PowerPoint Presentation

Population Dynamics

1 ObjectivesThe student will investigate and understand dynamic equilibrium within populations, communities, and ecosystems.

Key concepts include:

interactions within and among populations including carrying capacities, limiting factors, and growth curves;2Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. Population DynamicsPopulation: all the individuals of a species that live together in an area

Demography: the statistical study of populations, make predictions about how a population will change 3Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. 3 Key Features of PopulationsSize Density Dispersion (clumped, even/uniform, random) 4Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. 3 Key Features of Populations1. Size: number of individuals in an area

5Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. Growth RateBirth Rate (natality) - Death Rate (mortality)How many individuals are born vs. how many dieBirth rate (b) death rate (d) = rate of natural increase (r). 3 Key Features of Populations6Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. ImmigrationEmigrationNatalityMortalityPopulation++--Factors That Affect Future Population Growth7Population Dynamics

Addition of individuals to populationsRemoval of individuals from populations8 3 Key Features of Populations2. Density: measurement of population per unit area or unit volumeFormula: Dp= N

Pop. Density = # of individuals unit of space S9Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. Factors that Affect DensityImmigration- movement of individuals into a population

Emigration- movement of individuals out of a population 10 Factors that Affect DensityDensity-dependent factors- Biotic factors in the environment that have an increasing effect as population size increasesEx. disease competition parasites11Humans Are Not Exempt from Natures Population ControlsIrelandPotato crop in 1845

Bubonic plagueFourteenth century

AIDSGlobal epidemic

12 Factors that Affect DensityDensity-independent factors- Abiotic factors in the environment that affect populations regardless of their densityEx. temperature storms habitat destruction drought 13Density-Independent Factors (e.g., weather)

Good Times!(in Australia) 3 Key Features Populations3. Dispersion: describes their spacing relative to each other clumped even or uniform random 15Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

clumpedeven (uniform)random16Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

Clumped Dispersion of Population

Clumped dispersion implies some sort of cohesive force, e.g., either individuals seek other individuals out, or individuals are limited in where then can reside

Uniform Dispersion of Population

Uniform dispersion implies some sort of antagonistic interaction, e.g., either individuals actively repel other individuals

Random Dispersion of Population

Random dispersion implies a minimum of interspecific interactions that impact where individuals reside

Other Factors That Affect Population GrowthLimiting factor- any biotic or abiotic factor that restricts the existence of organisms in a specific environment.

EX.- Amount of water Amount of food Temperature20

Many organisms presentFew organisms presentFew organisms presentNoneNoneLimiting Factor- Zone of Tolerance21Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. Other Factors that Affect Population GrowthCarrying Capacity- the maximum population size that can be supported by the available resourcesThere can only be as many organisms as the environmental resources can support22Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. No Population Can Continue to Increase in Size Indefinitely

Biotic Potential = Intrinsic growth rate: Maximum potential for growth occurs where there is unlimited resources23Logistic Growth of a Sheep Population on the Island of Tasmania, 18001925

Oscillations about K (the carrying capacity)_24Exponential Growth, Overshoot, and Population Crash of a Reindeer

Irruptive Population Curve25Population Cycles for the Snowshoe Hare and Canada Lynx

Boom and Bust Population Curve262 Life History Patterns r Strategistsshort life span small body sizereproduce quickly have many young little parental care Ex: cockroaches, weeds, bacteria

272 Life History Patterns K Strategistslong life spanlarge body size reproduce slowly have few young provides parental care Ex: humans, elephants

28Idealized Survivorship curves

Survivorship Curves Three types of survivorship curveslate loss (Type I) Example: Humans constant loss (Type II) Examples: Birds, Fishearly loss (Type III) Example: Mice

How is Population Data Gathered? Births minus Deaths Immigration and Emigration 1,345 645= 700 natural increase Age structure Diagrams

Tag and Recapture

The Human PopulationDefine the following vocabulary a. Total fertility level b. Replacement level fertility c. Infant mortality rate d. Doubling time e. Zero population growthThe Human PopulationWho was Thomas Malthus and what did he predict?

Human Population Growthhttp://www.populationconnection.org/site/PageServer?pagename=issues_main

36Hyperlink to World Population Video

Human Population Growth

38-

http://www.ibiblio.org/lunarbin/worldpop

Growth RateWhat is the formula for finding natural increase (growth rate)?r = b dr = 26/1000 - 5/1000r = 0.026 0.005 = 0.021 0.021 X 100 = 2.1% per yearOR (the easy way)

r = 26/10 - 5/10 r = 2.6 - .5 = 2.1 or 2.1% per yearDoubling TimeRule of 70 determines the number of years it will take a countrys population to double.

Doubling time = 70/%growth rate Growth rate = 70/doubling time

Lets practice: A countrys growth rate is 1.5%. How many years will it take that countrys population to double? 70/1.5 = 46.7 years

How do population pyramids help us learn about population?

PRE-REPRODUCTIVEREPRODUCTIVEPOST-REPRODUCTIVE43

Population pyramids are used to show information about the age and gender of people in a specific country.MaleFemalePopulation in millionsIn this country there is a high Birth Rate

There is also a high Death Rate.This population pyramid is typical of countries in poorer parts of the world (LEDCs.)

In some LEDCs the government is encouraging couples to have smaller families. This means the birth rate has fallen.

MaleFemalePopulation in millionsIn this country the number of people in each age group is about the same.The largest category of people were born about 40 years ago.In this country there is a low Birth Rate and a low Death Rate.This population pyramid is typical of countries in the richer parts of the world (MEDCs.)

Population in millionsMaleFemaleIn this country the birth rate is decreasing.In the future the elderly people will make up the largest section of the population in this country.This is happening more and more in many of the worlds richer countries.

MaleFemalePopulation in thousandsThis country has a large number of temporary workers. These are people who migrate here especially to find a job.

Population pyramid for Mozambique.Population pyramid for Iceland.

What happens next?

What is going to happen to Japans population in the future?Why does this matter?

?

?

?You decide!

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58What is the Demographic Transition?The shift from high to low mortality and fertilityA sign of socio-economic progress?TimeNaturalincreaseBirth rateDeath rateNote: Natural increase is produced from the excess of births over deaths.59The shift from high mortality and fertility to low mortality and fertility is known as the demographic transition. It is based on the experience of Western Europe, in particular England and Wales.This model was first described by the American demographer Warren Thompson in 1929.In 1945, Frank W. Notestein further developed this theory and suggested that there was a relationship between population change and industrialization. A debate continues questioning if population growth must decline for economic development or if economic progress (or industrialization) leads to slower population growth.In light of this debate, the completion of the demographic transition has come to be associated with socioeconomic progress.

[FYI The factors that drive childbearing trendssuch as the economy, education, gender relations, and access to family planningare numerous and complex. These same factors are signs of socioeconomic development.]Demographic TransitionRead pages 210-211What is the definition of demographic transition?Identify the characteristics of each stage. Stage DescriptionFirst Stage Pre IndustrialSecond Stage -- TransitionalThird Stage -- IndustrialFourth Stage Post Industrial

Demographic Transition in Sweden and Mexico Sources: B.R. Mitchell, European Historical Statistics 1750-1970 (1976): table B6; Council of Europe, Recent Demographic Developments in Europe 2001 (2001): tables T3.1 and T4.1; CELADE, Boletin demografico 69 (2002): tables 4 and 7; Francisco Alba-Hernandez, La poblacion de Mexico (1976): 14; and UN Population Division, World Population Prospects: The 2002 Revision (2003): 326.

Births/Deaths per 1,000175061Compare the transitions between these two countries to the classic model.Why are the two countries so different? [A: The short answer is that Swedens transition occurred gradually over 150 years. Mexico experienced rapid declines in death rates due to rapid implementation of better health care and sanitation technologies. The result was that Mexicos population boomed during this period. It took time for the decline in birth rates to catch up. At the same time, this boom created its own momentum as all these new families have children of their own. Eventually Mexicos population will likely stabilize (or even shrink), but at a much greater overall population. This pattern was repeated in many nations in the 20th Century, fueling a global population explosion. However, were also seeing in several countries including Sweden birth rates have dropped below death rates leading to population decline in most of Europe, Japan, and some other nations.]