The evolution of sex ratios has produced, in most plants and animals

Question

The evolution of sex ratios has produced, in most plants and animals with separate sexes, approximately equal numbers of males and females. Why should this be so? Two main kinds of answers have been offered. One is couched in terms of advantage to population. It is argued that the sex ratio will evolve so as to maximize the number of meetings between individuals of the opposite sex. This is essentially a “group selection” argument. The other, and in my view correct, type of answer was first put forward by Fisher in 1930. This “genetic” argument starts from the assumption that genes can influence the relative numbers of male and female offspring produced by an individual carrying the genes. That sex ratio will be favored which maximizes the number of descendants an individual will have and hence the number of gene copies transmitted. Suppose that the population consisted mostly of females: then an individual who produced sons only would have more grandchildren. In contrast, if the population consisted mostly of males, it would pay to have daughters. If, however, the population consisted of equal numbers of males and females, sons and daughters would be equally valuable. Thus a one-to-one sex ratio is the only stable ratio; it is an “evolutionary stable strategy.” Although Fisher wrote before the mathematical theory of games had been developed, his theory incorporates the essential feature of a game—that the best strategy to adopt depends on what others are doing.

Since Fisher’s time, it has been realized that genes can sometimes influence the chromosome or gamete in which they find themselves so that the gamete will be more likely to participate in fertilization. If such a gene occurs on a sex-determining (X or Y) chromosome, then highly aberrant sex ratios can occur. But more immediately relevant to game theory are the sex ratios in certain parasitic wasp species that have a large excess of females. In these species, fertilized eggs develop into females and unfertilized eggs into males. A female stores sperm and can determine the sex of each egg she lays by fertilizing it or leaving it unfertilized. By Fisher’s argument, it should still pay a female to produce equal numbers of sons and daughters. Hamilton, noting that the eggs develop within their host—the larva of another insect—and that the newly emerged adult wasps mate immediately and disperse, offered a remarkably cogent analysis. Since only one female usually lays eggs in a given larva, it would pay her to produce one male only, because this one male could fertilize all his sisters on emergence. Like Fisher, Hamilton looked for an evolutionary stable strategy, but he went a step further in  recognizing  that he was looking for a strategy.   1 
 1. The author suggests that the work of Fisher and Hamilton was similar in that both scientists

(A) conducted their research at approximately the same time
(B) sought to manipulate the sex ratios of some of the animals they studied
(C) sought an explanation of why certain sex ratios exist and remain stable
(D) studied game theory, thereby providing important groundwork for the later development of strategy theory
(E) studied reproduction in the same animal species

2 
 It can be inferred from the passage that the author considers Fisher’s work to be

(A) fallacious and unprofessional
(B) definitive and thorough
(C) inaccurate but popular, compared with Hamilton’s work
(D) admirable, but not as up-to-date as Hamilton’s work
(E) accurate, but trivial compared with Hamilton’s work

3 
 3. The passage contains information that would answer which of the following questions about wasps?

I. How many eggs does the female wasp usually lay in a single host larva?
II. Can some species of wasp determine sex ratios among their offspring?
III. What is the approximate sex ratio among the offspring of parasitic wasps?

(A) I only
(B) II only
(C) III only
(D) I and II only
(E) II and III only

4 
 4. It can be inferred that the author discusses the genetic theory in greater detail than the group selection theory primarily because he believes that the genetic theory is more

(A) complicated
(B) accurate
(C) popular
(D) comprehensive
(E) accessible

5 
 5. According to the passage, successful game strategy depends on

(A) the ability to adjust one’s behavior in light of the behavior of others
(B) one’s awareness that there is safety in numbers
(C) the degree of stability one can create in one’s immediate environment
(D) the accuracy with which one can predict future events
(E) the success one achieves in conserving and storing one’s resources

6 
 6. It can be inferred from the passage that the mathematical theory of games has been

(A) developed by scientists with an interest in genetics
(B) adopted by Hamilton in his research
(C) helpful in explaining how genes can sometimes influence gametes
(D) based on animals studies conducted prior to 1930
(E) useful in explaining some biological phenomena

7 
 7. Which of the following is NOT true of the species of parasitic wasps discussed in the passage?

(A) Adult female wasps are capable of storing sperm.
(B) Female wasps lay their eggs in the larvae of other insects.
(C) The adult female wasp can be fertilized by a male that was hatched in the same larva as herself.
(D) So few male wasps are produced that extinction is almost certain.
(E) Male wasps do not emerge from their hosts until they reach sexual maturity.

KM666 · Accepted Answer

workout

1.The author suggests that the work of Fisher and Hamilton was similar in that both scientists

(A) conducted their research at approximately the same time 
Crossed out.
We only have one specific year - 1930, and nothing else.
Moreover, this statement, 'Since Fisher’s time, it has been realized that genes can sometimes...', implies that some time has passed between the discussion offered in the second paragraph and the explanation offered by Fisher (in the first paragraph).

(B) sought to manipulate the sex ratios of some of the animals they studied 
Crossed out.
New information. 
Nothing of the sort is mentioned in the passage.

(C) sought an explanation of why certain sex ratios exist and remain stable 
YES
And that's what the passage is all about - a discussion of the evolution of sex ratios, and the explanations of two people in particular.

(D) studied game theory, thereby providing important groundwork for the later development of strategy theory 
Crossed out.
New information.
(and game theory itself isn't even the primary focus of the passage)

(E) studied reproduction in the same animal species 
Crossed out.
New information. 
Nothing of the sort is mentioned in the passage.

*****

It can be inferred from the passage that the mathematical theory of games has been

(A) developed by scientists with an interest in genetics 
Crossed out.
New information. 
Nothing of the sort is mentioned in the passage.

(B) adopted by Hamilton in his research 
Crossed out.
Bait choice.
It's mentioned that "he went a step further in recognizing that he was looking for a strategy", but looking for a strategy DOES NOT NECESSARILY mean that "the mathematical theory of games has been adopted by Hamilton in his research".
Strategies are a part of Game Theory, not GT itself.
The choice is trying to create that information in your head (and thus tricking you into choosing it) when the actual, precise information is nowhere in the passage.

(C) helpful in explaining how genes can sometimes influence gametes 
Crossed out.
I see that this is the second most opted choice.
But it's wrong.
In the third sentence of the second paragraph, "But more immediately relevant to game theory..." implies that the idea that "genes can sometimes influence the chromosome or gamete" is also relevant to game theory. 
"More immediately relevant" means that the theory can be more readily applied to the latter subject (large excess of females in parasitic wasps), and it means nothing more.
'Readiness of application' DOES NOT equal to the 'application' itself.
If activity X CAN be applied to stuff Z, and that's all what has been said, then then doesn't necessarily mean that activity X HAS been applied to stuff Z.
By choosing C, you're saying that 'the mathematical theory of games has been helpful in explaining how genes can sometimes influence gametes'. That implies APPLICATION. But only the 'readiness of application' is stated in the passage, not the (information about) any application itself!

(D) based on animals studies conducted prior to 1930 
Crossed out.
New information. 
Nothing of the sort is mentioned in the passage.
(Even contradicts the given information - Fisher's explanation was given in 1930, "before the mathematical theory of games had been developed")

(E) useful in explaining some biological phenomena 
YES
You could either get here by reduction, or by pushing more analysis into the choices.
From all that's been said in the passage, this is the ONLY choice that fits.
We can safely say that "the mathematical theory of games has been useful in explaining some biological phenomena".

______
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Skywalker18 · Answer

1.The author suggests that the work of Fisher and Hamilton was similar in that both scientists

(A) conducted their research at approximately the same time - Incorrect - Fisher put forward 2nd view in 1930.
Although no time explicitly has been mentioned for Hamilton, we can infer that sometime has been passed since Fisher's research because of"Since Fisher’s time, it has been realized that genes can "
(B) sought to manipulate the sex ratios of some of the animals they studied - Incorrect - Nowhere has manipulation been discussed.
(C) sought an explanation of why certain sex ratios exist and remain stable - Correct - a one-to-one sex ratio is the only stable ratio; it is an “evolutionary stable strategy
(D) studied game theory, thereby providing important groundwork for the later development of strategy theory - Incorrect 
(E) studied reproduction in the same animal species - Incorrect

2. It can be inferred from the passage that the mathematical theory of games has been

(A) developed by scientists with an interest in genetics - Out of scope - The passage DOES NOT mention who develops the game theory
(B) adopted by Hamilton in his research - ISWAT- Like Fisher, Hamilton looked for an evolutionary stable strategy, but he went a step further in recognizing that he was looking for a strategy.
Based on this we CANNOT infer that Hamilton adopted game theory in research.
(C) helpful in explaining how genes can sometimes influence gametes - Irrelevant - Since Fisher’s time, it has been realized that genes can sometimes influence the chromosome or gamete in which they find themselves so that the gamete will be more likely to participate in fertilization. If such a gene occurs on a sex-determining (X or Y) chromosome, then highly aberrant sex ratios can occur. 
(D) based on animals studies conducted prior to 1930 - Incorrect - The other, and in my view correct, type of answer was first put forward by Fisher in 1930. This “genetic” argument starts from the assumption that genes can influence the relative numbers of male and female offspring produced by an individual carrying the genes.
Fisher developed the 2nd view but nowhere in the passage is it mentioned that game theory is based on Fisher's research
(E) useful in explaining some biological phenomena - Correct

Although Fisher wrote before the mathematical theory of games had been developed, his theory incorporates the essential feature of a game—that the best strategy to adopt depends on what others are doing.

But more immediately relevant to game theory are the sex ratios in certain parasitic wasp species that have a large excess of females.

Answer E

ShankSouljaBoi · Answer

For question 2, C is irrelevant because it is not explaining how genes influence gametes. Rather , per the exceprt,

But more immediately relevant to game theory are the sex ratios in certain parasitic wasp species that have a large excess of females.

we can be sure of the game theory's applicability to the wasps aberrantly high sex ratio. In short, just an example of applicabilty of game theory has been stated and this is irrelevant to the explanation.

Please point out flaw in my reasoning, if any.

Regards

dhilavikash · Answer

Please explain question number 5

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sidharth2412 · Answer

Please someone provide explanation of q3,4
In q3 why can't the III part be correct, as we can determine the sex ratio on basis of fertilized and unfertilized eggs.

Sajjad1994 · Answer

Explanation

5. According to the passage, successful game strategy depends on

Difficulty Level:   600

Explanation

(A) the ability to adjust one’s behavior in light of the behavior of others

It is clearly mentioned in the lines:

Although Fisher wrote before the mathematical theory of games had been developed, his theory incorporates the essential feature of a game—  that the best strategy to adopt depends on what others are doing.

(B) one’s awareness that there is  safety in numbers

Nothing about safety is discussed

(C) the  degree of stability  one can create in one’s immediate environment

We don't know anything about the degree of stability

(D) the accuracy with which one can predict future events

Out of context

(E) the success one achieves in conserving and storing one’s resources

Out of context

Answer: A

Sajjad1994 · Answer

Explanation

3. The passage contains information that would answer which of the following questions about wasps?

Difficulty Level:   650

Explanation

Reference lines from the passage: Only the second paragraph discusses wasp

But more immediately relevant to game theory is the sex ratios in certain parasitic wasp species that have a large excess of females. In these species, fertilized eggs develop into females and unfertilized eggs into males. A female stores sperm and can determine the sex of each egg she lays by fertilizing it or leaving it unfertilized. By Fisher’s argument, it should still pay a female to produce equal numbers of sons and daughters. Hamilton, noting that the eggs develop within their host—the larva of another insect—and that the newly emerged adult wasps mate immediately and disperse, offered a remarkably cogent analysis.

All this text supports only II

Answer: B

4. It can be inferred that the author discusses the genetic theory in greater detail than the group selection theory primarily because he believes that the genetic theory is more

Difficulty Level:   600

Explanation

This is comparatively a straightforward question, the lines that lead to the answer are:

The other, and   in my view correct  , type of answer was first put forward by Fisher in 1930.

That is why only accurate is correct.

Answer: B

junii · Answer

Please explain Q2 and Q7?

Bambi2021 · Answer

junii

The following sentences are important to answer Q2.

"The other, and in my view correct, type of answer was first put forward by Fisher in 1930."

The author thinks Fisher's theory is correct.

"Although Fisher wrote before the mathematical theory of games had been developed, his theory incorporates the essential feature of a game—that the best strategy to adopt depends on what others are doing."

The author may be inferred to admire Fisher because Fisher was "before his time".

"Since Fisher’s time, it has been realized that genes can sometimes influence the chromosome or gamete in which they find themselves so that the gamete will be more likely to participate in fertilization."

The author implies that more recent research are based on a deeper understanding of some phenomenon, i.e. is more "up-to-date".

D is the best answer.

Posted from my mobile device

AbhishekP220108 · Answer

sajjad  can you please provide the explanation for question no. 6? Thanks in advance

Sajjad1994 · Answer

Hello AbhishekP220108

6. It can be inferred from the passage that the mathematical theory of games has been

Read the relevant text from the passage:

"Although Fisher wrote before the mathematical theory of games had been developed, his theory incorporates the essential feature of a game—that the best strategy to adopt depends on what others are doing."

This text tells us Fisher’s idea (1930) had a game-theoretic logic even before formal game theory existed.

"  But   more immediately relevant to game theory are the sex ratios in certain parasitic wasp species ... Hamilton ... offered a remarkably cogent analysis. ... Like Fisher, Hamilton looked for an evolutionary stable strategy, but he went a step further in recognizing that he was looking for a strategy."

This shows Hamilton used an evolutionarily stable strategy (ESS) concept, which is part of game theory, in his analysis of sex ratios in wasps.

Now read the answer choices one by one.

(A)  The passage doesn’t say game theory was developed by geneticists rather game theory was developed in mathematics/economics; later applied in biology. Out.

(B)  Hamilton’s reasoning (ESS) aligns with game theory. The passage says Fisher’s theory had game-like thinking before game theory was formalized, but Hamilton (writing later) is explicitly discussed in relation to the theory. Lets find somehting more relevant than this.

(C)  That’s about meiotic drive/gene influencing gametes, the passage mentions this in a different paragraph but doesn’t tie it to game theory.

(D)  No, Fisher’s pre-1930 work was before game theory was developed, not based on it.

(E)  Yes! the passage shows game theory concepts (ESS) useful for explaining sex ratios in parasitic wasps (Hamilton’s analysis). This is broader and directly supported: the passage describes how the game theory idea applies to biology.  (E)  is best because the text mentions game theory in direct relation to explaining biological sex ratios.

Answer: E

The evolution of sex ratios has produced, in most plants and animals

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The evolution of sex ratios has produced, in most plants and animals

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