首页
登录
职称英语
Although numbers of animals in a given region may fluctuate from year to yea
Although numbers of animals in a given region may fluctuate from year to yea
游客
2024-01-13
22
管理
问题
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.
The first theory attributes a relatively constant population to periodic cli- matic 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.
A second theory argues that population growth is primarily density-de- pendent—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 in- crease, 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 hor- monal changes in the pituitary and adrenal glands 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.
A third theory, proposed by Wynne- Edwards and termed "epideic-tic," argues that organisms have evolved a "code"in the form of social or epideic- tic behavior displays, such as winterroosting aggregations or group vocalizing; such codes provide organisms with information on population size in a region so that they can, if necessary, ex- ercise reproductive restraint. However, Wynne-Edwards’ theory, linking animal social behavior and population control, has been challenged, with some justification, by several studies. [br] Which of the following, if true, would best support the density-dependent theory of population control as it is described in the passage?
选项
A、As the number of foxes in Minnesota decrease, the growth rate of this population of foxes begins to increase.
B、As the number of woodpeckers in Vermont decreases, the growth rate of this population of woodpeckers also begins to decrease.
C、As the number of prairie dogs in Oklahoma increases, the growth rate of this population of prairie dogs also begins to increase.
D、After the number of beavers in Tennessee decreases, the number of predators of these beavers begins to increase.
E、After the number of eagles in Montana decreases, the food supply of this population of eagles also begins to decrease.
答案
A
解析
哪一个能支持密度决定论?密度决定论的内容,见原文L25~29,种群数增加,增长就会放慢,反之亦然。∴A正确,当一种狐狸数下降时,其种群增长速度会加快。B、C、D、E明显和原文论述相反或无关。
转载请注明原文地址:https://tihaiku.com/zcyy/3357530.html
相关试题推荐
Althoughheknewlittleaboutthelargeamountofworkdoneinthefield,hesuc
Fiftyyearsago,wealthypeoplelikedhuntingwildanimalsforfun______sightse
Young______heis,heknowswhatistherightthingtodo.A、thatB、asC、although
Althoughmultitaskingkidsmaybebetterpreparedinsomewaysfortoday’sfast-
Althoughthesebearsarestrongswimmers,theyarenomatchforlightningswift
这种疾病困扰着大多数以米饭为主食的东方人。ItdistressedlargenumbersofEasternpeoplewholivedmai
Althoughitisraininghard,______.A、TomstillwantstogooutB、andTomstill
Rabbitsarequietanimals,()theyareabletomake20differentsounds.A、howB、i
BythetimeIfinishedhighschool,myinterestinanimalshadgrown,anden
BythetimeIfinishedhighschool,myinterestinanimalshadgrown,anden
随机试题
Weenjoyfinefoodfromthefirsttastetothelast.Similarly,goodwriting
[originaltext]ThanksgivingDayisthemosttrulyAmericanofthenationalHolid
下列技术中,不属于现有技术的是()。A.在国外出版物上公开发表的技术 B.
对于《政府核准的投资项目目录》以外的企业投资项目,实行( )。A.核准制 B
青霉素族分子结构中6-APA结构部分所具有共性的作用为A.鉴别阿莫西林 B.鉴
甲公司依据买卖合同,在买受人乙公司尚未付清全部货款的情况下,将货物发运给乙公司。
阅读材料回答下列问题:下面是某求助者的WAIS.RC的测验结果: 从测验结
乙醇中毒发生惊厥者可酌用A.苯甲酸钠咖啡因 B.苯巴比妥 C.呋塞米 D.
给水处理构筑物包括()清水池等。A.混凝沉淀池 B.澄清池 C.过滤池
某开发商在一大型商场项目的开发建设中,违反国家规定,擅自降低工程质量标准,因而造
最新回复
(
0
)