首页
登录
职称英语
POPULATION ECOLOGY1 Population ecology is the science that
POPULATION ECOLOGY1 Population ecology is the science that
游客
2025-02-08
17
管理
问题
POPULATION ECOLOGY
1 Population ecology is the science that measures changes in population size and composition and identifies the causes of these fluctuations.
Population ecology is not concerned solely with the human population.
In ecological terms.a population consists of the individuals of one species that simultaneously occupy the same general area.rely on the same resources, and are affected by similar environmental factors.The characteristics of a population are shaped by its size and by the interactions among individuals and between individuals and their environment.
2 Population size is a balance between factors that increase numbers and factors that decrease numbers.Some factors that increase populations are favorable light and temperature,adequate food supply, suitable habitat, ability to compete for resources, and ability to adapt to environmental change.Factors that decrease populations are insufficient or excessive light and temperature, inadequate food supply, unsuitable or destroyed habitat, too many competitors for resources, and inability to adapt to environmental change.
3 An important characteristic of any population is its density.Population density is the number of individuals per unit, such as the number of maple trees per square kilometer in a county.Ecologists can rarely determine population size by actually counting all individuals within geographical boundaries.Instead, they often use a variety of sampling techniques to estimate densities and total population sizes.In some cases,they estimate population size through indirect indicators, such as the number of nests or burrows, or signs such as tracks or droppings.
4 Another important population characteristic, dispersion, is the pattern of spacing among individuals with the population’s geographical boundaries.Various species are distributed in their habitats in different ways to take better advantage of food supplies and shelter, and to avoid predators or find prey.Within a population’s
range
, densities may vary greatly because not all areas provide equally suitable habitat, and also because individuals space themselves in relation to other members of the population.
5 Three possible patterns of dispersion are clumped, uniform, and random.A clumped dispersion pattern means that individuals are gathered in
patches
throughout their habitat. Clumping often results from the irregular distribution of resources needed for survival and reproduction.For example, fallen trees keep the forest floor moist, and many forest insects are clumped under logs where the humidity is to
their
1iking.Clumping may also be associated with mating, safety, or other social behavior.Crane flies, for example, swarm in great numbers, a behavior that increases mating chances, and some fish swim in large schools so they are less likely to be eaten by predators.
6 A uniform or evenly spaced distribution results from direct interactions among individuals in the population.For example, regular spacing of plants may result from shading and competition for water.In animal populations, uniform distribution is usually caused by competition for some resource or by social interactions that
set up
individual territories for feeding,breeding, or resting.
7 Random spacing occurs in the absence of strong attraction or repulsion among individuals in a population.Overall, random patterns are rare in nature, with most populations showing a tendency toward either clumped or uniform distribution.
8 Populations change in size, structure, and distribution as they respond to changes in environmental conditions.Four main variables—births, deaths,
immigration
, and
emigration
—determine the rate of change in the size of the population over time.A change in the birth rate or death rate is the major way that most populations respond to changes in resource availability.Members of some animal species can avoid or reduce the effects of environmental stress by emigrating from one area and immigrating to another with more favorable environmental conditions, thus altering the population’s dispersion. [br] Which of the following is an indirect indicator of a population’s density?
选项
A、The distribution of food in a given area
B、The number of nests in a given area
C、The number of births in a given period of time
D、The number of individuals counted in a given area
答案
B
解析
The number of nests in a given area is an indirect indicator of a population’s density.Clues:...indirect indicators, such as the number of nests...(1.1)
转载请注明原文地址:https://tihaiku.com/zcyy/3947634.html
相关试题推荐
POPULATIONECOLOGY1Populationecologyisthesciencethat
POPULATIONECOLOGY1Populationecologyisthesciencethat
POPULATIONECOLOGY1Populationecologyisthesciencethat
POPULATIONECOLOGY1Populationecologyisthesciencethat
POPULATIONECOLOGY1Populationecologyisthesciencethat
POPULATIONECOLOGY1Populationecologyisthesciencethat
POPULATIONECOLOGY1Populationecologyisthesciencethat
POPULATIONECOLOGY1Populationecologyisthesciencethat
NarratorListentopartofalectureinacomputerscienceclass.
NarratorListentoaconversationbetweentwostudentsafterascience
随机试题
Thebossgavehimaraiseinsalarybecauseofhisexcellent(perform)______at
急性左心衰竭治疗下列哪种措施为主输液量过大A.吗啡 B.快速利尿 C.
假定某客户现有5万元的资金和每年年底1万元的储蓄,投资报酬率为3%,则下列理财目
下列各项,不属于目眩的临床意义是A.风热上袭 B.痰湿上蒙 C.肝火上炎
Thechangeinthatvillagewasmiraculou
截至2015年底,中国创业投资各类机构数已达1775家,同比增长14.4%。其中
以下有关行政的生效规则描述不正确的是( )。A.随时生效,行政行为一经作出即有
采用换填垫层法处理的地基,下列关于其地基承载力的确定或修正的说法中,正确的选项有
我国商业银行经过几年的管理实践,在资产分类方面已经积累了一定的经验,普遍采取以国
根据《房屋建筑和市政基础设施工程施工验收备案管理办法》,工程竣工验收合格后,负责
最新回复
(
0
)