首页
登录
职称英语
[img]2012q2/ct_eyyjscz2008b_eyyjscreadb_0021_20121[/img] When was the last t
[img]2012q2/ct_eyyjscz2008b_eyyjscreadb_0021_20121[/img] When was the last t
游客
2024-08-18
23
管理
问题
When was the last time you saw a frog? Chances are, if you live in a city, you have not seen one for some time. Even in wet areas once teeming with frogs and toads, it is becoming less and less easy to find those slimy, hopping and sometimes poisonous members of the animal kingdom. All over the world, even in remote jungles on the far side of the globe, frogs are losing the ecological battle for survival, and biologists are at a loss to explain their demise. Are amphibians
simply over-sensitive to changes in the ecosystem? Could their rapid decline in numbers be signalling some coming environmental disaster for us all?
This frightening scenario is in part the consequence of a dramatic increase over the last quarter of a century in the development of once natural areas of wet marshland; home not only to frogs but to all manner of wildlife. Yet, there are no obvious reasons why certain frog species are disappearing from rainforests in the Southern Hemisphere which are barely touched by human hands. The mystery is unsettling to say the least, for it is known that amphibian species are extremely sensitive to environmental variations in temperature and moisture levels. The danger is that planet Earth might not only lose a vital link in the ecological food chain (frogs keep populations of otherwise pestilent insects at manageable levels) , but we might be increasing our output of air pollutants to levels that may have already become irreversible. Frogs could be inadvertently warning us of a catastrophe.
An example of a bizarre occurrence regarding a species of frog dates from the summer of 1995 , when "an explosion” of multi-coloured frogs of the species Rana klepton esculenta occurred in the Netherlands. Normally these frogs are brown and greenish-brown, but some unknown contributory factor is turning these frogs yellow and / or orange. Nonetheless, so far, the unusual bi- and even tri-coloured frogs are functioning similarly to their normal-skinned contemporaries. It is thought that frogs with lighter coloured skins might be more likely to survive in an increasingly warm climate due to global warming.
One theory put forward to explain extinct amphibian species that seems to fit the facts concerns the depletion of the ozone layer, a well-documented phenomenon which has led to a sharp increase in ultraviolet radiation levels. The ozone layer is meant to shield the Earth from UV rays, but increased radiation may be having a greater effect upon frog populations than previously believed. Another theory is that worldwide temperature increases are upsetting the breeding cycles of frogs. [br] Some unknown contributory factor is turning frogs yellow and / or orange in the______.
选项
答案
Netherlands
解析
(答案见第三段。Netherlands荷兰。)
转载请注明原文地址:https://tihaiku.com/zcyy/3725211.html
相关试题推荐
Whichdieisdifferentfromtheotherthree?[img]2012q2/ct_eyyjsdz2006a_eyyjsdi
Whatnumbershouldreplacethequestionmark?[img]2012q2/ct_eyyjsdz2011a_eyyjsd
Howmanylinesappearbelow?[img]2012q2/ct_eyyjsdz2011a_eyyjsdiq_0064_20121[/im
Howmanylinesappearbelow?[img]2012q2/ct_eyyjsdz2011a_eyyjsdiq_0064_20121[/im
HowmanytimeswillshapeTfitintoshapeS?[img]2012q2/ct_eyyjsdz2005b_eyyjsd
[img]2012q2/ct_eyyjsdz2011a_eyyjsdcloze_0016_20121[/img]ThisisMattDrudge
[img]2012q2/ct_eyyjsdz2011a_eyyjsdcloze_0016_20121[/img]ThisisMattDrudge
[img]2012q2/ct_eyyjsdz2011a_eyyjsdcloze_0016_20121[/img]ThisisMattDrudge
[img]2012q2/ct_eyyjsdz2011a_eyyjsdcloze_0016_20121[/img]ThisisMattDrudge
[img]2012q2/ct_eyyjsdz2011a_eyyjsdcloze_0016_20121[/img]ThisisMattDrudge
随机试题
Tenyearsago,JoeAllenbeganstudyingadiversegroupofseventhgradersn
[originaltext]Americanslearnsportsaspartoftheireducation.Theylearn
[originaltext]M:2466.Simonspeaking.W:Hello.Isthistherightnumberfort
Cellphonescanmakeourlife______.[br]Oneoftheadvantagesofusingcellp
生产经营单位的特种作业人员必须按照国家有关规定经生产经营单位组织的安全作业培训,
医疗机构发现重大食物中毒事件时,应当在多长时间内向所在地县级人民政府卫生行政主管
如果中国人没有金融市场或者社会保障去_______家庭、家族这个“养子防老”体系
申请独立董事的任职资格,应当具备的条件有( )。A.具有大学本科以上学历,并且
基础心理学是研究()。 (A)正常成人心理现象的心理学基础学科 (B
男,55岁.进行性吞咽困难3个月,体重下降5kg,查无阳性所见。食管吞钡X线片描
最新回复
(
0
)