17.鸟叫研究(是原文吗??)
鸟的叫声的property,有两种类型，一种intergroup,另一种withgroup(不确定是不是这个叫 法)，intergroup很好的documented了，因为分布范围广，有差异什么的，鸟对特定叫声就作出特定反应，而withgroup研究困难， 因为鸟很少对鸣叫作出特定反应;问题中问到了recent research对intergroup研究到什么成果;
Over the years, biologists have suggested two main pathways by which sexual selection may have shaped the evolution of male birdsong. In the first, male competition and intrasexual selection produce relatively short, simple songs used mainly in territorial behavior. In the second, female choice and intersexual selection produce longer, more complicated songs used mainly in mate attraction; like such visual ornamentation as the peacock’s tail, elaborate vocal characteristics increase the male’s chances of being chosen as a mate, and he thus enjoys more reproductive success than his less ostentatious rivals. The two pathways are not mutually exclusive, and we can expect to find examples that reflect their interaction. Teasing them apart has been an important challenge to evolutionary biologists.
Early research confirmed the role of intrasexual selection. In a variety of experiments in the field, males responded aggressively to recorded songs by exhibiting territorial behavior near the speakers. The breakthrough for research into intersexual selection came in the development of a new technique for investigating female response in the laboratory. When female cowbirds raised in isolation in sound-proof chambers were exposed to recordings of male song, they responded by exhibiting mating behavior. By quantifying the responses, researchers were able to determine what particular features of the song were most important. In further experiments on song sparrows, researchers found that when exposed to a single song type repeated several times or to a repertoire of different song types, females responded more to the latter. The beauty of the experimental design is that it effectively rules out confounding variables; acoustic isolation assures that the female can respond only to the song structure itself.
If intersexual selection operates as theorized, males with more complicated songs should not only attract females more readily but should also enjoy greater reproductive success. At first, however, researchers doing fieldwork with song sparrows found no correlation between larger repertoires and early mating, which has been shown to be one indicator of reproductive success; further, common measures of male quality used to predict reproductive success, such as weight, size, age, and territory, also failed to correlate with song complexity.
The confirmation researchers had been seeking was finally achieved in studies involving two varieties of warblers. Unlike the song sparrow, which repeats one of its several song types in bouts before switching to another, the warbler continuously composes much longer and more variable songs without repetition. For the first time, researchers found a significant correlation between repertoire size and early mating, and they discovered further that repertoire size had a more significant effect than any other measure of male quality on the number of young produced. The evidence suggests that warblers use their extremely elaborate songs primarily to attract females, clearly confirming the effect of intersexual selection on the evolution of birdsong.
21. The passage is primarily concerned with
(A) showing that intrasexual selection has a greater effect on birdsong than does intersexual selection
(B) contrasting the role of song complexity in several species of birds
(C) describing research confirming the suspected relationship between intersexual selection and the complexity of birdsong
(D) demonstrating the superiority of laboratory work over field studies in evolutionary biology
(E) illustrating the effectiveness of a particular approach to experimental design in evolutionary biology
22. The author mentions the peacock’s tail in line 8 most probably in order to
(A) cite an exception to the theory of the relationship between intrasexual selection and male competition
(B) illustrate the importance of both of the pathways that shaped the evolution of birdsong
(C) draw a distinction between competing theories of intersexual selection
(D) give an example of a feature that may have evolved through intersexual selection by female choice
(E) refute a commonly held assumption about the role of song in mate attraction
23. According to the passage, which of the following is specifically related to intrasexual selection?
(A) Female choice
(B) Territorial behavior
(C) Complex song types
(D) Large song repertoires
(E) Visual ornamentation
24. Which of the following, if true, would most clearly demonstrate the interaction mentioned in lines 11-13?
(A) Female larks respond similarly both to short, simple songs and to longer, more complicated songs.
(B) Male canaries use visual ornamentation as well as elaborate song repertoires for mate attraction.
(C) Both male and female blackbirds develop elaborate visual and vocal characteristics.
(D) Male jays use songs to compete among themselves and to attract females.
(E) Male robins with elaborate visual ornamentation have as much reproductive success as rivals with elaborate vocal characteristics.
25. The passage indicates that researchers raised female cowbirds in acoustic isolation in order to
(A) eliminate confounding variables
(B) approximate field conditions
(C) measure reproductive success
(D) quantify repertoire complexity
(E) prevent early mating
26. According to the passage, the song sparrow is unlike the warbler in that the song sparrow
(A) uses songs mainly in territorial behavior
(B) continuously composes long and complex songs
(C) has a much larger song repertoire
(D) repeats one song type before switching to another
(E) responds aggressively to recorded songs
27. The passage suggests that the song sparrow experiments mentioned in lines 37-43 failed to confirm the role of intersexual selection because
(A) females were allowed to respond only to the song structure
(B) song sparrows are unlike other species of birds
(C) the experiments provided no evidence that elaborate songs increased male reproductive success
(D) the experiments included the songs of only a small number of different song sparrows
(E) the experiments duplicated some of the limitations of previous field studies
18.恐龙灭绝和行星撞地球
说65万年前恐龙灭绝是因为comet or other meterite的impact 造成的，其证据是因为在一个考古地方，65万年前的， 发现了一种元素Ir, 记不清具体的了，因为这种元素在地球很少见，只能是由于行星的撞击，因为非地球的行星富含这种元素，然后由于撞击而留在地球上，故可由此元素的含量来推测是行星撞击的。 同时在距今大概120万年的地方也发现了该元素，但是其含量只有65万年的十分之一，同时文章开头的意思是要证明120万年的这个也是由于行星撞击造成的。 文章最后结尾说起撞击的行星也有可能含这种元素较少，而且comet全是由冰构成的， 所以撞击120的那个可能只是一个小星星， 只能引起小范围的灭绝，不能引起全部的生物灭绝，但是65的那种是全球灭绝。
题目有一道问你， 由于120 的Ir元素只有65的十分之一，则可以推测120的那颗星星与65导致恐龙灭绝的那颗有什么区别， 我选的是那个Ir元素含量与行星撞击的impact没有直接联系 。
Iridium, a hard, whitish metal similar to platinum, is extremely rare on Earth. Extremely high concentrations of iridium on Earth result from only two scenarios: massive volcanic eruptions that release iridium from deep within the Earth and meteorites that shower down on Earth from space. When scientists found concentrations of iridium 30 times higher than normal in rock stratum from 65 million years ago, they concluded that a massive meteor or comet hit the Earth and caused the massive extinction of the dinosaurs.
Which of the following, if true, most strongly supports the scientist’s conclusion?
A. Volcanoes massive enough to generate high concentrations of iridium are very rare.
B. Massive volcanic eruptions occurred frequently 80 million years ago.
C. Most scientists support the hypothesis that a cosmic impact wiped out the dinosaurs.
D. The massive extinction that occurred 70 million years ago killed not only the dinosaurs but also 70 percent of all life on Earth.
E. A comet struck the earth some 120 million years ago, but no widespread extinction occurred.
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