首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
Wild elephants roam across the crowded plains of India; forested river banks wind through cattle ranches in Brazil; a ribbon of
Wild elephants roam across the crowded plains of India; forested river banks wind through cattle ranches in Brazil; a ribbon of
admin
2013-09-16
71
问题
Wild elephants roam across the crowded plains of India; forested river banks wind through cattle ranches in Brazil; a ribbon of green stretches across Europe where the Iron Curtain used to be. Using such wildlife corridors to link up larger but isolated protected areas are the most widely adopted strategy for halting biodiversity decline, with millions of dollars spent creating and protecting them every year.
But has enthusiasm for a neat idea got ahead of the science?
The principle is simple. As wildlife habitat is broken into isolated fragments by farms, roads, and settlements, we need to link them up with corridors of green. Then even if the entire habitat cannot be re-created, old migration patterns can be revived, escape routes created ahead of climate change and—perhaps most crucially—isolated populations can interbreed, enhancing their genetic diversity and their resilience to encroaching threats.
Recently, Paul Beier, a veteran conservation biologist from Northern Arizona University, and his colleague Andrew Gregory, warned that "despite much research, there is little evidence that conservation corridors work as intended. " There is, they say, plenty of evidence that wild animals will move through corridors. But advocates of the corridors want, and claim, much more than this. They say that animals don’t just go for a walk in their conservation woods, but that they move permanently and interbreed with neighboring populations. In this way corridors supposedly unite isolated, threatened populations into an interbreeding and much more resilient—whole.
Such claims sometimes hold up. In the United Kingdom, the expansion of Kielder Forest in the 1960s provided a link between isolated populations of threatened red squirrel. Genes from isolated populations have now "leapfrogged through hundreds of forest fragments" across 100 kilometers and more. But the Kielder Forest is much wider than a conventional corridor. Few studies have looked for gene flow in genuine corridors; even fewer have found it. One study investigated the genetic diversity of small marsupials in a narrow forest corridor traversing 4. 5 kilometers of grasslands in Queensland, Australia. It found that genetically distinct populations had persisted at either end. Mixing was a myth.
Other studies have shown that conservation corridors work. But most have looked at short corridors of 100 meters through largely natural landscape. "That species can travel a-long short corridors in a natural setting does not mean that they will be successful dispersing along much longer corridors embedded in a heavily impacted landscape," says Gregory. "Still less that such movements occur frequently enough to allow enough gene flow to occur so that the connected habitat blocks function as one population. "
Perhaps we should not make the perfect the enemy of the good. Surely any corridor is better than none? But consider this. The edges of wild areas are known danger zones for wildlife, where predators and diseases may invade. Linking two existing protected areas with a long narrow corridor may expose it to greater danger along these edges. Unless the benefit exceeds the threat, then there is serious potential to do harm.
Kielder Forest is mentioned in paragraph 4 as an example of______.
选项
A、primitive corridors
B、unsuccessful corridors
C、conventional corridors
D、non-typical corridors
答案
D
解析
例子上文(第三段)介绍了野生动物走廊倡导者的观点:走廊可以使隔离的邻近动物群之间相互杂交、融为一体。
转载请注明原文地址:https://kaotiyun.com/show/qnO4777K
0
考研英语一
相关试题推荐
Theproblemtobetakenupandthepointatwhichthesearchforasolutionwillbeginarecustomarilyprescribedbytheinvesti
Theproblemtobetakenupandthepointatwhichthesearchforasolutionwillbeginarecustomarilyprescribedbytheinvesti
Theproblemtobetakenupandthepointatwhichthesearchforasolutionwillbeginarecustomarilyprescribedbytheinvesti
Whichofthefollowingadjectivesmaybestdescribethetoneofthistext?Whatthepeoplereallyignoreinthedebateisthat
Inthefollowingtext,somesentenceshavebeenremoved.ForQuestions41-45,choosethemostsuitableonefromthelist(A、B、C、
SomeyearsagoIwasofferedawritingassignmentthatwouldrequirethreemonthsoftravelthroughEurope.Ihadbeenabroada
SomeyearsagoIwasofferedawritingassignmentthatwouldrequirethreemonthsoftravelthroughEurope.Ihadbeenabroada
Forthepasttwoyears,Ihavebeenworkingonstudentsevaluationofclassroomteaching.Ihavekeptarecordofinformalconve
Icouldnotconcentratebecausetherehadbeenalotof______throughoutthewholeevening.
Byanystandard,moneymanagerMalcolmGissenhashadacomplicatedrelationshipwithriskoverthepastcoupleofyears.After
随机试题
纯铜具有()的特性,因而在工业上被广泛应用。
WhatMakesaSoccerPlayerGreat?Soccerisplayedbymillionsofpeopleallovertheworld,buttherehaveonlybeenfewpl
一般情况下,肾小球滤过率主要取决于
犬阴囊疝内容物常见的是
A、阻断中枢5-HT受体B、使突触间隙的NA浓度下降C、阻断中枢多巴胺D2受体D、抑制中枢PG合成E、抑制外周PG合成解热镇痛药的解热作用机制是
依据《促进产业结构调整暂行规定》,自规定施行之日起,同时废止的产业目录有()。
质量委员会通常由企业的()组成。
下列战役中,使用火攻的主要有()。①官渡之战②赤壁之战③夷陵之战④淝水之战
Ithasbeennecessarytoreferrepeatedlytotheeffectsofthetwoworldwarsinpromotingallkindsofinnovation.Itshouldb
A、HewasJamesOliver’sassistant.B、HewasborninEurope.C、Hewasopposedtoscientificagriculture.D、Hespenthisownmoney
最新回复
(
0
)