Section Review 15-1 1. Beagle 2. theory of evolution 3. varied 4. Darwin s curiosity might have led him to make many observations and ask questions about the natural world. His analytical nature may have helped Darwin to record and organize his observations, allowing him to recognize patterns and trends. 5. The vice-governor of the Galápagos Islands told Darwin that the shell shape of a tortoise could be used to identify the island it inhabited. 6. Because the Isabela Island tortoise has such a short neck, it would require a habitat where food is easy to reach. 7. Because of its long neck, the Hood Island tortoise would most easily obtain food that is hard to reach. 8. Because birds use their beaks to eat or capture food, differently shaped beaks would mean that the birds lived on different diets.
Section Review 15-2 1. a 2. b 3. c 4. b 5. a 6. b 7. a 8. Darwin asked, If Earth could change over long periods of time, then could life change as well? He also realized that if life could change as he was suggesting, then it would take many, many years to occur. 9. Lamarck s idea that species are adapted to their environment is true. Lamarck s idea that acquired characteristics are inheritable is false. 10. Darwin realized that plants and animals often produce thousands or millions of seeds or eggs, yet most potential offspring die. He asked what factors determine which offspring die and which survive and reproduce.
Section Review 15-3 1. Darwin stated that nature provides the variation among organisms, and humans select and breed for the variations they find useful or appealing. 2. Over time, natural selection results in a change in the inherited characteristics of a population, increasing the population s fitness. 3. 6. (in any order) the fossil record, geographic distribution of living species, homologous body structures, and similarities in early development of animals 7. The higher an animal s level of fitness in its particular environment, the better its chances for survival and reproduction. 8. The forelimbs have the same kinds of bones in approximately the same positions. 9. The bones are noticeably similar in structure and arrangement. It is, therefore, reasonable to assume that they derived from a common ancestral form.
Chapter 15 Vocabulary Review 1. a 2. c 3. b 4. i 5. g 6. j 7. d 8. e 9. f 10. h 11. A theory is a well-supported, testable, explanation of phenomena that have occurred in the natural world. 12. Artificial selection occurs when humans select naturally occurring variations that they found useful. 13. Survival of the fittest is a phrase that implies that those organisms best adapted to their environments will live the longest and have the most reproductive success. 14. Descent with modification means that each living species has descended, with changes, from other species over time. 15. a 16. d 17. b 18. c 19. a 20. a 21. To Darwin, fossils provided a detailed record of the evolution of different life forms over Earth s long history. 22. High birth rates lead to potentially large populations that require more resources than are available to meet their needs. 23. Successful adaptations enable organisms to become better suited to their environment and thus better able to survive and reproduce. 24. Descent with modification implies that today s different species have had common ancestors in the distant past.
Section Review 16-1 1. 2. mutations, genetic shuffling from sexual reproduction 3. phenotypes 4. genes 5. Mutations, one source of genetic variation, involve changes in DNA. These might be changes in a single code or in lengthy sections of a chromsome. 6. A widow s peak is a single-gene trait because it is controlled by a single gene 7. Allele H has a relative frequency of 58 percent. 8. The mutation was most likely a point mutation. 9. Both mutations and gene shuffling are a source of genetic variation. Mutations involve changes in DNA. Gene shuffling involves recombinations of existing DNA as parental genes are passed on during sexual reproduction. 10. Possible answers: Single-gene traits usually appear as one of a few distinct phenotypes, whereas polygenic traits usually appear as several phenotypes that vary across a range.
Section Review 16-3 1. Species are said to be reproductively isolated when they cannot interbreed and produce fertile offspring. 2. Behavioral isolation occurs when dissimilar courtship rituals or other types of behavior prevent mating. Geographic isolation occurs when a feature of the landscape prevents populations from coming together to mate. Temporal isolation occurs when different populations mate at different times. 3. 3 4. 6 5. 1 6. 4 7. 2 8. 5 9. Possible answer: Geographic isolation could result from a new body of water formed during a flood, the rerouting of a river, or changes in landforms from earthquakes or human development. 10. Possible answers: The allele frequencies of the founders were different from those of their ancestors; under the different environmental conditions on the islands, different individuals were able to pass their genes to the next generation.
Chapter 16 Vocabulary Review 1. gene pool 2. relative frequency 3. single-gene trait 4. polygenic traits 5. relative frequency 6. b 7. a 8. c 9. d 10. b 11. c 12. b 13. c 14. a 15. b 16. b 17. a 18. b 19. c 20. d