Chapter 17 The Means of Evolution: Microevolution
Biology: A Guide to the Natural World, 5e (Krogh)
1) Organisms that can interbreed with each other in nature but are genetically isolated from all other organisms are a:
A) genus.
B) clone.
C) species.
D) family.
Answer: C
Topic: Section 17.1
Skill: Knowledge/Comprehension
2) Which of the following statements about evolution is true?
A) Evolution involves maintaining a constant frequency of alleles in the gene pool.
B) Populations evolve.
C) Individuals evolve.
D) Evolution can proceed to a limited extent without the occurrence of mutation.
Answer: B
Topic: Section 17.1
Skill: Knowledge/Comprehension
3) A population is:
A) a group of organisms that can successfully interbreed in nature but do not interbreed with other such groups.
B) all the members of a species that live in a defined geographic region at the same time.
C) all the different species that live in a defined geographic area at the same time.
D) a group of different species that share common features.
Answer: B
Topic: Section 17.1
Skill: Knowledge/Comprehension
4) The gene pool for a particular gene would include:
A) the sum of all the alleles for all the traits in the population.
B) all the alleles for a given trait in a particular individual organism of the population.
C) the sum of all the phenotypes in the population.
D) all the alleles for a particular gene in all the individuals in the population.
Answer: D
Topic: Section 17.1
Skill: Knowledge/Comprehension
5) The genetic makeup of any organism is its ________, which determines the physical characteristics called its ________.
A) genotype; alleles
B) gene pool; alleles
C) phenotype; genotype
D) genotype; phenotype
Answer: D
Topic: Section 17.1
Skill: Knowledge/Comprehension
6) If every sexually reproducing organism has only two alleles for each gene, how can there be a range of traits seen for a physical characteristic?
A) One of the alleles in an organism is expressed at different levels, while the other is turned off.
B) Sometimes one of the alleles works, and other times the other allele works.
C) There can be more than two variations of a gene in a population.
D) In a population there are only two variations of a gene, but they are blended differently during sexual reproduction.
Answer: C
Topic: Section 17.1
Skill: Application/Analysis
7) At its most basic level, evolution is a:
A) change in the frequency of alleles in a population.
B) change in the frequency of alleles in an individual.
C) new species arising from an existing species.
D) change in an individual's phenotype caused by mutations.
Answer: A
Topic: Section 17.2
Skill: Knowledge/Comprehension
8) What is the difference between microevolution and macroevolution?
A) Microevolution is hypothetical because changes are too small to be observed, whereas macroevolution is detectable.
B) Microevolution deals with microscopic organisms, whereas macroevolution deals with larger ones.
C) Microevolution describes what happens in small populations, whereas macroevolution deals with large populations.
D) Microevolution describes changes within a population over a short period of time, whereas macroevolution describes larger changes such as the formation of new species over longer periods of time.
Answer: D
Topic: Section 17.2
Skill: Knowledge/Comprehension
9) The formation of new species over many generations is an example of:
A) microevolution.
B) macroevolution.
C) gene pools.
D) allelic variants.
Answer: B
Topic: Section 17.2
Skill: Knowledge/Comprehension
10) If within a large population no mutations occur, no migration occurs, all mating is random, and each individual has an equal chance of reproducing, which of the following will probably happen?
A) No evolution will occur.
B) A bottleneck will occur.
C) A change in allele frequency will lead to rapid evolution.
D) Extinction will occur.
Answer: A
Topic: Section 17.3
Skill: Application/Analysis
11) As world travel becomes easier and human populations intermix, the occurrence of what phenomenon will probably decrease?
A) mutation
B) sexual selection
C) immigration
D) founder effect and genetic drift
Answer: D
Topic: Section 17.3
Skill: Application/Analysis
Refer to the scenario below, and then answer the following question(s).
Two European men and two Polynesian women settled on a previously uninhabited tropical island. All four of the settlers have brown eyes, a dominant trait, but one of the Europeans is heterozygous and carries the recessive gene for blue eyes.
12) No new settlers arrive, and nobody leaves the island. After a few generations, the percentage of blue-eyed individuals increases from the original zero to 25 percent. This is probably due to which of the following factors?
A) genetic drift
B) mutation
C) gene flow
Answer: A
Topic: Section 17.3
Skill: Application/Analysis
13) After several generations, 35 percent of the island population is found to have AB+ blood. This is much higher than the percentage of AB+ people in the populations from which the original settlers came. The high percentage of AB+ blood is probably due to:
A) founder effect.
B) selective mutation.
C) disruptive selection.
D) nonrandom mating.
Answer: A
Topic: Section 17.3
Skill: Application/Analysis
14) Which of the following is ultimately responsible for introducing new alleles into a population?
A) mutation
B) natural selection
C) sexual selection
D) genetic drift
Answer: A
Topic: Section 17.3
Skill: Knowledge/Comprehension
15) The only known population of a reptile species lives on an African mountain. The population is relatively large, but no close relatives of this species are known. Suppose you could stop all mutations within the population and all emigration out of this population. Which statement best describes the probable future of this population?
A) The population will decline and become extinct after a few generations because of excessive inbreeding.
B) Evolution will continue as natural selection acts on the genetic variability that exists in the population.
C) Although the population will cease to change, it may survive for as long as the environment remains constant.
D) Genetic drift will cause major evolutionary changes in the population.
Answer: B
Topic: Section 17.3
Skill: Application/Analysis
16) Shrews have been documented to travel across frozen lakes and establish populations on previously uninhabited islands; thus, the shrews have a limited gene pool. If this limited gene pool has allele frequencies that are very different from the allele frequencies found in the original population, then this would be an example of:
A) natural selection.
B) population bottleneck.
C) divergent evolution.
D) founder effect.
Answer: D
Topic: Section 17.3
Skill: Application/Analysis
17) Imagine a population of monkeys in South America whose habitat has been reduced to the point where only 25 monkeys survive. This is an example of:
A) population bottleneck.
B) founder effect.
C) genetic drift.
D) natural selection.
Answer: A
Topic: Section 17.3
Skill: Application/Analysis
18) The most immediate effect of sexual displays and contests in animals (such as bighorn sheep bashing their heads together) is:
A) mutations.
B) differential mating success.
C) disruptive selection.
D) stabilizing selection.
Answer: B
Topic: Section 17.3
Skill: Application/Analysis
19) Genetic drift occurs when:
A) chance occurrences alter gene frequencies.
B) reproduction is nonrandom within the population.
C) gene flow within the population is less than gene flow between populations.
D) the population has not yet stabilized.
Answer: A
Topic: Section 17.3
Skill: Knowledge/Comprehension
20) The mate-attracting elaborate plumage of the male peacock is a result of:
A) genetic drift.
B) adaptation to the environment.
C) sexual selection.
D) gene flow.
Answer: C
Topic: Section 17.3
Skill: Knowledge/Comprehension
21) Evolution by genetic drift is most obvious in:
A) invertebrate species.
B) migratory species.
C) aquatic populations.
D) small populations.
Answer: D
Topic: Section 17.3
Skill: Knowledge/Comprehension
22) Mutations:
A) are always detrimental.
B) account for most of the change in allele frequency in a population.
C) may do nothing, may be harmful, or may be beneficial.
D) are always beneficial.
Answer: C
Topic: Section 17.3
Skill: Knowledge/Comprehension
23) Which of the following processes is not an agent of microevolution?
A) gene flow
B) natural selection
C) mutation
D) polygenic inheritance
E) genetic drift
Answer: D
Topic: Section 17.3
Skill: Knowledge/Comprehension
24) ________ is necessary for a population to survive over successive generations in response to environmental changes.
A) Adaptation
B) Sexual selection
C) Speciation
D) Gene flow
Answer: A
Topic: Section 17.3
Skill: Knowledge/Comprehension
25) In order for migration to alter allele frequencies in another population:
A) a large portion of the population must die off.
B) a large portion of the population must leave as new individuals arrive.
C) the gene pool of the migrating population must be different from the population it is joining.
D) the gene pools of the populations involved must be very similar.
Answer: C
Topic: Section 17.3
Skill: Knowledge/Comprehension
26) Two nearby populations in which there is some movement of individuals between the populations are an example of:
A) disruptive selection.
B) bottleneck effect.
C) genetic drift.
D) gene flow.
Answer: D
Topic: Section 17.3
Skill: Knowledge/Comprehension
27) A bottleneck may be dangerous to a population because:
A) the potential for natural selection is greatly increased.
B) mutation rate is increased.
C) genetic variability is diminished.
D) mutation rate is decreased.
Answer: C
Topic: Section 17.3
Skill: Application/Analysis
28) Which of the following is most likely to cause genetic changes in a population that make it better adapted to its environment?
A) nonrandom mating
B) natural selection
C) gene flow
D) genetic drift
Answer: B
Topic: Section 17.3
Skill: Knowledge/Comprehension
29) The term "natural selection" is not interchangeable with the term "evolution" because:
A) natural selection is just a theory, whereas evolution has been proven.
B) a population may evolve in ways other than through natural selection.
C) Darwin coined the term "natural selection," but not "evolution."
D) natural selection does not always lead to evolution.
Answer: B
Topic: Section 17.3
Skill: Application/Analysis
30) Habitats set aside for endangered species are often sectioned into areas by roads, producing separate small populations. This causes problems in conservation because it reduces:
A) gene flow between populations.
B) the number of potential leaders.
C) sharing of resources.
D) interaction among generations.
Answer: A
Topic: Section 17.3
Skill: Application/Analysis
31) Even though in a similar habitat, a founder population that breaks away from the parent population may become very different because of:
A) mutation.
B) genetic drift.
C) natural selection.
D) the bottleneck effect.
Answer: B
Topic: Section 17.3
Skill: Knowledge/Comprehension
32) Extreme hunting pressure has caused northern elephant seals to become less genetically diverse because of:
A) genetic drift.
B) population bottleneck.
C) natural selection.
D) founder effect.
Answer: B
Topic: Section 17.3
Skill: Application/Analysis
33) Which of the following is incorrectly paired?
A) gene flow: genes move from one population to another
B) bottleneck effect: changes in allele frequencies due to chance events
C) founder effect: only a small portion of an original population's gene pool are represented
D) sexual selection: mating based on phenotype
Answer: B
Topic: Section 17.3
Skill: Knowledge/Comprehension
34) The greater prairie chicken once flourished on the prairies of Illinois. The conversion of prairie to farmland reduced their numbers from millions to only 50 birds by 1993. Poor genetic diversity resulted in only 50 percent of eggs hatching. Bringing in birds from neighboring states increased their genetic diversity, which improved the egg-hatching rate to 90 percent. These changes in genetic diversity were the result of:
A) loss of genetic diversity through natural selection and restoration of genetic diversity by genetic drift.
B) loss of genetic diversity through mutation and restoration of genetic diversity by gene flow.
C) loss of genetic diversity through genetic drift and restoration of genetic diversity by natural selection.
D) loss of genetic diversity through genetic drift and restoration of genetic diversity by gene flow.
Answer: D
Topic: Section 17.3
Skill: Application/Analysis
35) Which of the following statements is true?
A) The advantage a trait conveys depends on its environmental context.
B) A population will always evolve to fit current conditions.
C) All traits are simultaneously maximized in a population.
D) All traits currently in a population must have provided a reproductive advantage at some point in time.
Answer: A
Topic: Section 17.4
Skill: Knowledge/Comprehension
36) Which of the following males in a given population would be considered the most fit in an evolutionary sense?
A) one that produced 1,000 offspring, of which 100 survived but 99 did not reproduce
B) one that produced 100 offspring, of which 10 survived but 9 did not reproduce
C) one that produced 1,000 offspring, all of which died before reaching reproductive age
D) one that produced two offspring, both of which survived and produced offspring of their own
Answer: D
Topic: Section 17.4
Skill: Application/Analysis
37) Which of the following possibilities is the best indicator of an organism's evolutionary fitness?
A) the number of eggs it produces over its lifetime
B) the number of gametes it produces during the years when it is likely to be reproducing
C) the number of offspring it produces over its lifetime that survive to breed.
D) the number of offspring it produces over its lifetime
Answer: C
Topic: Section 17.4
Skill: Application/Analysis
38) For the Galapagos Islands finch species Geospiza fortis, drought conditions produced a change in the population in which the next generation had larger beaks than the previous one. What produced this change in the population?
A) Birds with larger beaks had higher fitness, so they could produce more offspring that inherited the same trait.
B) Birds with smaller beaks flew to nearby islands where food was more plentiful.
C) Birds with smaller beaks had higher fitness, but they were outcompeted by birds with larger beaks.
D) Birds with smaller beaks had higher fitness, but they waited to reproduce until wet weather returned.
Answer: A
Topic: Section 17.4
Skill: Application/Analysis
39) Which of these humans is the "fittest" as far as natural selection is concerned?
A) a person with seven children who is killed in an automobile accident at age 40
B) a person who lives to the age of 105 and has two children
C) a person who lives to the age of 110 and has no children
D) a very popular film star who is still alive, is very rich, and has three children from three spouses
Answer: A
Topic: Section 17.4
Skill: Application/Analysis
40) How successful an individual is at passing on its genes to the next generation is known as:
A) microevolution.
B) adaptation.
C) fitness.
D) sexual selection.
Answer: C
Topic: Section 17.4
Skill: Knowledge/Comprehension
Read the statement below, and then answer the following question(s).
A small population of deer is introduced to an island. All the males have 11 to 13 points on their antlers.
41) If after several generations most males have antlers with 20 points, this development will have been the result of:
A) directional selection.
B) disruptive selection.
C) founder effect.
D) bottleneck effect.
Answer: A
Topic: Section 17.5
Skill: Application/Analysis
42) If after several generations 30 percent of the males have antlers with 9 to 11 points, 40 percent have antlers with 15 to 17 points, and 20 percent have antlers with 12 to 14 points, this development will have been the result of:
A) directional selection.
B) disruptive selection.
C) founder effect.
D) stabilizing selection.
Answer: B
Topic: Section 17.5
Skill: Application/Analysis
43) If after several generations all males have 12-point antlers, this development will have been due to:
A) directional selection.
B) disruptive selection.
C) founder effect.
D) stabilizing selection.
Answer: D
Topic: Section 17.5
Skill: Application/Analysis
44) Phenotypes that show a wide range of almost continuous variation, such as height or skin color in humans, are probably:
A) due to several sets of alleles working together.
B) due to both alleles of one gene working together.
C) acquired characteristics.
D) dominant.
Answer: A
Topic: Section 17.5
Skill: Knowledge/Comprehension
45) You are studying leaf size in a natural population of plants. The second season is particularly dry, and the following year the average leaf size in the population is smaller than the year before. But the amount of overall variation is the same, and the population size hasn't changed. Also, you've done experiments that show that small leaves are better adapted to dry conditions than are large leaves. Which of the following has occurred?
A) stabilizing selection
B) directional selection
C) genetic drift
D) disruptive selection
Answer: B
Topic: Section 17.5
Skill: Application/Analysis
46) The most important kind of selection acting on a well-adapted population in a relatively constant environment is:
A) disruptive.
B) stabilizing.
C) directional.
D) catastrophic.
Answer: B
Topic: Section 17.5
Skill: Knowledge/Comprehension
47) Disruptive selection operates whenever:
A) a phenotype is more successful because it is rare.
B) natural selection is disrupted by genetic drift.
C) the extremes in a distribution of phenotypes are more fit than the average.
D) only the largest individuals survive.
Answer: C
Topic: Section 17.5
Skill: Knowledge/Comprehension
48) How have Caesarean sections and intensive neonatal (near-birth) medical care likely affected the average birth weight of American babies?
A) Birth weight is now subject to disruptive selection instead of stabilizing selection.
B) Average birth weights have significantly decreased.
C) Gene flow will occur in the direction of larger and smaller infants.
D) Stabilizing selection for birth weight no longer has as much of an influence.
Answer: D
Topic: Section 17.5
Skill: Application/Analysis
49) For a particular character, natural selection can favor an average phenotype or extreme phenotypes. In order to do this, a character must be:
A) under the control of many genes.
B) under the control of only two alleles for a gene.
C) not under the control of any genes.
D) controlled by a dominant allele for a gene.
Answer: A
Topic: Section 17.5
Skill: Knowledge/Comprehension
50) African black-bellied seedcracker finches have beaks that are either large or small. Only large-beaked birds can crack open hard seeds, and small-beaked birds are more adept at handling small seeds. Both have an advantage over intermediate-sized beaks. This is an example of a response to:
A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) sexual selection.
Answer: C
Topic: Section 17.5
Skill: Application/Analysis
51) Male guppies are known for their bright colors. Having bright colors attracts mates, but it also attracts predators. So in an environment with a lot of predators, male guppies have more dull colors. In an experiment, guppies were removed from an area with predators to an area without predators. Over a period of 12 months the population became much more colorful. This is an example of a response to:
A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) mutation.
Answer: A
Topic: Section 17.5
Skill: Application/Analysis
52) The basic units that evolve are species.
Answer: FALSE
Topic: Section 17.1
Skill: Knowledge/Comprehension
53) There can be more than two varieties of alleles for a particular gene in a population.
Answer: TRUE
Topic: Section 17.1
Skill: Knowledge/Comprehension
54) A small minority of mutations is adaptive, providing an improvement to the gene pool of the population.
Answer: TRUE
Topic: Section 17.3
Skill: Knowledge/Comprehension
55) Genetic drift has a much more significant effect on small populations than on large populations.
Answer: TRUE
Topic: Section 17.3
Skill: Knowledge/Comprehension
56) Without mutation, evolution would eventually cease, because mutations create the variation that evolution acts upon.
Answer: TRUE
Topic: Section 17.3
Skill: Application/Analysis
57) A population of salamanders migrates from a sand beach to a pebble beach and evolves over many generations from a solid color to speckled coloration. This process is called stabilizing selection.
Answer: FALSE
Topic: Section 17.5
Skill: Application/Analysis
58) If a species of bird with an intermediate beak size evolves into two varieties, one with large beaks and one with small beaks, this could result from disruptive selection.
Answer: TRUE
Topic: Section 17.5
Skill: Application/Analysis
Match the following.
A) sexual selection
B) stabilizing selection
C) founder effect
D) genetic drift
E) gene flow
59) A small number of individuals from one area establish a new isolated population in another area. The gene frequencies of the new population differ from those of the original population.
Topic: Section 17.3
Skill: Knowledge/Comprehension
60) Females tend to mate with brightly colored males.
Topic: Section 17.3
Skill: Knowledge/Comprehension
61) Alleles migrate into or out of a population from neighboring populations.
Topic: Section 17.3
Skill: Knowledge/Comprehension
62) Chance events change allele frequencies in populations.
Topic: Section 17.3
Skill: Knowledge/Comprehension
63) Individuals with average phenotypes are favored over those with extreme phenotypes.
Topic: Section 17.5
Skill: Knowledge/Comprehension
Answers: 59) C 60) A 61) E 62) D 63) B
64) The smallest unit that can participate in evolution is a ________.
Answer: population
Topic: Section 17.1
Skill: Knowledge/Comprehension
65) The original source of variation within a population comes from ________.
Answer: mutations
Topic: Section 17.3
Skill: Knowledge/Comprehension
66) When a population decreases in number until a small remnant of the original population remains, a ________ has occurred.
Answer: bottleneck
Topic: Section 17.3
Skill: Knowledge/Comprehension
67) In ________ selection, individuals with an intermediate phenotype are favored over other individuals in the population.
Answer: stabilizing
Topic: Section 17.5
Skill: Knowledge/Comprehension
68) ________ characters are continuously variable.
Answer: Polygenic
Topic: Section 17.5
Skill: Knowledge/Comprehension
69) Cheetahs are not a healthy species. Several million years ago they were widespread in Africa and Asia, but their numbers fell drastically during the last ice age and again when they were hunted to near extinction in the nineteenth century. Now, they suffer from low survivorship (a large number of animals dying), poor sperm quality, and greater susceptibility to disease. Normally, an animal will reject tissue transplanted from another animal, but cheetahs will not reject tissue grafted on to them from another cheetah. What happened to the cheetah? How did their genetic variation change? Where does genetic variation ultimately come from? What mechanism can maintain and increase genetic variation in natural populations?
Answer: Cheetahs went through a bottleneck twice, once during the last ice age and again when they were hunted to near extinction. This caused a significant reduction in the genetic variation in their gene pool, and cheetahs now have very little genetic variation. With little genetic variation, the members of the species are all genetically very similar. Genetic variation ultimately comes from mutations, which produces new alleles. Genetic variation can be maintained and increased through gene flow.
Topic: Section 17.3
Skill: Application/Analysis
70) One solution to the problem of species extinction is captive breeding in zoos and gardens. What are some of the problems associated with this solution?
Answer: The resulting population, because it is small, will have a low genetic diversity. Such programs mimic the bottleneck effect unless efforts are made to increase diversity.
Topic: Section 17.3
Skill: Application/Analysis
71) List five mechanisms by which gene frequencies in a population can be altered. Describe each briefly.
Answer: Gene frequencies can be altered by mutation, which changes allele frequencies or creates new alleles; gene flow, which introduces new alleles into a population; genetic drift, which changes allele frequencies due to random events; natural selection, in which traits that confer a reproductive advantage grow more common in a population; and sexual selection, which produces differential reproductive success.
Topic: Section 17.3
Skill: Knowledge/Comprehension
72) Male long-tailed widowbirds have unusually long tails, about 20 inches in length, whereas the females have short tails. In an experiment with long-tailed widowbirds, one group of males had their tails clipped to 5 inches, a second group were left with normal 20-inch tails, and a third group had their tails lengthened to 30 inches by gluing on feathers clipped from the tails of other birds. If sexual selection is responsible for the males having such long tails, predict what will happen when similar numbers of females are placed in the territories of each group of males.
Answer: The males have longer tails because that characteristic was sexually selected for by females. One plausible hypothesis is that, because female preference is for longer tails, the males from the third group with 30-inch tails will attract more females.
Topic: Section 17.3
Skill: Synthesis/Evaluation
73) The concept of evolution has always been connected with some notion of progress–natural selection pushing populations toward better and better adaptations to create "perfect organisms." How would you argue that evolution does not craft perfect organisms?
Answer: Natural selection adapts populations to their constantly changing environments. It acts on those more fit for their environments, but the environments may change over time. An organism is only more fit than others of its population at a particular time; the organism is not necessarily a perfect match for its environment and is not a perfect organism by human criteria. What constitutes a best match at one time may be a less perfect match as the environment changes.
Topic: Section 17.4
Skill: Synthesis/Evaluation
Refer to the figure below, and then answer the question that follows.
74) Human birth weights are an example of:
A) disruptive selection.
B) stabilizing selection.
C) directional selection.
D) sexual selection.
Answer: B
Topic: Section 17.5
Skill: Knowledge/Comprehension
Refer to the figure below, and then answer the question that follows.
75) The changes in cranial capacity over the course of human evolution are an example of:
A) disruptive selection.
B) stabilizing selection.
C) directional selection.
D) sexual selection.
Answer: C
Topic: Section 17.5
Skill: Knowledge/Comprehension