关于GWD 鲑鱼迷路和人类活动关系的那篇文章的 问题

dkswoah

Over the last 150 years, large stretches of salmon habitat have been eliminated by human activity: mining, livestock grazing, timber harvesting, and agriculture as well as recreational and urban development.
The numerical effect is obvious:
there are fewer salmon in degraded regions than in pristine ones; however, habitat loss also has the potential to reduce genetic diversity.
This is most evident in cases where it results in the extinction of entire salmon populations.
Indeed, most analysts believe that some kind of environmental degradation underlies the demise of many extinct salmon populations. Although some rivers have been recolonized, the unique genes of the original populations have been lost.



Large-scale disturbances in one locale also have the potential to alter the genetic structure of populations in neighboring areas, even if those areas have pristine habitats.
Why?
Although the homing instinct of salmon to their natal stream is strong, a fraction of the fish returning from the sea (rarely more than 15 percent) stray and spawn in nearby streams.
Low levels of straying are crucial, since the process provides a source of novel genes and a mechanism by which a location can be repopulated should the fish there disappear.
Yet high rates of straying can be problematic because misdirected fish may interbreed with the existing stock to such a degree that any local adaptations that are present become diluted.
Straying rates remain relatively low when environmental conditions are stable, but can increase dramatically when streams suffer severe disturbance.
The 1980 volcanic eruption of Mount Saint Helens, for example, sent mud and debris into several tributaries of the Columbia River.
For the next couple of years, steelhead trout (a species included among the salmonids) returning from the sea to spawn were forced to find alternative streams.
As a consequence, their rates of straying,
initially 16 percent, rose to more than 40 percent overall.


Although no one has quantified changes in the rate of straying as a result of the disturbances caused by humans, there is no reason to suspect that the effect would be qualitatively different than what was seen in the aftermath of the Mount Saint Helens eruption.
Such a dramatic increase in straying from damaged areas to more pristine streams results in substantial gene flow, which can in turn lower the overall fitness of subsequent generations.


GWD1-Q12:

The author mentions the “aftermath of the Mount Saint Helens eruption” most likely in order to

A.     A.provide an example of the process that allows the repopulation of rivers whose indigenous salmon population has become extinct

B.     B indicate the extent to which the disturbance of salmon habitat by human activity in one stream might affect the genetic structure of salmon populations elsewhere

C.     C provide a standard of comparison against which the impact of human activity on the gene flow among salmon populations should be measured

D.     D show how salmons’ homing instinct can be impaired as a result of severe environmental degradation of their natal streams

E.     E show why straying rates in salmon populations remain generally low except when spawning streams suffer severe environmental disturbance


答案是C。

这道题要定位到  下面这句

Although no one has quantified changes in the rate of straying as a result of the disturbances caused by humans, there is no reason to suspect that the effect would be qualitatively different than what was seen in the aftermath of the Mount Saint Helens eruption.
这句话    看了两种翻译了  
一种说   尽管没有人可以量化人类行为引起的对于salmon迷失率的变化，但是没有理由怀疑（人类行为）带来的后果和MSH爆发带来的后果确实有本质的上的不同。（有不同）
另一种说  尽管不曾有人量化有人类引起的扰动带来的迷失率，没有理由怀疑人类扰动带来的影响会和圣海伦火山喷发后带来的影响有什么本质不同。
   是我汉语没学好么 ？          我怎么 读着第二种翻译  有一种认为    这两种 影响没 什么区别呢？
反正一切都取决于   句子中的 would be qualitatively different than 的 翻译了    这里是虚拟么？  要是表达与事实相反  那也就是没区别咯？   

文章主要就是说    第一段 鲑鱼数量减少和人类破坏有关   但是人类破坏也对基因多样性产生了影响   主要是多样性的减少 导致了  数量减少
                             第二段 举例子说怎么对基因多样性产生的影响  （ 鲑鱼回家的时候会迷路   跑到别的河里   少量的迷路有好处   一个地方没有余鱼 迷路的鱼过去就成当地的鱼了                      大量 的迷路就会导致鱼相互杂交  导致无法繁殖   数量就减少了    环境稳定时   迷路率就低  环境不稳定 迷路率就高    举例子就说火山爆发  环境不稳定就导致了迷路率高了）
                              第三段  就是刚才那句话  看这个逻辑    最后一段应该就是总结啊   承接前两段    应该说火山的影响 和  人类破坏环境的影响 没有什么不同   都是增加了迷路率 而这种高的迷路率就降低了基因多样性   降低下一代的适应性了
                              以上纯属本人看法哈 。

另外就是 这道题选C 还是选B 的疑问了  
关于不选B 有人解释说  文章说的是  gene flow  不是enetic structure           elsewhere 也有问题   
可是之前下载的  GWD 题目说这题答案是B        别的网站上说的都是C    我就纠结了    选B 的  说 文章没有说到 measured   所以 不选C   
  我理解的B是 说火山的问题  表达  了    （由 于人类对鲑鱼栖息地的破坏   影响     其他地方鲑鱼基因结构 的）程度
           C说的是   火山的问题  提供了一个  （人类活动  对 应该被测量的鲑鱼人口的基因流量 的影响）的比较 标准
请求会做这道题的分析一下  这文章说火山到底是为了  表示程度   还是提供了 比较标准啊？
虽然看着  拿 火山和  人类活动 做了比较       但是实在没有找到 should be measured的 定位  难道说  定位句前半部分的although没有得到量化的  表达了一种希望得到量化的愿望 所以用了虚拟语气？      
可能 字太多了      上面就是我对这道题的分析     我想听听 XDJM 们的看法呀 。。。。一开始错选了B  做这种题真是无语了  不知道怎么做

dkswoah

希望明天能看到回复哇        杀G的童鞋   心肠都是好好哒~~~~~

成成儿

现在回复可能过期了哦～～
对于这个问题：

这道题要定位到  下面这句

Although no one has quantified changes in the rate of straying as a result of the disturbances caused by humans, there is no reason to suspect that the effect would be qualitatively different than what was seen in the aftermath of the Mount Saint Helens eruption.
这句话    看了两种翻译了  
一种说   尽管没有人可以量化人类行为引起的对于salmon迷失率的变化，但是没有理由怀疑（人类行为）带来的后果和MSH爆发带来的后果确实有本质的上的不同。（有不同）
另一种说  尽管不曾有人量化有人类引起的扰动带来的迷失率，没有理由怀疑人类扰动带来的影响会和圣海伦火山喷发后带来的影响有什么本质不同。

我的理解是：suspect在Longman的解释是：to think that something is probably true, especially something bad. 翻译成中文应该是：怀疑。。。是正确的/可信的
那么there is no reason to suspect that A. 直译是：没有理由认为A是正确的，即A是不正确的，而A是【自然灾害和人为影响有区别】，所以整个的意思是【自然灾害和人为影响没有区别】，联系上下文，作者要说的是人为影响和那次自然灾害影响一样，即把那次自然灾害当成了一个标杆～～