Animal signals, such as the complex songs of birds, tend to be costly. A bird, by singing, may forfeit time that could otherwise be spent on other important behaviors such as foraging or resting. Singing may also advertise an individual's location to rivals or predators and impair the ability to detect their approach. Although these types of cost may be important, discussions of the cost of singing have generally focused on energy costs. Overall the evidence is equivocal: for instance, while Eberhardt found increases in energy consumption during singing for Carolina wrens, Chappell found no effect of crowing on energy consumption in roosters.
To obtain empirical data regarding the energy costs of singing, Thomas examined the relationship between song rate and overnight changes in body mass of male nightingales. Birds store energy as subcutaneous fat deposits or 'body reserves'; changes in these reserves can be reliably estimated by measuring changes in body mass. If singing has important energy costs, nightingales should lose more body mass on nights when their song rate is high. Thomas found that nightingales reached a significantly higher body mass at dusk and lost more mass overnight on nights when their song rate was high.
These results suggest that there may be several costs of singing at night associated with body reserves. The increased metabolic cost of possessing higher body mass contributes to the increased overnight mass loss. The strategic regulation of evening body reserves is also likely to incur additional costs, as nightingales must spend more time foraging in order to build up larger body reserves. The metabolic cost of singing itself may also contribute to increased loss of reserves. This metabolic cost may arise from the muscular and neural activity involved in singing or from behaviors associated with singing. For example, birds may expend more of their reserves on thermoregulation if they spend the night exposed to the wind on a song post than if they are in a sheltered roost site. Thomas's data therefore show that whether or not singing per se has an important metabolic cost, metabolic costs associated with singing can have an important measurable effect on a bird's daily energy budget, at least in birds with high song rates such as nightingales.
The primary purpose of the passage is to ______.
[考点] 主旨的理解 1．做题分析 ①Animal signals, such as the complex songs of birds, tend to be costly.②A bird, by singing, may forfeit time that could otherwise be spent on other important behaviors such as foraging or resting.③Singing may also advertise an individual's location to rivals or predators and impair the ability to detect their approach.④Although these types of cost may be important, discussions of the cost of singing have generally focused on energy costs.⑤Overall the evidence is equivocal: for instance, while Eberhardt found increases in energy consumption during singing for Carolina wrens, Chappell found no effect of crowing on energy consumption in roosters. ⑥To obtain empirical data regarding the energy costs of singing, Thomas examined the relationship between song rate and overnight changes in body mass of male nightingales.⑦Birds store energy as subcutaneous fat deposits or 'body reserves'; changes in these reserves can be reliably estimated by measuring changes in body mass.⑧If singing has important energy costs, nightingales should lose more body mass on nights when their song rate is high.⑨Thomas found that nightingales reached a significantly higher body mass at dusk and lost more mass overnight on nights when their song rate was high. ⑩These results suggest that there may be several costs of singing at night associated with body reserves.⑪The increased metabolic cost of possessing higher body mass contributes to the increased overnight mass loss.⑫The strategic regulation of evening body reserves is also likely to incur additional costs, as nightingales must spend more time foraging in order to build up larger body reserves.⑬The metabolic cost of singing itself may also contribute to increased loss of reserves. ⑭This metabolic cost may arise from the muscular and neural activity involved in singing or from behaviors associated with singing.⑮For example, birds may expend more of their reserves on thermoregulation if they spend the night exposed to the wind on a song post than if they are in a sheltered roost site.⑯Thomas's data therefore show that whether or not singing per se has an important metabolic cost, metabolic costs associated with singing can have an important measurable effect on a bird's daily energy budget, at least in birds with high song rates such as nightingales. 2．文章结构 文章主要讲鸟类唱歌对自身能量消耗问题，并列举了一个相关的实验予以证明。第一段提出比如鸟类唱歌之类的动物信号对动物的影响，但是目前的实验结果都很模糊；第二段讲一个科学家Thomas的验证实验，包括这个实验的合理性、实验方法和结论；第三段讲一些根据实验结果得到的其他结论。 第一段： 主题：动物信号，比如鸟类的歌声对动物本身的消耗是很大的。 细节1：代价大的两个理由。 细节2：对这类代价的研究主要聚焦于能量消耗。 第二段： 主题：为了探究唱歌对鸟类的能量消耗，科学家Thomas对唱歌导致的鸟类隔天体重变化做了探究。 细节1：这个实验的合理性。 细节2：预期的结果。 细节3：实验结果。 第三段： 主题：唱歌还会给鸟类带来其他类型的消耗。 细节1：鸟类唱歌引起新陈代谢水平增加。 细节2：新陈代谢水平增加对鸟类的影响。 3．文章精析 第一段：第一句给出一个结论性质的主题，后面用两句话证明这个结论，最后两句说明目前存在的问题。 ①这是本段主题，讲释放动物信号对于动物来说是一件代价很大的事(costly)，插入语是一个动物信号的例子，即鸟类的歌声，也是本文主要的讨论对象。 ②没有取反词，这句话是细节，用来证明上一句的costly，因为鸟类唱歌时会消耗它们本来可以用于觅食(foraging)或休息(resting)的时间(forfeit time)。 ③没有取反词，这句话是细节，also表示并列，是另一个costly的证据。唱歌会把自己的位置暴露给(advertise an individual's location)对手或捕食者(rivals or predators)。 ④出现取反词Although，这是另一个主题。虽然这些代价都是很重要的，对于这些代价的讨论主要聚焦于能量消耗(energy costs)，说明实际存在很多类型的消耗。 ⑤没有取反词，这句话是细节。对于能量消耗的证据是比较模糊的(the evidence is equivocal)，冒号后面列举了两个结果相反的实验证明了equivocal：Eberhardt的实验表明鸟类唱歌时能量消耗增加，而Chappell对公鸡的实验发现没有能量消耗增加。 第二段：第二段讲述一个验证实验，这一段分别讲述了实验是通过什么方法验证的，这个实验的预期是什么，以及实验结论。 ⑥这是本段主题，讲述实验目的和实验内容。目的是获得唱歌带来的能量消耗的实验数据(obtain empirical data regarding the energy costs of singing)，具体手段是验证鸟唱歌频率和体重损失之间的关系。 ⑦没有取反词，这句话是细节，讲这个实验的合理性。因为鸟类会在身体中储存能量(body reserves)，这样体重的变化就能代表它们能量消耗的情况。 ⑧没有取反词，这句话是细节，讲这个实验的预期结果。如果唱歌导致能量消耗，那么歌唱频率高时(song rate is high)，体重损耗就会变大(lose more body mass)。 ⑨没有取反词，这句话是细节，讲这个实验的结果。Thomas发现，当鸟更频繁地唱歌时，它们会在傍晚储存更多的体重(a significantly higher body mass at dusk)并且晚上会损失很多的体重(lost more mass overnight)。 第三段：这一段讲根据这个实验带来的其他结论：唱歌还会带来其他类型的损耗，因为鸟类的新陈代谢水平增加了。结尾给出结论：通过这个实验证明唱歌确实对鸟类能量有很大影响。 ⑩这是本段主旨，These results指代上文的实验结果。这些结果说明唱歌造成的能量消耗与储存的体能有关(associated with body reserves)。 ⑪没有取反词，这句话是细节，相当于实验结果的解释。这里higher body mass就是高的body reserves，体重增加之后，新陈代谢水平也增加(The increased metabolic cost)，这样晚上损失的体重也会增加(increased overnight mass loss)。 ⑫没有取反词，这句话是细节，The strategic regulation of evening body reserves指的是前一句中“储存多，消耗也多”的调节方式，这会导致额外的能量消耗(incur additional costs)。因为鸟类会更多地去觅食(spend more time foraging)增加自己的能量储存(build up larger body reserves)。 ⑬、⑭没有取反词，细节。说明新陈代谢水平增加本身也会带来额外的消耗(contribute to increased loss of reserves)，这些消耗包括唱歌过程中肌肉和神经的活动(muscular and neural activity)。 ⑮没有取反词，这句话是细节，用例子来证明上一句的观点，粗略读一下即可：当鸟在不同的地方唱歌时，它们自身存在不同的热量调节(thermoregulation)。 ⑯没有取反词，这句话是细节，Thomas's data指的是实验结果，这里是对相关推论的一个总结：无论唱歌是否造成了很大的由于新陈代谢带来的损耗，这都对鸟类每天的能量使用有很大影响(have an important measurable effect on a bird's daily energy budget)，至少是对晚上唱歌很频繁的种类(比如实验中使用的那种鸟)。 题型：主旨题 本文的主旨句是Animal signals, such as the complex songs of birds, tend to be costly，主要内容是用实验证明唱歌对鸟类能量有很大消耗，强调的是costly，所有选项中只有C选项主题正确且important体现了costly，答案是C。
For the following question, consider each of the choices separately and select all that apply.
The passage implies that during the day before a night on which a male nightingale's song rate is high, that nightingale probably does which of the following? ______
[考点] 细节的定位和理解 题型：不定项选择题 这道题根据a male nightingale's song rate is high定位到第二段，不定项选择题看选项排除：A选项的thermoregulation出现在第三段，不在定位范围，错误；B选项，符合实验结果的reached a significantly higher body mass at dusk，正确；C选项，predators出现在第一段，不在定位范围，错误。答案是B。
For the following question, consider each of the choices separately and select all that apply.
It can be inferred from the passage that compared with other costs of singing, which of the following is true of the energy costs of singing? ______
[考点] 全文细节的理解 题型：不定项选择题 题目问与其他能量消耗相比，关于唱歌造成能量消耗的哪个观点正确。这道题的定位范围在第一和第三段，不定项选择题看选项排除：A选项，我们只知道唱歌造成的能量损耗很大，但是不知道是不是最大的，错误；B选项符合第一段的Although these types of cost may be important, discussions of the cost of singing have generally focused on energy costs，正确；C选项，文章没有讨论不同种鸟类的问题，错误。答案是B。