AP Biology Reading Guide
CHAPTER 23: The Evolution of Populations
Directions
1) Before you read the chapter, decide whether you think each statement is true or false. Circle your
choice. If you are uncertain, write in a question mark and circle it.
2) As you read the chapter, identify whether each statement is true or false according to what you have
read. Circle the answer and note the evidence in complete sentences.
3) Was your thinking changed or reinforced by what you read? If so, in what way?
4) Be prepared to share your answers with the class.
Before
Reading
True
False
Statement
True
False
2. A population, a localized group of organisms that all belong to the same species,
is united by its gene pool, the aggregate of half of the alleles in the population.
Evidence:
True
False
True
False
3. Although many populations approximate Hardy-Weinberg equilibrium, the
equilibrium in its strictest applies only if the population is small, mating is nonrandom, mutation is negligible, there is no gene flow from other populations, and all
individuals have unequal reproductive success.
Evidence:
True
False
True
False
4. New genes and alleles originate only by mutation. Most mutations increase
adaptation.
Evidence:
True
False
1. The modern synthesis integrates Mendelian genetics with the Darwinian theory of
evolution by natural selection and focuses on individuals as the basic unit of
evolution.
Evidence:
After
Reading
True
False
True
False
5. Genetic recombination between sexually reproducing organisms produces most of
the variation in traits that make adaptation possible.
Evidence:
True
False
True
False
6. Differential success in reproduction results in certain alleles being passed to the
next generation in greater proportions than others.
Evidence:
True
False
True
False
7. Chance fluctuations in allele frequencies from generation to generation tend to
reduce genetic variance in populations.
Evidence:
True
False
True
False
8. Genetic exchange between populations tends to reduce differences between
populations over time.
Evidence:
True
False
True
False
9. Genetic variation includes variation among individuals within a population in
discrete and quantitative characters, as well as geographic variation between
populations.
Evidence:
True
False
True
False
10. One organism has a greater relative fitness than another if it leaves fewer
descendants. Selection favors certain genotypes in a population by acting on the
phenotypes of individual organisms. Natural selection can favor relatively rare
individuals at one end of the phenotype range (stabilizing selection), can favor
individuals at both extremes of the range rather than intermediate phenotypes
True
False
(directional selection), or can act against extreme phenotypes (disruptive selection).
Evidence:
True
False
11. Diploidy maintains a reservoir of concealed recessive variation in heterozygotes.
Balanced polymorphism may maintain variation at some gene loci as a result of
heterozygote advantage or frequency dependent selection.
True
False
Evidence:
True
False
12. Sexual selection leads to the evolution of secondary sex characteristics, which
can give individuals a disadvantage in mating.
Evidence:
True
False
True
False
13. Enhanced disease resistance based on genetic variation is one possible
explanation for the persistence of sexual reproduction despite its lesser reproductive
output compare to asexual reproduction.
Evidence:
True
False
True
False
14. Structures result from modified ancestral anatomy: adaptations are often perfect
solutions; the gene pool can be affected by genetic drift; and natural selection can
act only on available variation.
True
False
Evidence: