科目: 來源:同步題 題型:閱讀理解
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 relationship between the ancient woolly mammoth and mastodon to
modern elephants-the Asian elephant, African forest elephant,and African savanna elephant.
Once they obtained DNA sequences (序列) 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 elephant and
the African forest elephant have been distinct species for several million years.The divergence
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 2.5 metres.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
Illinois, said, "We now have to treat the forest and savanna elephants as two different units for
conservation purposes.Since 1950, all African elephants have been conserved as one species.
Now that we know the forest and savanna elephants are two very distinctive animals, the forest elephant should become a bigger priority(優(yōu)先) for conservation purposes."
A. The conservation of African elephants.
B. The purpose of studying African elephants.
C. The way to divide African elephants into two units.
D. The reason for the distinction of African elephants.
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閱讀理解 | |
下面文章中有5處(第1~5題)需要添加小標題。請從以下選項(A、B、C、D、E和F)中 選出符合各段意思的小標題,并在答題紙上將相應選項的標號涂黑。選項中有一項是多余 選項。
The Marine Science Center offers nearly four hours of an educational adventure. Observing restoring Sea Turtles, lab experiments, taking our Exhibit Gallery challenge, and learning from educational beach activities are a unique and fun way to educate all ages about the fragile environment in Florida. 2. __________ We require a 1 to 10 ratio of guardians to students. All guardians within that ratio are free. The fee is $3 per student and $6 per any extra adults. The fee includes a three and a half hour program with interactive activities for the students. Payment should be made upon the arrival to the Marine Science Center. Please make checks payable to: County of Volusia Marine Science Center. 3. __________ This program can accommodate groups up to forty students. The students must be divided into groups of ten before arriving at the center. The students will be rotated(輪換) throughout all of the activities provided. 4. __________ The Marine Science Center is located at 100 Lighthouse Drive in Ponce Inlet. If arriving by bus, please stop the bus on the north (right) side of Lighthouse Drive directly across from the Marine Science Center entrance sign. Students will be accompanied up the main sidewalk to the front entrance of the Marine Science Center. If arriving by separate cars, please park in the main parking lot to the right on Lighthouse Drive. Take the boardwalk to the Marine Science Center. 5. __________ The bus must be available to take students to and from the Marine Science Center and Lighthouse Point Park during the field trip for beach activities. Upon arrival the driver will get specific instructions on your program schedule. |
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