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  3. There are both great similarities and considerable diversity in the ecosyste

There are both great similarities and considerable diversity in the ecosyste

游客2023-12-25  10
问题     There are both great similarities and considerable diversity in the ecosystems that evolved on the islands of Oceania in and around the Pacific Ocean. The islands, such as New Zealand, that were originally parts of continents still carry some small plant and animal remnants of their earlier biota (animal and plant life), and they also have been extensively modified by evolution, adaptation, and the arrival of new species. By contrast, the other islands, which emerged via geological processes such as volcanism, possessed no terrestrial life, but over long periods, winds, ocean currents, and the feet, feathers, and digestive tracts of birds brought the seeds of plants and a few species of animals. Only those species with ways of spreading to these islands were able to undertake the long journeys, and the various factors at play resulted in diverse combinations of new colonists on the islands. One estimate is that the distribution of plants was 75 percent by birds, 23 percent by floating, and 2 percent by wind.
    The migration of Oceanic biota was generally from west to east, with four major factors influencing their distribution and establishment. The first was the size and fertility of the islands on which they landed, with larger islands able to provide hospitality for a wider range of species. Second, the further east the islands, generally the less the species diversity, largely because of the distance that had to be crossed and because the eastern islands tended to be smaller, more scattered, and remote. This easterly decline in species diversity is well demonstrated by birds and coral fish. It is estimated that there were over 550 species of birds in New Guinea, 127 in the Solomon Islands, 54 in Fiji, and 17 in the Society Islands. From the west across the Pacific, the Bismarck Archipelago and the Solomon Islands have more than 90 families of shore fish (with many species within the families), Fyi has 50 families, and the Society Islands have 30.Third, the latitude of the islands also influenced the biotic mix, as those islands in relatively cooler latitudes, notably New Zealand, were unsuited to supporting some of the tropical plants with which Pacific islands are generally associated.
    Finally, a fourth major factor in species distribution, and indeed in the shaping of Pacific ecosystems, was wind. It takes little experience on Pacific islands to be aware that there are prevailing winds. To the north of the equator these are called north-easterlies, while to the south they are called south-easterlies. Further south, from about 30° south, the winds are generally from the west. As a result on nearly every island of significant size there is an ecological difference between its windward and leeward (away from the wind) sides. Apart from the wind action itself on plants and soils, wind has a major effect on rain distribution. The Big Island of Hawaii is often cited as a prime example; one can leave Kona on the leeward side in brilliant sunshine and drive across to the windward side where the city of Hilo is blanketed in mist and rain.  [br] Which of the sentences below best expresses the essential information in the highlighted sentence in the passage?
选项 A、Because of its latitude, New Zealand had a relatively cooler climate than other Pacific islands.
B、New Zealand, like other Pacific islands, showed the effects of latitudes on its rich tropical plants.
C、Because the latitudinal position of an island also affected its biotic mix, islands in cooler latitudes did not support some tropical species typical of the Pacific islands.
D、Pacific islands were notable for their impressive biotic mix and association with tropical plants.
答案 C
解析 画线句子意为“第3个因素是岛屿的纬度。处于纬度位置相对更高、气温相对更低的岛屿，例如比较有名的新西兰岛屿，不适合习惯了太平洋岛屿的热带植物生存”，这句话表达的关键信息是纬度对于生物种类的影响，纬度位置相对更高、气温相对更低的地区不合适热带植物生长，故C项正确。A项是利用cooler设置的干扰项，文中没有将新西兰的纬度位置与太平洋其他岛屿的纬度位置进行对比，只是说它这种相对纬度更高、气温更低的环境不适合热带植物生长，故排除A项，原文提到新西兰岛因为气温更低，不适合种植热带植物，因此its rich tropical plants这个说法是错误的，可排除B项。D项在文中未被提及，也可排除。
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