the difference between sympatric speciation and allopatric speciation and give an
example.
.
9. Label the above diagram: the allopatric speciation and the sympatric speciation.
10. Which type of speciation would occur by a barrier such as the Grand Canyon?
11. How can speciation occur in populations that live in the same geographic area (sympatric
speciation)? You should find three ways. Explain how each leads to speciation.
12. Using the diagram, label and explain allopolyploid speciation.
Concept 22.3 Hybrid zones reveal factors that cause reproductive isolation.
13. What are hybrid zones?
14. Explain the outcomes of hybrid zones over time:
a. reinforcement of barriers
b. fusion of species
c. stability
Concept 22.4 Speciation can occur rapidly or slowly and can result from changes in few or
many genes.
15. Stephen Jay Gould and Niles Eldredge coined the term “punctuated equilibrium”. What is
meant by this term?
16. This figure shows 2 different views of speciation. Labe this figure and explain how each of
the pictures explains speciation.
17. Give one example of how genetics leads to speciation.