Chpt 21 Microevolution

1. A group of individuals of a single species that live together in the same place and time is referred to as a(n) ____.

c. population

2. The development of penicillin-resistant bacteria represents an example of ____.

d. microevolution

3. What is the most accurate definition of microevolution?

a. heritable changes in the genetics of a population

4. Bacterial resistance to penicillin began to appear ____.

e. within a few years of its introduction into general use

5. Characters that exist in two or more discrete states are described as exhibiting ____.

b. qualitative variation

6. The existence of discrete variants of a particular character is known as ____.

d. a polymorphism

7. Mendel inferred the genetic basis of ____, such as flower color in peas, by crossing plants with different phenotypes.

e. qualitative traits

8. John G. Swallow and his colleagues used ____ techniques to demonstrate that the observed differences in activity levels of house mice have a genetic basis.

a. artificial selection

9. Researchers study the inheritance of particular human traits by ____.

c. analyzing genealogical pedigrees

10. Most new alleles probably arise from ____.

d. small-scale mutations in DNA

11. In the 1960s, evolutionary biologists identified protein polymorphisms using ____, which allowed them to infer how much genetic variation exists within populations.

b. gel electrophoresis

12. The Hardy-Weinberg formula is used to calculate changes in ____.

c. allele frequencies

13. In humans, a diploid organism, an individual's genotype includes ____ of each autosomal gene.

b. two copies

14. The sum of all gene copies at all gene loci in all individuals in a population defines a ____.

d. gene pool

15. The gene locus governing flower color in snapdragons exhibits ____ because heterozygous individuals appear pink while homozygous individuals are either white or red.

e. incomplete dominance

16. For an autosomal gene locus, there are ____ possible genotypes and ____ possible alleles.

c. three; two

17. In some studies that use observational rather than experimental data, investigators develop ____, which conceptually predict what they would see if a particular factor had no effect.

b. null models

18. The Hardy-Weinberg principle specifies the conditions under which a population of diploid organisms achieves ____.

e. genetic equilibrium

19. According to the Hardy-Weinberg principle, microevolution occurs when ____.

a. a population experiences a shift in allele frequencies

20. In an isolated population of fruit flies, 4 percent of the individuals have pink eyes, a homozygous recessive condition, and 96 percent have the dominant black eye phenotype. What percentage of the population are heterozygotes?

a. 32%

21. Which circumstance violates the conditions of the Hardy-Weinberg model?

e. nonrandom mating with respect to genotypes occurs between individuals

22. The agent of microevolutionary change that is most likely to introduce genetic variation from another population is referred to as ____.

b. gene flow

23. Microevolutionary change resulting from the differential survivorship or reproduction of individuals with different genotypes is known as ____.

d. natural selection

24. If there are two alleles for a gene in a population, and the frequency of the dominant allele (p) is .5, then the frequency of the recessive allele (q) is ____.

a. .5

25. In humans, ____ mutations cause forms of Ehlers-Danlos syndrome, a disruption of collagen synthesis that may result in loose skin or weak joints.

b. deleterious

26. If a lethal mutation occurs in a dominant allele, ____ individuals will die from its effects

d. both homozygous dominant and heterozygous

27. Dispersal agents, such as pollen-carrying wind or seed-carrying animals, are responsible for ____ in most plant populations because they often introduce novel alleles into a population.

a. gene flow

28. The phenomenon of chance events causing the allele frequencies in a population to change unpredictably is known as ____.

a. genetic drift

29. On occasion, a stressful factor such as disease, starvation, or drought kills a large proportion of the individuals in a population, producing ____ that dramatically reduces the population size.

e. a population bottleneck

30. The contribution an individual makes to the gene pool of the next generation compared to the contributions of other individuals is called ____.

c. relative fitness

31. Microevolution is ____.

d. a change in allele frequencies within a population

32. The high incidence of Ellis-van Creveld syndrome among the Old Order Amish population is caused by ____.

d. inbreeding

33. The source of new alleles within a population is ____.

b. mutation

34. The only survivors of a colony on Venus are a man and a woman, who both happen to originally be from southern Ukraine. Their descendants will show the effect of ____.

a. genetic drift

35. The process by which successful traits become more common in subsequent generations is called ____.

c. natural selection

36. Natural selection acts upon the ____ to create microevolutionary change.

e. phenotype of an individual organism

37. Dog breeders produced the long body and short legs of a dachshund by employing ____ selection.

b. directional

38. With ____ selection, the frequency of the mean phenotype decreases while the frequencies of extreme phenotypes increase.

c. disruptive

39. Directional selection favors ____.

b. phenotypes at one end of the distribution

40. Natural selection that shifts the adaptation of an entire population is known as ____.

b. directional selection

41. Natural selection results in ____.

a. adaptation

42. Changing environmental conditions would most likely cause an existing species to undergo ____.

c. directional selection

43. Genetic drift is most likely to lead to ____.

c. the founder effect

44. Natural selection exerts little or no effect on traits that appear during an individual's ____.

d. postreproductive life

45. When a few individuals colonize a distant locality and start a new population, the allele frequencies of the gene pool may be different than those in the original population. This is known as ____.

a. the founder effect

46. Very small and very large human newborns are less likely to survive than those born at an intermediate weight due to ____.

e. stabilizing selection

47. Genetic drift will have a progressively larger impact on allele frequencies in a population as ____.

b. population size decreases

48. Andrew P. Hendry and colleagues discovered that Galapagos ground-finches with small bills and ground-finches with large bills were more common and had higher fitness than birds with bills of intermediate size, a demonstration of ____ selection.

a. disruptive

49. When male moose engage in their annual battles, butting heads with their oversized antlers, they are exhibiting ____ selection.

d. intrasexual

50. Inbreeding is primarily due to ____.

b. nonrandom mating

51. In many species, sexual selection is the most probable cause of ____, differences in the size or appearance of males and females.

e. sexual dimorphism

52. Research by Malte Andersson suggests the long tail feathers of male African widowbirds are a product of ____ selection because females are more strongly attracted to males with long tails than to males with short tails.

b. intersexual

53. Snow geese usually select mates of their own color, an example of ____.

d. nonrandom mating

54. Disadvantageous recessive alleles are protected from natural selection due to ____.

b. diploidy

55. The stable presence of two or more phenotypes in a population is called a ____.

a. balanced polymorphism

56. Sometimes the most abundant color form of an animal is preyed upon more extensively than less common forms. This illustrates the phenomenon of ____ selection.

d. frequency-dependent

57. Individuals with one sickle cell allele and one normal hemoglobin allele are not affected by the malaria parasite because of ____.

b. heterozygote advantage

58. Genetic variations that confer no apparent selective advantage or disadvantage in a particular environment are said to be selectively ____.

c. neutral

59. The success of camouflage from predatory birds drives the predominant phenotypes in snail color. This is an example of ____.

a. predation as an agent of natural selection

60. With frequency-dependent selection, highest mortality can be expected in ____.

a. the most abundant genotype

61. Most copies of rare recessive alleles exist in ____.

b. heterozygotes

62. The accumulation of traits that increase the relative fitness of organisms in their environment over time results in ____.

b. adaptation

63. Which of the following evolution-related events is in the correct cause-and-effect sequence?

a. mutation → variation → natural selection → adaptation → speciation

64. Any product of natural selection that increases the relative fitness of an organism in its environment is called a(n) ____.

b. adaptive trait

65. Hybridization between different species is rare because it ____.

a. requires the breakdown of a barrier preventing interbreeding

66. A scientist could test how the traits of desert plants are adaptive by ____.

e. comparing them to traits in related species from moister habitats

67. The fossil record reveals that the structure of shoulder joints in birds, which is essential for flight, is an adaptation that originated in ____.

d. nonflying dinosaurs

68. Seeds of many plants fall to the ground when they mature. This is an example of a characteristic that is influenced by ____.

a. basic physical laws

69. The bipedal posture of humans evolved from ____.

c. quadrupedal ancestors

70. As adults, female ground finches on the Galapagos island of Daphne Major choose their mates according to characteristics they learned as young birds, a process known as ____.

d. sexual imprinting

71. Matching — heritable change in DNA

d. mutation

72. Matching — change in allele frequencies as individuals join a population and reproduce

a. gene flow

73. Matching — random changes in allele frequencies caused by chance events

c. genetic drift

74. Matching — differential survivorship or reproduction of individuals with different genotypes

e. natural selection

75. Matching — choice of mates based on their phenotypes and genotypes

b. nonrandom mating

76. Hardy-Weinberg: p

b. frequency of the dominant allele

77. Hardy-Weinberg: q

c. frequency of the recessive allele

78. Hardy-Weinberg: q²

e. frequency of homozygous recessive genotypes

79. Hardy-Weinberg: p²

f. frequency of homozygous dominant genotypes

80. Hardy-Weinberg: 2pq

a. frequency of heterozygotes

81. Hardy-Weinberg: p + q

d. the total gene pool for a gene with two alleles

82. Figure 21.1 — disruptive selection

c. C

83. Figure 21.1 — directional selection

a. A

84. Figure 21.1 — stabilizing selection

b.