2. 考研
  3. Prudent investors learned long ago that putting your eggs into lots of baskets reduces risk. Conservationists have now hit on a

Prudent investors learned long ago that putting your eggs into lots of baskets reduces risk. Conservationists have now hit on a

admin2010-06-17  75
问题     Prudent investors learned long ago that putting your eggs into lots of baskets reduces risk. Conservationists have now hit on a similar idea: a population of endangered animals will have a better chance of survival if it is divided into interconnected groups. The prospects of the species will be better because the chance that all the constituent subpopulations will die out at the same time is low. And, in the long term, it matters little if one or two groups do disappear, because immigrants from better-faring patches will eventually re-establish the species’ old haunts.
    One endangered species divided in just this way is the world’s rarest carnivore, the Ethiopian wolf, which lives high in the meadows of the Bale Mountains. Just 350 exist in three pockets of meadow connected by narrow’ valleys in the Bale Mountains National Park, with a further 150 outside this area.
    Two of the main threats to the Ethiopian wolf come from diseases carried by domestic dogs. One of these, rabies, is of particular concern because it is epidemic in the dog population. At first blush, vaccinating the wolves against rabies seems a simple solution. It would be ambitious, because the prevailing thinking—that all individuals matter and therefore all outbreaks of disease should be completely halted—implies that a large proportion of wolves would need to be vaccinated.
    Dan Haydon, of the University of Glasgow, and his colleagues believe that conservation biologists should think differently. With the exception of humans, species are important but individuals are not. Some outbreaks of disease can be tolerated. In a paper published this week in Nature, they recast the mathematics of vaccination with this in mind.
    On epidemiologists’ standard assumption that every individual counts, vaccination programmes are intended to prevent epidemics by ensuring that each infected animal, on average, passes the disease on to less than one healthy animal. This implies that around two-thirds of all the wolves would need to be vaccinated. A programme that sought to save a species rather than individuals would allow each infected wolf to pass the disease on to more than one healthy animal and hence require fewer vaccinations. Dr Haydon and his colleagues have calculated, using data from a rabies outbreak in 2003, that vaccinating between 10% and 25% would suffice, provided veterinarians gave jabs to those wolves living in the narrow valleys that connect the subpopulations.
    If the threat of rabies arose every five years, targeting all the wolves in the corridors would cut the risk of extinction over a 20-year period by fourfold. If this were backed up by vaccinating a mere 10% of the wolves in the three connected meadows, the chance of extinction would drop to less than one in 1,000. Saving a few seems to be an efficient way of protecting the many.
选项 A、conservationists got inspirations from it.
B、endangered animals can be protected in a similar way.
C、the prospects of some species depend on conservation.
D、the subpopulations will die without being put into different groups.
答案B
解析 推理判断题。第一句提到的谨慎投资者的想法是一种类比，把鸡蛋放到多个篮子里可以减少风险，说的是规避风险的方法，而第二句切入主题，环保主义者认为保护濒危动物也可以采取与此类似的方法，因此选项B正确。文中并没有说环保主义者的想法是从投资者那里得到的启发，排除A；选项C、D也不是由此推出的，均排除。
转载请注明原文地址:https://kaotiyun.com/show/h444777K
0

考研英语一

相关试题推荐
随机试题
最新回复(0)