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Chapter 17 Vocabulary Review
For Questions 1–8, complete each statement by writing the correct word or words.
1. In a small population, a random change in allele frequency is called
.
2. When birds cannot interbreed because they have different mating songs, they are
separated by
isolation.
3. A situation in which allele frequencies change as a result of the migration of a small
subgroup of a population is known as the
.
4. Two related species that live in the same area but mate during different seasons are
separated by
isolation.
5. A(n)
is a trait controlled by only one gene.
6. The
is a change in allele frequency following a dramatic
reduction in the size of a population.
7. __________________ is the number of times an allele occurs in a gene pool, compared to
the total number of alleles in that pool for the same gene.
For Questions 8–16, write True if the statement is true. If the statement is false,
change the underlined word or words to make the statement true.
8. All of the genes in a population make up the allele frequency of
the population.
9. Traits controlled by two or more genes are polygenic traits.
10. Reproductive isolation occurs when members of two populations
do not interbreed and produce fertile offspring.
11. The separation of two populations by barriers such as rivers or
mountains results in temporal isolation.
12. The Hardy-Weinberg principle states that allele frequencies in a
population should remain constant unless one or more factors
cause those frequencies to change.
13. Genetic drift is the formation of new species.
14. The founder effect occurs when the allele frequencies in a
population remain constant.
15. For polygenic traits, when individuals near the center of the bell
curve have higher fitness than individuals at either end, disruptive
selection takes place.
16. When researchers use a molecular clock, they compare stretches
of DNA to mark the passage of evolutionary time.
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