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又想起来了
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listen

英['lɪs(ə)n] 美['lɪsn]
vi. 听,倾听;听从,听信
n. 听,倾听

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草莓小菇凉:说的非常好,十分有道理,棒棒棒!

06-08 15:44:55

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TPO-11-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 offsprings’ 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.

动物们的许多信号似乎强加给信号员成本过于有害。一个典型的例子是,当一位父母带着食物返回巢穴时,nest叫的鸣禽乞求喧闹。这些大声的吱吱喳喳和偷看可能会把鸟巢的位置带到一只聆听的鹰或浣熊身上,导致无防御的雏鸟死亡。事实上,在一个含有鸡蛋的人造燕窝中播放乞讨树燕子的录像带时,37个试验中的29个在附近一个安静的巢穴中捕食或摧毁了那个“嘈杂”巢中的鸡蛋。

 

乞讨成本的进一步证据来自于研究在地上筑巢的莺类物种与在树木相对安全性中筑巢的乞讨物种的乞讨呼叫的差异。地面莺的年轻人比他们的树亲戚产生更高频率的乞讨che。这些更高频率的声音不会走得太远,因此可能更好地隐藏生产它们的个体,这些个体在巢穴中特别容易受到食肉动物的伤害。大卫·哈斯克尔(David Haskell)用粘土蛋制作了人造的巢穴,并将它们放在录音机旁边的地面上,这个录音机播放着树木嵌套或地面莺的乞讨电话。被树猎人“乞讨”电话“标榜”的鸡蛋被发现的咬得比地下巢人呼叫的鸡蛋要频繁得多。

 

乞求呼叫已经演变的属性降低了它们吸引捕食者的可能性,这就产生了一个预测:经历高巢捕食率的物种的幼鸟应该产生比窝捕食者更少受害的其他物种的雏鸟更高的软乞求信号。这一预测得到了亚利桑那州森林中24种物种调查数据的支持,更多的证据表明,食肉动物的压力有利于乞讨呼叫的演变,这些呼叫很难被发现和查明。

 

鉴于掠食者可以乞求食物,代价昂贵,乞求雏鸟从他们的交流中获得了什么?一种可能性是,一只嘈杂的小鸟可以提供真实的饥饿和健康的准确信号,使得听力父母可以在一个窝里给它喂食食物,而其他几个后代通常可以喂食。如果这个假设是真的,那么雏鸟应该调整他们信号的强度,以便与他们的竞争父母关注的巢穴产生的信号相关。当试验剥夺的宝宝知更鸟被放置在与正常喂养的兄弟姐妹一起的巢中时,饥饿的雏鸟比平时要求更大声,但是他们的喂养更好的兄弟姐妹,虽然不像饥饿的鸟那样响亮。

 

如果父母用乞讨的强度将食物引导到健康的后代,那么父母就应该根据他们的后代的要求作出食物分娩的决定。事实上,如果你把幼鸟从窝里拿出一小时喂一半,而另一半则饿死,当鸟在窝里被更换时,饥饿的幼鸽比喂食的鸟要求得更响,母鸟喂养积极的乞丐比那些乞讨少的多。

 

正如这些实验所表明的那样,乞讨显然提供了一个需要的信号,即父母用来判断哪个后代能够从喂养中受益最大。但是问题出现了,为什么雏鸟们不是在饿的时候大声乞求呢?通过这样做,他们可以获得更多的食物,这将导致更快的增长或更大的规模,这两者都是有利的。答案显然不在于夸大乞讨的能源成本的增加 - 这种能源成本相对于潜在的热量增加而言是小的,而是任何成功的作弊者对于彼此分享基因的兄弟姐妹所造成的损害。一个人在繁殖自己的基因方面的成功可能不仅仅受到个人生殖成功的影响。因为近亲有许多相同的基因,所以伤害近亲的动物实际上可能会破坏他们自己的一些基因。因此,一个以牺牲兄弟姐妹为代价来保证食物安全的乞讨雏鸟实际上可能会留下较少的基因拷贝。


中文翻译

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

  • Many signals that animals make seem to impose on the signalers costs that are overly damaging.  A increase for B remove from C place on D distribute to impose on
正确答案: C

网友解析

  • 用户头像

    恩恩耶  发表于 2018-08-29 11:38:09

    题型分类:词汇题
    原文定位:impose on:强加于。
    选项分析:
    A选项 增长;
    B选项 移除;
    C选项 强加于,正确;
    D选项 分配。

  • 用户头像

    joannazz  发表于 2018-01-04 17:54:42

    词汇题
    解析:impose on 强加于、施加影响于,最接近的是C。原句说动物发出的信号会impose on发出信号的动物,ABD都不搭

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