原文已被隐藏，你可用 快捷键 - 或点击 显示原文 按钮来查看原文
第1段
1 .<-NARRATOR:->Listen to part of a lecture in a biology class.
旁白：听一段生物课的讲座。
第2段
1 .<-FEMALE PROFESSOR:->Ok, I have an interesting plant species to discuss with you today.
教授：今天我们将要讨论一种有趣的植物品种。
2 .Um... it's a species of a very rare tree that grows in Australia, Eidothea hardeniana, but it's better known as the Nightcap Oak.
嗯...这是一种非常稀有的树种，它生长于澳洲，Eidothea hardeniana树，也被称为夜冠橡树。
第3段
1 .Now, it was discovered only very recently, just a few years ago.
直到近几年才为人们发现。
2 .Um... it remained hidden for so long because it's so rare, there are only about, oh, two hundred of ‘em in existence.
夜冠橡树因其罕见而隐藏了很久，目前存活个体仅有200株。
3 .They grow in a rain forest, in a mountain ridge, range in the north part of New South Wales which is er... a state in Australia.
它们生长在澳大利亚新南威尔士州北部山脉的热带雨林区。
4 .So just two hundred individual trees in all.
所以，总共个体数只有200株。
第4段
1 .Now another interesting thing about the Nightcap Oak is that it is, it represents, er... a very old type, er... kind of tree that grew a hundred million years ago.
夜冠橡树的奇特之处在于，它代表某种存活于一亿多年前的古老树种。
2 .Um... we found fossils that old that bear remarkable resemblance to the tree.
并与迄今发现的古老化石具有惊人的相似之处。
3 .So, it's a primitive tree, a... a living fossil you might say.
因此可以说，夜冠橡树是原始植株，也是活化石。
4 .It's relic from earlier times and it has survived all these years without much change.
它是历经亿年风雨存活至今，没有发生多大改变的遗迹。
5 .And it, it's probably a kind of tree from which other trees that grow in Australia today evolved.
人们甚至可以推断，当今澳洲生长的诸多树种都是由夜冠橡树进化而来的。
第5段
1 .Just—just to give you an idea of what we are talking about, here's a picture of the leaves of the tree and its flowers.
以上是关于夜冠橡树的简介，下面请同学们观看一张夜冠橡树树叶和花朵的照片。
2 .I don't know how well you can see the flowers. they're those little clusters sitting at the base of the leaves.
我不知道大家是否能看清楚，那些位于树叶底部的小花簇就是其花朵。
第6段
1 .Okay, what have we tried to find out about the tree since we've discovered it?
夜冠橡树究竟有哪些谜题值得我们去探索呢？
2 .Hum... or how, why is, is it so rare? That's one of the first questions.
首先，为何它如此稀少？
3 .Um... how is it, um... how does it reproduce? This's another question. [inviting students to propose a theory]
另外，夜冠橡树是如何繁殖的呢？
4 .Um... maybe those two questions are actually related. [seeing hand raised] Jim?
也许这两个问题是紧密联系的。Jim你来谈谈？
第7段
1 .<-MALE STUDENT:->Hum... I don't know, but I can imagine that, for instance, seed dispersal might be a factor.
学生：嗯，我不确定，但我可以想象下，例如，种子的散播或许是影响橡树繁殖的一个因素。
2 .I mean if the, er... you know, if the seeds cannot really disperse in the wild area, then, you know, the tree may not colonize new areas, it can't spread from the area where it's growing.
如果夜冠橡树的种子无法在广阔区域内散播、生长，那麽树种就无法拓展新领域，因此其繁殖也就无法突破原生地的地理范围。
第8段
1 .<-FEMALE PROFESSOR:->Right. That's, that's actually a very good answer.
教授：回答得很好。
2 .Um... of course, you might think there might not be many areas where the tree could spread into, er... because, um... well, it's very specialized in terms of the habitat.
同学们或许认为夜冠橡树能够生存的区域很稀有，因为它对生长环境的要求很独特（因此繁殖受到了限制）。
3 .But, that's not really the case here, uh... the suitable habitat, that is, the actual rain forest is much larger than the few hectares where the Nightcap Oak grows.
但事实并非如此，适合夜冠橡树生长的热带雨林区面积广阔，远远超过其现今存活的几公顷范围。（所以，种子散播并非导致夜冠橡树极为罕有的原因。）
第9段
1 .Now this tree is a flowering tree as I showed you, uh uh, it—it produces a fruit, much like a plum, on the inset inside there’s a seed with a hard shell.
请同学们思考一下，正像我给你们展示的，夜冠橡树是开花植株，能够结出像李子一样的果实，其种子外包有坚硬的外壳。
2 .It, it appears that the shell has to crack open or break down somewhat to allow the seed to soak up water.
只有在外壳被击破或打碎的情况下，种子才能吸收到水分。
3 .If the Nightcap Oak remains, if their seeds remain locked inside their shell, they will not germinate.
一旦种子被封闭在外壳内，那麽发芽生长就无法实现。
4 .Now actually, the seeds, er... they don't retain the power to germinate for very long, maybe two years, so there's actually quite a short window of opportunity for the seed to germinate.
事实上，种子不会长时间保持发芽的能力，大概只能保持两年，所以这种树的种子发芽的时间很短。
5 .So the shell somehow has to be broken down before this, um... germination ability expires.
因此夜冠橡树的种子必须在发芽能力到期前突破外壁。
6 .And, and then there's a kind of rat that likes to feed on the seeds as well.
另外，当地某种鼠类也喜欢以橡树种子为食（这也对夜冠橡树的繁殖造成了威胁）。
7 .So, given all these limitations, not many seeds that the tree produces will actually germinate.
因此，由于以上原因，仅有少数夜冠橡树种子能够成功地发芽生长。
8 .So this is a possible explanation for why the tree does not spread.
这是夜冠橡树为什么无法广泛传播的一个可能的解释。
9 .It doesn't necessarily explain how it became so rare, but it explains why it doesn't increase.
这不一定能够解释夜冠橡树如何变得如此罕见的，但是至少可以解释它为什么数量无法激增。
第10段
1 .OK, so it seems to be the case that the species, this Nightcap Oak is not very good at spreading.
综上所述，夜冠橡树似乎并不是善于扩展领地积极繁殖的物种
2 .However... it seems, though we can't be sure, that it's very good at persisting as a population.
但它的确是生命力极强的物种。
3 .Um... we, there are some indications to suggest that the population of the Nightcap Oak has not declined over the last uh, y’know, many hundreds of years.
部分证据显示，夜冠橡树的数量在过去的数百年内都未发生明显减少，其个体数量极为稳定。
4 .So it's stayed quite stable; it—it’s not a remnant of some huge population that is dwindled in last few hundred years for some reason.
因此，其个体数量极为稳定，现存的200株夜冠橡树并非数百年前丰盛繁殖之后由于某种原因衰退的剩余。
5 .It's not necessarily a species in retreat.
它也并不处于物种衰退期。
6 .Ok, so it cannot spread very well, but it's good at maintaining itself.
可以说，夜冠橡树繁殖力不强，但生命力强。
7 .It's rare, but it's not disappearing.
它虽然稀少却并不面临灭绝的危险。
第11段
1 .Ok, the next thing we might want to ask about the plant like that is what chances does it have to survive into the future.
那麽接下来我们将要讨论，夜冠橡树一类的植物种群在未来得以存活的几率有多大。
2 .Let's look at that.
让我们继续分析。