Final Exam - Summary Questions and Answers

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Chapter 22 (Jellyfish Ch. 25; Forest Ch. 2) • Questions 1-16 Test Your Knowledge 1. True or false? Some traits are considered vestigial because they existed long ago. - False 2. CAUTION Why does the presence of extinct forms and transitional features in the fossil record support the pattern component of the theory of evolution by natural selection? a. It supports the hypothesis that individuals change over time. b. It supports the hypothesis that weaker species are eliminated by natural selection. c. It supports the hypothesis that species evolve to become more complex and better adapted over time. d. It supports the hypothesis that species change over time. 3. Traits that are derived from a common ancestor, like the bones of human arms and bird wings, are said to be - Homologous 4. CAUTION How can evolutionary fitness be estimated? a. Document how long individuals survive. b. Compare the number of healthy, fertile offspring produced. c. Determine which individuals are strongest. d. Determine which phenotype is the most common. Test Your Understanding 5. CAUTION According to data presented in this chapter, which one of the following statements is correct? a. When individuals change in response to challenges from the environment, their altered traits are passed on to offspring. b. Species are created independently of each other and do not change over time. c. Populations—not individuals—change when natural selection occurs. d. The traits of populations become more perfect over time. 6. 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. 7. CAUTION 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. 8. SOCIETY Explain why the overprescription of antibiotics by doctors, or the overuse of everyday soaps containing antibiotics, can be a health risk. Test Your Problem-Solving Skills 9. The average height of humans in industrialized nations has increased steadily for the past 100 years. This trait has clearly changed over time. Most physicians and human geneticists hypothesize that the change is due to better nutrition and a reduced incidence of disease. Has human height evolved? a. Yes, because average height has changed over time. b. No, because changes in height due to nutrition and reduced incidence of disease are not heritable. c. Yes, because height is a heritable trait. d. No, because height is not a heritable trait. 10. PROCESS OF SCIENCE 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 fulfills these six criteria? species, not individuals, change over time, and that evolution does not perfect organisms or necessarily make them more complex and better adapted Evolutionary fitness refers to the ability of an organism to pass its genes on to the next generation, not its speed, strength, or longevity The heritable characteristics of individuals do not change in response to the environment. Instead, change occurs in populations. But populations do not become more perfect over time due to the many constraints on natural selection. Mutation produces new genetic variations, at random, with no forethought about which variations might prove adaptive in the future. Individuals with mutations that are disadvantageous won’t produce many offspring, but individuals with beneficial mutations will produce many offspring. The beneficial mutations will thus increase in frequency through selection. Fitness refers to number of healthy offspring produced, not strength or speed. When antibiotics are overused, susceptible bacteria are constantly being killed off, even when an infection is not present. However, any individual bacteria that are resistant to these antibiotics will survive and multiply, reducing the likelihood that because changes in height due to nutrition and reduced incidence of disease are not heritable The theory of evolution fits the six criteria as follows. (1) and (2): It provides a common underlying mechanism responsible for puzzling observations such as homology, geographic proximity of similar species, the law of succession in the fossil record, vestigial traits, and extinctions. (3) and (4): It suggests new lines of research to test predictions about the outcome of changing environmental conditions in populations, about the presence of transitional forms in the fossil record, and so on. (5): It is a simple idea that explains the tremendous diversity of living and fossil organisms and why species continue to change today. (6): The realization that all organisms are related by

11. Compare and contrast how evolution by inheritance of acquired characters and the theory of evolution by natural selection would explain the observation of white mice living on light soil and brown mice living on dark soil. 12. CAUTION 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. 13. Apply Darwin’s four postulates to a population of mice living on sand dunes in coastal Florida. 14. PROCESS OF SCIENCE A team led by evolutionary biologist Hopi Hoekstra set out to test the hypothesis that predators are an agent of natural selection on mouse colour. 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. 15. QUANTITATIVE The researchers placed white and brown mouse models both in abandoned fields, called oldfields, 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 colour is adaptive? 16. PROCESS OF SCIENCE When a statistical test was used to compare the results for white models versus brown models, the P value (see BioSkills 3 ) was 0.01 for each habitat. Does this result increase or decrease your confidence in your take-home message? Explain. Evolution by inheritance of acquired characteristics predicts that the mice in the different environments needed to change colour, so they did so and then passed their traits on to their offspring. The theory of evolution by natural selection is not goal oriented. It predicts that white and brown mice are descendants of an ancestral population that varied in colour. The white mice had higher fitness in the beach environment, where they were more likely to escape the notice of predators. Likewise, the brown mice had a higher fitness in the mainland evolutionary adaptations are very different from adaptations in the everyday sense. Since adaptations are heritable traits, they cannot change during an organism’s lifetime, and they cannot change in response to “want” or (1) Fur colour varies within mouse populations. (2) Fur colour is heritable. (3) More mice are produced than can survive, and some produce many surviving offspring while others produce few or none. (4) Mice with certain heritable traits, such as the ability to avoid predators by blending in with their environment (camouflage), survive and produce more offspring. One disadvantage of using models is that they do not have the same smell and behaviours as real mice. One advantage of models is that all the mice are exactly alike except for colour, enabling the control of all variables except the one being studied. Models are also easier to work with than live mice. The data show that mice that do not match the colour of the soil are attacked more often than mice that do match. This supports the hypothesis that fur colour is Biologists consider a P value less than 0.05 to be statistically significant, that is, showing a real difference and not just sampling error. Since 0.01 < 0.05, you can be confident that the mice that were camouflaged were attacked less than those that were not.

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