Download Chapter 16

187
Chapter 16
Microevolution:
How Does a Population
Evolve?
THEMES AND OBJECTIVES
The following is a list of the main themes covered in this chapter and some study objectives. As
you study, focus on these areas. Understand how the information you study fits into these themes
and how these themes relate to each other. Be sure you master each objective before moving on.
1.
Even when evolution was accepted, it took some time and many different theories before
natural selection was accepted as the mechanism by which evolution occurs.
 Explain the assorted theories that were put forth to explain how species change.
 Review the events and theories that led to final acceptance of natural selection.
 Explain the significance of the modern synthesis.
2.
All genetic variation begins with mutation.
 Discuss mutations.
 Explain why some mutations are dangerous while others have no effect.
 Explain why even lethal alleles are maintained in a gene pool.
3.
Sexual reproduction alone does not change allele frequencies within a population.
 Thoroughly discuss the Hardy-Weinberg Principle and conditions under which it works.
 Discuss reasons many natural populations do not reach Hardy-Weinberg Equilibrium.
4. Natural selection is the only thing that consistently leads to adaptive changes in allele
frequency within a population.
 Discuss ways in which natural selection can change allele frequency.