BIOLOGY
12th Edition
ISBN: 9781260169614
Author: Raven
Publisher: RENT MCG
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Chapter 21, Problem 5S
The ancestor of horses was a small, many-toed animal that lived in forests, whereas today’s horses are large animals with a single hoof that live on open plains. A series of intermediate fossils illustrate how this transition has occurred, and for this reason, many old treatments of horse evolution portrayed it as a steady increase through time in body size accompanied by a steady decrease in toe number. Why is this interpretation incorrect?
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Scientists have long believed that the 14 species of finches on the Galapagos Islands evolved from a single species of finch that migrated to the islands one to five million years ago. Recent DNA analyses support the conclusion that all of the Galapagos finches evolved from the mainland warbler finch. Different species live on different islands. One of the major changes in the finches is in their beak sizes and shapes. How would an evolutionary biologist today best answer the following question?
In the finch population, what are the primary changes that occur gradually over time?
A.
The proportions of finches having different traits within a population change.
B.
The traits of each finch within a population gradually change.
C.
Mutations occur to meet the needs of the finches as the environment changes.
D.
Successful behaviors learned by the finches are passed on to offspring.
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?
Group of answer choices
Forelimb evolution was adaptive in people and bats, but not in whales.
Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy.
Humans and bats evolved by natural selection, and whales evolved by Lamarckian mechanisms.
Genes mutate faster in whales than in humans or bats.
Changes in the traits of the fossils studied are consistent with what is expected to be favored by natural selection, given environmental changes during that time. Thus, from the late Miocene, modern horses evolved to have the following traits, consistent with grassland ecosystems becoming more common, EXCEPT for --
A. Formation of hooves and fused forelimb bones.
B. Teeth adapted for browsing rather than grazing..
C. A muscle and tendon system allowing for a springing motion in galloping.
D. Larger animals better designed for grazing.
Chapter 21 Solutions
BIOLOGY
Ch. 21.1 - Prob. 1LOCh. 21.1 - Prob. 2LOCh. 21.2 - Prob. 1LOCh. 21.2 - Distinguish between demonstrating that evolution...Ch. 21.3 - Contrast the processes of artificial and natural...Ch. 21.3 - Prob. 2LOCh. 21.4 - Prob. 1LOCh. 21.4 - Prob. 2LOCh. 21.4 - Prob. 3LOCh. 21.5 - Explain the evolutionary significance of...
Ch. 21.5 - Prob. 2LOCh. 21.6 - Prob. 1LOCh. 21.6 - Prob. 2LOCh. 21.7 - Characterize the criticisms of evolutionary theory...Ch. 21.7 - Prob. 2LOCh. 21 - Suppose that a male with a beak depth of 10 mm...Ch. 21 - Prob. 1IQCh. 21 - Prob. 2IQCh. 21 - Prob. 3IQCh. 21 - Why might the evolutionary line leading to...Ch. 21 - Artificial selection is different from natural...Ch. 21 - Gaps in the fossil record a. demonstrate our...Ch. 21 - The evolution of modern horses (Equus) is best...Ch. 21 - Homologous structures a. are structures in two or...Ch. 21 - Convergent evolution a. is an example of...Ch. 21 - Prob. 6UCh. 21 - The possession of fine fur in 5-month human...Ch. 21 - In Darwins finches, a. occurrence of wet and dry...Ch. 21 - Prob. 2ACh. 21 - Convergent evolution is often seen among species...Ch. 21 - What conditions are necessary for evolution by...Ch. 21 - Explain how data shown in figure 21.2a and b...Ch. 21 - Prob. 3SCh. 21 - Refer to figure 21.5, artificial selection in the...Ch. 21 - The ancestor of horses was a small, many-toed...
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