Listen to part of lecture in a biology class.
OK, I'd like to get started please. Today, we are
going gonna to look at some very unusual planets plants and animals that evaval that've evolved on summer outer remote motion ocean islands. And of course what I've said when I say that, the first thing that probably comes to mind is...? diglapago Islands. The Galapagos lslands.
diglapago Islands. The Galapagos lslands., which are located...?
pecific Pacific ocean of off the coast of south America.
That's right. About six hundred miles off the coast. And
been being so isolated from the mainland, the species that developed there were quite different from those developed own on the mainland. And of course after trials the dar Charles Darwin observed all these of this, it got his wills wheels turning and he eventually came up with this famous theory of natural selection. And that's you've all heard of the ivgalopical science. Galapagos Islands.
But we're not
gonna going to talk about the golopical science Galapagos Islands. today, no ,no.
Way out in the middle of the
indian oceans Indian Ocean somewhere between Africa and India, there's another little quiester violence cluster of islands, not nearly as famous, but every beauty bit is fasnating fascinating in my opinion. Umm, a little group of violence islands called the scells Seychelles.
of it have heard of them? Okay, a few hiteh of you then.
Well, it's just so
happen's I'll spend happens that I've spent some time in this stchells the Seychelles in a few years ago, so there's come they're kind of close to my heart. Ummm, and just like in the golopical ilance Galapagos Islands, an amazing variety of unusual speices have avolve evolved there. Since you weren't Things you won't find anywhere else in on the world. For example, one of things I thought saw there 's was a tiny frog, that's not a whole that lot bigger than an ant. In fact, it's one of the smallest vertibers vertebrates on earth.
Okay, here's a little
mistery mystery for you. You rarely get frogs calling colonizing that remote ocean Islands like scells Seychelles. Ummm, you have some other animals that in an ocean current could carry out there from the mainland, but frogs are too delicade delicate, they couldn't with stand withstand the thought salt in and the sun and so on for that limb length of time. So, how do you think the ancestors of these little frogs got there, Kam Ken?
People brought them?
Hmm, good guess. People have been responsible for transporting a lot of species from one place to another.
Oh, maybe there used to be some kind of land bridge that used to connect the island to mainland, you know, like the one that used to connect
agent Asia and North America.
Kam Ken. Actually the theory is, millions , millions, and millions of years ago, the Earth has only two huge land maths masses, two super contenents supercontinents. And then, around two hundred million years ago, part of one of these land maths masses broke away. And began to loose move slowly out into the ocean. And is as that chunk moved away, fragments of the egg it also break broke off and were left behind. And that's how the secells Seychelles formed. And, so the theory goes. For many of planets and animals, living on this these island were strended stranded out there in the middle of ocean and isolated from the mainland. These tiny frogs are just one of the species that send descended from one of straigntant those stranded species . Diana ,Diane.
I'm just curious, how did they figure out that the
secells Seychelles were one's part of one big contenent.
OKay, that's a fair question. Well, there are two ways that
I've known I know off.
First, you have some species in the
secells Seychelles, whose closest relatives are in asia, and then you have others there, that have distant relatives in both Asia and Africa.
Now, of course,
there are various species of animals and plants can drift or fly from island to island, so that in itself doesn't prove anything.
Ummm, and then, I'm not a geologist so I don't know
often all the details, but I do know that part of how they came to that conclusion was because the secells Seychelles were made of solid granid granite bedrock. Granik Granite is a type of rock that's typicall of continents. Islands are typically made of vocanic rock. So if the islands an island is made of granic granite, that suggests that it once was is one of the part of a continent. In fact, the secells Seychelles are the only islands in the middle of ocean, made of solid granic granite.
glopical islands Galapagos Islands, the wire Hawaiian Islands, there are products of underwater vocanoes. Their composition is very different from that of steshells the Seychelles .
Uh, okay, where was I? Ohhh, ok, ok, so then, you had a relatively small number of plants and animals isolated
from for long time out in the middle of ocean. Maybe with a few comers newcomers drifting in now and then. Until And so you got some very interesting thing of offfin evolving.
And speaking of that, I just happen to have with me, a few hundred
slies slides I talk took when I was there. No, No, just kidding, but I do have few slice slides that of some things you've probably never seen before. Alright, with would someone get the lights, please?
- that've evolved
- cluster of islands 簇岛群 （还不是习惯听到cluster of)
- a little group of islands called （听成violence）
- Pacific Ocean 太平洋
- coast 海岸
- Charles Darwin 查尔斯·达尔文
- Galapagos Islands. 加拉帕戈斯群岛。
- fascinating 迷人
- Seychelles 塞舌尔
- the Seychelles 塞舌尔群岛
- vertebrates 脊椎动物
- colonizing 殖民化
- ocean current 海流；洋流
- delicate 细腻的；纤弱；易碎
- withstand 经受
- masses 块、堆、大多数
- two huge land masses 两个巨大的土地
- supercontinents 超大陆
- chunk 大块
- stranded 搁浅
- stranded out 滞留
- descended 后代
- descended from 起源于
- drift 漂流
- granite 花岗岩
- bedrock 基岩
- continents 大洲
- relatively 相对
- evolving 不断发展（这里不是 进化 的意思）
- evolved 进化的
- slides 幻灯片（slide原意是滑动，slides指滑梯，但是这里指幻灯片可能是因为幻灯片是“滑动的”）
- slideshow 幻灯片放映
- we're gonna look at
- the first thing that probably comes to mind
- that's a fair question 这是一个公平的问题
- a few hundred slides 几百张幻灯片