21. Evolution by Natural Selection

Darwin originally defined evolution as __________.

Which of the following is a key observation that must be explained in a unifying theory about life?

The scala naturae, or scale of nature, is based on the ideas of __________.

At the time Darwin voyaged on HMS Beagle, the popularly accepted theory in Western culture that explained the origin of Earth's plants and animals held that the various species __________.

Carolus Linnaeus is considered to be the founder of __________, and he __________.

The modern idea of extinction as a common occurrence in Earth's history was first proposed in the early-19th-century writings of __________.

Lyell's principle of uniformitarianism __________.

Which of the following is a true statement about Charles Darwin?

At the time Charles Darwin sailed on HMS Beagle, __________.

Because he was well aware of the effect his theory of evolution would have on the public and on the Church of England, Darwin delayed publishing his work for several decades while he gathered additional evidence. After invoking selective breeding of domesticated species as evidence that groups of organisms are capable of change, he then proposed that natural populations can change as well. On which two lines of evidence did he base this proposal?

During his voyage around the world, Darwin was inspired to think about evolution by __________.

In Darwin's view of descent with modification, __________.

What insight did Darwin gain from reading Thomas Malthus's essay on human suffering?

The breeding of plants and animals for particular traits by humans is called __________.

The smallest unit that can evolve is a(n) __________.

During periods of rapid environmental change, what may happen to a species that was well suited to the former environment?

According to the theory of evolution, anatomical and molecular homologies should __________.

When they were first sold, aerosol insecticides were highly effective in killing flies and mosquitoes. Now, several decades later, a much smaller proportion of these insects die when sprayed. The reason fewer insects die when they are sprayed is that __________.

To describe evolution as a "scientific theory" means that __________.

What did Darwin observe about species on islands?

Evidence from molecular biology supports the theory of evolution by demonstrating that __________.

All known organisms translate genetic information to produce protein molecules via the same genetic code. This finding strongly supports the hypothesis that __________.

A population of zooplankton is exposed to a small number of predatory fish that feed on the larger-sized (adult) zooplankton. Which of the following predictions would most likely occur based on the principles of natural selection?

How did some strains of Staphylococcus aureus become resistant to antibiotic drugs?

Seemingly dissimilar organisms such as hummingbirds, humans, and whales have similar skeletal structures. This most directly suggested to biologists that __________.

Animals that possess homologous structures probably __________.

Vestigial organs are __________.

Which of the following is an example of convergent evolution?

On an evolutionary tree, __________.

What observations did Darwin make on the Galápagos Islands that helped convince him that evolution occurs? a. the existence of animals that did not fit into Linnaeus's classification system; b. the similarities and differences among cacti and tortoises on the different islands; c. the presence of species he had seen on other tropical islands far from the Galápagos; d. the radioactive age of the rocks of the islands; e. fossils of human ancestors

Which of the following is an observation or inference on which natural selection is based? (A) Individuals do not vary in their heritable characteristics. (B) Only well-adapted individuals produce offspring. (C) Species produce more offspring than the environment can support. (D) Nearly all of each individual's offspring will survive and reproduce.

Which of the following is not an observation or inference on which natural selection is based? a. There is heritable variation among individuals. b. Poorly adapted individuals never produce offspring. c. Species produce more offspring than the environment can support. d. Only a fraction of an individual's offspring may survive.

Summarize the key points of Darwin's theory of descent with modification, including his proposed mechanism of evolution.

True or false? Some traits are considered vestigial because they existed long ago.

What types of drugs have helped reduce the death rate due to tuberculosis infection, and why have they become less effective more recently?

What are three ways monosaccharides differ from one another?

Define artificial selection, and compare and contrast it with natural selection.

Which of the following observations helped Darwin shape his concept of descent with modification? a. Species diversity declines farther from the equator. b. Fewer species live on islands than on the nearest continents. c. Birds live on islands located farther from the mainland than the birds' maximum nonstop flight distance. d. South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.

Complete this concept map describing potential causes of evolutionary change within populations. a. b. c. d. e. f. g.

What type of bond is formed between two sugars in a disaccharide? a. glycosidic linkage b. phosphodiester bond c. peptide bond d. hydrogen bond

Which of the following observations is not part of the theory of natural selection? a. Populations of organisms have more offspring than will survive; b. There is variation among individuals in a population; c. Modern organisms are unrelated; d. Traits can be passed on from parent to offspring; e. Some variants in a population have a higher proba­bility of survival and reproduction than other variants do.

Within six months of effectively using methicillin to treat S. aureus infections in a community, all new S. aureus infections were caused by MRSA. How can this best be explained? a. A patient must have become infected with MRSA from another community. b. In response to the drug, S. aureus began making drug- resistant versions of the protein targeted by the drug. c. Some drug-resistant bacteria were present at the start of treatment, and natural selection increased their frequency. d. S. aureus evolved to resist vaccines.

Traits that are derived from a common ancestor, like the bones of human arms and bird wings, are said to be                .

Which of the following did not influence Darwin as he synthesized the theory of evolution by natural selection? a. examples of artificial selection that produce large and relatively rapid changes in domesticated species b. Lyell's Principles of Geology, on gradual geologic changes c. comparisons of fossils with living organisms d. Mendel's paper describing the laws of inheritance

Traits that are derived from a common ancestor, like the bones of human arms and bird wings, are said to be                .

What holds cellulose molecules together in bundles large enough to form fibers? a. the cell wall b. peptide bonds c. hydrogen bonds d. hydrophobic interactions

The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a common ancestor at about the same time. Which of the following is the most likely explanation for these data? a. Forelimb evolution was adaptive in people and bats, but not in whales. b. Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy. c. Genes mutate faster in whales than in humans or bats. d. Whales are not properly classified as mammals.

Natural selection is sometimes described as 'survival of the fittest.' Which of the following best measures an organism's fitness? a. how many fertile offspring it produces b. how strong it is when pitted against others of its species c. its ability to withstand environmental extremes d. how much food it is able to make or obtain

How can evolutionary fitness be measured? Select True or False for each statement. T/F Document how long individuals survive. T/F Count the number of healthy, fertile offspring produced. T/F Determine which individuals are strongest. T/F Determine which phenotype is the most common.

What are the primary functions of carbohydrates in cells? a. cell identity, energy storage, raw material source for synthesis, and structure b. catalysis, energy storage, metabolism, and structure c. catalysis, digestion, energy storage, and information storage d. energy storage, information storage, polymerization, and raw material source for synthesis

Which of the differences listed here could be found among molecules of the same monosaccharide? Select True or False for each statement. T/F There is a difference in the orientation of a hydroxyl group in the ring form. T/F There is a difference in the number of carbons. T/F There is a difference in the position of the carbonyl group in the linear form. T/F There is a difference in the overall shape of the molecule—one is a ring and the other is linear.

The best definition of evolutionary fitness is                   . a. physical health; b. the ability to attract members of the opposite sex; c. the ability to adapt to the environment; d. survival and reproduction relative to other members of the population e. overall strength

The theory of common descent states that all modern organisms                   . a. can change in response to environmental change; b. descended from a single common ancestor; c. descended from one of many ancestors that originally arose on Earth; d. have not evolved; e. can be arranged in a hierarchy from 'least evolved' to 'most evolved'

DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that a. humans and chimpanzees share a relatively recent common ancestor. b. humans evolved from chimpanzees. c. chimpanzees evolved from humans. d. convergent evolution led to the DNA similarities.

According to data presented in this chapter, which of the following are correct? Select True or False for each statement. T/F When individuals change in response to challenges from the environment, their altered traits are passed on to offspring. T/F Species are created independently of each other and do not change over time. T/F Populations—not individuals—change when natural selection occurs. T/F The traits of populations become more perfect over time.

An adaptation is a trait of an organism that increases                   . a. its fitness; b. its ability to survive and replicate; c. in frequency in a population over many generations; d. A and B are correct; e. A, B, and C are correct

The DNA sequence for the same gene found in several species of mammals                   . a. is identical among all species; b. is equally different between all pairs of mammal species; c. is more similar between closely related species than between distantly related species; d. provides evidence for the hypothesis of common descent; e. more than one of the above is correct

Some biologists summarize evolution by natural selection with the phrase 'mutation proposes, selection disposes.' Mutation is a process that creates heritable variation. Explain what the phrase means.

Although cellulose and starch are identical in terms of stored chemical energy, our ability to harvest the energy from these two polysaccharides differs considerably. What is responsible for this difference?

Marsupial mammals give birth to young that complete their development in a pouch on the mother's abdomen. All the native mammals of Australia are marsupials, while these types of mammals are absent or uncommon on other continents. This observation is an example of a.developmental evidence for evolution; b. biogeogra­phic evidence for evolution; c. genetic evidence for evolution; d. fossil evidence for evolution; e. not useful evidence for evolution

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from the air-breathing organ (a simple lung) of an ancestral fish is an example of a. exaptation. b. changes in Hox gene expression. c. paedomorphosis. d. adaptive radiation.

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. Evidence indicates that early fish gulped air into primitive lungs, helping them survive in stagnant waters. The evolution of the swim bladder from lungs of an ancestral fish is an example of a. an evolutionary trend. b. paedomorphosis. c. the gradual refinement of a structure with the same function. d. exaptation.

Why don't the biggest and strongest individuals in a population always produce the most offspring? a. The biggest and strongest individuals always have higher fitness. b. In some environments, being big and strong lowers fitness. c. Sometimes the biggest and strongest individuals may choose to have fewer offspring. d. Sometimes the number of offspring is not related to fitness.

If you were given a solution that has a pH of 8.5, what would be its concentration of protons? What is the difference in proton concentration between this solution and one that has a pH of 7?

Contrast the structure of glycogen and chitin in terms of their monosaccharides, glycosidic linkages, and interactions between polysaccharide chains.

Consider the reaction between carbon dioxide and water to form carbonic acid: CO2(g)+H2O(l)⇌CH2O3(aq) In the ocean, carbonic acid immediately dissociates to form a proton and bicarbonate ion, as follows: CH2O3(aq)+H+(aq)⇌CHO3−(aq) If an underwater volcano bubbled additional CO2 into the ocean, would this sequence of reactions be driven to the left or the right? How would this affect the pH of the ocean?

Since the modern synthesis, the technical definition of evolution is a change in                    in a                    over the course of generations. a. traits, species; b, allele frequency, population; c. natural selection, natural environment; d. adaptations, single organism; e. fitness, population

Even though marsupial mammals give birth to live young, an eggshell forms briefly early in their development. This is evidence that a.marsupials share a common ancestor with some egg-laying species; b. marsupials are not really mammals; c. all animals arose from a common ancestor; d. marsupial mammals were separately created by God; e. the fossil record of marsupial mammals is incorrect

Lysozyme, an enzyme found in human saliva, tears, and other secretions, catalyzes the hydrolysis of the ββ-1,4-glycosidic linkages in peptidoglycan. Predict the effect of this enzyme on bacteria and how it may be involved in human health.

Within a few weeks of treatment with the drug 3TC, a patient's HIV population consists entirely of 3TC-resistant viruses. How can this result best be explained? a. HIV can change its surface proteins and resist vaccines. b. The patient must have become reinfected with a resistant virus. c. A few drug-resistant viruses were present at the start of treatment, and natural selection increased their frequency. d. HIV began making drug-resistant versions of its enzymes in response to the drug.

Explain why the overprescription of antibiotics by doctors, or the overuse of everyday soaps containing antibiotics, can be a health risk.

Evaluate this statement: Evolution is said to occur when new traits accumulate over time, increasing complexity.

Galactosemia is a potentially fatal disease that occurs in humans who lack the enzyme that converts galactose to glucose. If you were a physician treating a person with this disease, which of the following would you have them exclude from their diet? a. maltose b. starch c. mannose d. lactose

Similarity in skin color among different human populations appears to be primarily the result of                   . a. natural selection; b. convergent evolution; c. which biological race they belong to; d. A and B are correct; e. A, B, and C are correct

A species of crayfish that lives in caves produces eyestalks like its above-ground relatives, but has no eyes. Eyestalks in cave-dwelling crayfish are thus                   . a. an evolutionary error; b. a dominant mutation; c. biogeographical evidence of evolution; d. a vestigial trait; e. evidence that evolutionary theory may be incorrect

When H2 and CO2 react, acetic acid can be formed spontaneously while the production of formaldehyde requires an input of energy. Which of these conclusions can be drawn from this observation? a. More heat is released when formaldehyde is produced compared to the production of acetic acid. b.Compared to the reactants that it is formed from, formaldehyde has more potential energy than does acetic acid. c. Entropy decreases when acetic acid is produced and increases when formaldehyde is produced. d. Only acetic acid could be produced under conditions that existed in early Earth.

Which of the following taxonomic levels contains organisms that share the most recent common ancestor? a. family; b. order; c. phylum; d. genus; e. class

The geneticist James Crow wrote that successful scientific theories have the following characteristics: (1) They explain otherwise puzzling observations; (2) they provide connections between otherwise disparate observations; (3) they make predictions that can be tested; and (4) they are heuristic, meaning that they open up new avenues of theory and experimentation. Crow added two other elements of scientific theories that he considered important on a personal, emotional level: (5) They should be elegant, in the sense of being simple and powerful; and (6) they should have an element of surprise. How well does the theory of evolution by natural selection fulfill these six criteria?

From what you have learned about water, why do coastal regions tend to have milder climates with cooler summers and warmer winters than do inland areas at the same latitude?

Most mice living on the mainland of Florida are brown, but the mice that live on the sand dunes of the barrier islands have white fur. The differences in color are heritable, determined by genes such as MC1R. It is intuitive that the light color of beach-dwelling mice is an adaptation for blending into their environment—and thus evading predators. Compare how evolution by inheritance of acquired characters and the theory of evolution by natural selection would explain the observation of white mice living primarily on light soil and brown mice living primarily on dark soil.

Most mice living on the mainland of Florida are brown, but the mice that live on the sand dunes of the barrier islands have white fur. The differences in color are heritable, determined by genes such as MC1R. It is intuitive that the light color of beach-dwelling mice is an adaptation for blending into their environment—and thus evading predators. What is an evolutionary adaptation? a. a trait that improves the fitness of its bearer, compared with individuals without the trait b. a trait that changes in response to environmental influences within the individual's lifetime c. the ability of an individual to adjust to its environment d. a trait that an individual wants so that it can survive

How can the Darwinian concept of descent with modification explain the evolution of such complex structures as an eye?

Apply Darwin's four postulates to a population of mice living on sand dunes in coastal Florida.

A team led by evolutionary biologist Hopi Hoekstra set out to test the hypothesis that predators are an agent of natural selection on mouse color. They made 250 plasticine models of mice that were alike in every way except that half were painted white and half were painted brown. Suggest one advantage and one disadvantage of using model mice instead of real mice in this experiment.

A population of snails is preyed on by birds that break the snails open on rocks, eat the soft bodies, and leave the shells. The snails occur in both striped and unstriped forms. In one area, researchers counted both live snails and broken shells. Their data are summarized below: Which snail form seems better adapted to this environment? Why? Predict how the frequencies of striped and unstriped snails might change in the future.

The researchers placed white and brown mouse models both in abandoned fields on the mainland (dark soil) and on sand dunes on the islands (light soil) and then measured the percentage of models that were attacked by predators. What is the take-home message of the data? Do the data support or reject the hypothesis that mouse color is adaptive?