英语听力：自然百科 鸭嘴兽

 They are extremely awkward on land, and not exactly graceful¹ in the water. But there's something endearing about these egg-laying mammals. Platypuses³ can only be found in the rivers, streams and lakes along the east coast of Australia. But they range as far north as northern Queensland, all the way down to the southern Island of Tasmania. That's quite a range for these little creatures. But there are gaps between populations. Large tracks of land between the rivers and lakes make it difficult for the platypuses to migrate from one area to another. Researchers believe it's possible that isolated⁴ pockets of animals could have evolved differently, could even be separate subspecies.

 

"The interesting things about platypuses are that as you come up to the coast in Tasmania, they get smaller, as well as that the total body size is actually less than some of the northern ones. So the maximum weight for one in this area is somewhere in the region of a kilogram, about 2.5 pounds, whereas, they're round about 3 times that weight in Tasmania."

 

Stephen Kolymyjec from James Cook University is using genetic⁶ material to determine gene⁵ flow from one population to another. He examines the size and health of the population as well. What fascinates him the most are the differences between the northern and southern platypuses.

 

"The platypuses up here in north Queensland are about a 3rd the size of the ones down south, which is a pretty big size difference. It may be because of climate, but may be because of actual differences in the species itself. "

 

"Populations here are isolated from the populations in the south. So we're interested in looking at the effect of the gaps and the ranges, and especially this far north. And one of the tools that we're using to do that is the population genetics. "

 

Stephen and his colleague David Blair are working in some of the oldest rainforest in the world.

 

"This is Dirran Creek⁷. It's a tributary⁸ of the North Johnstone River Catchment. It's one of the many upland freshwater streams in northern Queensland and it's abundant in platypuses."

 

Collecting genetic samples from a platypus² can be rather challenging. Special nets are carefully placed in the streams. They are not weighted down. So platypuses can swim up to the surface once they become entangled⁹ to prevent drowning. With the nets in place, the team awaits until nightfall when platypuses are more active. Then it's time to collect their subjects. Here’s something most people might not be aware of—a platypus should always be held by its tail, especially if it's a male. They are one of the few venomous mammals with a spur on the hind¹¹ foot, capable of injecting some rather potent¹² and painful venom¹⁰. So gripping the fatty tail is best for the platypus and the hanger¹³. Now it's time to collect the necessary data. The platypus is weighed (200) and measured, both the body (43) and the sizeable bill (53). The scientists extract samples of DNA¹⁴. 

 

"The principal samples we are collecting, for that is a small piece of skin from the toe web on the edge of the foot. That gives us enough DNA when /we take that back to the laboratory to be able to do quite a lot of genetic analysis. In addition to that, we are collecting a little bit of toe skin to go to a laboratory in Adelaide, where researchers are making cell cultures for further genetic work, that interested in chromosome¹⁵ studies, that interested in studies on the other strange sex chromosome that platypuses have. Well, most mammals have an XY sex determining system. Well, the platypus has gone a rather long way further than that. The Platypus has 5 X chromosomes¹⁶ and 5 Y chromosomes. You can ask the question why? I can't give you an answer. "

 

Once the platypus is microchipped, it's released back into the water.

 

"Just let him go, darling. "

 

"We ought to learn how much difference there is between northern populations from southern populations. Up here in the north there are a few gaps where they just do not occur, and there're no historical records of them ever occurring in those areas. And so we're looking at what kind of effect these gaps had on their genetic health. The actual species, they might be very different, they might be not different. It depends on when the last platypus is able to cross these gaps. "

 

If the smaller northern platypuses are found to be genetically¹⁷ different from the southern platypuses, they may be recognized as a newly identified subspecies, making them an even more unique version of one of the most unique animals on the planet.

1 graceful   

adj.优美的，优雅的；得体的

参考例句：

• His movements on the parallel bars were very graceful.他的双杠动作可帅了!
• The ballet dancer is so graceful.芭蕾舞演员的姿态是如此的优美。

2 platypus   

n.鸭嘴兽

参考例句：

• The platypus spends a great deal of its time looking for food. 鸭嘴兽要用大量的时间去觅食。
• One of the mascots was the platypus.吉祥物之一是鸭嘴兽。

3 platypuses   

n.鸭嘴兽( platypus的名词复数 )

参考例句：

• Like humans, platypuses carry an X and a Y chromosome. 鸭嘴兽跟人类一样，也有X和Y染色体。 来自互联网

4 isolated   

adj.与世隔绝的

参考例句：

• His bad behaviour was just an isolated incident. 他的不良行为只是个别事件。
• Patients with the disease should be isolated. 这种病的患者应予以隔离。

5 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

6 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

7 creek   

n.小溪，小河，小湾

参考例句：

• He sprang through the creek.他跳过小河。
• People sunbathe in the nude on the rocks above the creek.人们在露出小溪的岩石上裸体晒日光浴。

8 tributary   

n.支流；纳贡国；adj.附庸的；辅助的；支流的

参考例句：

• There was a tributary road near the end of the village.村的尽头有条岔道。
• As the largest tributary of Jinsha river,Yalong river is abundant in hydropower resources.雅砻江是金沙江的最大支流，水力资源十分丰富。

9 entangled   

adj.卷入的；陷入的；被缠住的；缠在一起的v.使某人（某物/自己）缠绕，纠缠于（某物中），使某人（自己）陷入（困难或复杂的环境中）( entangle的过去式和过去分词 )

参考例句：

• The bird had become entangled in the wire netting. 那只小鸟被铁丝网缠住了。
• Some military observers fear the US could get entangled in another war. 一些军事观察家担心美国会卷入另一场战争。 来自《简明英汉词典》

10 venom   

n.毒液，恶毒，痛恨

参考例句：

• The snake injects the venom immediately after biting its prey.毒蛇咬住猎物之后马上注入毒液。
• In fact,some components of the venom may benefit human health.事实上，毒液的某些成分可能有益于人类健康。

11 hind   

adj.后面的，后部的

参考例句：

• The animal is able to stand up on its hind limbs.这种动物能够用后肢站立。
• Don't hind her in her studies.不要在学业上扯她后腿。

12 potent   

adj.强有力的，有权势的；有效力的

参考例句：

• The medicine had a potent effect on your disease.这药物对你的病疗效很大。
• We must account of his potent influence.我们必须考虑他的强有力的影响。

13 hanger   

n.吊架，吊轴承；挂钩

参考例句：

• I hung my coat up on a hanger.我把外衣挂在挂钩上。
• The ship is fitted with a large helicopter hanger and flight deck.这艘船配备有一个较大的直升飞机悬挂装置和飞行甲板。

14 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

15 chromosome   

n.染色体

参考例句：

• Chromosome material with exhibits of such behaviour is called heterochromatin.表现这种现象的染色体物质叫做异染色质。
• A segment of the chromosome may become lost,resulting in a deletion.染色体的一个片段可能会丢失，结果产生染色体的缺失。

16 chromosomes   

n.染色体( chromosome的名词复数 )

参考例句：

• Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
• Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》

17 genetically   

adv.遗传上

参考例句：

• All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
• Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物