外刊超精读:科学美国人 美国人, 科学, 精读

小叮铛

1〉Spring is the season for flashy mates, at least for finches. It is only later in the year that the females choose based on genetic diversity,
   According to new research from two scientists at the University of Arizona., Their 10-year study of a colony of 12,000 finches in Montana has revealed the seasonal dynamics of finch attraction and thereby resolved an evolutionary conundrum.


2〉Previous research had shown that female birds go for the most resplendent mates; in the case of finches, this means the males with the reddest breast. Some scientists argue that such sexual selection is the driving force behind apparently useless displays, such as red breasts or the brilliance of a male peacock's tail. "For such elaborate traits to evolve, you have to have mating patterns where everyone wants the same thing," ecologist Kevin Oh explains.


3> On the other hand, in a relatively stable population, if all females mated with the flashiest guy, the charm of finches would become inbred. Instead, female finches should seek out males with the most genetic difference from themselves. But this would lead to a variety of hues for male finch breasts. "Even though preference for genetically complementary mates is widely documented, it has always puzzled people that individual differences in mate preference do not prevent the evolution of elaborate ornaments," ecologist Alexander Badyaev notes.


4> Badyaev has spent the last 10 years photographing, taking DNA samples and measuring a charm of house finches in Montana. By 2004, he had the intimate details of the entire population, including who was mating with whom, who was cheating on whom, and whose genes got passed on to the next generation. He also has pictures of the relative rosiness of any given male finches breast. "We have 10 sequential generations of wild birds completely genotyped," he says. "It's never been done before."


5> By analyzing that record, the researchers found that early in the mating season, females chose the male finch with the reddest breast. But as the season wore on--and new females entered the charm--they typically chose males with strong genetic differences from themselves. And those tempted to stray typically chose a mate more genetically different than their regular partner, according to the research presented in Proceedings of the Royal Society B.
   


6> Although it remains unclear how finches sense genetic difference, the finding does reveal a new strategy for evolving elaborate ornamentation while preventing inbreeding. And that means this behavior might apply to more than just one charm of finches in Montana.

[ 本帖最后由 小叮铛 于 2006-6-27 11:22 AM 编辑 ]

小叮铛

On the other hand, in a relatively stable population, if all females mated with the flashiest guy, the charm of finches would become inbred. Instead, female finches should seek out males with the most genetic difference from themselves. But this would lead to a variety of hues for male finch breasts. "Even though preference for genetically complementary mates is widely documented, it has always puzzled people that individual differences in mate preference do not prevent the evolution of elaborate ornaments," ecologist Alexander Badyaev notes.

词汇:

Difference 这类名词有与之对应的形容词 different.这类名词与后面介词的搭配往往和形容词一样.既: difference from, different from.

后面句子中的preference也可以这样搭配.即preference to .(丁SIR好象在第7期文摘精读中,更为详细地讲了该词.可以参考)

还有诸如.association(associate) with  Priority(prior) to , .等.


搭配及固定表达:

stable population  稳定的数量

mate with与…交配                seek out搜出, 挑出   

genetic difference基因差异          a variety of一系列

genetically complementary基因互补   individual differences个体差异

elaborate ornaments精雕细琢的装饰(与前文出现的flashy .resplendent adj. brilliance. n.同等关系)

结构:

第一句:利用假设---如果都按照第2段的观点,会出现一些情况即吸引力则变成天生的.on the other hand 这类”文眼”,提供了行文的思路.

第二句:INSEAD. 文眼又出现了,我们已经能够判断,作者要提出一个以之前观点不符的事实了.

第三句:but 出现了.即.如果都按照第二句中的观点,那么会出现与事实不符的情况.

第四句:用一个科学家的话,总结了全段.表达了困惑所在:既然基于基因互补的交配方式大量存在,那么应该出现一系列不同的魅力(主要是颜色),但事实确是魅力一直进化趋于一致.这种情况是相悖的.但是该句也为下文展开铺垫

小叮铛

Previous research had shown that female birds go for the most resplendent mates; in the case of finches, this means the

      males with the reddest breast. Some scientists argue that such sexual selection is the driving force behind apparently useless displays, such as red breasts or the brilliance of a male peacock's tail. "For such elaborate traits to evolve, you have to have mating patterns where everyone wants the same thing," ecologist Kevin Oh explains.





词组及固定搭配:

go for 追寻     in the case of 在…例子中.注意与in case 的区别.

sexual selection  性选择.     driving force驱动力

mating patterns  交配模式

句型:

Previous research had shown that…;in the case of….这类”无灵句” 句型,往往表达客观的事实.这在作文中,也可以套用,尤其是图表类.如,the chart reveals/shows that ….;in the case of +整体中某个具体部分+其他成分.

Some scientists argue that….表达某些科学家的观点.

结构:

第一句.引入先前研究的观点.

第二句.更详细描述先前研究的观点.

第三句.引用某个科学家的话,为观点佐证.

[ 本帖最后由 小叮铛 于 2006-6-27 11:30 AM 编辑 ]

小叮铛

1〉  Spring is the season for flashy mates, at least for finches. It is only later in the year that the females choose based on genetic diversity, according to new research from two scientists at the University of Arizona. Their 10-year study of a colony of 12,000 finches in Montana has revealed the seasonal dynamics of finch attraction and thereby resolved an evolutionary conundrum.
词汇:

      flashy adj浮华, 一组相关词汇2〉段中resplendent adj. brilliance. n. 3)段中elaborate ornaments精雕细琢的装饰

词组及固定搭配:

based on 基于…   

     genetic diversity   .基因的多样性

     seasonal dynamics 季节性的变动

resolve a conundrum=riddle=problem 解决一个难题。

句型:

It is only later in the year that….. 强调句(作者在此强调时间,这类句型可能是考查的重点.可以想象,既然作者强调某部分的信息,那么该部分在全文应该有重要地位,可以想个问题:在春天的时候,雀类根据什么选择交配伙伴?在比较靠近年底的时候,又是如何选择?)在作文中,如果自己想强调某部分的内容,也许该句型能效劳.

   结构:

    第一句:提出作者的判断.

    第二句:用具体的研究作为论据支持.

    第三句:进一步说明该研究,并说明解决一个进化难题.是什么难题??这就为作者下文展开提供必要的交代.此外,注意该句中:thereby的应用,这类启承转合的词汇往往说明句子或全文的逻辑关系,在此句中表现为因果关系:即研究解决难题.

[ 本帖最后由 小叮铛 于 2006-6-27 11:27 AM 编辑 ]

小叮铛

词汇运用，固定搭配，句型不帖了。这种东西自己要实践。丁SIR的超精读绝对是经典，老师带我们入门了，剩余的只能靠自己在实践中加深体会。正所谓：纸上得来终觉浅，觉知此事要躬行。



文章的结构：总(1段)+分(2段)+分(3,4,5段)+总(6段),其中2与3,4,5又是并列.



1>先说明研究解决了一个conundrum- conundrum是什么意思,根据下文自己猜.



2>引入一个关于finches进化的观点.该段的首句给读者提供了信息, Previous research……怎么怎么样。



3>段再引入一个与2段中观点相悖的观点.然后利用4和5段中的事实论证该观点.注意：on the other hand。



6.>总结全文,

呵，觉得这结构挺经典的，真题还没敢研究，不太了解出题思路。但是比如在第一段的第二句中，作者既然应用强调句型it is……that, 那么是否有可能这样考：choose based on genetic diversity是在什么时间A。spring. B.later in the year（B选项意思太容易理解，出题人也许可以改改），总之既然是强调句，那么必是作者表达的重点。一段最后一句：conundrum=riddle=problem是否也会考个语意题目？