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Wusong1 · 发表于 2004-6-14 03:01:00

Biologist:
Some speculate that the unusually high frequency of small goats found in island populations is a response to evolutionary pressure to increase the number of goats so as to ensure a diverse gene pool. However, only the reproductive success of a trait influences its frequency in a population. So, the only kind of evolutionary pressure that can reduce the average size of the members of a goat population is that resulting from small goats achieving greater reproductive success than their larger cousins.

The biologist's view, if true, provides the most support for which one of the following?
A. The evolutionary pressure to ensure a diverse gene pool could have the effect of increasing the frequency of a gene for small size.

B. The unusual frequency of small goats in island populations is not a result of the greater reproductive success small goats possess when space is limited.

C. Contrary to what some believe, large goats achieve greater reproductive success than small goates even when space is limited.

D. The evolutionary pressure to ensure a diverse gene pool does not have the effect of increasing the frequency of a gene for small size.

E. A diverse gene pool cnanot be achieved in a goat ppulation unless the average size of its members is reduced.

juju · 发表于 2004-6-14 03:08:00

是D 吗？

mindfree · 发表于 2004-6-14 03:20:00

Wusong1 · 发表于 2004-6-14 09:57:00

A little more analysis, please!

kingsoft · 发表于 2004-6-14 13:59:00

原文推论：环境胁迫——》小羊多（错）

小羊对大羊的生殖优势——》小羊多（对）

理由是：only the reproductive success of a trait influences its frequency in a population

问支持：

D说环境胁迫不能增加（促使羊）长的（个体）小的基因的频率——》环境胁迫不会让羊变小

cranberry · 发表于 2004-6-14 14:32:00

文章的意思是小羊的多数只能是其基因的繁衍优势的体现，所以可以让羊的个头变小的唯一进化的压力是小型羊取得了繁衍优势。由于小型羊取得繁衍优势是唯一原因，那么当然保证基因多样性的进化压力一定不能有这个效果。

tianwan · 发表于 2004-6-14 14:38:00

Biologist:
Some speculate that the unusually high frequency of small goats found in island populations is a response to evolutionary pressure to increase the number of goats so as to ensure a diverse gene pool. However, only the reproductive success of a trait influences its frequency in a population. So, the only kind of evolutionary pressure that can reduce the average size of the members of a goat population is that resulting from small goats achieving greater reproductive success than their larger cousins.
问几个阅读问题。
to increase the number of goats 修饰哪一个？

so as to ensure a diverse gene pool是不是to increase的目的状语。

that是什么意思，替代pressure？

achieving是做small goats的定语，还是result from的动名词宾语？？

Wusong1 · 发表于 2004-6-15 01:56:00

Thanks for kingsoft and cranberry!

Who will answer the questions from tianwan? I am also not so sure

about it, especially about this 'That'.

Bunch of Thanks!

Wusong1 · 发表于 2004-6-15 13:26:00

robertchu · 发表于 2004-6-15 14:06:00

以下是引用tianwan在2004-6-14 14:38:00的发言：

Biologist:
Some speculate that the unusually high frequency of small goats found in island populations is a response to evolutionary pressure to increase the number of goats so as to ensure a diverse gene pool. However, only the reproductive success of a trait influences its frequency in a population. So, the only kind of evolutionary pressure that can reduce the average size of the members of a goat population is that resulting from small goats achieving greater reproductive success than their larger cousins.
问几个阅读问题。
to increase the number of goats 修饰哪一个？

so as to ensure a diverse gene pool是不是to increase的目的状语。

that是什么意思，替代pressure？

achieving是做small goats的定语，还是result from的动名词宾语？？

to increase the number of goats 修饰前面的"response"

so as to ensure a diverse gene pool是to increase的目的状语。

that替代revolution pressure.

"small goats achieving greater reproductive success than their larger cousins" 是 "sb. doing sth."　结构，作"resulting from"的宾语．

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