首页
登录
职称英语
(1)Although numbers of animals in a given region may fluctuate from year to
(1)Although numbers of animals in a given region may fluctuate from year to
游客
2024-08-31
9
管理
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. [br] 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://tihaiku.com/zcyy/3738169.html
相关试题推荐
Humanbehaviorismostlyaproductoflearning,______thebehaviorofanimalsd
_______,hesometimescannotstandthewayshesolvesproblems.A、Althoughmuch
Enginesaretomachines______heartsaretoanimals.A、thatB、whichC、whenD、wha
_______,hesometimescannotstandthewayshesolvesproblems.A、Althoughmuch
______,hesometimescannotstandthewayshesolvesproblems.A、Althoughmuchh
It’s______thecaseintheregion;astoryalwayssoundsclearenoughatadist
Someexpertsbelievethatuniversitiesshouldacceptequalnumbersofmalea
(1)Naturally,inagroupofanimalsasdiverseasthesnakes,andwithsoma
(1)Naturally,inagroupofanimalsasdiverseasthesnakes,andwithsoma
(1)Althoughnumbersofanimalsinagivenregionmayfluctuatefromyearto
随机试题
IntheUnitedStates,thefirstdaynurserywasopenedin1854.Nurseriesw
WhowontheWorldCup1994footballgame?WhathappenedattheUnitedNations?H
Clearly,the2.5%gapbetweenthemaleandfemaleunemploymentmakesforan
A.变大 B.变小 C.无变化 D.无法确定
地下低压燃气管道与污水、雨水排水管道之间的水平净距不应小于()m。A.1.0
过渡乳A.免疫球蛋白较多 B.总乳量增多,含脂肪量最高,矿物质逐渐增高 C.
下面四个成语或俗语中,()说的是典型的迁移现象。A.举一反三 B.聪明过人
下面有关公司设立方式的说法正确的是( )。A.发起设立适用于有限责任公司、股份
患者,女,13岁。右膝关节急性化脓性关节炎,抗生素治疗后3天,体温已恢复正常,以
电抗器接地体连接螺丝松动等引起接地体连接不良属于()(A)一般缺陷(B)重
最新回复
(
0
)