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Chapter Chapter 13: How Populations Evolve
 
Chapter Quiz
 

1 .       Which of the following is a true statement about Charles Darwin? (13.1) [Hint]

 He was the first to discover that living things can change, or evolve.
 He based his theory on the inheritance of acquired characteristics.
 He worked out the principles of population genetics.
 He proposed natural selection as the mechanism of evolution.
 He was the first to realize that Earth is billions of years old.
2 .       At the time Darwin voyaged on HMS Beagle, the popularly accepted theory in Europe that explained the origin of Earth's plants and animals held that the various species ____________. (13.1) [Hint]

 arose continually from nonliving materials by spontaneous generation
 had been created by divine intervention a few thousand years before
 had evolved from now extinct organisms
 arose from a single species that had survived the biblical flood
 were all related to one another
3 .       The main ideas of Darwin's theory of evolution came from his observations of life on the Galápagos Islands. Where are these islands located? (13.1) [Hint]

 off the west coast of South America
 off the east coast of South America
 in the Indian Ocean
 southeast of Australia
 southwest of Australia
4 .       During his voyage around the world, Darwin was inspired to think about evolution by _____. (13.1) [Hint]

 the books he read
 fossils he collected
 studying adaptations of organisms to their environments
 the unique organisms he saw in the Galápagos Islands
 all of the above
5 .       Which one of the following statements best reflects Darwin's view of human evolution? (13.1) [Hint]

 Humans are descended from monkeys.
 Humans are the product of artificial selection.
 Humans and apes have a common ancestor.
 Humans are not a product of evolution.
 Humans are more abundant than any other animal species.
6 .       Darwin was well aware of what effect his theory of evolution would have on the lay public and on the Church of England. This, in fact, was why he delayed publication for several decades while he gathered additional evidence. Which one of the following was NOT evidence he used to support his theory? (13.1) [Hint]

 Earth is about 6,000 years old.
 Many more offspring are produced than can survive.
 When breeders select for specific traits, these become fixed in future generations.
 Some individuals leave more descendants than other individuals.
 In a population of organisms, every individual is different from every other one.
7 .       Which one of the following statements most closely agrees with the theory of evolution by means of natural selection, as put forth by Darwin and Wallace? (13.1) [Hint]

 Only the best-adapted organisms will survive.
 Humans arose from chimpanzees.
 Organisms mutate under unfavorable conditions to become better adapted.
 Only favorable traits are passed from one generation to the next.
 Organisms better adapted to their immediate environment are most likely to survive and reproduce.
8 .       The breeding of plants and animals by humans is called _____. (13.2) [Hint]

 natural selection
 sexual recombination
 founder effect
 artificial selection
 neutral variation
9 .       Darwin inferred that individuals of a species compete with one another, observing that _____. (13.2) [Hint]

 some individuals are larger and stronger than others
 natural population sizes do not usually expand as fast as they can
 many different traits coexist within a species
 some peas have purple flowers while others have white flowers
 gene frequencies in a population change over time
10 .       "Differential success in reproduction" is just another way of saying _____. (13.2) [Hint]

 natural selection
 mutation
 variation
 recombination
 genetic drift
11 .       "Natural selection" and "evolution" are two terms that are sometimes confused, even by freshman biology students. What is the relation between natural selection and evolution? (13.2) [Hint]

 They are the same thing.
 Any phenomenon that causes evolution is natural selection.
 Natural selection is one of several mechanisms of evolution.
 When natural selection is occurring, evolution is not, and vice versa.
 None of the above.
12 .       In natural selection, __________ determines which phenotypes are successful. (13.2) [Hint]

 chance
 the environment
 sample size
 genetic drift
 human intervention
13 .       Which one of the following is NOT a requirement for, nor a feature of, natural selection? (13.2) [Hint]

 excess numbers of individuals
 variation in individuals
 heritable traits
 greater numbers of offspring from the better adapted
 environmentally induced acquisition of traits
14 .       An adaptation is _________. (13.2) [Hint]

 an individual's attempt to conform to its environment
 a trait that confers a reproductive advantage on the individual possessing it
 a variable allele that changes expression in response to the environment
 a trait that is seldom expressed
 all of the above
15 .       Fossils are most likely to be found in _____. (13.3) [Hint]

 the continental shelves
 unglaciated terrain
 sedimentary rock
 igneous rock
 volcanic archipelagos, such as the Galápagos and Hawaiian Islands
16 .       An important challenge to traditional (pre-1860) ideas about species was the observation that seemingly dissimilar organisms, such as hummingbirds, humans, and whales, have similar skeletal structures. This most directly suggested to biologists that ____________. (13.3) [Hint]

 only the best-adapted organisms can survive
 advantageous changes can be passed along to offspring
 most evolution occurs rapidly following a mass extinction
 dissimilar organisms might have evolved from a distant, common ancestor
 all of the above
17 .       Animals that possess homologous structures probably _____. (13.3) [Hint]

 are headed for extinction
 evolved from the same ancestor
 have increased genetic diversity
 by chance had similar mutations in the past
 are not related
18 .       The bones of the wings of bats are homologous to the bones of the __________ of their ancestors. (13.3) [Hint]

 jaws
 front limbs
 brain case
 ribs
 hind limbs
19 .       Evidence from molecular biology supports the theory of evolution by showing that _____. (13.3) [Hint]

 homologous proteins have arisen separately in many different animal groups
 closely related animal species have similar geographic distributions
 closely related organisms have more similar DNA and proteins
 closely related organisms have similar stages of development
 none of the above
20 .       The approach to evolution that involves the study of similar structures that appear during the development of different organisms is known as the study of _____. (13.4) [Hint]

 comparative anatomy
 comparative embryology
 biogeography
 molecular biology
 cladistics
21 .       All known organisms transcribe genetic information to protein molecules via the same genetic code. This finding strongly supports the hypothesis that _____. (13.4) [Hint]

 there's only one possible way to encode information in a macromolecule
 the earliest macromolecules probably arose when lightning struck an oxygen-free atmosphere
 all organisms are descended from a single common ancestor
 the genetic code will never be broken
 none of the above
22 .       Which one of the following is NOT homologous to a human arm? (13.4) [Hint]

 chicken wing
 seal flipper
 crayfish claw
 horse's front leg
 frog's front leg
23 .       Biologists have noticed that most human beings enjoy sex. How would they explain this in evolutionary terms? (13.4) [Hint]

 If sex were not enjoyable, the human species would have died out.
 Early humans who enjoyed sex most had the most babies.
 Only body structures evolve, not behavior, so enjoyment cannot evolve.
 This was due to a random mutation, so it did not affect evolution.
 Biologists are baffled by the phenomenon of sex.
24 .       Which of the following factors is NOT an important part of natural selection? (13.4) [Hint]

 limited environmental resources
 unequal reproduction with individuals best meeting environmental demands having the most success
 heritable variation
 selective breeding of domestic plants and animals
 individuals better adapted to an environment being more likely to survive
25 .       Assume there are two varieties of mice, brown and gray, living on an island. They are the prey for the hawks on the island. They are distributed through rocky areas in the north of the island and across the fields in the south part. Which of the following is predicted by natural selection? (13.4) [Hint]

 If they stay as a mixed population, they will remain mixed because the two varieties will not interbreed with each other.
 Since brown mice blend better with the ground and gray mice blend better with the rocks, these are the ones that will be missed by the hawks and the mouse distribution will tend to indicate this.
 Hawks find the mice by movement so it won't matter.
 The hawks will starve to death because they get confused.
 A mouse population that starts as a random mixture will never adapt to the environment.
26 .       Traits that enhance an individual's ability to compete for limited resources are called _____. (13.5) [Hint]

 genotypes
 adaptations
 isolating mechanisms
 randomizations
 allopatric
27 .       According to the modern synthesis of evolutionary theory, which of the following is true? (13.6) [Hint]

 Populations are the units of evolution.
 Only certain animal species are sexual.
 Evolution is independent of genetics.
 Segregation and independent assortment explain evolution of the individual and not the species.
 All of the above.
28 .       A number of mosquito populations today are resistant to specific insecticides even though those species were not resistant when the insecticides were first introduced. Biologists believe that insecticide resistance evolved in mosquitoes because _____. (13.6) [Hint]

 individual mosquitoes built up an immunity to an insecticide after being exposed to it
 mosquitoes needed to develop insecticide resistance to survive after the insecticide was used
 a few mosquitoes were probably resistant to the insecticide before it was ever used, and these survived to reproduce
 mosquitoes attempted to adapt to their environment
 individual mosquitoes built up an immunity to an insecticide after being exposed to it, and mosquitoes needed to develop insecticide resistance to survive after the insecticide was used
29 .       If members of a population have traits that are both heritable and variable among individuals, then ___________. (13.6) [Hint]

 advantageous traits may become more widespread in subsequent generations
 no evolutionary change is likely to occur over time
 only neutral evolutionary change can occur over time
 the environment will have no influence on phenotypes
 genes will have no influence on an organism's physical appearance
30 .       When they were first sold, aerosol insecticides were highly effective in killing flies and mosquitoes. Today, some 30 years later, a much smaller proportion of these insects die when sprayed. The reason fewer insects are being killed is that ____________. (13.6) [Hint]

 mosquitoes that survive spraying develop an immunity to the insecticide
 many mosquitoes today are descendants of mosquitoes with insecticide-resistant characteristics
 mosquitoes are deliberately adapting themselves to this man-made change in the environment
 the original spraying has caused a permanent mutation, giving the insects genetic resistance to the spray
 none of the above
31 .       The major weakness of Darwin's theory (as it existed in 1859) was that it could NOT explain _____. (13.6) [Hint]

 why species become extinct
 why different parts of the world have different plants and animals
 why vestigial structures exist
 how advantageous traits can be passed to offspring
 any of the above
32 .       Which of the following was NOT a part of Darwin's explanation of natural selection? (13.6) [Hint]

 Most organisms commonly produce more offspring than can possibly survive.
 Mutation (a change in DNA structure) occurs spontaneously and gives rise to new variations.
 Species consist of individuals that vary from one another.
 Members of a species compete with each other for food and space.
 Some traits confer a reproductive advantage and are passed along more frequently than others.
33 .       A population is _____. (13.6) [Hint]

 all living organisms on Earth
 the number of humans per unit area
 organisms of different species that live together
 a group of individuals of the same species occupying a given area
 the number of organisms in a particular habitat
34 .       Natural selection primarily acts on _____. (13.6) [Hint]

 phenotypes
 genotypes
 mutations
 heterozygotes
 homozygotes
35 .       The smallest unit that can evolve is a _____. (13.6) [Hint]

 species
 genotype
 gene
 population
 morph
36 .       Members of the same population _____. (13.6) [Hint]

 share a common gene pool
 cannot interbreed under natural conditions
 share the same genotype
 are in reproductive isolation from one another
 none of the above
37 .       What is the term for a change in the relative frequencies of alleles in a population over several generations? (13.7) [Hint]

 gene pool
 independent assortment
 macroevolution
 reservoir
 microevolution
38 .       In the Hardy-Weinberg theorem, p2 represents _____. (13.7) [Hint]

 the total alleles in the gene pool
 the frequency of heterozygous dominants in the gene pool
 the frequency of homozygous recessives in the gene pool
 all of the possible phenotypes in the gene pool
 the frequency of homozygous dominants in the gene pool
39 .       In the Hardy-Weinberg theorem, 1 represents _____. (13.7) [Hint]

 the sum of the frequencies of all the alleles of a particular gene that exists in a gene pool
 the frequency of heterozygous dominants in the gene pool
 the frequency of homozygous recessives in the gene pool
 all the possible phenotypes in the gene pool
 the frequency of homozygous dominants in the gene pool
40 .       Approximately 1 out of every 2,500 Caucasians in the United States is born with the recessive disease cystic fibrosis. According to the Hardy-Weinberg equilibrium equation, approximately how many people are carriers? (13.7) [Hint]

 1 in 50
 96 in 100
 1 in 25
 1 in 10
 none of the above
41 .       Suppose that, with regard to a particular genetic locus with two alleles, A and a, we know that 60% of the alleles in the gene pool of a particular large population are A. Suppose further that we observe this population for five generations, during which we know that no mutation, selection, or migration has occurred. After this period, the frequency of the a allele is expected to be _____. (13.7) [Hint]

 0.6
 0.4
 0.25
 0.16
 0.5
42 .       In a large population of bonobos, the frequency of the recessive allele is initially 0.1. There is no migration and no selection. What is the frequency of the dominant allele? Assume that there are two alleles of this gene. (13.7) [Hint]

 10%
 20%
 50%
 90%
 99%
43 .       In a certain group of African people, 4% are born with sickle-cell anemia (homozygous recessive). If this group is in Hardy-Weinberg equilibrium, what percentage of the group has the selective advantage of being more resistant to malaria (heterozygous) than those individuals who are homozygous for normal hemoglobin or for sickle-cell anemia? (13.7) [Hint]

 2%
 4%
 8%
 16%
 32%
44 .       Which of the following conditions is NOT required for Hardy-Weinberg equilibrium? (13.9) [Hint]

 a large population
 no migration of individuals or gametes in or out of the population
 no mutations altering the gene pool
 sexual selection
 random mating
45 .       A moth population is at Hardy-Weinberg equilibrium. Which one, if any, of the following conditions would NOT tend to disturb the Hardy-Weinberg equilibrium? If all these conditions would disturb the equilibrium, choose answer (4). (13.9) [Hint]

 The population consists of only six breeding pairs.
 Moths are flying in and out of this population all the time.
 Pollution is causing a high rate of mutation in the moths.
 All of the above conditions would disturb the Hardy-Weinberg equilibrium.
 None of these conditions would disturb a Hardy-Weinberg equilibrium.
46 .       If a population is in Hardy-Weinberg equilibrium and remains in equilibrium, which of the following will be true? (13.9) [Hint]

 Allelic and genotypic ratios will gradually change from one generation to the next.
 The relative frequencies of three genotypes (AA, Aa, aa) will gradually become stabilized at 1.
 Sexual organisms will evolve.
 Asexual organisms will not evolve.
 There will be no mutations.
47 .       Which of the following scenarios would most likely result in the microevolution of a population of humans? (13.9) [Hint]

 Only random mating takes place in all the people that reproduce in North America.
 A colony of humans on the moon is isolated from Earth.
 The incidence of skin cancer in adults over age 40 rises significantly.
 All of the people in Georgia are killed in a natural disaster.
 Both random mating and an increase in middle-aged skin cancer.
48 .       Which of the following is the best example of gene flow? (13.9) [Hint]

 A polyploid plant develops.
 Genes are shuffled by the crossing over of chromosomes during meiosis.
 An earthquake results in the formation of a canyon, splitting a population of toads apart.
 Wind blows pollen from one population of plants to another and cross-fertilization occurs.
 All the mutations in a population were neutral.
49 .       If an earthquake hit a small island so that all but a tiny group of lizards were eliminated and the survivors spread out over the island, this would be an instance of _____. (13.9) [Hint]

 founder effect
 bottleneck effect
 gene flow
 mutation
 nonrandom mating
50 .       The original source of all genetic variation is _____. (13.9) [Hint]

 mutation
 meiosis
 a need for new traits
 natural selection
 recombination
51 .       The evolutionary effects of genetic drift are greatest when _____. (13.9) [Hint]

 the population size is large
 intraspecific competition is intense
 the population size is small
 intraspecific competition is weak
 sexual selection occurs
52 .       A moth population is at Hardy-Weinberg equilibrium. From this statement, you know that in this population _____ (13.9) [Hint]

 the allelic frequencies are stable
 the proportion of each genotype in the population will be the same, generation after generation
 the population is not evolving
 all of the above
 none of the above
53 .       The severe reduction in genetic variability seen in the endangered cheetah is probably attributable to _____. (13.10) [Hint]

 natural selection
 mutation
 having gone through at least one bottleneck
 gene flow
 none of the above
54 .       Rabbits living farther north tend to have smaller ears. This is an example of _____. (13.11) [Hint]

 a cline
 polymorphism
 artificial selection
 heterozygote advantage
 genetic drift
55 .       German shorthaired pointers, Scottish terriers, and beagles are capable of interbreeding and producing viable, fertile offspring. The diversity in morphologies seen in these breeds of dogs is the result of _____. (13.12) [Hint]

 natural selection
 sexual recombination during meiosis
 artificial selection
 chance
 Any of the above could have produced these and the other currently recognized breeds of dogs.
56 .       Sexual recombination occurs when chromosomes are shuffled in _____ and fertilization. (13.12) [Hint]

 mitosis
 genetic drift
 natural selection
 mutation
 meiosis
57 .       Which of the following changes in the gene pool results in an adaptation to the environment? (13.12) [Hint]

 nonrandom mating
 genetic drift
 natural selection
 gene flow
 mutation
58 .       A geneticist studied a grass population growing in an area of erratic rainfall and found that plants with alleles for curled leaves reproduced better in dry years, and plants with alleles for flat leaves reproduced better in wet years. This situation would _____. (13.12) [Hint]

 cause genetic drift in the grass population
 preserve the variability in the grass population
 lead to directional selection in the grass population
 lead to uniformity in the grass population
 cause gene flow in the grass population
59 .       Bacteria can adapt to changes in the environment by means of mutation alone because _____. (13.12) [Hint]

 they are so small
 their populations are very isolated from one another
 a bacterium is much more likely to mutate than a larger organism
 they multiply so rapidly
 their populations are so large
60 .       _____ and _____ generate variation, while _____ results in an adaptation to the environment. (13.12) [Hint]

 Genetic drift ... natural selection ... mutation
 Mutation ... sexual recombination ... natural selection
 Overproduction of offspring ... mutation ... sexual recombination
 Natural selection ... mutation ... sexual recombination
 Sexual recombination ... natural selection ... overproduction
61 .       Each of us is part of the ongoing evolution of the human species. Which of the following occurrences would have the greatest impact on the future biological evolution of the human population? (13.12) [Hint]

 You work out every day so that you stay physically fit and healthy.
 A mutation occurs in one of your skin cells.
 You move to Hawaii, the state with the longest life expectancy.
 A mutation occurs in one of your sperm or egg cells.
 You encourage your children to develop their intellectual abilities.
62 .       Genetic variation in a population of animals or plants depends mainly on which of the following? (13.12) [Hint]

 mutation
 sexual recombination
 the organism being haploid
 migration of genes among the chromosomes
 massive die-offs
63 .       Critics like to point out that the theory of evolution is flawed because it is based on random changes: mutations. They say that a random change in an organism (or a car or a TV set) is likely to harm it, not make it function better. What logical statement refutes these critics? (13.12) [Hint]

 Fossils prove without a doubt that mutations drive evolution.
 Mutation is random; natural selection is not.
 Mutation has little to do with evolution.
 This is a weak spot in the theory that remains to be worked out.
 Mutations are not random.
64 .       Antibiotic resistance in bacteria is an example of which of the following? (13.13) [Hint]

 stabilizing selection
 directional selection
 diversifying selection
 Hardy-Weinberg equilibrium
 none of the above
65 .       Scientists have warned doctors of the danger of their increasing use of antibiotics (for instance, penicillin) for treating minor illnesses. They are concerned because ____________. (13.13) [Hint]

 humans will become tolerant to the effects of drugs
 excessive use of these drugs leads to a diminished sensitivity to them
 strains of microorganisms that are resistant to these drugs will be selected
 the drugs will be metabolized more quickly by our bodies, decreasing their effectiveness
 none of these
66 .       How does the overprescription of antibiotics contribute to a major public health threat? (13.13) [Hint]

 The antibiotic will become ineffective as you become immune to it.
 Indiscriminant use of antibiotics selects for resistant bacteria.
 Its use in cattle feed promotes the growth of larger cattle; larger cattle belch more methane than smaller cattle, and this results in an even greater increase in atmospheric levels of greenhouse gasses
 The overprescription of antibiotics will result in the evolution of antibiotic-resistant viruses.
 The antibiotics consumed along with animal flesh are a major cause of gastrointestinal tract disturbances in humans
67 .       Under some conditions, heterozygotes have greater reproductive success than homozygotes. What is this called? (13.14) [Hint]

 polymorphism
 clines
 genetic drift
 codominance
 heterozygote advantage
68 .       Which of the following would seem to be an example of neutral variation? (13.14) [Hint]

 homozygosity of the cheetah population
 polymorphism of the Galápagos finches
 founder effect
 human fingerprints
 moth coloration
69 .       Which of the following statements best describes how the process of natural selection works to change allele frequencies? (13.14) [Hint]

 The best-adapted organisms will leave behind more offspring.
 A small population size encourages genetic diversity.
 The best-adapted organisms will survive.
 Allele frequencies will change in response to changes in population size.
 Beneficial mutations will arise in response to a new environment.
70 .       Tay Sachs disease, which is lethal, results from having the homozygous recessive condition of the responsible gene. Which one of the following statements is true? (13.15) [Hint]

 Because homozygous recessive individuals die, the recessive allele will eventually be lost from the population.
 Only homozygous dominant individuals will be able to survive and reproduce.
 Heterozygous individuals will survive and be able to pass the recessive allele on to their offspring.
 In the heterozygous condition, the dominant allele will overcome the recessive allele and only the dominant will be passed on to offspring.
 Homozygous dominant individuals will be more likely to reproduce than heterozygous individuals.
71 .       Natural selection is sometimes described as survival of the fittest. Which of the following most accurately measures an organism's Darwinian fitness? (13.15) [Hint]

 how strong it is when pitted against others of its species
 its mutation rate
 how many fertile offspring it produces
 its ability to withstand environmental extremes
 how much food it is able to make or obtain
72 .       In a population of bears, which is most likely to be considered to have the greatest Darwinian fitness? (13.15) [Hint]

 the biggest bear
 the bear having the largest number of mutations
 the bear that blends in with its environment the best
 the strongest, fiercest bear
 the bear that leaves the most descendants
73 .      

Biologists often use the term "fitness" when speaking of evolution. Below are descriptions of four male grizzly bears. According to your understanding of evolution, which bear would biologists consider the most fit? (13.15)
NAME
George
Ben
Spot
Sandy
SIZE
10 ft

1,200 lb
8.5 ft

1,000 lb
9 ft

1,100 lb
9 ft

1,000 lb
NUMBER OF CUBS FATHERED
19
25
20
20
NUMBER OF CUBS SURVIVING TO ADULTHOOD
15
14
14
19
COMMENTS George is very large, very healthy. The strongest bear.Ben mated with the greatest number of females.When the area that Spot lived in was destroyed by fire, Spot was able to move to a new area and change his feeding habits.Sandy was killed by an infection resulting from a cut in his foot.
AGE AT DEATH
13 yr
16 yr
12 yr
9 yr

The fittest bear was _________.

[Hint]

 George
 Ben
 Spot
 Sandy
 There is not enough information to answer the question.
74 .       To be successful in evolutionary terms, an organism must _________. (13.15) [Hint]

 adapt to environmental changes
 acquire characteristics that help it survive
 survive longer than other members of the population
 have the maximum number of mutations
 pass its genes on to the next generation
75 .       Birds with average-sized wings survived a severe storm more successfully than other birds in the same population with longer or shorter wings. This illustrates _____. (13.16) [Hint]

 the founder effect
 stabilizing selection
 artificial selection
 gene flow
 diversifying selection
76 .       A population of squirrels is preyed on by small hawks. The smaller squirrels can escape into burrows. The larger squirrels can fight off the hawks. After several generations, the squirrels in the area tend to be very small or very large. What process is responsible for this outcome? (13.16) [Hint]

 stabilizing selection
 directional selection
 diversifying selection
 artificial selection
 Hardy-Weinberg equilibrium
77 .       In a large population of randomly breeding individuals, the frequency of a recessive allele is initially 0.3. There is no migration and no selection. Humans enter this ecosystem and selectively hunt individuals showing the dominant trait. When the gene frequency is reexamined at the end of the year, ____________. (13.16) [Hint]

 the frequency of the homozygous dominants will go down, the frequency of the heterozygous genotype will go up, and the frequency of the homozygous recessives will remain the same
 the frequency of the homozygous dominants will go down, the frequency of the heterozygous genotype will remain the same, and the frequency of the homozygous recessives will go up
 the frequency of the homozygous dominants will go up, the frequency of the heterozygous genotype will go down, and the frequency of the homozygous recessives will go down
 the frequency of the homozygous dominants will go up, the frequency of the heterozygous genotype will go down, and the frequency of the homozygous recessives will go up
 the frequency of the individuals who express the dominant phenotype will go down and the frequency of homozygous recessive individuals will go up
78 .       Stabilizing selection _____. (13.16) [Hint]

 favors intermediate variants in a population
 prevents mutations from occurring
 occurs when some individuals migrate to an area with different environmental conditions
 can take place only in species exhibiting sexual dimorphism
 occurs only in plants
79 .       Selection that acts, over evolutionary time, to preserve traits that increase an individual's ability to mate is known as _____. (13.17) [Hint]

 directional selection
 disruptive selection
 wide selection
 sexual selection
 channel selection
80 .       Which of these is NOT one of the reasons why natural selection does not fashion perfect organisms? (13.18) 

 Not all evolution is adaptive.
 Selection can only edit existing variation.
 Adaptations are often compromises.
 Organisms are locked into historical constraints.
 None of the above.