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  3. Cuckolds are men whose wives gave birth to infants that were blatantly not their own. The well known trickery of the cuckoo, the

Cuckolds are men whose wives gave birth to infants that were blatantly not their own. The well known trickery of the cuckoo, the

admin2016-10-21  29
问题     Cuckolds are men whose wives gave birth to infants that were blatantly not their own. The well known trickery of the cuckoo, the bird from which "cuckold" is derived, is as a nest parasite — laying eggs for other birds to hatch and raise. New research suggests the cuckoo has another trick it uses to ruffle its victims’ feathers.
    Common cuckoos usually lay a single egg in the nest of a host bird. The eggs often look remarkably similar to the host’s. Upon hatching, the cuckoo chick eliminates any of its potential rival chicks by pushing them or their eggs out of the nest. However, there is more to this elaborate deceit than is generally realized.
    As far back as ancient times a similarity has been noted between many cuckoo species and hawks, in size, shape and plumage. More recently researchers have discovered that hawk-like markings are more prevalent in cuckoo species that engage in nest parasitism than in cuckoo species that do not. Researchers wondered whether this similarity was noticed by birds too.
    They set up peanut feeding stations and over two years found that great and blue tits, both of which are not parasitised by cuckoos, were the main visitors. They then experimented by placing a mounted specimen of a sparrowhawk, cuckoo, dove, or duck, at the feeders for five minutes. The team reported that the tits were as scared of cuckoos as they were of sparrowhawks, raising alarm calls and staying away from feeders at all costs. With the duck and dove they detected no such behavior.
    When researchers covered the hawk-like markings on the cuckoo the tits treated it as if it were a duck or dove. Covering the same markings on the sparrowhawk had no such effect, but adding them to the dove caused the tits to treat the dove as they would a sparrowhawk or a cuckoo.
    The authors argue that actual cuckoo hosts, such as meadow pipits, dunnocks and reed warblers, may have directed the evolution of the cuckoo’s resemblance to hawks by attacking cuckoos that approached their nests. If a cuckoo with slightly hawk-like plumage caused hosts to delay or avoid an attack in the past, this would have favored the evolution,of hawk mimicry.
    It is an arms race —-and a matter of adapting and counter-adapting. The better the cuckoo disguises its eggs and itself, the more host birds improve their ability to spot the impostor. Although such an evolutionary dynamic may seem like something that exists only in the wild, it is possible for it to happen in human society as well — between cuckolds and their cheating partners, constantly driving men to be better at detecting adultery and women to be better at getting away with it.
Which of the following experiments has NOT been done by researchers?
选项 A、They placed a sparrowhawk, cuckoo, dove, or duck around the tits and observed the tits’ reaction.
B、They set up feeding stations and observed why tits are not parasitized by cuckoos.
C、They covered hawk-like markings on the cuckoo and observed the tits’ reaction.
D、They added hawk-like markings on the dove and observed the tits’ reaction.
答案B
解析 细节题。从第四段的内容可以直接看出A正确。研究者们建立feeding stations的原因是为了观察山雀为何没被布谷鸟占据巢穴，这个原因在原文中无从得知，而原文提到建立饲养站的原因实际上是引诱山雀来做实验，所以B错误。从第六段可以直接看出C和D正确。
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