阅读理解 A New Study on Elephants
A recent study of ancient and modern elephants has come up with the unexpected conclusion that the African elephant is divided into two distinct (不同的) species.
The discovery was made by researchers at York and Harvard universities when they were examining the genetic (基因的) relationship between the ancient woolly mammoth and mastodon to modern elephants—the Asian elephant, African forest elephant and African savanna (热带草原) elephant.
Once they obtained DNA sequences from two fossils (化石) , mammoths and mastodons. The team compared them with DNA from modern elephants. They found to their amazement that modern forest and savanna elephants are as distinct from each other as Asian elephants and mammoths.
The scientists used detailed genetic analysis to prove that the African savanna elephants and the African forest elephants have been distinct species for several million years. The divergence (分离)of the two species took place around the time of the divergence of Asian elephants and woolly mammoths. This result amazed all the scientists.
There has long been debate in the scientific community that the two might be separate species but this is the most convincing scientific evidence so far that they are indeed different species.
Previously, many naturalists believed that African savanna elephants and African forest elephants were two populations of the same species despite the elephants' significant size differences. The savanna elephant has an average shoulder height of 3. 5 metres while the forest elephant has an average shoulder height of 2. 5metres. The savanna elephant weighs between six and seven tons, roughly double the weight of the forest elephant. But the fact that they look so different does not necessarily mean they are different species. However, the proof lay in the analysis of the DNA.
Alfred Roca, assistant professor in the department of Animal Sciences at the University of Minois, said, " We now have to treat the forest and savanna elephants as two different units for conservation purpose. Since 1950 all African elephants have been conserved as one species. Now that we know the forest and savanna elephants are two very distinct animals, the forest elephant should become a bigger priority (优先)for conservation purpose. "

单选题 1.A recent study shows that the African elephants have two different and distinct species.

单选题 2.Researchers at York and Harvard universities examined only the genes of the ancient woolly mammoth and mastodon.

【正确答案】 B

【答案解析】题干要求判断约克大学和哈佛大学的研究人员是否仅仅检测了古代长毛猛犸象和乳齿象的基因。第二段提到“they were examining the genetic relationship between the ancient woolly mammoth and mastodon to modern elephants”，意思是“他们检测了古代长毛猛犸象和乳齿象与现代大象之间的基因关系”，并非只检测了古代长毛猛犸象和乳齿象的基因，所以题干表述是错误的。

单选题 3.The modern elephants have three species, the Asian elephant, African forest elephant and African savanna elephant.

单选题 4.Those scientists are surprised to find that modern forest and savanna elephants don' t have the same progenitor (祖先).

【正确答案】 C

【答案解析】题干要求判断科学家是否对现代森林大象和热带草原大象没有共同祖先的发现感到惊讶。第三段仅仅提到了科学家吃惊地发现“modern forest and savanna elephants are as distinct from each other”，意思是“现代森林大象和热带草原大象是彼此不同的两个物种”，但是并没有告诉我们它们是否没有共同的祖先，所以无法判断题干是否正确。

单选题 5.Asian elephants and mammoths are distinct from each other.

单选题 6.The divergence of the African savanna elephants and the African forest elephants took place long before the time of the divergence of Asian elephants and woolly mammoths.

【正确答案】 B

【答案解析】题干要求判断非洲热带草原大象和非洲森林大象的分离是否比亚洲大象和长毛猛犸象分离的时间要早很多。文中第四段涉及了这个细节，“The divergence of the two species took place around the time of the divergence of Asian elephants and wooly mammoths”，分离发生的时间与亚洲大象和长毛猛犸象分离的时间大致一致，所以题干表述是错误的。

单选题 7.There are convincing evidences to prove that the African savanna elephants and the African forest elephants are indeed different species.

单选题 8.African savanna elephants and African forest elephants are different in size because their food is different.

【正确答案】 C

【答案解析】题干要求判断非洲热带草原大象和非洲森林大象在体型上不同是否是因为他们吃的食物不同。文中第六段提到了非洲热带草原大象和非洲森林大象在身高和体重上都差别很大，“of the same species despite the elephants’significant size differences”，但是没有告诉我们是不是因为他们吃的食物不同才造成的，所以无法判断题干是否正确。