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
2023-11-16
37
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 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.
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.
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,句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,因此选项D为本题答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3193130.html
相关试题推荐
Whatcanweinferfromthepassage?[br][originaltext]Animalsperformman
Whatcanweinferfromthepassage?[br][originaltext]Animalsperformman
Whatcanweinferfromthepassage?[originaltext]Animalsperformmanyusef
Ifyoukeepgettingwrongnumbers,yourphonecouldbe_______.A、deceptiveB、def
Whatarethewaysanimalscommunicate?[br][originaltext]Whenwethinkof
Whatarethewaysanimalscommunicate?[br][originaltext]Whenwethinkof
Biologically,thereisonlyonequalitywhichdistinguishesusfromanimals
Biologically,thereisonlyonequalitywhichdistinguishesusfromanimals
Biologically,thereisonlyonequalitywhichdistinguishesusfromanimals
Sick______shewas,shehastopreparefoodforthewholefamily.A、althoughB、as
随机试题
[originaltext]TheAmericanAcademyofPediatricsrecentlyadvisedparentst
按通风系统的作用范围分类,下图所采用的是何种通风方式,该通风方式的工作原理及特点
下列哪项是扩张型心肌病的主要病理特征A.左心室或双心室扩张,室壁多变薄,有收缩功
关于五味说法,下述错误的是A.是药物作用规律的高度概括B.是部分药物真实滋味的具
接触性皮炎使用糖皮质激素治疗各种疾病,请选择剂量与治疗法A.大剂量突击疗法B.小
自评价工作方案的内容应包括()。评价范围$;$评价任务$;$组织
(2016年真题)列入第二类精神药品管理的是A.复方甘草片 B.含可待因复方口
治疗病毒性乙型肝炎的一线药物是()A.利巴韦林 B.依非韦伦 C.阿昔
常用于牙髓失活的药物是A.氯亚明 B.甲醛甲酚 C.呋喃西林 D.多聚甲醛
对某项目进行单因素敏感性分析时,选取了两个不确定因素Y1和Y2,分析指标为财务内
最新回复
(
0
)