2. 考研
  3. Peahens, though not as showy as cocks, are by no means plain. Their heads have attractive crests and their necks are bright blue

Peahens, though not as showy as cocks, are by no means plain. Their heads have attractive crests and their necks are bright blue

admin2019-08-08  9
问题    Peahens, though not as showy as cocks, are by no means plain. Their heads have attractive crests and their necks are bright blue. Such decoration is costly to grow and likely to attract predators. If you do not have to show off your stuff to get a mate, why do you need it? Even more confusingly, in many species both sexes are equally showy. To understand things better James Dale of Massey University, in Auckland, New Zealand, and his colleagues have therefore examined the feathers of both sexes of all 5,983 species of passerine bird (雀形目鸟类) and compared them in exquisite detail. 【F1】The researchers started from the fact that, despite the exceptions, showiness is still more a male than a female phenomenon.
   【F2】Their first observation, as they report this week in Nature, was that in species where a few males exclusively control all the females, with a consequent lack of male involvement in parental care, males were more colourful than females. This is what the theory of sexual selection would predict. What it would not predict in its simple form, though, was a second finding—that females in co-operatively breeding species (those in which, for lack of other opportunities, several females collaborate to raise the young of only one of them) are more ornamented than those in which all adult females have a chance of breeding. 【F3】In this case it is females who are competing for the right to reproduce, thus putting themselves in a more male-like position.
   Another widespread belief Dr Dale and his colleagues confirmed is that tropical species are more colourful than those from temperate climes. But again, there was a twist—the effect was much more marked in females than in males. 【F4】It may be that tropical birds, which face more intense competition for food and nesting sites than temperate ones do because the tropics have more species, form more stable and collaborative pair-bonds than do temperate birds. In these circumstances males also need to be choosy, and females competitive.
   The final effect the researchers found was that big species are more colourful than small ones. That is true of both sexes, and probably reflects the fact that bigger birds are more difficult prey and thus have less need to hide. When released from the threat of predation, then, females tend to be showy. 【F5】That suggests showiness is always good when it can be got away with and probably explains the decorated necks and heads of peahens, which are among the biggest of birds.
【F3】
选项
答案此种情况下，需通过竞争才能获得繁衍后代权利的角色正是雌性，这使得她们扮演更像雄性的角色。
解析 ①本句为It is…who强调句型，强调主语females，正常表达为females are competing for the right to reproduce“雌性为繁衍后代的权利而竞争”。②In this case作状语，表示“在这种情况下”，this case指代前文中的females in…species are more ornamented than…。③thus putting…在句中作结果状语，表明“雌性通过竞争获得繁衍后代的权利”的结果。反身代词themselves指代females，即雌性自己。
转载请注明原文地址:https://kaotiyun.com/show/zX2Z777K
0

考研英语一

相关试题推荐
随机试题
最新回复(0)