首页
登录
职称英语
(l)Although numbers of animals in a given region may fluctuate from year to
(l)Although numbers of animals in a given region may fluctuate from year to
游客
2024-09-15
11
管理
问题
(l)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] According to the Wynne-Edwards’ theory, epideictic behavior displays serve the function of_____.
选项
A、determining roosting aggregations
B、locating food
C、attracting predators
D、regulating sexual activity
答案
D
解析
细节题。末段首句是一个长难句,旬末的结果从句表明生物体类似社会或传播行为的信号的功能,选项D表达了相同的功能,因此选D。
转载请注明原文地址:https://tihaiku.com/zcyy/3758652.html
相关试题推荐
AlthoughIndonesiagovernmentandseparatistrebelsagreed_____aftertheIndia
[originaltext]W:Frank,wejustgotoursalesfiguresinandthenumbersareve
[originaltext]W:Frank,wejustgotoursalesfiguresinandthenumbersareve
[originaltext]W:Frank,wejustgotoursalesfiguresinandthenumbersareve
Althoughourbosshadbeensounkindtous,weheapedcoalsoffireonhis______
Althoughourbosshadbeensounkindtous,weheapedcoalsoffireonhis______
[A]school[B]numbers[C]emphasize[D]continue[E]significant[F]undoubtedly[
[A]school[B]numbers[C]emphasize[D]continue[E]significant[F]undoubtedly[
[A]school[B]numbers[C]emphasize[D]continue[E]significant[F]undoubtedly[
[A]school[B]numbers[C]emphasize[D]continue[E]significant[F]undoubtedly[
随机试题
Acommonassumptionabouttheprivatesectorofeducationisthatitcater
Whichofthefollowingsentenceshasanobjectcomplement?A、Jane’sclassmatesma
Highstreetshopsuseavarietyofmeanstoattractshoppers,suchasstriki
Pleasepardon______you.A、mydisturbingB、disturbingC、metodisturbD、thatId
患者,男,2006年大学毕业,同年5月右腿麻木,8月左腿也麻木,9月出现行走困难
关于管道施工作业队伍要求,不正确的是( 。 A、施工单位应取得相应的施工资质
女患者,14岁,癫痫病史2年,现服用丙戊酸钠进行抗癫痫治疗,最近症状控制不佳来做
下列关于投标文件提交的说法中,正确的是()。A.投标文件一经寄出,即具有法律效
(2013年真题)依据《安全生产法》的规定,安全生产监管部门有权依法对生产经营单
根据《民事诉讼法解释》的规定,人民法院确定举证期限,第一审普通程序案件不得少于(
最新回复
(
0
)