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托福TPO/Official 11 Passage 3阅读原文题目答案及解析-新东方托福官方网校手机版

很多动物发出来的信号看上去其实都是代价非常惨重的。

Many signals that animals make seem to impose on the signalers costs that are overly damaging.

一个非常典型的例子是，当鸟爸爸鸟妈妈带着食物回到巢里，雏鸟会发出尖锐的噪声。

A classic example is noisy begging by nestling songbirds when a parent returns to the nest with food.

这些叽叽喳喳的声音可能会把鸟巢的位置暴露给巢外的老鹰和浣熊，导致毫无防御的雏鸟的死亡。

These loud cheeps and peeps might give the location of the nest away to a listening hawk or raccoon, resulting in the death of the defenseless nestlings.

事实上，当在一个盛有鸟蛋的人工鸟窝旁播放燕子讨食的磁带时，37次中有29次结果都是，这个“吵闹”鸟巢里的蛋比周围安静的鸟巢里的树燕蛋更早被捕食者掠走或毁坏。

In fact, when tapes of begging tree swallows were played at an artificial swallow nest containing an egg, the egg in that “noisy” nest was taken or destroyed by predators before the egg in a nearby quiet nest in 29 of 37 trials.

关于讨食的代价的更多的证据来自于对于 在地面筑巢和在相对安全的树上筑巢的莺的讨食叫声的差异性的研究。

Further evidence for the costs of begging comes from a study of differences in the begging calls of warbler species that nest on the ground versus those that nest in the relative safety of trees.

年幼的在地面筑巢的莺讨食产生的鸣叫声要比在树上筑巢的频率要高。

The young of ground-nesting warblers produce begging cheeps of higher frequencies than do their tree-nesting relatives.

这些高频率的叫声不会传播的很远，所以可能会更好的隐藏发出这些叫声的鸟的位置，尤其是那些在地面筑巢的对于捕食者而言较脆弱的鸟。

These higher-frequency sounds do not travel as far, and so may better conceal the individuals producing them, who are especially vulnerable to predators in their ground nests.

戴维·哈斯克尔制作了装有粘土蛋的人工巢，并将它们放在录音机旁边的地面上，录音机播放在树上或在地面筑巢的莺的讨食叫声。

David Haskell created artificial nests with clay eggs and placed them on the ground beside a tape recorder that played the begging calls of either tree-nesting or of ground-nesting warblers.

因为讨食叫声而被“广而告之”的在树上筑巢的蛋被发现要比那些在地面筑巢的被咬的严重得多。

The eggs “advertised” by the tree-nesters’ begging calls were found bitten significantly more often than the eggs associated with the ground-nesters’ calls.

一种假说认为，讨食鸣叫已经进化出能降低吸引捕食者风险的特性，这种假说也做出了预测：相比那些不太会被捕食者伤害的雏鸟，那些有更高风险被捕食的雏鸟应该会产生更高频率更柔软的讨食信号。

The hypothesis that begging calls have evolved properties that reduce their potential for attracting predators yields a prediction: baby birds of species that experience high rates of nest predation should produce softer begging signals of higher frequency than nestlings of other species less often victimized by nest predators.

这个预测被从亚利桑那州森林24个物种收集的数据所支持，更多的证据也表明捕食者的存在使得那些讨食鸣叫很难去侦测和定位到的。

This prediction was supported by data collected in one survey of 24 species from an Arizona forest, more evidence that predator pressure favors the evolution of begging calls that are hard to detect and pinpoint.

基于捕食者会让这些讨食行为代价惨重这一事实，那么究竟从这些交流中雏鸟会获得什么好处呢？

Given that predators can make it costly to beg for food, what benefit do begging nestlings derive from their communications?

一种可能是，一个发出叫声的雏鸟会发出精准的信号来传达出它的饥饿和良好健康状况，这样对于那些正在听的准备喂食的鸟爸爸妈妈是值得的，因为在巢附近有其他几个雏鸟也在等待喂食。

One possibility is that a noisy baby bird provides accurate signals of its real hunger and good health, making it worthwhile for the listening parent to give it food in a nest where several other offspring are usually available to be fed.

如果这个假说是正确的话，那么雏鸟应该根据巢周围其他的雏鸟的叫声来调整自己发出信号的密度，这些雏鸟会争夺父母的注意力。

If this hypothesis is true, then it follows that nestlings should adjust the intensity of their signals in relation to the signals produced by their nestmates, who are competing for parental attention.

实验中，将饥饿的知更鸟雏鸟放进那些正常喂养的鸟里面，饥饿的雏鸟会发出比平时更响亮的乞食声，但是其他被喂的更好的雏鸟们也是如此，虽然它们没有饥饿的雏鸟们叫地响。

When experimentally deprived baby robins are placed in a nest with normally fed siblings, the hungry nestlings beg more loudly than usual—but so do their better-fed siblings, though not as loudly as the hungrier birds.

如果鸟爸爸妈妈用讨食声音强度来分配给能发出有力的叫声的健康雏鸟食物的话，那么鸟爸爸妈妈应该针对他们幼崽叫声来做出食物分配的决定。

If parent birds use begging intensity to direct food to healthy offspring capable of vigorous begging, then parents should make food delivery decisions on the basis of their offspring’s calls.

事实上，如果你将树燕雏鸟从鸟巢带走一个小时，然后喂一半雏鸟饿着另外一半的话，当把雏鸟们放回巢时，饥饿的雏鸟们会比已经吃饱的雏鸟们叫得更大声，而鸟爸爸妈妈会给积极乞食的雏鸟们喂更多的食物。

Indeed, if you take baby tree swallows out of a nest for an hour, feeding half the set and starving the other half, when the birds are replaced in the nest, the starved youngsters beg more loudly than the fed birds, and the parent birds feed the active beggars more than those who beg less vigorously.

正如这些实验表明的，很明显乞食行为为鸟父母提供了需求信号，这个信号能让鸟父母判断谁能吃的最多的。

As these experiments show, begging apparently provides a signal of need that parents use to make judgments about which offspring can benefit most from a feeding.

但是问题又出现了，为什么雏鸟不在它们饱的时候大声乞食呢？

But the question arises, why don’t nestlings beg loudly when they aren’t all that hungry?

通过做这个，它们就可能保证获得更多的食物，这会使得它们更快地成长或者长得更大个，哪一个都是有利的。

By doing so, they could possibly secure more food, which should result in more rapid growth or larger size, either of which is advantageous.

很显然，答案不在于过分乞食消耗的更多能量——相比于其潜在能得到的热量来说，损耗的能量只是很小部分——而是因为这种作弊的做法会给与它们拥有相同基因的同伴们造成危害。

The answer lies apparently not in the increased energy costs of exaggerated begging—such energy costs are small relative to the potential gain in calories—but rather in the damage that any successful cheater would do to its siblings, which share genes with one another.

单个个体的基因传播的成功不仅仅受到他自己繁殖成功的影响。

An individual’s success in propagating his or her genes can be affected by more than just his or her own personal reproductive success.

因为近亲中有很多相似基因，那些伤害它们的近亲的动物很可能会因此毁灭一些它们自己的一些的基因。

Because close relatives have many of the same genes, animals that harm their close relatives may in effect be destroying some of their own genes.

因此，一个乞食的雏鸟如果以牺牲它的兄弟姐妹为代价来获取食物的话，事实上可能它能保存下来的基因要比不这么做的话，要少得多。

Therefore, a begging nestling that secures food at the expense of its siblings might actually leave behind fewer copies of its genes overall than it might otherwise.

The phrase “impose on” in the passage is closest in meaning to

According to paragraph 1, the experiment with tapes of begging tree swallows establishes which of the following?

Paragraph 2 indicates that the begging calls of tree-nesting warblers

The experiment described in paragraph 2 supports which of the following conclusions?

In paragraphs 4 and 5, what evidence supports the claim that the intensity of nestling begging calls is a good indicator of which offspring in a nest would most benefit from a feeding?

It can be inferred from paragraphs 4 and 5 that parent songbirds normally do not feed

In paragraph 6, the author compares the energy costs of vigorous begging with the potential gain in calories from such begging in order to

According to paragraph 6, which of the following explains the fact that a well-fed nestling does not beg loudly for more food?

Look at the four squares  that indicate where the following sentence could be added to the passage. The cheeping provides important information to the parent, but it could also attract the attention of others.  Where would the sentence best fit? Click on a square  to add the sentence to the passage.

Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

Begging by Nestlings Many signals that animals make seem to impose on the signalers costs that are overly damaging.  A classic example is noisy begging by nestling songbirds when a parent returns to the nest with food.  These loud cheeps and peeps might give the location of the nest away to a listening hawk or raccoon, resulting in the death of the defenseless nestlings.  In fact, when tapes of begging tree swallows were played at an artificial swallow nest containing an egg, the egg in that “noisy” nest was taken or destroyed by predators before the egg in a nearby quiet nest in 29 of 37 trials.  Further evidence for the costs of begging comes from a study of differences in the begging calls of warbler species that nest on the ground versus those that nest in the relative safety of trees. The young of ground-nesting warblers produce begging cheeps of higher frequencies than do their tree-nesting relatives. These higher-frequency sounds do not travel as far, and so may better conceal the individuals producing them, who are especially vulnerable to predators in their ground nests. David Haskell created artificial nests with clay eggs and placed them on the ground beside a tape recorder that played the begging calls of either tree-nesting or of ground-nesting warblers. The eggs “advertised” by the tree-nesters’ begging calls were found bitten significantly more often than the eggs associated with the ground-nesters’ calls. The hypothesis that begging calls have evolved properties that reduce their potential for attracting predators yields a prediction: baby birds of species that experience high rates of nest predation should produce softer begging signals of higher frequency than nestlings of other species less often victimized by nest predators. This prediction was supported by data collected in one survey of 24 species from an Arizona forest, more evidence that predator pressure favors the evolution of begging calls that are hard to detect and pinpoint. Given that predators can make it costly to beg for food, what benefit do begging nestlings derive from their communications? One possibility is that a noisy baby bird provides accurate signals of its real hunger and good health, making it worthwhile for the listening parent to give it food in a nest where several other offspring are usually available to be fed. If this hypothesis is true, then it follows that nestlings should adjust the intensity of their signals in relation to the signals produced by their nestmates, who are competing for parental attention. When experimentally deprived baby robins are placed in a nest with normally fed siblings, the hungry nestlings beg more loudly than usual—but so do their better-fed siblings, though not as loudly as the hungrier birds. If parent birds use begging intensity to direct food to healthy offspring capable of vigorous begging, then parents should make food delivery decisions on the basis of their offspring’s calls. Indeed, if you take baby tree swallows out of a nest for an hour, feeding half the set and starving the other half, when the birds are replaced in the nest, the starved youngsters beg more loudly than the fed birds, and the parent birds feed the active beggars more than those who beg less vigorously. As these experiments show, begging apparently provides a signal of need that parents use to make judgments about which offspring can benefit most from a feeding. But the question arises, why don’t nestlings beg loudly when they aren’t all that hungry? By doing so, they could possibly secure more food, which should result in more rapid growth or larger size, either of which is advantageous. The answer lies apparently not in the increased energy costs of exaggerated begging—such energy costs are small relative to the potential gain in calories—but rather in the damage that any successful cheater would do to its siblings, which share genes with one another. An individual’s success in propagating his or her genes can be affected by more than just his or her own personal reproductive success. Because close relatives have many of the same genes, animals that harm their close relatives may in effect be destroying some of their own genes. Therefore, a begging nestling that secures food at the expense of its siblings might actually leave behind fewer copies of its genes overall than it might otherwise.