Anole Lizards

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Anole Lizards

by joyseychow » Wed Aug 12, 2009 1:56 am
Anole Lizard Species that
occur together (sympatrically)
on certain Caribbean islands
Line occupy different habitats:
(5) some live only in the grass,
some only on tree trunks, and
some only on twigs. These
species also differ morpho-
logically: grass dwellers are
(10) slender with long tails, tree
dwellers are stocky with long
legs, twig dwellers are slender
but stubby-legged. What is
striking about these lizards
(15) is not that coexisting species
differ in morphology and habi-
tat use (such differences are
common among closely related
sympatric species), but that
(20) the same three types of habi-
tat specialists occur on each
of four islands: Puerto Rico,
Cuba, Hispaniola, and Jamaica.
Moreover, the Puerto Rican
(25) twig species closely resembles
the twig species of Cuba,
Hispaniola, and Jamaica in
morphology, habitat use, and
behavior. Likewise, the spe-
(30) cialists for other habitats are
similar across the islands.
The presence of similar
species on different islands
could be variously explained.
(35) An ancestral species might
have adapted to exploit a
particular ecological niche on
one island and then traveled
over water to colonize other
(40) islands. Or this ancestral
species might have evolved
at a time when the islands
were connected, which some
of these islands may once
(45) have been. After the islands
separated, the isolated lizard
populations would have become
distinct species while also
retaining their ancestors’ niche
(50) adaptations. Both of these
scenarios imply that speciali-
zation to each niche occurred
only once. Alternatively, each
specialist could have arisen
(55) independently on each of the
islands.
If each type of specialist
evolved just once, then similar
specialists on different islands
(60) would be closely related.
Conversely, if the specialists
evolved independently on each
island, then a specialist on one
island would be more closely
(65) related to other types of anoles
on the same island—regardless
of their ecological niches—
than it would be to a similar
specialist on a different island.
(70) Biologists can infer how
species are related evolu-
tionarily by comparing DNA
sequences for the same genes
in different species. Species
(75) with similar DNA sequences
for these genes are generally
more closely related to each
other than to species with less-
similar DNA sequences. DNA
(80) evidence concerning the anoles
led researchers to conclude
that habitat specialists on one
island are not closely related
to the same habitat specialists
(85) elsewhere, indicating that spe-
cialists evolved independently
on each island.


Q. According to the passage, sympatric anole lizard species resemble many other closely related sympatric species in that the anole lizard species

A) differ from one another in morphology and habitat use

B) evolved on islands that were once connected

C) appear to have adapted unusually quickly to new habitats

D) have been able to colonize areas remote from their ancestral habitat

E) occupy the same range of habitats in a number of different locations

OA is A, Pls explain. Thks

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Re: Anole Lizards

by ketkoag » Wed Aug 12, 2009 7:17 am
joyseychow wrote:Anole Lizard Species that
occur together (sympatrically)
on certain Caribbean islands
Line occupy different habitats:

(5) some live only in the grass,
some only on tree trunks, and
some only on twigs. These
species also differ morpho-
logically
: grass dwellers are
(10) slender with long tails, tree
dwellers are stocky with long
legs, twig dwellers are slender
but stubby-legged. What is
striking about these lizards
(15) is not that coexisting species
differ in morphology and habi-
tat use
(such differences are
common among closely related
sympatric species
), but that
(20) the same three types of habi-
tat specialists occur on each
of four islands: Puerto Rico,
Cuba, Hispaniola, and Jamaica.
Moreover, the Puerto Rican
(25) twig species closely resembles
the twig species of Cuba,
Hispaniola, and Jamaica in
morphology, habitat use, and
behavior. Likewise, the spe-
(30) cialists for other habitats are
similar across the islands.
The presence of similar
species on different islands
could be variously explained.
(35) An ancestral species might
have adapted to exploit a
particular ecological niche on
one island and then traveled
over water to colonize other
(40) islands. Or this ancestral
species might have evolved
at a time when the islands
were connected, which some
of these islands may once
(45) have been. After the islands
separated, the isolated lizard
populations would have become
distinct species while also
retaining their ancestors’ niche
(50) adaptations. Both of these
scenarios imply that speciali-
zation to each niche occurred
only once. Alternatively, each
specialist could have arisen
(55) independently on each of the
islands.
If each type of specialist
evolved just once, then similar
specialists on different islands
(60) would be closely related.
Conversely, if the specialists
evolved independently on each
island, then a specialist on one
island would be more closely
(65) related to other types of anoles
on the same island—regardless
of their ecological niches—
than it would be to a similar
specialist on a different island.
(70) Biologists can infer how
species are related evolu-
tionarily by comparing DNA
sequences for the same genes
in different species. Species
(75) with similar DNA sequences
for these genes are generally
more closely related to each
other than to species with less-
similar DNA sequences. DNA
(80) evidence concerning the anoles
led researchers to conclude
that habitat specialists on one
island are not closely related
to the same habitat specialists
(85) elsewhere, indicating that spe-
cialists evolved independently
on each island.


Q. According to the passage, sympatric anole lizard species resemble many other closely related sympatric species in that the anole lizard species

A) differ from one another in morphology and habitat use refer to the bold part in the passage above.. it states clearly that morphology and habitat differences are common among anole and other lizard species..
what is unique among the anole lizard species is that "the same three types of habitat specialists occur on each of four islands" as mentioned in line 20..


B) evolved on islands that were once connected

C) appear to have adapted unusually quickly to new habitats

D) have been able to colonize areas remote from their ancestral habitat

E) occupy the same range of habitats in a number of different locations

OA is A, Pls explain. Thks

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by joyseychow » Wed Aug 12, 2009 8:23 pm
Ketkoag, thks for pointing out.

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by TheGraduate » Sun Nov 27, 2016 11:25 pm
Q. According to the passage, sympatric anole lizard species resemble many other closely related sympatric species in that the anole lizard species

A) differ from one another in morphology and habitat use refer to the bold part in the passage above.. it states clearly that morphology and habitat differences are common among anole and other lizard species..
what is unique among the anole lizard species is that "the same three types of habitat specialists occur on each of four islands" as mentioned in line 20..
Still cannot grasp the idea. The question asks about related sympatric species. Choice A speaks of differing morphology.

The passage is from GMATPrep. But is the question also from GMATPrep? Could anyone find out?

Secondly, I have another question from the same passage.

Q. It can be inferred that the DNA evidence mentioned in the highlighted text supports which of the following statements about the twig-dwelling anole lizards of any one of the four Caribbean islands mentioned in the passage.

A) They evolved from an ancestral species of twig dwellers at a time when their island was connected with the other three islands.
B) They were once more similar morphologically to twig dwellers on the other three islands than they are at present.
C) They are more closely related to tree and grass dwelling anoles on their island than they are to twig dwellers on the other three islands.
D) Their habitat specialization as twig dwellers was influenced by the differences in the types of vegetation on the other three islands.
E) Their DNA more closely resembles that of non-anole lizard species on their island that it does the DNA of anoles on the other three islands.

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by MartyMurray » Mon Nov 28, 2016 4:53 am
TheGraduate wrote:
Q. According to the passage, sympatric anole lizard species resemble many other closely related sympatric species in that the anole lizard species

A) differ from one another in morphology and habitat use refer to the bold part in the passage above.. it states clearly that morphology and habitat differences are common among anole and other lizard species..
what is unique among the anole lizard species is that "the same three types of habitat specialists occur on each of four islands" as mentioned in line 20..
Still cannot grasp the idea. The question asks about related sympatric species. Choice A speaks of differing morphology.
As you can tell by reading the passage, "closely related sympatric species" means "similar species that live together in the same geographic area."

The three types of anole lizards are therefore closely related sympatric species.

The passage goes on to say "What is striking about these lizards is not that coexisting species differ in morphology and habitat use (such differences are common among closely related sympatric species)".

Do you now see why the answer is correct?
Secondly, I have another question from the same passage.

Q. It can be inferred that the DNA evidence mentioned in the highlighted text supports which of the following statements about the twig-dwelling anole lizards of any one of the four Caribbean islands mentioned in the passage.

A) They evolved from an ancestral species of twig dwellers at a time when their island was connected with the other three islands.
B) They were once more similar morphologically to twig dwellers on the other three islands than they are at present.
C) They are more closely related to tree and grass dwelling anoles on their island than they are to twig dwellers on the other three islands.
D) Their habitat specialization as twig dwellers was influenced by the differences in the types of vegetation on the other three islands.
E) Their DNA more closely resembles that of non-anole lizard species on their island that it does the DNA of anoles on the other three islands.
The OA to this question is C.

None of the other answer choices are at all supported by the passage. for instance there is no reason at all to think that D is correct, as nothing in the passage indicates that anything on one island influenced the development of species on another island.

The passage supports one aspect of C, the idea that the twig dwelling anole lizards on one island are not closely related to the lizards on the other islands by saying "DNA evidence concerning the anoles led researchers to conclude that habitat specialists on one island are not closely related to the same habitat specialists elsewhere".

Then, to support the other aspect of C, that the twig dwelling anole lizards are related to the other types of anole lizards on the same island, you have to find in the second to last paragraph the following, "if the specialists evolved independently on each island, then a specialist on one island would be more closely related to other types of anoles on the same island regardless of their ecological niches than it would be to a similar specialist on a different island."
The passage is from GMATPrep. But is the question also from GMATPrep? Could anyone find out?
One GMAT Prep RC passage can be followed by various different sets of questions. So the fact that these questions do not appear in a certain set posted online does not indicate that they are not actual GMAT Prep questions. Further, the subtlety and tight construction of these questions tends to indicate that they are in fact official questions.
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