POPULATION POPULATION DENSITYDENSITY

NUMBER OF INDIVIDUALS PER NUMBER OF INDIVIDUALS PER UNIT AREAUNIT AREA

POPULATION POPULATION CHARACTERISTICSCHARACTERISTICS

Geographic Geographic distributiondistribution

DensityDensity Growth rateGrowth rate Age StructureAge Structure

POPULATION GROWTHPOPULATION GROWTH

Number of birthsNumber of birthsBirth rate>Death rate (increase)Birth rate>Death rate (increase)Birth rate=Death rate (same size)Birth rate=Death rate (same size) Number of deathsNumber of deathsBirth rate<Death rate (decrease)Birth rate<Death rate (decrease) Number of individuals entering Number of individuals entering

(immigration)(immigration) and leaving and leaving (emigration)(emigration) populationpopulation

WORLD BIRTH/DEATH WORLD BIRTH/DEATH RATESRATES

Which continent is Which continent is having greatest having greatest population growth?population growth?

What is the population What is the population growth rate of the growth rate of the United States?United States?

Correlation between Correlation between birth and death rates in birth and death rates in particular parts of the particular parts of the worldworld

COMPARING COMPARING BIRTH/DEATH RATESBIRTH/DEATH RATES

Developing countries haveDeveloping countries have high birth rateshigh birth rates

High birth rate: High birth rate: Expectation that some will Expectation that some will die because of the high die because of the high infant mortality rate infant mortality rate

Help in looking after the Help in looking after the farm farm

Care for parents if they Care for parents if they become old or sick; there become old or sick; there may not be a old age may not be a old age pension scheme pension scheme

Shortage of family planning Shortage of family planning facilities and advicefacilities and advice

COMPARING COMPARING BIRTH/DEATH RATESBIRTH/DEATH RATES

Developed countries have Developed countries have low birth rateslow birth rates

Expensive to look after Expensive to look after large families large families

More women prefer to More women prefer to concentrate on careers concentrate on careers

Women have more Women have more control over their own control over their own fertility fertility

Ready availability of Ready availability of contraception and contraception and family planning advice family planning advice

EXPONENTIAL GROWTHEXPONENTIAL GROWTH

Reproduction of a Reproduction of a population at a population at a constant rateconstant rate

Initial slow growthInitial slow growth Exponential growth Exponential growth

would continue under would continue under ideal conditions with ideal conditions with unlimited resourcesunlimited resources

Bacteria colonyBacteria colony growthgrowth

J CURVE

LOGISTIC GROWTHLOGISTIC GROWTH

Growth slows/stopsGrowth slows/stops following a period of following a period of exponential growthexponential growth

Graph is Graph is S-shapedS-shaped Point of graph where it Point of graph where it

levels off (roughly zero levels off (roughly zero growth) is the growth) is the carryingcarrying capacitycapacity (largest number (largest number of individuals of individuals environment can environment can support)support)

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1200 penguins at beginning of year1200 penguins at beginning of year

1600 penguins at end of year1600 penguins at end of year

WHAT WAS POPULATION GROWTH?WHAT WAS POPULATION GROWTH? During year 250 penguin chicks diedDuring year 250 penguin chicks died

WHAT WAS POPULATION GROWTH?WHAT WAS POPULATION GROWTH? During same year, 220 adults diedDuring same year, 220 adults died

WHAT WAS POPULATION GROWTH?WHAT WAS POPULATION GROWTH?

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Define and/or describe how the following factors affect the size of a population::birth rate): b. mortality (= death rate): c. growth rate: d. immigration: e. emigration:

Briefly describe exponential growth and what it looks like when graphed.

Briefly describe logistic growth, and what it looks like when graphed. Define carrying capacity and describe how it affects logistic growth

LIMITS TO GROWTHLIMITS TO GROWTH

Factors that cause Factors that cause population growth to population growth to decreasedecrease

Density-dependent Density-dependent factorsfactors

--competition--competition --predation--predation --parasitism--parasitism --Disease--Disease

Density-Dependent Density-Dependent FactorsFactors

Strongly affect a large, Strongly affect a large, dense population, dense population, NOT NOT small, scattered small, scattered populationspopulations as greatly as greatly

CompetitionCompetition --food/water--food/water --space--space --sunlight--sunlight Larger populations use Larger populations use

up available resources up available resources faster than smaller onesfaster than smaller ones

Density-Dependent Density-Dependent FactorsFactors

PredationPredation Prey population Prey population

decreases over timedecreases over time Predator decline will Predator decline will

soon followsoon follow Lag time between Lag time between

decline an risedecline an rise

Density-Dependent Density-Dependent FactorFactor

Parasitism-DiseaseParasitism-Disease

Density-Independent Density-Independent FactorsFactors

Affect all populations in similar ways, Affect all populations in similar ways, regardless of sizeregardless of size

Unusual weather, natural disasters, Unusual weather, natural disasters, seasonal cycles, human activitiesseasonal cycles, human activities

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Identify as density-dependent or density-Identify as density-dependent or density-independent:independent:

--flood--flood

--lack of food source--lack of food source

--clear cutting forests--clear cutting forests

--predation--predation

--parasitism--parasitism

Human Population Human Population GrowthGrowth

DemographyDemography: scientific study of human : scientific study of human populationspopulations

Age StructureAge Structure DiagramsDiagrams: Show population by : Show population by age and gender groupsage and gender groups

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Why might a contagious virus that causes a fatal Why might a contagious virus that causes a fatal disease be considered a density-dependent limiting disease be considered a density-dependent limiting factor?factor?

Using the age-structure, describe the population Using the age-structure, describe the population demographic transition of Sweden.demographic transition of Sweden.