Pleistocene Rewilding托福听力原文翻译及问题答案

Pleistocene Rewilding托福听力原文翻译及问题答案

一、Pleistocene Rewilding托福听力原文：

NARRATOR:Listen to part of a lecture in a zoology class.

FEMALE PROFESSOR:A mass extinction as when numerous species become extinct over a very short time period.Short,geologically speaking that is,like when the dinosaurs died out 65 million years ago.And the fossil record,it indicates that in all the time that animals have inhabited Earth,there have been five great mass extinctions,dinosaurs being the most recent.In each of the others up to half of all land animals and up to 95 percent of marine species disappeared.

Well,today,we're witnessing a sixth mass extinction,but unlike the others,the current loss of biodiversity can be traced to human activity.Since the Stone Age,humans have been eliminating species and altering ecosystems with astounding speed?countless species have disappeared due to overhunting,habitat destruction and habitat fragmentation,pollution,and other unnatural,human causes.So,as a way of repairing some of that damage,a group of conservation biologists has proposed an ambitious—some might say a radical—plan involving large vertebrates,or megafauna.Megafauna include elephants,wild horses,big cats,camels—large animals. Uh,actually,the proposal focuses on a particular subset of megafauna—the kind that lived during the Pleistocene epoch.

OK.The Pleistocene epoch,most commonly known as the Ice Age,stretched from 1.8 million to 11,500 years ago. In the Americas,most megafauna began disappearing by the end of the Pleistocene.

So here is the biologists?idea: Take a select group of animals—megafauna from places like Africa and Asia,and introduce them into other ecosystems similar to their current homes,beginning in the western United States.They call their plan Pleistocene rewilding.

Now,the advocates of Pleistocene rewilding cite two main goals. One is to help prevent the extinction of some endangered megafauna by providing new refuges,new habitats for them.The other's to restore some of the evolutionary and ecological potential that's been lost in North America. Wh-what do I mean by"restore evolutionary potential"?Well,as you know,the evolution of any species is largely influenced by its interactions with other species.

So,during the Pleistocene epoch...let's take the now-extinct American cheetah,for instance.We believe it played a pivotal role in the evolution of the pronghorn antelope—the antelope's amazing speed,to be exact,because natural selection would favor those antelope that could outrun a cheetah.When the American cheetahs disappeared,their influence on the evolution of pronghorn,and presumably on other prey animals,stopped.So,it's conceivable that the pronghorn antelope would've continued to evolve,get faster maybe,if the cheetahs were still around.That't what't meant by"evolutionary potential." Importing African cheetahs to the western United States could,in theory,put the pronghorn back onto its,uh,natural evolutionary trajectory,according to these biologists.

Another example is the interaction of megafauna with local flora,in particular,plants that rely on animals to disperse their seeds.Like Pleistocene rewilding could spark the re-emergence of large seeded American plants,such as the maclura tree.Many types of maclura used to grow in North American,buy today,just one variety remains and it is found in only two states.

In the distant past,large herbivores like mastodons dispersed maclura seeds,each the size of an orange in their droppings.Well,there aren't any mastodons left,but there are elephants,which descended from mastodons.Introduce elephants into that ecosystem and they might disperse those large maclura seeds,like their ancestors did.Get the idea?Restoring some of the former balance to the ecosystem?But as I alluded to earlier,Pleistocene rewilding is extremely controversial.A big worry is that these transplanted megafauna might devastate plants and animals that are native to the western United States.In the years since the Pleistocene epoch,native species have adapted to the changing environmental there,plants,smaller animals,they have been evolving without megafauna for millennia.Also,animal species that went extinct 11,000 years ago,uh,some are quite different genetically from their modern-day counterparts,like elephants don't have thick coats like their mastodon ancestors do when they graze the prairies of the America West during the Ice Age.Granted,the climate today is not as cold as it was in the Pleistocene.

But winters on the prairie can still get pretty harsh today.And there are many more considerations.Well,you see how complex this is.If you think about it though,the core problem with this sixth mass extinction is human interference.Pleistocene rewilding is based on good intentions,but you know,it probably would just be more of the same thing.

二、Pleistocene Rewilding托福听力中文翻译：

旁白：在动物学课上听一节课的一部分。

女教授：大规模灭绝，如许多物种在很短的时间内灭绝。简而言之，从地质学角度来说，就像6500万年前恐龙灭绝的时候。化石记录表明，在动物居住地球的所有时间里，有五次大规模灭绝，恐龙是最新的。在其他每个国家，多达一半的陆地动物和95%的海洋物种消失了。

今天，我们目睹了第六次大灭绝，但与其他物种不同的是，目前生物多样性的丧失可以追溯到人类活动。自石器时代以来，人类一直在以惊人的速度消灭物种和改变生态系统？由于过度狩猎、栖息地破坏和栖息地破碎、污染以及其他非自然的人类原因，无数物种已经消失。因此，作为修复部分破坏的一种方式，一群保护生物学家提出了一项雄心勃勃的计划，有些人可能会说这是一项涉及大型脊椎动物或巨型动物群的激进计划。大型动物包括大象、野马、大型猫科动物、骆驼和大型动物；呃，事实上，该提案关注的是大型动物群的一个特定子集，即生活在更新世时期的那种动物。

好啊更新世，最广为人知的冰期，从180万年前一直延续到11500年前；在美洲，大多数大型动物群在更新世末开始消失。

生物学家来了？想法：；从非洲和亚洲等地挑选一组大型动物群，从美国西部开始，将它们引入与其当前家园类似的其他生态系统。他们把他们的计划称为更新世的重绕。

现在，更新世重熔的倡导者列举了两个主要目标；一是为一些濒危巨型动物提供新的避难所和栖息地，以防止它们灭绝。另一个是恢复北美失去的一些进化和生态潜力；我说的“恢复进化潜力”是什么意思？正如你所知，任何物种的进化在很大程度上都受到其与其他物种相互作用的影响。

所以，在更新世时期。。。以现已灭绝的美国猎豹为例。我们相信它在叉角羚的进化过程中起到了关键作用，确切地说，叉角羚的惊人速度，因为自然选择会青睐那些跑得比猎豹快的羚羊。当美洲猎豹消失后，它们对叉角羚进化的影响，可能对其他捕食动物的影响就停止了。所以，可以想象，如果猎豹还在的话，叉角羚羊会继续进化，可能会更快。这不是“进化潜力”的意思&nbsp；根据这些生物学家的说法，从理论上讲，将非洲猎豹进口到美国西部可以使叉角羚回到其自然进化轨道上。

另一个例子是大型动物群与当地植物群的相互作用，特别是依赖动物传播种子的植物。像更新世一样，重绕可能会引发大型种子美国植物的重新出现，例如马克鲁拉树。过去在北美种植的许多种类的麦卢拉，今天购买，只剩下一种，只有两个州有。

在遥远的过去，像乳齿象这样的大型食草动物散布着麦卢拉种子，每个种子的粪便中都有一个橘子大小。嗯，已经没有乳齿象了，但有大象，它们是乳齿象的后裔。将大象引入生态系统，它们可能会像它们的祖先一样传播那些大的麦卢拉种子。明白了吗？恢复生态系统以前的一些平衡？但正如我早些时候提到的，更新世的重绕是非常有争议的。令人担忧的是，这些移植的巨型动物群可能会破坏美国西部的动植物。在更新世以来的几年里，本地物种已经适应了那里不断变化的环境，植物和小型动物，它们在没有大型动物的情况下进化了数千年。此外，11000年前灭绝的动物物种，呃，有些在基因上与现代同类有很大不同，比如大象不像他们的乳齿象祖先在冰河时期放牧美国西部大草原时那样有厚厚的皮毛。诚然，今天的气候不像更新世时那么冷。

但大草原上的冬天今天仍然会变得相当严酷。还有更多的考虑。你看这有多复杂。如果你仔细想想，第六次大灭绝的核心问题是人类的干扰。更新世的重绕是基于良好的意图，但你知道，这可能只是更多的相同的事情。

三、Pleistocene Rewilding托福听力问题：

Q1:1.What is the lecture mainly about?

A.A proposal to identify all the animals that became extinct dining the Pleistocene epoch

B.A strategy for reintroducing native plants to an ecosystem

C.A process for identifying alternative habitats for large animals

D.A proposal to re-create features of ecosystems of the Pleistocene epoch

Q2:2.According to the professor,what are the two main goals of Pleistocene rewilding?[Click on 2 answers.]

A.To restore some evolutionary processes that ended during the Pleistocene epoch

B.To help prevent the extinction of certain species of mega fauna

C.To increase populations of native animal species in the western United States

D.To create a living laboratory where animal interactions can be observed

Q3:3.According to the professor,how did the American cheetah influence the pronghorn antelope during the Pleistocene epoch?

A.The cheetah prevented the antelope’s population from growing too large.

B.The cheetah was a factor in the development of the antelope’s speed.

C.The cheetah dispersed the seeds of plants that the antelope needed to survive.

D.The cheetah caused the antelope to migrate out of the western United States.

Q4:4.What point does the professor make when she discusses the maclura tree?

A.The feeding habits of large animals could help revive some diminishing plant species.

B.The climate has changed in North America since the Pleistocene epoch.

C.Mass extinctions of animals are generally preceded by mass extinctions of plants.

D.The maclura tree has changed very little since the Ice Age.

Q5:5.Why does the professor say that plants and small animals have continued to evolve since the Pleistocene?

A.To indicate why the western United States is well suited for Pleistocene rewilding

B.To suggest a way to balance an ecosystem using Pleistocene rewilding

C.To identify a potential problem with the Pleistocene rewilding concept

D.To explain how the idea for Pleistocene rewilding came about

Q6:6.What does the professor mean when she says this:

A.Pleistocene rewilding has been tried before without success.

B.Pleistocene rewilding should be tried with just a few species.

C.Pleistocene rewilding has already been thoroughly researched.

D.Pleistocene rewilding is another form of human interference.

四、Pleistocene Rewilding托福听力答案：

A1:正确答案：D

A2:正确答案：AB

A3:正确答案：B

A4:正确答案：A

A5:正确答案：C

A6:正确答案：D