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Re: Paleontologist: Scientists have used evidence about bone structure to [#permalink]
­ameya.satyawadi

It seems like option D is not connected to the conclusion. It has no relationship/effect on the argument that small genomes were not an evolutionary adaptation. 

Option A strenghtens the argument. If we take another look, the flying animals with small genomes evolved from their flightless ancestors, who did not need small genomes to conserve energy to fly-- since they did not fly. So the modern flying animals did not adopt the small genomes out of evolutionary necessity either. ­
ameya.satyawadi wrote:
Raman109 wrote:
Understanding the argument - ­
Paleontologist: Scientists have used evidence about bone structure to infer that carnivorous dinosaurs like Trynnasauraus rex had genomes - sets of genetic information in their DNA - much smaller than those of most modern mammals. - background info. 
Modern birds have genomes about the same size as those of human dinosaurs, from which they evolved. - Fact. 
Therefore, the hypothesis that small genomes in birds were an evolutionary adaptation functioning to conserve energy for flight is probably false. - Conclusion. 

As the size of the genome of birds and carnivorous dinosaurs like Trynnasauraus rex (could not fly) is the same, we can't say that birds have smaller genomes as an evolutionary adaptation to conserve energy for flight. 

Which of the following, if true, most strengthen the argument?

Option Elimination - 

A. Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species. - strengthens the conclusion that small bird genomes were not an evolutionary adaptation to conserve energy for flight.

B. Flying mammals such as bats have genomes about the same size as modern bird genomes. - out of scope. 

C. Species with small genomes typically use energy much more efficienly than do closely related species with larger genomes. - but in birds, there is no change in genomes with respect to carnivorous dinosaurs like Trynnasauraus rex. Out of scope. 

D. Many animal species that lived in the period as Tyrannosaurus rex but were not ancestors of modern birds also had relatively small genomes. - out of scope. 

E. At least some flightless species that evolved from carnivorous dinosaurs and were ancestors to modern bird species had much larger genomes than modern birds have. - out of scope. 

­Raman109 I chose option D because it shows that there are many animal species that did not have flying capabilities but still had small genomes, that is why I had a confusion among options A and D. I got your point justifying A nevertheless how is option D out of scope?­ plus how am I to completely eliminate this option

­
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Re: Paleontologist: Scientists have used evidence about bone structure to [#permalink]
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don't really understand this question. Human dinosaurs --- what is this in the question?
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Re: Paleontologist: Scientists have used evidence about bone structure to [#permalink]
Human dinosaurs " are the recent flightless ancestors from which birds evolved.
MartyMurray KarishmaB
Can you please help on this question ?

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Re: Paleontologist: Scientists have used evidence about bone structure to [#permalink]
Basically we need to prove that the small genomes in birds are not an evolutionary adaptation to conserve energy during flight.
It was small in case of their recent ancestors and that's why it is also small in them ( birds).
Option A states that this feature of small genome is present amongst other flying animals too ( other than birds ) and also in case of their flightless ancestors .
Since this same thing can be seen amongst other flying animals too ,
the conclusion gets strengthened that the evolutionary adaptation is not what is causing the small genomes. Small genomes are present in the birds because they were present amongst their ancestors . They ( the birds) simply inherited it just the way other flying animals did from their flightless ancestors.
MartyMurray Sir / KarishmaB maa'm , request you to check my reasoning.

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Re: Paleontologist: Scientists have used evidence about bone structure to [#permalink]
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sayan640 wrote:
MartyMurray Sir / KarishmaB maa'm , request you to check my reasoning.

­This part doesn't capture what choice (A) says:
Quote:
Option A states that this feature of small genome is present amongst other flying animals too ( other than birds ) and also in case of their flightless ancestors .
Since this same thing can be seen amongst other flying animals too

The choice (A) says the following:

A. Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species.

Notice that choice (A) does not say species other than birds have "this feature of small genome." Quite the contrary, it says that their genomes are "no smaller" than those of their ancestors. In other words, they may be quite large.

So, the point is that other flying animals do not have genomes that are smaller than those of flightless ancestors even thought they fly. This information indicates that animals that evolve to fly don't tend to evolve smaller genomes. That information indicates that birds have small genomes just because their ancestors did.
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Re: Paleontologist: Scientists have used evidence about bone structure to [#permalink]
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­Paleontologist: Scientists have used evidence about bone structure to infer that carnivorous dinosaurs like Trynnasauraus rex had genomes - sets of genetic information in their DNA - much smaller than those of most modern mammals. Modern birds have genomes about the same size as those of carnivorous dinosaurs, from which they evolved. Therefore, the hypothesis that small genomes in birds were an evolutionary adaptation functioning to conserve energy for flight is probably false.

The conclusion of the argument is the following:

the hypothesis that small genomes in birds were an evolutionary adaptation functioning to conserve energy for flight is probably false

The reasoning of the argument is basically the following. Birds evolved from dinosaurs that had small genomes. So, it's probable that the  reason birds have small genomes is not that they evolved small genomes to conserve energy but simply that they evolved from ancestors that had small genomes and thus ended up with small genomes.

Which of the following, if true, most strengthen the argument?

This is a Strengthen question, and the correct answer will somehow help to support or confirm the conclusion.

A. Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species.

This choice is interesting.

If species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species, then what we see is that, when animals have evolved from being flightless to flying, their genomes haven't become smaller.

While that information doesn't prove that birds didn't evolve relatively small genomes to conserve energy for flight, it helps to support that conclusion.

After all, if these other animals didn't evolve smaller genomes as they evolved to flying, then it could be that relatively small genomes aren't very helpful for flying.

Therefore, maybe birds didn't evolve small genomes to help with flying. In that case, it's quite possible that birds' genomes are relatively small just because their ancestors' genomes were relatively small.

So, this choice helps to confirm that the conclusion of the argument is correct.

Keep.

B. Flying mammals such as bats have genomes about the same size as modern bird genomes.

This choice weakens the support for the conclusion.

After all, if flying mammals such as bats have genomes about the same size as modern bird genomes, then we have other examples of flying animals with relatively small genomes. The fact that other flying animals also have relatively small genomes tends to indicate that flying animals evolve to have small genomes for some purpose that they all share, which could be to conserve energy for flight.

By supporting the conclusion that flying animals evolve to have small genomes to conserve energy for flight, this choice weakens rather than strengthens the case for the conclusion of the argument.

Eliminate.

C. Species with small genomes typically use energy much more efficienly than do closely related species with larger genomes.

If anything, this choice weakens the support for the conclusion.

After all, if this choice is true, then it make sense that birds would have evolved relatively small genomes to conserve energy for flight.

Of course, by indicating that that makes sense, this choice weighs against the conciusion of the argument.

Eliminate.

D. Many animal species that lived in the period as Tyrannosaurus rex but were not ancestors of modern birds, also had relatively small genomes.

This information about other animal species doesn't indicate whether birds evolved relatively small genomes to conserve energy or just retained small genomes from their ancestors.

After all, these other animals have no clear relationship with birds. They just happened to have small genomes.

Eliminate.

E. At least some flightless species that evolved from carnivorous dinosaurs and were ancestors to modern bird species had much larger genomes than modern birds have. 

If anything, this choice slightly weakens the argument.

After all, if this choice is true, then flightless ancestors of some birds had larger genomes than those birds have.

That information indicates that some birds evolved to have genomes that are smaller than their flightless ancestors had, which in turn tends to indicate that those birds have relatively small genomes because they fly, and thus benefit from conserving energy, whereas their ancestors didn't fly.

That train of logic goes against the conclusion of the argument.

Eliminate.

Correct answer: A
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Re: Paleontologist: Scientists have used evidence about bone structure to [#permalink]
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Thank you marty !! 
MartyMurray wrote:
sayan640 wrote:
MartyMurray Sir / KarishmaB maa'm , request you to check my reasoning.

­This part doesn't capture what choice (A) says:
Quote:
Option A states that this feature of small genome is present amongst other flying animals too ( other than birds ) and also in case of their flightless ancestors .
Since this same thing can be seen amongst other flying animals too

The choice (A) says the following:

A. Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species.

Notice that choice (A) does not say species other than birds have "this feature of small genome." Quite the contrary, it says that their genomes are "no smaller" than those of their ancestors. In other words, they may be quite large.

So, the point is that other flying animals do not have genomes that are smaller than those of flightless ancestors even thought they fly. This information indicates that animals that evolve to fly don't tend to evolve smaller genomes. That information indicates that birds have small genomes just because their ancestors did.

­
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Re: Paleontologist: Scientists have used evidence about bone structure to [#permalink]
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