Download Name: Period: ____ Date: ______ Population Genetics and

Name: ________________________________________ Period: ____ Date: ________
Population Genetics and Speciation
In the space provided, write the letter of the description that best matches the term or phrase.
_______ 1. genetic drift
_______ 2. stabilizing selection
_______ 3. gene flow
_______ 4. natural selection
A. results from immigration and emigration
B. range of phenotypes become narrower;
more individuals in the middle range
C. can result from small group being
separated from the main population
D. one of the most powerful agents of
genetic change
______ 5. morphology
______ 6. reproductive isolation
______ 7. evolution
A. changes in a population’s genetic material
B. choosing a mate that resembles oneself
______ 8. gene flow
______ 9. sexual selection
______ 10. assortative mating
C. an organism’s structure and appearance
D. alterations of DNA
E. females choosing a mate based on
appearance
______ 11. mutation
______ 12. geographic isolation
F. anatomical barriers to successful breeding
G. physical separation of populations
H. movement of genes between populations
In the space provided, circle the letter of the term or phrase that best completes each statement or
best answers each question.
13. Not all mutations
a. result in genetic changes.
b. result in phenotypic changes.
c. result in genotypic changes.
d. cause emigration
14. The movement of alleles into or out of a population is called
a. mutation.
b. gene flow.
c. nonrandom mating.
d. natural selection.
15. Cheetahs are in danger of extinction because of the effects of
a. mutations.
b. genetic drift.
c. gene flow.
d. natural selection.
16. Natural selection shapes populations by acting on
a. genes.
b. recessive alleles.
c. phenotypes.
d. all of the above.
17. Allele frequency is least affected by
a. genetic drift.
b. gene flow.
c. mutations.
d. nonrandom mating.
18. The type of selection that eliminates one extreme from a range of phenotypes is called
a. directional selection.
b. disruptive selection.
c. natural selection.
d. stabilizing selection.
19. A demographer studying the adult height in males finds that more men are of average height
now than 100 years ago, and there are fewer men who are very short or very tall. Which of the
following may explain this trend?
a. directional selection.
b. genetic drift.
c. stabilizing selection.
d. gene flow.
20. When directional selection eliminates one extreme from a range of phenotypes, the alleles
promoting the extreme trait
a. increase in the population.
b. do not change from generation to generation.
c. become less common in the population.
d. None of the above.
21. Scientists studying the remains of extinct dinosaurs would use which of the following to
determine whether or not the remains were different species?
a. geographic isolation.
b. allopatric speciation.
c. the biological species concept.
d. the morphological concept of species.
22. Two closely related species of salamanders that live in the same area, but mate at different
times of the year would
a. be geographically isolated.
b. undergo allopatric speciation.
c. have prezygotic isolation.
d. have postzygotic isolation.
Read each question, and write your answer in the space provided.
23. Explain how stabilizing selection decreases genetic diversity.
24. What is genetic drift?
25. Explain the difference allopatric and sympatric speciation.
26. What are the five conditions that must be met to establish genetic equilibrium in a population?
27. Explain the difference between punctuated equilibrium and gradual evolutionary change.
28. Explain the difference between the morphological and biological concepts of species.
Complete each statement by writing the correct term or phrase from the list below in the space
provided.
allele frequency
directional selection
microevolution
gene flow
nonrandom mating
phenotype frequency
postzygotic isolation
stabilizing selection
genetic drift
immigration
emigration
sympatric speciation
morphology
29. The evolutionary forces include the mutation of genes and _____________________
______________________, which is the movement of alleles into or out of a population.
30. sometime individuals prefer to mate with others that live nearby or are of their own phenotype,
a situation called _______________________ _______________________.
31. In small populations, the frequency of an allele can be greatly changed by a chance event, such
as a fire or landslide. This change in allele frequency is called ___________________
_______________________.
32. If you were to plot the height of everyone in your class on a graph, the values would probably
form a hill-shaped curve called a(n) _________________________________
_________________________.
33. When selection causes the frequency of a particular trait to move in one direction, this form of
selection is called _______________________ __________________________.
34. When selection eliminates extremes at both ends of a range of phenotypes, the frequencies of
the intermediate phenotypes increase. This form of selection is called
_______________________ ___________________________.
35. Evolution that occurs at the genetic level is called ____________________________.
36. The _______________________ _______________________ is determined by dividing
the number of certain alleles by the total number of alleles of all types in a population.
37. The movement of individuals into a population is called _______________________.
38. A _____________________ ______________________ is equal to the number of
individuals with a particular phenotype divided by the total number of individuals in the population.
39. When two subpopulations become reproductively isolated within the same geographic area
________________________ __________________________ occurs.
40. The movement of individuals out of a population is called _____________________.
41. The ______________________ of an organism is the internal and external structure and
appearance of the organism.
42. The type of isolation that occurs after fertilization is called _______________________
______________________________.