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    Anole lizard species that occur together (sympatrically) on certain Caribbean islands occupy different habitats: some live only in the grass, some only on tree trunks, and some only on twigs. These species also differ morphologically: grass dwellers are slender with long tails, tree dwellers are stocky with long legs, twig dwellers are slender but stubby-legged. What is striking about these lizards is not that coexisting species differ in morphology and habitat use (such differences are common among closely related sympatric species), but that the same three types of habitat specialists occur on each of four islands: Puerto Rico, Cuba, Hispaniola, and Jamaica.Moreover, the Puerto Ricantwig species closely resembles the twig species of Cuba, Hispaniola, and Jamaica in morphology, habitat use, and behavior. Likewise, the specialists for other habitats are similar across the islands.

    The presence of similar species on different islands could be variously explained. An ancestral species might have adapted to exploit a particular ecological niche on one island and then traveled over water to colonize other islands. Or this ancestral species might have evolved at a time when the islands were connected, which some of these islands may once have been. After the islands separated, the isolated lizard populations would have become distinct species while also retaining their ancestors' niche adaptations. Both of these scenarios imply that specialization to each niche occurred only once. Alternatively, each specialist could have arisen independently on each of the is lands.

    If each type of specialist evolved just once, then similar specialists on different islands would be closely related. Conversely, if the specialists evolved independently on each island, then a specialist on one island would be more closely related to other types of anoles on the same island-regardless of their ecological niches-than it would be to a similar specialist on a different island.

    Biologists can infer how species are related evolutionarily by comparing DNA sequences for the same genes in different species. Species with similar DNA sequences for these genes are generally more closely related to each other than to species with less-similar DNA sequences. DNA evidence concerning the anoles led researchers to conclude that habitat specialists on one island are not closely related to the same habitat specialists elsewhere, indicating that specialists evolved independently on each island.
It can be inferred form the passage that which of the following is true of the Cuban tree-dwelling anole lizard and the Jamaican tree-dwelling anole lizard?
答案:A
问题:根据问题定位到第一段后部,发现说的都是相似的信息,所以排除掉不同的CD,在比较ABE的时候,觉得E说的最虚,而且觉得如果AB对,E一定对,因为E的范围包含AB所以就选了E。不知道我的思路错误在哪,请老师解答,谢谢! 查看答疑
问题:老师请问这道题是主旨题还是细节题,我选的E,根据文章最后一段的DNA描述,可是答案是A,A的解释从第一段就可以找到,因为Cuban tree dwelling 和Jamaican tree dwelling 都是tree dwelling,而第十行又说到tree dwellers are stocky with...要是根据答案这么推只需要读第一段的这几行就行了是吗 查看答疑

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