Professor:
So! Continuing our discussions of environmental adaptation, today I want to focus on a species of fish, called the Notothenioids. A bit of a mouthful, I know.
Scientists have documented over 90 species of Notothenioids, in both deep and shallow waters. If you’re getting creeped out by the powerpoint slide, don’t worry, they really only live around Antarctica. Most of them are pretty small. However, a few species can weigh up to 150 kilograms.
These fish can be identified by their huge eyes, insulated with a layer of thick transparent protective tissue. This kind of tissue protects the fluid in their eyeballs from freezing in the incredibly cold saltwater. Remember, saltwater has a lower freezing point than freshwater, so moisture in an animal’s tissue would be particularly vulnerable to freezing and causing cell death.
So while the cold ocean of Antarctica could freeze and kill most fish, the Notothenioids end up thriving in these icy waters. They actually make up nearly 95% of all fish species in the southern ocean around that cold continent. That kind of thing is a stark contrast to tropical oceans, where the biodiversity is extremely high. When you think of a tropical reef, for instance, you probably imagine a plethora of different types of fish and sea creatures living together and preying on each other. The average coral reef supports over four thousand types of fish, sponges, crustaceans, and others. To have one species of fish in an entire section of ocean? Pretty impressive. Yes! Amy?
Amy:
How, er, when did the Notothenioids end up taking over the southern ocean?
Professor:
I'm glad you asked. That was actually my next point of interest. So, about thirty million years ago, the water in that area was a lot warmer than it is today. Way back then, South America and Antarctica were actually connected. The air from around the equator could travel south to heat up the chilly Antarctic waters. The warm tropical waters could also flow southwards, bringing the rich biodiversity along with it.
Because Antarctica’s waters were relatively warm back then, it could support a lot of different types of animals. We confirmed this by looking at the fossil record, even finding out that 90 or so of the Notothenioids even existed back then.
Historians think that somewhere between five and fourteen million years ago, two huge changes occurred. First of all, a chance mutation allowed the Notothenioids to develop a special protein that now flows through their body. Umm this special protein is actually a type of antifreeze. It works by bonding to an ice crystal that formed inside their flesh, preventing it from growing any larger.
So! At the time, the waters they swam in were still decently warm, and the protein didn’t do much for their overall survival rates. Still, somewhere around this time period, there are records of a colossal shift that moved around the Earth’s tectonic plates. This movement is now known as Continental drift. It pushed Antarctica away from ..umm.. South America and down toward the chilly southern end of the earth. This caused a current to swirl up and form, encircling the cooling continent with a rush of cold water. This cold water prevented warmer tides from intermingling. It eventually dropped to the sub-zero icy landscape we know today
As you may have guessed, the tropical fish didn’t do so well in the sudden drop of environmental temperatures, and many species went extinct. Luckily for the Notothenioids, they had ahandy dandy gene mutation that let them produce this antifreeze protein. Now the only type of fish that could survive the cold waters, it had virtually no competition for food or resources and went wild.
So! As its population increased dramatically, they migrated into different parts of oceans. Over time they developed into different physical adaptations to survive in their particular environment. Eventually they split off into subspecies, mutated a bit more, had a bit of geologic morphology going on, very cool stuff. We call this kind of physical differentiation a process of Adaptive Radiation. It really only happens when a species rapidly changes, and ends up with quite a few new species to fill empty niches that either didn’t exist before, or weren’t available.
So now we have about 90 species of Notothenioids, kicking it in the southern ocean.
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Listening Tips
In most cases, the first question after each lecture is a main idea question also known as a gist question. At the beginning of a listening lecture, the professor usually mentions what the main topic of the lecture will be about, but sometimes the topic might be branched into something more specific. Please note the topic can change, so always be prepared to note down any new topics.
Listen to the speaker's tone of voice
Sometimes you'll be asked questions regarding the speaker's attitude or opinion. To answer these questions correctly, tone of voice matters. For example, does the speaker sound excited, confused, sad...etc?
Listen to how ideas are connected throughout the lecture
When listening to a lecture, make note of the way the ideas in the lecture are connected. In other words, how the professor organized the lecture. When you encounter a question asking you how the lecture is organized, you can refer back to your notes. Some of the main relationships between ideas include cause/effect, compare/contrast, and steps in a process.
Listen for key points not specific details
TOEFL listening questions will not test you on small details. For example, you won't see questions that are about a specific year, name, or location. Instead, questions will test your understanding of key points mentioned in the lecture.
Listen for signal words that indicate different parts of the lecture
To help you capture key points in the lecture, you need to learn to listen for signal words or transition words. These words are like the road signs that tell you what is coming next. Signal words can tell you the beginning or the end of a topic. They can also help you move through the middle of the lecture by introducing topics.
| Signal words |
| "Okay", "Well", "Now", "But", and "So" 1. "Okay" and "Now" are usually used to transition into a different topic or a different key point. 2. "Well" is usually used before answering a question. 3. "But" and "So" are usually followed by a key point. |
| Examples |
|
All right folks, let’s continue our discussion of alternative energy sources and move on to what’s probably the most well-known alternative energy source--- solar energy. The sun basically provides earth with virtually unlimited source of energy every day, but the problem has always been how do we tap this source of energy. Can anyone think of why it’s so difficult to make use of solar energy? OK. Another ancient Greek philosopher we need to discuss is Aristotle—Aristotle’s ethical theory. What Aristotle’s ethical theory is all about is this: he’s trying to show you how to be happy—what true happiness is. Now, why is he interested in human happiness? It’s not just because it’s something that all people want to aim for. It’s more than that. But to get there we need to first make a very important distinction. Let me introduce a couple of technical terms: extrinsic value and intrinsic value. All right, so far we have been looking at some of the core areas of linguistics, like syntax, phonology, semantics. Now I’d like to talk about the branch of historical linguistics, and the comparison of several different languages, or the comparison of different stages of a single language. Now, if you are comparing different languages, and you notice that they have a lot in common. Maybe they have similar sounds and words that correspond to one another that have the same meaning and that sound similar. |
| Signal words |
|
Let's move on to ... This brings me to my next point, which is…. So far we have have been looking at…. Now I'd like to…. So now that we've covered… What … is all about is this… |
| Examples |
|
All right folks, let's continue our discussion of alternative energy sources and move on to what's probably the most well-known alternative energy source--- solar energy. The sun basically provides earth with virtually unlimited source of energy every day, but the problem has always been how do we tap this source of energy. Can anyone think of why it's so difficult to make use of solar energy? OK. Another ancient Greek philosopher we need to discuss is Aristotle—Aristotle's ethical theory. What Aristotle's ethical theory is all about is this: he's trying to show you how to be happy—what true happiness is. Now, why is he interested in human happiness? It's not just because it's something that all people want to aim for. It's more than that. But to get there we need to first make a very important distinction. Let me introduce a couple of technical terms: extrinsic value and intrinsic value. All right, so far we have been looking at some of the core areas of linguistics, like syntax, phonology, semantics. Now I'd like to talk about the branch of historical linguistics, and the comparison of several different languages, or the comparison of different stages of a single language. Now, if you are comparing different languages, and you notice that they have a lot in common. Maybe they have similar sounds and words that correspond to one another that have the same meaning and that sound similar. |
| Signal words |
|
(opinion) I think, It appears that, It is thought that (theory) In theory, the hypothesis is that |
| Examples |
|
You have an advertising budget to spend, but how do you to spend it wisely. Again, research is the key. Good research gives you facts, facts that can help you decide, well, as we already mentioned, decide the right market to target, and the best media to use. But also: When to advertise? or…or how to get the best rates? Like, maybe you're advertising Sport equipment, and you have been spending most of your budget during the holiday season when people buy gifts for each other. Now, in theory, that would seem a great time to advertise, but maybe a research shows you're wrong, that the customers who buy sports equipment tend not to give it as a holiday gift, but want to use it themselves. In that case, advertising during a different season of the year might give you better results. We recently noticed an increase in cloud cover over an area of the ocean waters around Antarctica. An increased area of low thick clouds, the type that reflects a large portion of solar energy back to space and cools the Earth. Well, the reason for this increased cloud cover, it turns out, is the exceptionally large amount of microscopic marine plants. Well, the current hypothesis is that these microorganisms produce a chemical that interacts with the oxygen in the air, creating conditions that lead to the formation of the low thick clouds we observed. Well, that's true. It could have huge implications. So, maybe we are talking about controlling the weather. Perhaps, if the microorganisms near Antarctica really are responsible, perhaps we can accelerate the process somehow. |
Pay attention to the following transition words which can help you capture the main ideas and examples:
| Type of connection | Transition words |
| These words show the order of ideas. |
First/Second/Third Firstly (or "First of all")/Secondly/Thirdly (or "Lastly") For one thing/For another thing/Finally (or "Lastly") In the first place/in the second place/Finally (or "Lastly") |
| These words show the addition of information | In addition, furthermore, additionally, also, next, moreover, what's more, on top of that |
| These words shows conclusions. | To sum up, in summary, in conclusion, to conclude, all in all, all things considered ,overall, taking everything into consideration, in a nutshell |
| These words demonstrate contrast | Conversely, on the contrary, by contrast, by way of contrast, on one hand/on the other hand |
| These words compare or demonstrate similarity | Similarly, likewise, by the same token, along similar lines |
| These words show result. | As a result, as a consequence, consequently, therefore |
| These words state a generalization. | Generally, on the whole, in most cases, in general |
| These words clarify a point. | That is, in other words, to put it simply, That is to say, just to reiterate |
| These words give examples. | For example, for instance, take something, for example, to give a clear example |
| These words state an alternative. | Alternatively, as another possibility |
Tips to Improve TOEFL listening score
Unlike the reading section, in the listening section you CANNOT skip answers and come back. If you skip a question, you will not be able to go back and answer it.
Make an educated guess on questions you are unsure of
When you don't know the answer, try to figure out which choice is most consistent with the main idea of the conversation or lecture. Another way is to eliminate obvious wrong answers.
Don't take more than two minutes to answer a question.
If you spend more than two minutes on a question, you might run out of time. It is not worth it. Leave time for other questions that you have more confidence on. It's better to have an educated guess and move on than it is to miss out on potential easy questions because you ran out of time.
Note-taking tips
| Symbol | Meaning | Examples |
| = | refer to, occur, ..etc | A concept that people make choices to describe a situation in a positive or negative way is referred to as word framing Word framing = ppl describe a situation in ✓ or X way. |
| ∵ | Because, as a result of, due to, because, owing to | Due to the increasing popularity of e-books, there has been a fall in paper book sales.
∵↑e-books, paper books $↓ |
| ∴ | Therefore | Element 43 has radioactive decay, therefore element 43 doesn't last very long, which means if that ever had been present on earth,
it would have decayed ages ago. Elem43 has radioa. decay ∴ it ≠ last long |
| => | result in, lead to, contribute to, give rise to, cause | Carbon dioxide significantly contributes to global warming. CO => global warming |
| ≠ | isn't, doesn't, don't, can't etc. |
Element 43 has radioactive decay, therefore element 43 doesn't last very long, which means if that ever had been present on earth,
it would decayed ages ago. Elem43 has radioa. decay ∴ it ≠ last long |
| + | many, lots of, a great deal of, etc. | Because potatoes have the ability to provide abundant and extremely nutritious food crop, no other
crop grew in Northern Europe. As a result, the nutrition of the general population improved tremendously and population
soared in the early 1800s. ∵ potatoes /nutri crop/+vitamins => popul↑ in Europe 1800s |
| ++ | Comparatives |
Older and more experienced birds who nest in the high density shrub areas have significantly more offspring than those
in low density areas, which suggests the choice of where to nest does have an impact on the number of chicks they have.
older birds /nest in high shrub ++offsprings birds/nest in low shrub |
| +++ | Superlatives | What was even more surprising were all the large
organisms that lived down there. The most distinctive of these was
something called the tube worm. Here, let me show you a picture.
The tube of the tube worm is really, really long. They can be up to one
and half meters long, and these tubes are attached to the ocean floor,
pretty weird looking, huh?
! +++special = tube warm /long/tubes attached to ocean floor |
| - | Little, few, lack ,in short of/ be in shortage of, etc. | As I said the monsoon migrated itself, so there was less rain in the Sahara.
The land started to get drier, which in turn caused huge decreases in the amount of vegetation,
because vegetation doesn't grow as well in dry soil, right? And then, less vegetation means the soil can't hold water and
the soil loses its ability to retain water when it does rain. So then you have less moisture to help clouds form, nothing
to evaporate for cloud formation. - rain in Sahara land ++dry => vegetation↓ --vegetation => soil ≠ hold water => -water to form cloud |
| ! | Important, interesting | But what's particularly interesting about these volcanoes is that most of the volcanoes here on Earth are not shield volcanoes.
Instead, they are other volcano types, like strata volcanoes, for example, which are a result of tectonic plate movement. ! volcanoes on earth ≠ shield volcanoes = strata volcanoes tectonic plate => volcanoes on earth |
Other symbols:
| Symbol | Meaning |
| & | And, also, in addition, etc. |
| ~ | about/around, approximately, etc. |
| ... | And so on |
| $ | Sales, money, cost |
| e.g. | For example |
| i.e. | That is |
| x | Wrong, incorrect, bad, detrimental, negative, etc. |
| ✓ | Right, good, positive, etc. |