[分享] 戴爾美語練功坊 托福閱讀(12/30)
戴爾美語練功坊 托福閱讀(12/30)
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. 1. According to paragraph 1, the experiment with tapes
of begging tree swallows establishes which of the following? (A) Begging
by nestling birds can attract the attention of predators to the nest.
(B) Nest predators attack nests that contain nestlings more frequently than
they attack nests that contain only eggs. (C) Tapes of begging nestlings
attract predators to the nest less frequently than real begging calls do.
(D) Nest predators have no other means of locating bird nests except the
begging calls of nestling birds. 2. Paragraph 2 indicates that the begging
calls of tree nesting warblers (A) put them at more risk than ground-nesting
warblers experience (B) can be heard from a greater distance than those of
ground-nesting warblers (C) are more likely to conceal the signaler than
those of ground-nesting warblers (D) have higher frequencies than those
of ground nesting warblers 3. The experiment described in paragraph 2
supports which of the following conclusions? (A) Predators are unable to
distinguish between the begging cheeps of ground-nesting and those of
tree-nesting warblers except by the differing frequencies of the calls.
(B) When they can find them, predators prefer the eggs of tree-nesting
warblers to those of ground-nesting warblers. (C) The higher frequencies
of the begging cheeps of ground-nesting warblers are an adaptation to the
threat that ground-nesting birds face from predators. (D) The danger of
begging depends more on the frequency of the begging cheep than on how
loud it is. 4. The word " derive " in the passage is closest in meaning to
(A) require (B) gain (C) erupt (D) renounce 5. 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? (A) When placed in a nest with hungry robins, well-fed
robins did not beg for food. (B) Among robin nestlings, the intensity of
begging decreased the more the nestlings were fed. (C) Hungry tree
swallow nestlings begged louder than well-fed nestlings in the same nest.
(D) Hungry tree swallow nestlings continued to beg loudly until they were
fed whereas well-fed nestlings soon stopped begging. 6. It can be inferred
from paragraphs 4 and 5 that parent songbirds normally do not feed
(A) nestlings that are too weak to beg for food as vigorously as their
nestmates (B) more than one hungry nestling during a single visit to the
nest (C) offspring that were fed by the parents on the previous visit to the
nest (D) nestlings that have been removed and then later put back into their
nest 7. In paragraph 6, the author compares the energy costs of vigorous
begging with the potential gain in calories from such begging in order to
(A) explain why begging for food vigorously can lead to faster growth and
increased size (B) illustrate how begging vigorously can increase an
individual's chance of propagating its own genes (C) point out a weakness
in a possible explanation for why nestlings do not always beg vigorously
(D) argue that the benefits of vigorous begging outweigh any possible
disadvantages Answers: 1. 根據第一段, 利用燕子(swallow) 鳴叫聲之
錄音帶所進行的實驗得知下列何結果? 關鍵字詞 key words : tapes of
begging tree , 返回原文進行定位---- 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. Trial = experiment 實驗 ;
判讀該播放鳥鳴聲之鳥巢之鳥蛋配掠食者(predator)所破壞.
正確答案選 A. 2. 第二段中提及築巢於樹上之鳴禽(warbler) 之叫聲
指出: 搜索核心關鍵字詞 : begging calls of tree nesting warblers ----
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. 該句中論述 tree-nesting warbler 與 ground-nesting warbler
進行對照比 較; ground-nesting 比較起 tree-nesting 發出聲音頻率高;
因而高頻之聲音 無法傳遞至遠距離. 此訊息暗示 tree-nesting
鳴聲頻率低, 可傳至較遠處. 答案為 B . 3. 下列何者為第二段支持
下列何結論? 本題之邏輯分析同上題;因tree-nesting 與
ground-nesting 之音頻差異造成tree-nesting 比起 ground-nesting
更易遭致攻擊. 反之 ground-nesting 則演化較不會遭致掠食者
攻擊威脅. The eggs "advertised" by the tree-nesters' begging calls
were found bitten significantly more often than the eggs associated
with the ground-nesters' calls. 正確答案選 C. 4. derive (v.) 得到 ;
衍生 (A) require 需要; 要求 (B) gain 取得 = obtain = acquire
= procure = garner (C) erupt 爆炸 volcanic eruption 火山爆發
(D) renounce 放棄 = abandon = abdicate = desert = forgo = forsake
= relinquish = waive = jettison = discard 答案為 B . 5. 第四與第五段中,
何種證據支持" 雛鳥之叫聲強度intensity of nestling begging calls is a
good indicator 乃為一個指出小雛鳥(nestlings)間可獲得母鳥餵食之
好處之指標? " 原文: 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. 雛鳥鳴叫
聲越大生證明自己飢餓與健康之表現, 因而可獲母鳥之青睞俾以將其
食物餵食該幼鳥. 答案選擇 C . 6. 第四與第五段中推論出"從母鳥
正常狀況下不會餵食": 此類型題為推論題 (Inference) --- 利用文中
(1) 轉折語 ; (2) 極致詞; (3) 強調字等原則進行分析. 此題之分析角度
與上述之原因相同, 母鳥餵食予健康且饑餓之雛鳥; 反向推論牠會
餵食體弱之子孫( offspring) 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. 答案為 A. 7. 第六段中作者比較有活力之鳥鳴叫聲
與可能取得之卡路里(calories) 為何目的? 本題此題主要測驗
"修辭目的" (Rhetorical Purpose) 原文 --- 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. 文中論述到為何當雛鳥沒有饑餓時,
其叫聲不那麼大聲, 藉由如此行為以獲取更 多食物 calories ; 然而
此論點遭到反駁(not …. but….) , 並非以獲得能量, 乃是會對於與牠們
共同基因之兄弟姐妹(siblings). 因此作者提此句之用意乃駁斥原本之
問題解釋. 答案為 C.
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