Population Ecology

4-1: Population DynamicsPopulations are described as follows:

DensitySpatial distributionGrowth rate

Would an individual be considered a population?

Population CharacteristicsPopulation density – number of organisms

per unit of areaSpatial distribution

Dispersion (availability of resources is the most important factor) Uniform Clumped groups Random

Which of these dispersion types would be the easiest to predict?

Population ranges

Only certain areas an organism can be located (i.e. Iiwi vs. Peregrine Falcon)

A species might not be able to expand its population range because it cannot survive the abiotic conditions found in the expanded region.

Is it possible for a population to grow unchecked in size?

Population – Limiting FactorsDensity-independent factors

Population size does NOT matterUsually abioticEx. Weather

Density-dependentPopulation size does matterUsually bioticDisease, parasites & competition

Disease – outbreaks can be transmitted faster between individuals

Competition – when food and space become limited – fights will break out

Parasites – similar to disease

Population Growth RateNatality vs. Mortality (most important)

Emigration vs. Immigration

Exponential growth model (geometric growth)No limitsLag phase (slow at beginning)J shaped curve

Logistic Growth ModelS shaped curveIncludes carrying capacity (population that can

be supported by resources

Reproductive PatternsR-strategists

SmallShort life spansMany offspringLittle to no energy spent on offspringAn adaptation to unstable environments

Reproductive PatternsK-strategists

LargeLong life spansNot many offspringLots of energy spent on offspringAn adaptation to stable environments

--Carrying capacity demonstration

4-1 HOMEWORKPretend you are living in the 16 and 17 hundreds.

Create an advertisement (possible group of two) urging American settlers to move westward using knowledge gained from the section. Be creative!!

Using the 3 dispersion patterns – find organisms that are defined by each and explain why.

Create a comic strip from the perspective of any r-strategist

Give me a real world example of a density-independent factor and a density-dependent factor. Research this – none from discussion or book allowed.

Section 2: Human Population

Human Population GrowthDemography – size, density, distribution,

movement, birth & death ratesWorld population expected to double in about

53 years

http://www.pbs.org/wgbh/nova/worldbalance/

Technological advancesWe have learned to alter our environment to

change carrying capacityHuman population growth rate

Although raising in overall population, the percent of increase is dropping Diseases such as AIDS Voluntary population control

Trends in Human Population GrowthDemographic transition (U.S. good example)Zero population growth

Births + immigration = deaths + emigrationAge structure

Pre-reproductive (0-20)Reproductive (20-45)Post-reproductive (45 – 80+)

Human Carrying Capacityhttp://www.footprintnetwork.org/en/index.php/GFN/page/calculators/

Trends in Human Population GrowthDemographic transition (U.S. good example)

4-2 HomeworkComprehension sentences for the chapter –

due on day of testPersonal feeling about human population

growth worldwide using at least 5 terms from the chapter