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Darwin proposed the theory of sexual selection to explain the origin

游客2025-02-22  8
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
Line    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. [br] According to the passage, which of the following determines the shape and coloring of the plumage of a given species of bird within a given ecological niche?
选项 A、The emergence of a competing species who rely upon the same food source as the first species
B、The physical appearance of the food supply available in the niche to the given species
C、The ability of the first species to collect and make use of the nutritional properties of the food within in the niche
D、The physical appearance of rival males within the species who compete for both the same food supply and females
E、The physiological effects on fertility of the food available in the niche
答案 B
解析
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