new species

IMO C

kaulnikhil wrote:The emergence of a new species from a parent species occurs due to a combination of geographical and genetic barriers. The effects of these barriers on different parent species vary widely; therefore, the emergence of new species should be distributed randomly over time. However, paleontologists have discovered a pattern in which extremely large and disparate groups of new species occasionally appear all at once.

Which of the following, if true, provides the best starting point for an explanation of the emergence of many new species at the same time?

(A) Parent species with few physiological differences among their members are less likely to evolve into a new species.
(B) Biologists use different evidence to identify the emergence of new species today than paleontologists use to identify such events that occurred in the past.
(C) Some new species develop exclusively because of geographical barriers between different groups of a parent species.
(D) Periodically, global disasters create sudden geographical divisions within many species' habitats which send subgroups of these species down different genetic paths.
(E) In some cases, one parent species will give rise to multiple new species that all possess a trait formerly unique to the parent species

I am confused b/w B and D
IMO D

IMO: D

because the statement the emergence of new species should be distributed randomly over time can be indictaive of something happening randomly.

The emergence of a new species from a parent species occurs due to a combination of geographical and genetic barriers. The effects of these barriers on different parent species vary widely; therefore, the emergence of new species should be distributed randomly over time. However, paleontologists have discovered a pattern in which extremely large and disparate groups of new species occasionally appear all at once.

Which of the following, if true, provides the best starting point for an explanation of the emergence of many new species at the same time?

(A) Parent species with few physiological differences among their members are less likely to evolve into a new species. (Out of scope - no mention of physiological difference)

(B) Biologists use different evidence to identify the emergence of new species today than paleontologists use to identify such events that occurred in the past. (how biologists and paleontologists use evidences - does not provide any explanation why new species emerge at sometime...out of scope)

(C) Some new species develop exclusively because of geographical barriers between different groups of a parent species. (contradicts argu...agru says combination of geo and genetic barriers....whereas choice says exclusively bcoz of geo; additionally, assuming choice is true...doesnot explain why new species emerge at sometime)

(D) Periodically, global disasters create sudden geographical divisions within many species' habitats which send subgroups of these species down different genetic paths. (shows emergence of new species and also shows 'global disasters' lead the emergence all at once)

(E) In some cases, one parent species will give rise to multiple new species that all possess a trait formerly unique to the parent species (shows why new species emerge but does not explain why all at once)

IMO - D

I believe the answer is D. What is the OA?

kaulnikhil wrote:The emergence of a new species from a parent species occurs due to a combination of geographical and genetic barriers. The effects of these barriers on different parent species vary widely; therefore, the emergence of new species should be distributed randomly over time. However, paleontologists have discovered a pattern in which extremely large and disparate groups of new species occasionally appear all at once.

Which of the following, if true, provides the best starting point for an explanation of the emergence of many new species at the same time?

(A) Parent species with few physiological differences among their members are less likely to evolve into a new species.
(B) Biologists use different evidence to identify the emergence of new species today than paleontologists use to identify such events that occurred in the past.
(C) Some new species develop exclusively because of geographical barriers between different groups of a parent species.
(D) Periodically, global disasters create sudden geographical divisions within many species' habitats which send subgroups of these species down different genetic paths.
(E) In some cases, one parent species will give rise to multiple new species that all possess a trait formerly unique to the parent species

this question is touch! really difficult cos i also dont understand its question.
i am considering C, D and E,
i dont like the phrase " in some cases" in E much and dunno what the answer. maybe D
what is the offcial answer and where is it? can you post the explaination?

a. does not support how new species evolve at same time.
b. out of scope. talks abt measureemnt techniques and not evolvement has happened
c. i thought this as wrong bcq Q stem asks abt many species where as this answers only for some species
d. correct
e. same reason as c

kaulnikhil wrote:The emergence of a new species from a parent species occurs due to a combination of geographical and genetic barriers. The effects of these barriers on different parent species vary widely; therefore, the emergence of new species should be distributed randomly over time. However, paleontologists have discovered a pattern in which extremely large and disparate groups of new species occasionally appear all at once.

Which of the following, if true, provides the best starting point for an explanation of the emergence of many new species at the same time?

(A) Parent species with few physiological differences among their members are less likely to evolve into a new species.
(B) Biologists use different evidence to identify the emergence of new species today than paleontologists use to identify such events that occurred in the past.
(C) Some new species develop exclusively because of geographical barriers between different groups of a parent species.
(D) Periodically, global disasters create sudden geographical divisions within many species' habitats which send subgroups of these species down different genetic paths.
(E) In some cases, one parent species will give rise to multiple new species that all possess a trait formerly unique to the parent species

kaulnikhil wrote:The emergence of a new species from a parent species occurs due to a combination of geographical and genetic barriers. The effects of these barriers on different parent species vary widely; therefore, the emergence of new species should be distributed randomly over time. However, paleontologists have discovered a pattern in which extremely large and disparate groups of new species occasionally appear all at once.

Which of the following, if true, provides the best starting point for an explanation of the emergence of many new species at the same time?

(A) Parent species with few physiological differences among their members are less likely to evolve into a new species.
(B) Biologists use different evidence to identify the emergence of new species today than paleontologists use to identify such events that occurred in the past.
(C) Some new species develop exclusively because of geographical barriers between different groups of a parent species.
(D) Periodically, global disasters create sudden geographical divisions within many species' habitats which send subgroups of these species down different genetic paths.
(E) In some cases, one parent species will give rise to multiple new species that all possess a trait formerly unique to the parent species

D.

barriers -> new species occasionally.
more barriers -> more new species frequently.

IMO : D

But I am unable to discard C also.