Sensory Ecology
Some of the most important sensory information animals have to process comes from other animals. Interactions between predators and prey, parents and offspring, males and females both shape and are shaped by the characteristics of sensory systems. Most animals are subject to two conflicting selection pressures: be inconspicuous to predators but be conspicuous to potential mates.
One of the best illustrations of how the trade-off between these pressures has influenced signals and behavior involves the color patterns and mating behavior of guppies. Guppies are small South American fish that live in clear tropical streams. Mature males sport colored spots and patches that are used in courtship behavior. Male color pattern is heritable and varies in different populations. In experimental tests of the effectiveness of color patches, females are more likely to mate with males that have larger and brighter blue and orange, red, or yellow patches. Thus female choice creates sexual selection pressure for conspicuous coloration. In contrast, predators create selection pressure for cryptic coloration (coloration that helps hide organisms): duller, smaller color patches and patterns that match the background.
The effects of predation have been established in several ways. In the field, guppies are found in streams that have different numbers and kinds of visually hunting predators, mostly other fish. Males from populations with more predators are more cryptically colored. Prawns are thought to see poorly in the red end of the spectrum. As might therefore be expected, guppies in areas with heavy predation by prawns have more orange than guppies subject to predators with better red-orange vision. Predictions about the effects of predation have been tested directly by establishing guppies from a single genetic background and distribution of color patterns in laboratory “streams”and exposing them to different numbers and kinds of predators. In guppies’ natural habitat of forest streams, the intensity and color of light varies with the time of day. Visually hunting predators are most active in the middle of the day, but in both the laboratory and the field, guppies engage in more sexual display early and late in the day, that is, in relatively dim light. Taken all together, the transmission characteristics of tropical streams and the visual capabilities of guppies and their most common predators indicate that at the times of day when they are most likely to be courting, guppies’ colors are relatively more conspicuous to other guppies than to guppy predators.
The foregoing example illustrates how visual conspicuousness and crypticity vary by observer. Detailed sensory physiology may be needed to figure out whether color patterns that appear conspicuous or cryptic to us appear that way to the animals that normally view them. A particularly good example involves camouflage of crab spiders. Crab spiders make their living sitting on flowers waiting to grab bees or other pollinators that happen by. But by resting in such an exposed position, the spiders make themselves conspicuous to insect-eating birds. Clearly, they should be colored so as to be inconspicuous to both birds and bees, but this is not easy because bees and birds have different color sensitivities. Ecologist Marc Thery and colleagues collected crab spiders(Thomisus onustus) from the yellow centers of white marguerite daisies and measured the relative intensities of colors across the spectrum, including the ultraviolet, reflected by daisy petals and daisy centers and by crab spiders. The daylight reflectance spectra were then related to the color sensitivities of birds (blue tits, typical predators in the French meadows where the spiders were collected)and honeybees. These computations showed that the spiders color did not contrast sufficiently with the flower centers for them to be detected by either predator or prey. Their contrast with the petals was well above both birds’ and bees’ thresholds, which presumably explains why spiders rest in the center. To make matters even more interesting individuals of this species of crab spider also match their color to pink flowers, and they are similarly of low contrast to both birds and bees on this background as well.
1
One of the best illustrations of how the trade-off between these pressures has influenced signals and behavior involves the color patterns and mating behavior of guppies. Guppies are small South American fish that live in clear tropical streams. Mature males sport colored spots and patches that are used in courtship behavior. Male color pattern is heritable and varies in different populations. In experimental tests of the effectiveness of color patches, females are more likely to mate with males that have larger and brighter blue and orange, red, or yellow patches. Thus female choice creates sexual selection pressure for conspicuous coloration. In contrast, predators create selection pressure for cryptic coloration (coloration that helps hide organisms): duller, smaller color patches and patterns that match the background.
According to paragraph 2, which of the following is NOT true of guppies?
Negative Factual Information Questions否定事实信息题
AFully grown males have colored markings.
BAll guppy populations have a similar range of colors.
CParents pass down their color pattens to their offspring.
DGuppies live in clear tropical streams in South America.
2
One of the best illustrations of how the trade-off between these pressures has influenced signals and behavior involves the color patterns and mating behavior of guppies. Guppies are small South American fish that live in clear tropical streams. Mature males sport colored spots and patches that are used in courtship behavior. Male color pattern is heritable and varies in different populations. In experimental tests of the effectiveness of color patches, females are more likely to mate with males that have larger and brighter blue and orange, red, or yellow patches. Thus female choice creates sexual selection pressure for conspicuous coloration. In contrast, predators create selection pressure for cryptic coloration (coloration that helps hide organisms): duller, smaller color patches and patterns that match the background.
What can be inferred from paragraph 2 about male guppies that are preferred by females?
Inference Questions推理题
AThey are larger than less-preferred males.
BThey blend more easily into the background than less-preferred males do.
CThey are difficult to distinguish from less-preferred males.
DThey are more likely to get eaten by predators than are less-preferred males.
3
The effects of predation have been established in several ways. In the field, guppies are found in streams that have different numbers and kinds of visually hunting predators, mostly other fish. Males from populations with more predators are more cryptically colored. Prawns are thought to see poorly in the red end of the spectrum. As might therefore be expected, guppies in areas with heavy predation by prawns have more orange than guppies subject to predators with better red-orange vision. Predictions about the effects of predation have been tested directly by establishing guppies from a single genetic background and distribution of color patterns in laboratory “streams”and exposing them to different numbers and kinds of predators. In guppies’ natural habitat of forest streams, the intensity and color of light varies with the time of day. Visually hunting predators are most active in the middle of the day, but in both the laboratory and the field, guppies engage in more sexual display early and late in the day, that is, in relatively dim light. Taken all together, the transmission characteristics of tropical streams and the visual capabilities of guppies and their most common predators indicate that at the times of day when they are most likely to be courting, guppies’ colors are relatively more conspicuous to other guppies than to guppy predators.
Why does the author provide the information that “Prawns are thought to see poorly in the red end of the spectrum”?
Rhetorical Purpose Questions修辞目的题
ATo suggest that male guppies are no longer exposed to heavy predation by prawns
BTo explain why prawns prey less successfully on guppies than do other predators of guppies
CTo imply that each species of fish can see colors from only a narrow part of the visual spectrum
DTo illustrate one way in which predation pressures can affect the coloration of prey
4
The effects of predation have been established in several ways. In the field, guppies are found in streams that have different numbers and kinds of visually hunting predators, mostly other fish. Males from populations with more predators are more cryptically colored. Prawns are thought to see poorly in the red end of the spectrum. As might therefore be expected, guppies in areas with heavy predation by prawns have more orange than guppies subject to predators with better red-orange vision. Predictions about the effects of predation have been tested directly by establishing guppies from a single genetic background and distribution of color patterns in laboratory “streams”and exposing them to different numbers and kinds of predators. In guppies’ natural habitat of forest streams, the intensity and color of light varies with the time of day. Visually hunting predators are most active in the middle of the day, but in both the laboratory and the field, guppies engage in more sexual display early and late in the day, that is, in relatively dim light. Taken all together, the transmission characteristics of tropical streams and the visual capabilities of guppies and their most common predators indicate that at the times of day when they are most likely to be courting, guppies’ colors are relatively more conspicuous to other guppies than to guppy predators.
Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
Sentence Simplification Questions句子简化题
AThe transmission characteristics of tropical streams affect the visual capabilities of guppies and their predators.
BAt most times of day, the visual capabilities of guppies are superior to those of their most common predators.
CGuppies tend to engage in courting at times of day when they are more likely to be seen by prospective mates than by predators.
DThanks to the transmission characteristics of tropical streams, guppies’ colors are not very conspicuous to predators.
5
The effects of predation have been established in several ways. In the field, guppies are found in streams that have different numbers and kinds of visually hunting predators, mostly other fish. Males from populations with more predators are more cryptically colored. Prawns are thought to see poorly in the red end of the spectrum. As might therefore be expected, guppies in areas with heavy predation by prawns have more orange than guppies subject to predators with better red-orange vision. Predictions about the effects of predation have been tested directly by establishing guppies from a single genetic background and distribution of color patterns in laboratory “streams”and exposing them to different numbers and kinds of predators. In guppies’ natural habitat of forest streams, the intensity and color of light varies with the time of day. Visually hunting predators are most active in the middle of the day, but in both the laboratory and the field, guppies engage in more sexual display early and late in the day, that is, in relatively dim light. Taken all together, the transmission characteristics of tropical streams and the visual capabilities of guppies and their most common predators indicate that at the times of day when they are most likely to be courting, guppies’ colors are relatively more conspicuous to other guppies than to guppy predators.
According to paragraph 3, where are guppies with a lot of orange coloration likely to be found?
Factual Information Questions事实信息题
AIn streams where their main predators are prawns
BIn streams with very few predators
CIn laboratory “streams” where the environment is controlled by scientists
DIn forest streams, where the light changes depending on the time of day
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The foregoing example illustrates how visual conspicuousness and crypticity vary by observer. Detailed sensory physiology may be needed to figure out whether color patterns that appear conspicuous or cryptic to us appear that way to the animals that normally view them. A particularly good example involves camouflage of crab spiders. Crab spiders make their living sitting on flowers waiting to grab bees or other pollinators that happen by. But by resting in such an exposed position, the spiders make themselves conspicuous to insect-eating birds. Clearly, they should be colored so as to be inconspicuous to both birds and bees, but this is not easy because bees and birds have different color sensitivities. Ecologist Marc Thery and colleagues collected crab spiders(Thomisus onustus) from the yellow centers of white marguerite daisies and measured the relative intensities of colors across the spectrum, including the ultraviolet, reflected by daisy petals and daisy centers and by crab spiders. The daylight reflectance spectra were then related to the color sensitivities of birds (blue tits, typical predators in the French meadows where the spiders were collected)and honeybees. These computations showed that the spiders color did not contrast sufficiently with the flower centers for them to be detected by either predator or prey. Their contrast with the petals was well above both birds’ and bees’ thresholds, which presumably explains why spiders rest in the center. To make matters even more interesting individuals of this species of crab spider also match their color to pink flowers, and they are similarly of low contrast to both birds and bees on this background as well.
The word “intensities” in the passage is closest in meaning to
Vocabulary Questions词汇题
Astrengths
Bpositions
Cvarieties
Dcharacteristics
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The foregoing example illustrates how visual conspicuousness and crypticity vary by observer. Detailed sensory physiology may be needed to figure out whether color patterns that appear conspicuous or cryptic to us appear that way to the animals that normally view them. A particularly good example involves camouflage of crab spiders. Crab spiders make their living sitting on flowers waiting to grab bees or other pollinators that happen by. But by resting in such an exposed position, the spiders make themselves conspicuous to insect-eating birds. Clearly, they should be colored so as to be inconspicuous to both birds and bees, but this is not easy because bees and birds have different color sensitivities. Ecologist Marc Thery and colleagues collected crab spiders(Thomisus onustus) from the yellow centers of white marguerite daisies and measured the relative intensities of colors across the spectrum, including the ultraviolet, reflected by daisy petals and daisy centers and by crab spiders. The daylight reflectance spectra were then related to the color sensitivities of birds (blue tits, typical predators in the French meadows where the spiders were collected)and honeybees. These computations showed that the spiders color did not contrast sufficiently with the flower centers for them to be detected by either predator or prey. Their contrast with the petals was well above both birds’ and bees’ thresholds, which presumably explains why spiders rest in the center. To make matters even more interesting individuals of this species of crab spider also match their color to pink flowers, and they are similarly of low contrast to both birds and bees on this background as well.
The word “presumably” in the passage is closest in meaning to
Vocabulary Questions词汇题
Afortunately
Bcertainly
Cprobably
Dsimply
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The foregoing example illustrates how visual conspicuousness and crypticity vary by observer. Detailed sensory physiology may be needed to figure out whether color patterns that appear conspicuous or cryptic to us appear that way to the animals that normally view them. A particularly good example involves camouflage of crab spiders. Crab spiders make their living sitting on flowers waiting to grab bees or other pollinators that happen by. But by resting in such an exposed position, the spiders make themselves conspicuous to insect-eating birds. Clearly, they should be colored so as to be inconspicuous to both birds and bees, but this is not easy because bees and birds have different color sensitivities. Ecologist Marc Thery and colleagues collected crab spiders(Thomisus onustus) from the yellow centers of white marguerite daisies and measured the relative intensities of colors across the spectrum, including the ultraviolet, reflected by daisy petals and daisy centers and by crab spiders. The daylight reflectance spectra were then related to the color sensitivities of birds (blue tits, typical predators in the French meadows where the spiders were collected)and honeybees. These computations showed that the spiders color did not contrast sufficiently with the flower centers for them to be detected by either predator or prey. Their contrast with the petals was well above both birds’ and bees’ thresholds, which presumably explains why spiders rest in the center. To make matters even more interesting individuals of this species of crab spider also match their color to pink flowers, and they are similarly of low contrast to both birds and bees on this background as well.
According to paragraph 4, what was the main conclusion of the study by Théry and his colleagues?
Factual Information Questions事实信息题
ACrab spiders are typically hunted by blue tits
BBlue tits and honeybees have different color sensitivities.
CNeither blue tits nor honeybees can see crab spiders against yellow daisy centers.
DCrab spiders change their color to match that of a flower’s petals.
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The foregoing example illustrates how visual conspicuousness and crypticity vary by observer. Detailed sensory physiology may be needed to figure out whether color patterns that appear conspicuous or cryptic to us appear that way to the animals that normally view them. A particularly good example involves camouflage of crab spiders. Crab spiders make their living sitting on flowers waiting to grab bees or other pollinators that happen by. [■]But by resting in such an exposed position, the spiders make themselves conspicuous to insect-eating birds. [■]Clearly, they should be colored so as to be inconspicuous to both birds and bees, but this is not easy because bees and birds have different color sensitivities. [■]Ecologist Marc Thery and colleagues collected crab spiders(Thomisus onustus) from the yellow centers of white marguerite daisies and measured the relative intensities of colors across the spectrum, including the ultraviolet, reflected by daisy petals and daisy centers and by crab spiders. [■]The daylight reflectance spectra were then related to the color sensitivities of birds (blue tits, typical predators in the French meadows where the spiders were collected)and honeybees. These computations showed that the spiders color did not contrast sufficiently with the flower centers for them to be detected by either predator or prey. Their contrast with the petals was well above both birds’ and bees’ thresholds, which presumably explains why spiders rest in the center. To make matters even more interesting individuals of this species of crab spider also match their color to pink flowers, and they are similarly of low contrast to both birds and bees on this background as well.
Look at the four squaresthat indicate where the following sentence could be added to the passage
For example, birds tend to see red more easily than they see yellow, but the opposite is true for bees.
Insert Text Questions句子插入题
Where would the sentence best fit？Click on a square sentence to the passage.
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It is important for animals to be invisible to predators and prey but conspicuous to mates.
Prose Summary Questions概要小结题
Select 3 answers
ASome male animals have inconspicuous color patterns early in life when they are most in danger from predators, but they develop more visible coloring when they are ready to mate.
BWhereas female guppies are more likely to mate with males that have larger and brighter colored patches, predators create selection pressure for duller, smaller color patches.
CCrab spiders take advantage of birds’ and honeybees’ inability to distinguish between certain colors in order to hide from both of them.
DThe effects of predation generally outweigh the pressures of sexual selection, but guppies are an exception in that they will take extreme risks finding mates.
EGuppies limit their activity during times when visual hunters are most likely to be active, and they have evolved to display colors that are not clearly visible to local predators.
FPredators often have different light sensitivities. which explains why crab spiders move to different locations on a flower, depending on which predator they are trying to avoid.
