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  3. Darwin proposed the theory of sexual selection to explain the origin of

Darwin proposed the theory of sexual selection to explain the origin of

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问题          Darwin proposed the theory of sexual selection to explain the origin of
     ostentatious plumage in certain bird species, maintaining that the ornate
     features of males are a consequence of female mate selection based on an
     abstract aesthetic sense, not unlike the process of animal breeders producing
(5)   fancy-male varieties of pigeons by conscious artificial selection. Wallace
     suggested an alternative explanation: through greater physical energy the most
     highly adorned males are able to win the competition with rival males.
     Meanwhile Huxley pointed out that male adornment is instrumental in
     establishing dominance relationships among males: adornment reduces the
(10)  physical activity necessary to intimidate rivals.
         However, Jacobs later examined the process of female choice, concluding
     that what appeared to be choice of an adorned male by a female was really a
     mutual attraction to a certain reproductive site. Mate selection requires an
     awareness of features characteristic of a suitable breeding site, which might be
(15)  mirrored in the ornamentation of the male, and thus mate selection is related
     directly to adaptive niche specialization. From this insight, Austin proceeded to
     develop a food-courtship theory of mate selection: the population most efficient
     in use of the energy available in a particular niche will be the fittest to survive
     there. Through natural selection, organisms will tend to become specialized to
(20)  form isolated populations, each adapted to utilize the energy most efficiently
     that is available in a particular niche and this process of segregation and
     specialization of populations is facilitated by employing in the mating process
     samples of the food available in the preferred niche. In particular cases, the
     male may display the food to the female or feed it to her in the courtship
(25)  ceremony, maybe bearing permanent representations of specific foods on his
     plumage, and the female may be attracted to the male for these representations
     of the territorial foods.
          Austin’s theory may be applied to the case for mate choice among
     peafowls, whose males’ "eyespotted" tail feathers bear a striking resemblance
(30)  to blue berries. According to the food-courtship theory, it is because their
     plumage bears representations of food that peacocks attract peahens, which may
     explain why males with the most "eyespots" on their tail have the greatest
     mating success. Not inconsistent with a possible role of the "eyespots" in
     reproductive competition among males and in aesthetic selection, this
(35)  explanation seems more plausible than the suggestion that by selecting mates
     according to the perfection of their tail-feather "eyespots", peahens are able to
     identify mates with the greatest "fitness". This process, bringing together
     males and females of similar tastes and physiologies, may lead to speciation.
     Some of the male display features may come to be involved in species
(40)  identification, and it has also been noted that male adornment could have a dual
     function, repelling rival males as well as attracting females.
选项 A、contrasting the role of domination and courtship in determining the evolution of bird plumage
B、illustrating the effectiveness of a particular approach to categorizing various evolutionary innovations
C、documenting the origins of a currently accepted scientific theory about food and courtship
D、proposing a new explanation for the evolutionary reasons behind the ornamentation of male bird plumage
E、showing that physical adaptation plays an integral role in contributing to species identification of birds
答案 D
解析
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