Download Ch 23 Evolution of Populations Guided Rdg

Evolution of Populations Guided Reading
Biology, 8th Edition, Ch. 23 (468-485). If any of the questions is not explicitly defined in the
reading, you are responsible for using your text or another reliable source to answer the
questions.
1. Define the following terms:
a. Chromosome
b. Allele
c. Loci
d. Gene
e. Dominant Trait
f. Recessive Trait
g. Homozygote
h. Heterozygote
2. What is genetic variation?
3. Describe a way to measure genetic variability (p 469).
4. What is a mutation? How are mutations important for genetic variation?
5. What are the two events that increase genetic variation in a species? (Concept 23.1 on p 468)
6. What is a population?
7. What does it mean if we say a population is in Hardy-Weinberg equilibrium?
8. List the five conditions that must exist for a population to exist in Hardy-Weinberg
equilibrium.
9. What happens if a population does not meet one or more of the conditions listed above?
** 3 mechanisms that alter allele frequencies directly & cause most evolutionary change**
1) Natural Selection (Ch. 22)
2) Genetic Drift (Ch. 23)
3) Gene Flow (Ch. 23)
Genetic Drift
10. List and describe the two types of genetic drift explained on pages 476-477.
11. Both natural selection and genetic drift can change the allele frequencies in a population.
Explain how each of these causes an allele frequency change and what is different about the
way the change occurs.
Gene Flow
12. What is gene flow? Give an example.
Natural Selection (A closer look…)
13. What is relative fitness? How is it relevant to natural selection?
14. Why is it said that evolution acts on phenotypes rather than genotypes?
15. Define, give an example, and draw a graph illustrating each of the following:
a. Directional Selection
b. Disruptive Selection
c. Stabilizing Selection
16. Define the following:
a. Sexual Selection-
b. Sexual Dimorphism-
c. Intrasexual Selection-
d. Intersexual Selection-
17. Explain each mechanism that works to preserve genetic variation in a population:
a. Diploidy
b. Balancing Selection
c. Heterozygote Advantage
d. Frequency-Dependent Selection
e. Neutral Variation
18. List & briefly discuss each of the 4 reasons as to why Natural Selection cannot fashion
perfect organisms.
19. In the human eye, the retina is behind the nerves that form the optic nerve. Where the optic
nerve leaves the eye, there is a hole, which results in a blind spot. It would be far better for the
human eye to not have such a blind spot. How can it be that natural selection, the process that
leads to adaptations, can also result in imperfect organs?