Chapter 3-1-Population-liu Dandan 环境生态学英文版本课件

The Patterns of Space Utilization
The Allee law
➢ Gregarious animals have an advantage on the survivor, therefore, they enjoy a low mortality rate.
➢ Population has its own proper density, less than or more then that value would cause an inhibiting influence to their existence.
➢ Pyramid shape is rapid growth, many young (Rwanda) ➢ Kettle(壶) shape is declining population (Hungary) ➢ Rectangular shape is zero growth, stable population
the mean(m) and variance(方差)
S2 (Xi)2 Xi 2/n n1
sample size
Population variance
Numbers of sample
if s2/m =0, then regular distribution if s2/m =1, then random distribution if s2/m≥1, then clumped distribution
The Patterns of Space Utilization
➢ Dispersing Utilization: Individuals, maybe families, get gather in a tiny space (realm), additionally, there are no other individuals of the same species living at the same time. It prevails at animals, e.g. panda, 3.9-6.4km2
Population Ecology
What Is Population Ecology?
Concept of Population ecology ➢The science that describes how and why
populations change
➢Populations may stay the same, increase, or decrease
➢ Maximum Birth rate: The birth rate of one population merely restrained by its physical factors is out of control of any type of limiting factors, namely, access to abundant resources.
A static life table: to record the age at death of a large number of individuals. Or from the age distribution, consisting of the proportion of individuals of different ages within a population.
A cohort life table: The most reliable way is to identify a large number of individuals that are born at about the same time and keep records on them from birth to death. (However…)
Life-history Traits from Life Table
➢ Survivorship curve: Type I , Type II , Type III
Proposed by Deevey (1947), plotting age on the X-axis and lg(survivors) on the y-axis creates a survivorship curve
What Are Characteristics for Population?
Population in Nature
➢ Gray Whales rounding the point of land on their way feeding grounds off the coasts of Alaska and Siberia in which the calves(仔) were born. They travel a distance of about 18,000km with the entire population of over 20,000 gray whaerns
Why Different Types?
Recognize Different Patterns
The first step toward testing statistically between these three
types of distributions is to sample the population to estimate
Population Dynamics
Basic Population Ecology Attribute
Birth rate & Death rate
➢ Birth rate: GBiertnherraaltley mreefearnsstothteheabailviteyraogfereapbriolitdyuoctfiorenpfroordpuecrtion for fNeeaamcrhraoliewn.dlyivmideuaanlss irnatoioneofpothpeulnautimonberar tohfeyrotuhnang bpoarrtnlyout of tcheertagirnosnsuimnboenres poof pinudlaivtiidouna. ls’ attribute.
What Are Characteristics for Population?
We can characterize individual populations in terms of there…
➢ Size (average vs. variation) ➢ Density (impacts on size; density dependence) ➢ Patterns of Dispersion ➢ Demographics (age structure, sex ratios) ➢ Rates of growth (or decline) ➢ Limits on population growth
Distribution : a description of how organisms are
distributed within their community. ➢Climate, topography and all kinds of the physical environment may limit the distribution of a population ( Natural Selection).
Common Characteristics for Population
Density : the measure of how crowded organisms are
in their environment.
➢Because organisms compete for resources, keeping a balance is important. ➢If the population is too high, some organisms will die. ➢Population density declines with increasing organism size.
Population Dynamics
Population Statistics Parameters
Age Distribution (Structure)
➢ distribution of males and females in each age group of a population
➢ used to predict future population growth ➢ Individuals are categorized by three physical phrase:
➢ Aggregating Utilization: Individuals aggregate in areas where the environment is favorable, What might be the pattern of distribution in all kinds of species.
➢ Mortality curves: show how quickly individuals die. ➢ life Expectancy: ex is known as the average lifetime to
(b)Monarch butterflies fly thousands of kilometers from the Rocky Mountains to reach their winter roost(栖木）.
(a) The populations of gray whales migrate from subtropical waters off Baja California to the Arctic and back again.