The phrase alternative stable state in ecology refers to the

Question

The phrase “alternative stable state” in ecology refers to the tendency of many ecosystems to have different, stable configurations of biotic and abiotic conditions across large time scales separated by what are called regime or phase shifts. Alternative stable state theory claims that instead of a forest transitioning slowly along a gradient toward a different stable state, that forest will reach a crucial tipping point (known as an ecological threshold) as deforestation occurs. Any change beyond this threshold will lead to a rapid change towards the second stable state of the biome in question, in this case a grassland.

Ecologists typically describe this theory with an analogy: Picture a set of three hills, between which are two valleys with a ball sitting in one of them that you want to push into the other. If you don’t push enough, the ball just rolls back down to where it started, but if you give the ball a big enough push, it will roll all the way into the valley on the other side of the hill. From there, it would require a similarly big push to get the ball back to where it started. Stable states are the valleys – where the balls want to stay if no outside forces are involved. However, if there is a big enough change in the environment to cause the ball to roll all the way up the hill to its highest point (the ecological threshold), the ball can be forced from one valley into another relatively quickly – this is a phase shift.

Until recently, most work discussing alternative stable states was theoretical – the idea of purposefully changing an environment to this extent was considered unthinkable – but several cases of confirmed alternative stable states have been reported. For example, disrupting the balance of phosphorous in a clearwater lake can lead to out-of-control phytoplankton blooms. Reducing this addition of phosphorous has so far not been an effective way of stopping the phytoplankton blooms, leading researchers to think that the ecosystem has been pushed into a new local equilibrium. This idea of hysteresis – that the state of an environment depends at least in part on its history and not just its current state – is at the core of many debates surrounding alternative stable state theory. However, whether most ecosystems that can exist under multiple stable states will readily convert between the two is still an open debate.
    1 
 1. Which one of the following scenarios is most analogous to the type of ecological change predicted by alternative stable state theory?

A. After 30 years working at a bank, a man quits suddenly after a severe illness and then spends the rest of his life working as a patient advocate.
B. The stock market slowly rises over a 10-year period and then crashes precipitously after unexpected news regarding the health of the economy.
C. Over a period of a few years, a company switches from manufacturing a particular software product to consulting on that product after sales slowed.
D. The price of a certain stock that has been constant for months spikes dramatically on rumors of a takeover bid but then quickly returns to the old price after the rumor is debunked.
E. The ecology of a lake slowly changes as silt deposits increase from frequent flooding, but the lake returns to its original state as floodwaters recede.

2 
 2. Which of the following is confirmed in the passage as causing a phase shift in the environment?

A. the addition of phosphorous to a lake
B. the blooming of phytoplankton in a lake
C. the movement of balls over a hill
D. the presence of drought conditions in a certain region
E. the repeated logging of certain forests

3 
 3. The primary purpose of the passage is to

A. highlight the uncertainties and debates relating to a particular theory.
B. suggest that the alternative stable state theory is incomplete.
C. argue that the alternative stable state theory is primarily correct.
D. provide a thorough understanding of an important ecological theory.
E. give several detailed examples of the alternative stable state theory.

4 
 4. All of the following are discussed in the passage EXCEPT:

A. stable ecological configurations across short time frames
B. the importance of history in analyzing a particular environment
C. the addition of phosphorous to a clearwater lake
D. out-of-control phytoplankton blooms in a lake
E. the existence of multiple stable states for an ecosystem

AnirudhaS · Accepted Answer

Answers are in  bold .

1. Which one of the following scenarios is most analogous to the type of ecological change predicted by alternative stable state theory?
 A. After 30 years working at a bank, a man quits suddenly after a severe illness and then spends the rest of his life working as a patient advocate. 
B. The stock market slowly rises over a 10-year period and then crashes precipitously after unexpected news regarding the health of the economy.
C. Over a period of a few years, a company switches from manufacturing a particular software product to consulting on that product after sales slowed.
D. The price of a certain stock that has been constant for months spikes dramatically on rumors of a takeover bid but then quickly returns to the old price after the rumor is debunked.
E. The ecology of a lake slowly changes as silt deposits increase from frequent flooding, but the lake returns to its original state as floodwaters recede.

Explanation of question 1: 
The question is to find out which of the following options are most analogous to the stated theory. Well for these questions, first in your mind you chalk out a rough idea of what is the theory all about. Then use POE to get to the answer. In this passage, the alternative stable state" theory is basically when a RAPID change occurs to the ecological environment, the environment shifts to another stable state. The change happens RAPIDLY and the final state reached is STABLE. These are the two characteristics of the stated theory. Ok, lets go into the options.
A - quitting a job is instant. Instant means it is a RAPID change to lifestyle. I am liking this already. Ok then he spends the rest of his life as a patient advocate. This is STABILITY. I think we have got our answer.
B - Rises slowly, nope. Has to be rapid.
C - Over a period of few years, nope again has to be instantaneous.
D - Spikes is stock is rapid. Cool. However, it returns to its original. Alternate stable theory states it has to be a different stability. Out.
E - Slowly changes, wrong answer.
A is by far the best answer.

_______________________________________________________________________________________________________________________

2. Which of the following is confirmed in the passage as causing a phase shift in the environment?
 A. the addition of phosphorous to a lake 
B. the blooming of phytoplankton in a lake
C. the movement of balls over a hill
D. the presence of drought conditions in a certain region
E. the repeated logging of certain forests

Explanation of question 2: 
Lets first skim through the options and see what absolutely doesnt make sense. Then work our way from there.
B, C are absolutely not relevant, right? B says the blooming of phytoplankton in a lake. Think about it, does blooming of this cause a phase shift. Lol no! C says movement of balls. Haha this is even funnier. It was only mentioned to give an analogy. C is out as well. By the way, I do not mind getting silly options in my questions, the more silly the options, the easier our job to get to the right answer!
So A, D and E kind of makes sense. Now we have to delve into it a bit deeper.
A mentions addition of phosphorous. yes that is also mentioned in our passage - something on the lines of if there is a dis-balance of phosphorous, then phase shift might happen. Okay, this looks pretty good.
D might be true in real life, unfortunately this is not mentioned in the passage. Out.
E says logging. What does logging mean? is it deforestation? Because if it is deforestation then in the first paragraph it does mention deforestation causes phase shifts. Oh I know what logging is, it is basically felling trees and bunching them together and transported. Excessive logging MIGHT lead to deforestation, but well we do not have the information from the passage. This is definitely not an inference question, plus we have a strong option A.
I choose A.

_______________________________________________________________________________________________________________________

3. The primary purpose of the passage is to
A. highlight the uncertainties and debates relating to a particular theory.
B. suggest that the alternative stable state theory is incomplete.
C. argue that the alternative stable state theory is primarily correct.
 D. provide a thorough understanding of an important ecological theory. 
E. give several detailed examples of the alternative stable state theory.

Explanation of question 3: 
When I go through the passage, I usually write down what the tone of the passage is. It helps especially with the main point questions. In my humble opinion, it feels like the tone of author is very neutral (=) and he is stating some facts. Now lets go through the options.
A - I would not say uncertainties. Out.
B - incomplete? no. there is an open debate about the subject, but it is in no way incomplete. And besides that is just the last line of the passage. Definitely cannot be the main idea of the passage.
C - author is not arguing, he is just stating facts.
D - ecological theory in question is "alternative stable state". Thorough understanding of the theory yes, it is thorough with analogies and examples. I am happy with this.
E - Author does give examples, but is that all? No this passage is not all about examples. Out.

SiffyB · Answer

1. Which one of the following scenarios is most analogous to the type of ecological change predicted by alternative stable state theory?

A. After 30 years working at a bank, a man quits suddenly after a severe illness and then spends the rest of his life working as a patient advocate. 
 B. The stock market slowly rises over a 10-year period and then crashes precipitously after unexpected news regarding the health of the economy.
C. Over a period of a few years, a company switches from manufacturing a particular software product to consulting on that product after sales slowed.
D. The price of a certain stock that has been constant for months spikes dramatically on rumors of a takeover bid but then quickly returns to the old price after the rumor is debunked.
E. The ecology of a lake slowly changes as silt deposits increase from frequent flooding, but the lake returns to its original state as floodwaters recede.

According to the alternative stable state theory, from one stable state to another stable state requires to first reach a tipping point. Also the change has to be fast; it can't be gradual. (B), (C) and (E) are gradual changes. they are out.
Between (A) and (D), we don't know what might happen if nothing happens after the tipping point is reached. We know that a small change can transition the system to a new stable state. But we don't know that if that change does not happen, will it stay at its tipping point or return to first stable state. 
Thus, (A) is correct because it shows transition between stable state 1 and stable state 2.

2. Which of the following is confirmed in the passage as causing a phase shift in the environment?
 
  A. the addition of phosphorous to a lake
  B. the blooming of phytoplankton in a lake
C. the movement of balls over a hill
D. the presence of drought conditions in a certain region
E. the repeated logging of certain forests

The line "Reducing this addition of phosphorous has so..." tells us that the disruption in phosphorous levels was done by adding phosphorous to the lake. This addition "caused" the phase shift in the environment.

3. The primary purpose of the passage is to
 
A. highlight the uncertainties and debates relating to a particular theory.
B. suggest that the alternative stable state theory is incomplete.
C. argue that the alternative stable state theory is primarily correct.
  D. provide a thorough understanding of an important ecological theory. 
 E. give several detailed examples of the alternative stable state theory.

The first paragraph defines the an ecological theory. Second paragraph further explains it giving analogy to make the readers understand it better. Finally, the third paragraph tells us about an experimental validation about this theory. Thus, the passage, as a whole, is dedicated to explaining the alternative stable state theory thoroughly.

pabpinor · Answer

1. Which one of the following scenarios is most analogous to the type of ecological change predicted by alternative stable state theory?

A. After 30 years working at a bank, a man quits suddenly after a severe illness and then spends the rest of his life working as a patient advocate.  Right.   Explanation. 
B. The stock market slowly rises over a 10-year period and then crashes precipitously after unexpected news regarding the health of the economy.  Wrong.   Aplanation. 
C. Over a period of a few years, a company switches from manufacturing a particular software product to consulting on that product after sales slowed.  Wrong.   Aplanation. 
D. The price of a certain stock that has been constant for months spikes dramatically on rumors of a takeover bid but then quickly returns to the old price after the rumor is debunked.  Wrong.   Aplanation. 
E. The ecology of a lake slowly changes as silt deposits increase from frequent flooding, but the lake returns to its original state as floodwaters recede.  Wrong.   Aplanation.

2. Which of the following is confirmed in the passage as causing a phase shift in the environment?

A. the addition of phosphorous to a lake  Right.   The passage says that the addition of phosphorous generated a blooming of algae that changed the ecosystem. 
B. the blooming of phytoplankton in a lake  Wrong.   The blooming of phytoplankton is not the cause but the environment shift itself, this is an opposite answer. 
C. the movement of balls over a hill  Wrong.   This is a trap, the passage exemplifies the theory with a balls analogy, we should not fall for thinking an analogy is real. 
D. the presence of drought conditions in a certain region  Wrong.   This is new information, the passage does not talk about drought, it is logic to think that could be a cause for some environments but it is not our answer. 
E. the repeated logging of certain forests  Wrong.   Deforestation is mentioned as a possible cause, but again is logic to think that logging can cause deforestation, but can not cause it if it is done in a proper way, keeping some trees and causing minimal damage on the soil. This is not a right answer neither.

3. The primary purpose of the passage is to

A. highlight the uncertainties and debates relating to a particular theory.  Wrong.   There are no debates or uncertainties mentioned in the passage, this includes new information so it is not right. 
B. suggest that the alternative stable state theory is incomplete.  Wrong.   This may be wrongly infered from the last paragraph mention of some discussion, but it is not the goal of the passage, actually does the opposite (shows evidence of its reality). 
C. argue that the alternative stable state theory is primarily correct.  Right.   The passage starts talking about the alternative state theory, but then states that has recently changed from a theoretical theory to a proven one. Also ends saying that there are some discussions about it as new developments occur, so we could agree that is primarily right but may need some polishing. 
D. provide a thorough understanding of an important ecological theory.  A thorough understanding is not what a short passage provides, neither is discussed the importance of the theory, this is not right.   Aplanation. 
E. give several detailed examples of the alternative stable state theory.  Wrong.   This is a parcial answer, it does not give several detailed examples, just one, so we cannot say this, the passage is not listing multiple examples.

Regards,
Pablo

mimishyu · Answer

para1 : the introduce to the theory and concept of “alternative stable state” and how its transitioning pattern works, in that its phase shift occur rapidly rather than continually

para2 : take the analogy to hills and valleys as an example to further illustrate the concept of “phase shift”

para3 : though the passage as a whole affirmed the reported cases on the theory, he still hold a objective tone by raising the idea of hysteresis, in that further give the open debatable issue of whether, in reality, most ecosystems can exist under this theoretical ideal multiple stable states mention in para1&2

1. Which one of the following scenarios is most analogous to the type of ecological  change (THIS IS THE POINT) predicted by alternative stable state theory?

The theory is about.... Any change beyond this threshold will lead to a rapid change towards the second stable state of the biome in question, in this case a grassland.

refer to the analogous example, the hill and valleys, in para2

A. After 30 years working at a bank, a man quits suddenly after a severe illness and then spends the rest of his life working as a patient advocate.

spends the rest of his life working as a patient advocate.
.....CHANGE TO SECOND, OR SAY ANOTHER, STABLE STATE, correct

B. The stock market slowly rises over a 10-year period and then crashes precipitously after unexpected news regarding the health of the economy.

(BUT HOW IS THE “CHANGE” TO ANOTHER STATE?, IT ONLY SAYS THE CRASH HAPPEN SUDDENLY HOWEVER NOT MENTION ANYTHING ABOUT ITS AFTERMATH)

C. Over a period of a few years, a company switches from manufacturing a particular software product to consulting on that product after sales slowed.

this choice only address the “change” –and here we know, from “over a period...” not a sudden change--in the verb of “switch”, but how the things go after the change, is it stable or unstable, we do not know

D. The price of a certain stock that has been constant for months spikes dramatically on rumors of a takeover bid but then quickly  returns to the old price (SO STILL NO CHANGE IS CONCERNED HERE) after the rumor is debunked.

E. The ecology of a lake slowly changes(must be sudden, as the analogus require)) as silt deposits increase from frequent flooding, but the lake  returns to its original state (SO NO CHANGE IS CONCERNED HERE) as floodwaters recede.

2. Which of the following is confirmed in the passage as causing a phase shift in the environment?

A. the addition of phosphorous to a lake .....correct
B. the blooming of phytoplankton in a lake
C. the movement of balls over a hill
D. the presence of drought conditions in a certain region
E. the repeated logging of certain forests

para2
Until recently, most work discussing alternative stable states was theoretical – the idea of purposefully changing an environment to this extent was considered unthinkable – but several cases of confirmed alternative stable states have been reported. For example, disrupting the balance of phosphorous in a clear water lake can lead to out-of-control phytoplankton blooms. Reducing this addition of phosphorous has so far not been an effective way of stopping the phytoplankton blooms, leading researchers to think that the ecosystem has been pushed into a new local equilibrium.

here we had to find a choice that is the cause of “phase shift/effect”, which, in the example of para2, is phytoplankton blooms, from the third sentence we could clearly see that it’s the disruption of the balance of phosphorus which cause the phytoplankton blooms, thus only the quantity change of phosphorus will effect the cause, (A) be the correct answer

3. The primary purpose of the passage is to

A. highlight the uncertainties and debates relating to a particular theory.

although the author, in the last sentence of para3, say that this alternative stable states theory is still open to debate, also nowhere in the passage mention about uncertainties, and though the last sentence of para3 say this theory is “open to debate, the author doesn’t intend to “highlight” this debate, rather he’s quite neutral and objective in his tone

B. suggest that the alternative stable state theory is incomplete.

There’s nowhere in the passage says that this theory is “incomplete”

C. argue that the alternative stable state theory is primarily correct.

The purpose to this passage doesn’t intend to argue about anything or judge whether it be correct or not, and it says in the last sentence of para3 that this theory is “open to debate”, we could see the author is quite neutral to this point

D. provide a thorough understanding of an important ecological theory.

....correct, best fit to overall gist of this passage, the last sentence says its “open to debate”, this imply that the author is still quite objective to the viewing of this theory

E. give several detailed examples of the alternative stable state theory.

the whole passage only offer one example in para2 to analogize the theory in para1

Commendlionel · Answer

I disagree with the OA for question 1. According to the stable state's definition and analogy in the passage, it mentions the ability for the ball to roll back into the original valley, indicating that an environment under the stable state should theoretically be able to transition back into its original state, provided the extrinsic push is hard enough for the ball to crossover back to its initial valley.

In option A, there is no conceivable way this can be accomplished. Under what circumstances will permit the stable state ecology to transition back to the original valley? Even if the ex-banker's severe illness is magically cured instantly, does he return back to his initial job?

On the other hand, option D explicitly states that the stock price only returns back when "the rumour is debunked". In this option, the ball travels to the second valley upon news of the takeover bid, followed by a large enough push (which is the debunking of rumours) to bring the ball back to the first valley. If not for the rumours being debunked, it is only fair to assume that the news of the takeover bid is in fact true, and thus justifying the increased stock price. In such a case, the ball will stay in the second valley; the stock price will remain increased.

Would love to hear anyone's explanation if they disagree with regards to my POV of the ability to return to the original state.

AnirudhaS · Answer

Pranjal3107  asked a similar question as well so I have drawn a helpful diagram. The problem with D is it is not an "alternate stable state" but the same stable state - the original stock price. Whereas in A the guy does a different job, hence an "alternate" stable state.

To answer your second question, in fact you have answered it for me already so I will just quote you -  "Even if the ex-banker's severe illness is magically cured instantly, does he return back to his initial job?"  - Yes he might return to his original position if he chooses to - surely no one would mind given that he has 30 years worth of credibility in his previous position.

Hope the explanation is satisfactory.

VerbalBot · Answer

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The phrase alternative stable state in ecology refers to the

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