Over the years, biologists have suggested two main pathways by which

Question

Over the years, biologists have suggested two main pathways by which sexual selection may have shaped the evolution of male birdsong. In the first, male competition and intrasexual selection produce relatively short, simple songs used mainly in territorial behavior. In the second, female choice and intersexual selection produce longer, more complicated songs used mainly in mate attraction; like such visual ornamentation as the  peacock’s tail,  elaborate vocal characteristics increase the male’s chances of being chosen as a mate, and he thus enjoys more reproductive success than his less ostentatious rivals. The two pathways are not mutually exclusive, and we can expect to find examples that reflect their  interaction.  Teasing them apart has been an important challenge to evolutionary biologists.

Early research confirmed the role of intrasexual selection. In a variety of experiments in the field, males responded aggressively to recorded songs by exhibiting territorial behavior near the speakers. The breakthrough for research into intersexual selection came in the development of a new technique for investigating female response in the laboratory. When female cowbirds raised in isolation in sound-proof chambers were exposed to recordings of male song, they responded by exhibiting mating behavior. By quantifying the responses, researchers were able to determine what particular features of the song were most important. In further experiments on song sparrows, researchers found that when exposed to a single song type repeated several times or to a repertoire of different song types, females responded more to the latter. The beauty of the experimental design is that it effectively rules out confounding variables; acoustic isolation assures that the female can respond only to the song structure itself.

If intersexual selection operates as theorized, males with more complicated songs should not only attract females more readily but should also enjoy greater reproductive success. At first, however, researchers doing fieldwork with song sparrows found no correlation between larger repertoires and early mating, which has been shown to be one indicator of reproductive success; further, common measures of male quality used to predict reproductive success, such as weight, size, age, and territory, also failed to correlate with song complexity.

The confirmation researchers had been seeking was finally achieved in studies involving two varieties of warblers. Unlike the song sparrow, which repeats one of its several song types in bouts before switching to another, the warbler continuously composes much longer and more variable songs without repetition. For the first time, researchers found a significant correlation between repertoire size and early mating, and they discovered further that repertoire size had a more significant effect than any other measure of male quality on the number of young produced. The evidence suggests that warblers use their extremely elaborate songs primarily to attract females, clearly confirming the effect of intersexual selection on the evolution of birdsong.    1 
 1. The passage is primarily concerned with

(A) showing that intrasexual selection has a greater effect on birdsong than does intersexual selection
(B) contrasting the role of song complexity in several species of birds
(C) describing research confirming the suspected relationship between intersexual selection and the complexity of birdsong
(D) demonstrating the superiority of laboratory work over field studies in evolutionary biology
(E) illustrating the effectiveness of a particular approach to experimental design in evolutionary biology

2 
 2. The author mentions the peacock’s tail ( Highlighted ) most probably in order to

(A) cite an exception to the theory of the relationship between intrasexual selection and male competition
(B) illustrate the importance of both of the pathways that shaped the evolution of birdsong
(C) draw a distinction between competing theories of intersexual selection
(D) give an example of a feature that may have evolved through intersexual selection by female choice
(E) refute a commonly held assumption about the role of song in mate attraction

3 
 3. According to the passage, which of the following is specifically related to intrasexual selection?

(A) Female choice
(B) Territorial behavior
(C) Complex song types
(D) Large song repertoires
(E) Visual ornamentation

4 
 4. Which of the following, if true, would most clearly demonstrate the interaction ( Highlighted ) mentioned in lines 11-13?

(A) Female larks respond similarly both to short, simple songs and to longer, more complicated songs.
(B) Male canaries use visual ornamentation as well as elaborate song repertoires for mate attraction.
(C) Both male and female blackbirds develop elaborate visual and vocal characteristics.
(D) Male jays use songs to compete among themselves and to attract females.
(E) Male robins with elaborate visual ornamentation have as much reproductive success as rivals with elaborate vocal characteristics.

5 
 5. The passage indicates that researchers raised female cowbirds in acoustic isolation in order to

(A) eliminate confounding variables
(B) approximate field conditions
(C) measure reproductive success
(D) quantify repertoire complexity
(E) prevent early mating

6 
 6. According to the passage, the song sparrow is unlike the warbler in that the song sparrow

(A) uses songs mainly in territorial behavior
(B) continuously composes long and complex songs
(C) has a much larger song repertoire
(D) repeats one song type before switching to another
(E) responds aggressively to recorded songs

7 
 7. The passage suggests that the song sparrow experiments mentioned in third paragraph failed to confirm the role of intersexual selection because

(A) females were allowed to respond only to the song structure
(B) song sparrows are unlike other species of birds
(C) the experiments provided no evidence that elaborate songs increased male reproductive success
(D) the experiments included the songs of only a small number of different song sparrows
(E) the experiments duplicated some of the limitations of previous field studies

sumitkrocks · Answer

1. The passage is primarily concerned with
(A) showing that intrasexual selection has a greater effect on birdsong than does intersexual selection
(B) contrasting the role of song complexity in several species of birds
 (C) describing research confirming the suspected relationship between intersexual selection and the complexity of birdsong 
(D) demonstrating the superiority of laboratory work over field studies in evolutionary biology
(E) illustrating the effectiveness of a particular approach to experimental design in evolutionary biology

C is the best that involves conclusion of the passage

2. The author mentions the peacock’s tail (Highlighted) most probably in order to
(A) cite an exception to the theory of the relationship between intrasexual selection and male competition
(B) illustrate the importance of both of the pathways that shaped the evolution of birdsong
(C) draw a distinction between competing theories of intersexual selection
 (D) give an example of a feature that may have evolved through intersexual selection by female choice 
(E) refute a commonly held assumption about the role of song in mate attraction

Refer : ; like such visual ornamentation as the peacock’s tail, elaborate vocal characteristics increase the male’s chances of being chosen as a mate,
D is the answer

3. According to the passage, which of the following is specifically related to intrasexual selection?
(A) Female choice
 (B) Territorial behavior 
(C) Complex song types
(D) Large song repertoires
(E) Visual ornamentation
Refer: male competition and intrasexual selection produce relatively short, simple songs used mainly in territorial behavior

B is the answer

4. Which of the following, if true, would most clearly demonstrate the interaction (Highlighted) mentioned in lines 11-13?
 (A) Female larks respond similarly both to short, simple songs and to longer, more complicated songs. 
(B) Male canaries use visual ornamentation as well as elaborate song repertoires for mate attraction.
(C) Both male and female blackbirds develop elaborate visual and vocal characteristics.
(D) Male jays use songs to compete among themselves and to attract females.
(E) Male robins with elaborate visual ornamentation have as much reproductive success as rivals with elaborate vocal characteristics

In intrasexual selection deals in short and simple songs 
Intrasexual selection deals with more elaborate, longer and complicated songs

Questions mentions interaction so A is the right answer

5. The passage indicates that researchers raised female cowbirds in acoustic isolation in order to
 (A) eliminate confounding variables 
(B) approximate field conditions
(C) measure reproductive success
(D) quantify repertoire complexity
(E) prevent early mating

Refer: The beauty of the experimental design is that it effectively rules out confounding variables; acoustic isolation assures that the female can respond only to the song structure itself.

A is the right answer

6. According to the passage, the song sparrow is unlike the warbler in that the song sparrow
(A) uses songs mainly in territorial behavior
(B) continuously composes long and complex songs
(C) has a much larger song repertoire
 (D) repeats one song type before switching to another 
(E) responds aggressively to recorded songs
Refer: Unlike the song sparrow, which repeats one of its several song types in bouts before switching to another, the warbler continuously composes much longer and more variable songs without repetition.
D is the right answer

7. The passage suggests that the song sparrow experiments mentioned in third paragraph failed to confirm the role of intersexual selection because

(A) females were allowed to respond only to the song structure
(B) song sparrows are unlike other species of birds
 (C) the experiments provided no evidence that elaborate songs increased male reproductive success 
(D) the experiments included the songs of only a small number of different song sparrows
(E) the experiments duplicated some of the limitations of previous field studies

Refer: researchers doing fieldwork with song sparrows found no correlation between larger repertoires and early mating, which has been shown to be one indicator of reproductive success;
C is the right answer

MartyTargetTestPrep · Answer

Here's question 4.

4. Which of the following, if true, would most clearly demonstrate the interaction (Highlighted) mentioned in lines 11-13?

So, let's consider the relevant sentence.

The two pathways are not mutually exclusive, and we can expect to find examples that reflect their  interaction .

Since the sentence is about the interaction of "the two pathways," we should see what the two pathways are.

Looking above in the passage we see the following about the two pathways.

- In the first, male competition and intrasexual selection produce relatively short, simple songs used mainly in territorial behavior.

- In the second, female choice and intersexual selection produce longer, more complicated songs used mainly in mate attraction;

Notice that the description of the second pathways also goes on to say the following: "like such visual ornamentation as the peacock’s tail, elaborate vocal characteristics increase the male’s chances of being chosen as a mate."

So, as described, both pathways seem to involve male, rather than female, behavior.

Let's now consider the answer choices.

(A) Female larks respond similarly both to short, simple songs and to longer, more complicated songs.

This choice does not clearly highlight an interaction between territorial behavior and mating behavior. It indicates that two types of behavior could be mating behavior.

I guess, if we assume that the short, simple songs are territorial behavior, then there seems to be some kind of mixing of things here. Notice, however, that this choice does not say that larks ever actually use shorter songs for both territorial purposes and mating. It says only that the females react similarly to shorter and longer songs.

The main effect of this choice is to make clear that there are different possible types of mating behavior, not that there is an interaction between territorial behavior and mating behavior.

(B) Male canaries use visual ornamentation as well as elaborate song repertoires for mate attraction.

This is all about mating behavior, and does not show territorial and mating behavior interacting at all.

(C) Both male and female blackbirds develop elaborate visual and vocal characteristics.

Two types of birds doing similar things, not two types behavior interacting.

(D) Male jays use songs to compete among themselves and to attract females.

This choice is not ideal, but it's the closest to what we are looking for. It's basically saying that the same thing "songs," is both territorial behavior and mating behavior. Of course the passage has already said that short songs are territorial and that long songs are mating behavior. So, I'm not really sure what this choice adds. At the same time, of all the choices, this it the only one that shows an overlap, or "interaction," between territorial behavior and mating behavior.

(E) Male robins with elaborate visual ornamentation have as much reproductive success as rivals with elaborate vocal characteristics.

This is all about mating behavior, not about an interaction between territorial behavior and mating behavior.

Overall, this question is not great. Given what the passage says, it's not unreasonable to take Choice (A) as indicating that territorial behavior can also be mating behavior, and the OA, (D), does not really add new information. However, since (A) does not say that territorial behavior is actually ever used for mating behavior, and since (D) is the choice that most clearly describes a situation which there is an "interaction," or overlap, between territorial behavior and mating behavior, we have to go with (D).

Answer: (D)

Over the years, biologists have suggested two main pathways by which

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Reading Comprehension (RC) Questions

Over the years, biologists have suggested two main pathways by which

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards