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  3. Since the Hawaiian Islands have never been connected to other landmasses, the great variety of plants in Hawaii must be a result

Since the Hawaiian Islands have never been connected to other landmasses, the great variety of plants in Hawaii must be a result

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问题     Since the Hawaiian Islands have never been connected to other landmasses, the great variety of plants in Hawaii must be a result of the long-distance dispersal of seeds, a process that requires both a method of transport and an equivalence between the ecology of the source area and that of the recipient area.
    There is some dispute about the method of transport involved. Some biologists argue that ocean and air currents are responsible for the transport of plant seeds to Hawaii. Yet the results of flotation experiments and the low temperatures of air currents cast doubt on these hypotheses. More probable is bird transport, either externally, by accidental attachment of the seeds to feathers, or internally, by the swallowing of fruit and subsequent excretion of the seeds. While it is likely that fewer varieties of plant seeds have reached Hawaii externally than internally, more varieties are known to be adapted to external than to internal transport.
It can be inferred from information in the passage that the existence in alpine regions of Hawaii of a plant species that also grows in the southwestern United States would justify which of the following conclusions?
选项 A、The ecology of the southwestern United States is similar in important respects to the ecology of alpine regions of Hawaii.
B、There are ocean currents that flow from the southwestern United States to Hawaii.
C、The plant species discovered in Hawaii must have traveled from the southwestern United States only very recently.
D、The plant species discovered in Hawaii reached there by attaching to the feathers of birds migrating from the southwestern United States.
答案A
解析 在一些重要的方面，美国西南部的生态与夏威夷高山地区的生态大致相同。根据第一段，来源区(source area)和受援区(recipient area)的生态大致相同，两个地区就能长出同一种植物。在夏威夷的高山地区生长的植物也能在美国的西南部生长，这说明来源区和受援区的生态大致相同。
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