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
外语
(1)Although numbers of animals in a given region may fluctuate from year to year, the fluctuations are often temporary and, over
(1)Although numbers of animals in a given region may fluctuate from year to year, the fluctuations are often temporary and, over
admin
2022-12-18
52
问题
(1)Although numbers of animals in a given region may fluctuate from year to year, the fluctuations are often temporary and, over long periods, trivial. Scientists have advanced three theories of population control to account for this relative constancy.
(2)The first theory attributes a relatively constant population to periodic climatic catastrophes that decimate populations with such frequency as to prevent them from exceeding some particular limit. In the case of small organisms with short life cycles, climatic changes need not be catastrophic: normal seasonal changes in photoperiod (daily amount of sunlight), for example, can govern population growth. This theory—the density-independent view—asserts that climatic factors exert the same regulatory effect on population regardless of the number of individuals in a region.
(3)A second theory argues that population growth is primarily density-dependent—that is, the rate of growth of a population in a region decreases as the number of animals increases. The mechanisms that manage regulation may vary. For example, as numbers increase, the food supply would probably diminish, which would increase mortality. In addition, as Lotka and Volterra have shown, predators can find prey more easily in high-density populations. Other regulators include physiological control mechanisms: for example, Christian and Davis have demonstrated how the crowding that results from a rise in numbers may bring about hormonal changes in the pituitary (垂体) and adrenal glands (肾上腺) that in turn may regulate population by lowering sexual activity and inhibiting sexual maturation. There is evidence that these effects may persist for three generations in the absence of the original provocation. One challenge for density-dependent theorists is to develop models that would allow the precise prediction of the effects of crowding.
(4)A third theory, proposed by Wynne-Edwards and termed "epideictic", argues that organisms have evolved a "code" in the form of social or epideictic behavior displays, such as winter roosting aggregations or group vocalizing; such codes provide organisms with information on population size in a region so that they can, if necessary, exercise reproductive restraint. However, Wynne-Edwards’ theory, linking animal social behavior and population control, has been challenged, with some justification, by several studies.
The challenge posed to the Wynne-Edwards’ theory by several studies is regarded by the author with ________.
选项
A、complete indifference
B、qualified acceptance
C、skeptical amusement
D、perplexed astonishment
答案
B
解析
观点题。原文末段末句评价with some justification相当于“有条件地接受”之义。故选B。选项A“毫不关心”,选项C“怀疑”,选项D“困惑、惊讶”均不符题意。
转载请注明原文地址:https://kaotiyun.com/show/OpcD777K
0
专业英语四级
相关试题推荐
Britain’sprivateschoolsareoneofitsmostsuccessfulexports.Thechildrenofthewealthy【C1】________tothem,whetherfromC
Asimpleideasupportsscience:"trust,butverify".Resultsshouldalwaysbe【C1】________tochallengefromexperiment.Thatsimp
Asimpleideasupportsscience:"trust,butverify".Resultsshouldalwaysbe【C1】________tochallengefromexperiment.Thatsimp
Ifyoucan’tresistthechancetoputonabet,blameyourinsula—aregionofyourbrain.Scientiststhinkthatwhenthisbrain
Ifyoucan’tresistthechancetoputonabet,blameyourinsula—aregionofyourbrain.Scientiststhinkthatwhenthisbrain
Ifyoucan’tresistthechancetoputonabet,blameyourinsula—aregionofyourbrain.Scientiststhinkthatwhenthisbrain
[A]Intheory,statisticsshouldhelpsettlearguments.Theyoughttoprovidestablereferencepointsthateveryone—nomatterwh
Formorethanadecade,Dellhasposteddouble-digitgrowthbysellingcomputersdirectlytocustomers,mostofthemcorporatec
Formorethanadecade,Dellhasposteddouble-digitgrowthbysellingcomputersdirectlytocustomers,mostofthemcorporatec
Thewriteroccasionallyfoundhimself____________incontroversiesthathadkeptsomeofhisbooksfrombeingpublished.
随机试题
A.鹿角状菌丝B.梳状菌丝C.两者都有D.两者都没有毛癣菌()
某二叉树的前序序列为ABCDEFG,中序序列为DCBAEFG,则该二叉树的后序序列为()。
患者,男性,25岁。餐后运动时突发脐周腹痛伴恶心呕吐,并阵发性加重,发病来未排气排便。查体:体温37.3℃,血压88/62mmHg,心率110次/分;左侧腹部隆起,肠鸣音高亢,压痛明显。WBC10.5×109/L。最可能的诊断是
有关青蒿素的结构与活性研究结果表明双氢青蒿素是由
下列各项中,企业不应确认为无形资产的是( )。
关于个人不可循环授信额度,下列说法错误的是()。
根据票据法律制度规定,背书人在汇票上记载“不得转让”字样,其后手再背书转让的,将产生的法律后果是()。
(2010年卷二第92题)王某委托胡某销售一批货物,双方约定胡某不收取报酬。根据合同法及相关规定,下列说法哪些是正确的?
事物的质是指()。
在推进我国反腐倡廉建设的工作上,中国共产党一直坚持不懈地努力着,下列有关说法错误的是:
最新回复
(
0
)