Chapter 25 TEST

24 July 2022
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question
Which of the following statements about adaptive radiation is correct?
answer
Adaptive radiation occurs within a single lineage. (Adaptive radiation occurs when a single lineage produces many descendant species.)
question
Which organisms are not examples of an adaptive radiation?
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Mammals and reptiles in the post-dinosaur age. (Mammals and reptiles are not descended from a single lineage.)
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True or false? Convergent evolution is said to have occurred if the mouse species on two islands with similar habitats are found to have similar characteristics even though they originated from different species that did not have these characteristics.
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True. (Convergent evolution occurs when selective pressures produced by similar conditions (such as habitat) favor the evolution of similar solutions.)
question
Which Anolis lizard ecomorph has long legs?
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Trunk/ground. (These ecomorphs need long legs to jump from one broad perch to another.)
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Which of the following statements about the evolution of Anolis lizards in the Caribbean islands is true?
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The phylogeny of ecomorphs on a given island reveals that adaptive radiation has taken place. (This statement is true; the historical evidence of adaptive radiation on an island is recorded in the evolutionary history of the ecomorphs currently living on the island.)
question
What was the main selective pressure behind the evolution of different Anolis lizard species in the Caribbean?
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Specific ecological niches. (Different species evolved in response to the selective pressures created by specific ecological niches on the islands.)
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True or false? The evolution of different ecomorphs on the Caribbean islands is an example of stabilizing selection.
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False. (The evolution of different ecomorphs is an example of disruptive selection. Each new ecomorph had characteristics that were ideal for a particular habitat, but as these characteristics developed, the lizards lost the ability to survive effectively in the other habitats on the island.)
question
How did some stickleback populations come to live exclusively in fresh water?
answer
Some stickleback populations became trapped in lakes that formed at the end of the last ice age. (Freshwater stickleback populations were established when marine populations became trapped in the freshwater lakes where they migrate to spawn annually. At the end of the last ice age, these lakes, formerly connected to the ocean, were cut off by retreating ice fields.)
question
Why do some stickleback populations lack pelvic spines?
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1. In lakes with dragonfly larvae, pelvic spines can be disadvantageous, allowing the predatory larvae to grab the fish. 2. In lakes where there are no large predatory fish, there is no advantage to having pelvic spines. (Different environments can provide different selective pressures on an organism's morphology. In the threespine stickleback, pelvic spines provide a selective advantage in environments with large predatory fish but are a liability in environments with dragonfly larvae.)
question
Why did Kingsley and his team cross marine and freshwater sticklebacks?
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To find the location of the gene(s) causing the difference between stickleback populations with and without spines. (Geneticists use crosses to map the location of genes.)
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What did researchers discover about the genetic mutation causing the loss of pelvic spines?
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1. It occurred in a similar DNA region in freshwater stickleback populations all over the world. 2. It is found in a regulatory region (a "switch") upstream of the coding region of the Pitx1 gene. (Many mutations of evolutionary importance are found in regulatory regions. The gene remains intact, but the location of its expression changesโ€”conveying a new phenotype without losing existing capabilities.)
question
Bell and collaborators painstakingly documented a population of fossil sticklebacks from an ancient freshwater lake over a 20,000-year period. The prevalence of sticklebacks with full and reduced pelvises changed over time. Which is true?
answer
The population of fish with pelvic spines that arrived in the lake at time B evolved a reduced pelvis over time (beginning at time C). (Having a reduced pelvis must have been advantageous for this ancient stickleback population, just as it is for many current freshwater stickleback populations.)
question
How do multiple lines of evidence (from the field, the fossil record, and molecular genetics) work together to illustrate stickleback evolution?
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1. The fossil data show a pattern of evolution over long stretches of time. 2. If the same morphological changes occur in the fossil record as in living populations, we might deduce that the genetic mechanism discovered in the living populations might be responsible for the changes observed in fossils. 3. Genetic evidence reveals the precise molecular mechanism responsible for the change in pelvic structures in stickleback populations. 4. Data obtained by analyzing living fish in lakes show the selective pressures present in different environments. (Evolution repeats itself. The film uses three complimentary lines of evidence from field studies, molecular genetics, and fossil populations to show evolution of the same trait over and over again, across hundreds of thousands of years.)
question
The oxygen revolution changed Earth's environment dramatically. Which of the following took advantage of the presence of free oxygen in the oceans and atmosphere?
answer
the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules
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Which factor most likely caused animals and plants in India to differ greatly from species in nearby southeast Asia?
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India was a separate continent until 45 million years ago.
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Adaptive radiations can be a direct consequence of four of the following five factors. Select the exception.
answer
genetic drift
question
The figure shows eyes found among living molluscs, ranging from a patch of pigmented cells in a limpet to a complex, image-forming eye in a squid. Is it possible that a structure as complex as an image-forming eye evolved by natural selection?
answer
Yes, if the photoreceptor cells and simple eyes that preceded it were useful to the animals in which they arose. (In fact, such photoreceptors and simple eyes can be seen in many living animals. Read about the evolution of a complex eye.)
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A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped make possible the evolution of the tetrapod limb. This type of change is illustrative of
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a change in a developmental gene or in its regulation that altered the spatial organization of body parts.
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A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from lungs of an ancestral fish is an example of
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exaptation
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The oldest fossils usually
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are found in the deepest strata (Younger sediments are deposited over older sediments; thus, relatively older fossils are found in deeper strata than relatively younger fossils.)
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The earliest organisms were most likely
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prokaryotic (Prokaryotes originated a few hundred million years after Earth's crust cooled and solidified.)
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The atmosphere of early Earth probably contained no O2 until the emergence of organisms that
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used water as an electron source for photosynthesis (Oxygen began to accumulate in the atmosphere due to the action of photosynthetic cyanobacteria.)
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How does continental drift affect living organisms?
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1. It causes climate change, which puts selective pressure on organisms. 2. It causes changes in habitats, such as when large amounts of shallow marine habitat were lost in the formation of Pangaea. 3. It may cause an increase or decrease in competition among different species. (Continental drift affects organisms by changing the current environment in all of these ways. Organisms may have to adapt, move, or go extinct.)
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Hox genes are thought to play an important role in the development of different morphologies because
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they provide positional information in the embryo (Changes in Hox genes can have large effects on body plans in different organisms.)
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Evolution works by
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"tinkering" with existing structures (Evolution, and in particular natural selection, can only select for the best available traits. Modifications to those traits are usually made in small, incremental steps, and new inventions are rare.)