Ecology NotesEcology Notes

Can’t we all just get along?Can’t we all just get along?

Population DensityPopulation Density

The total number The total number of individuals living of individuals living in a specific areain a specific area

Example Example person/km2person/km2

Population DistributionPopulation Distribution

RandomRandom

ClumpedClumped

UniformUniform

Gains and Losses in Population Gains and Losses in Population SizeSize

Immigration- Organisms that move Immigration- Organisms that move into a populationinto a population

Emigration- Organisms that move Emigration- Organisms that move out of a populationout of a population

Gains and Losses in Population Gains and Losses in Population SizeSize

Mortality-similar to death rate; the Mortality-similar to death rate; the number of organisms that have diednumber of organisms that have died

Natality- birth of organismsNatality- birth of organisms

Population growthPopulation growth

How would you calculate growth rate How would you calculate growth rate of a population?of a population?

Immigration – emigration + births - deathsImmigration – emigration + births - deaths

Exponential Growth/Doubling TimeExponential Growth/Doubling Time Exponential = Growth Exponential = Growth

that occurs very rapidly that occurs very rapidly ppxx

Doubling time = time it Doubling time = time it takes for a population to takes for a population to double “rule of 70”double “rule of 70”

All populations go All populations go through an exponential through an exponential growth stage but some growth stage but some rely on it and are called rely on it and are called r-selected life strategistsr-selected life strategists

Biotic PotentialBiotic Potential The rate at which a population could grow The rate at which a population could grow

if nothing was holding it back, no limitsif nothing was holding it back, no limits

What are the limits or “Limiting factors” What are the limits or “Limiting factors” – space, light, water, nutrients, and shelterspace, light, water, nutrients, and shelter

Carrying CapacityCarrying Capacity

The maximum limit a population can The maximum limit a population can hold in a given environment.hold in a given environment.

Most organisms Most organisms

follow this and it follow this and it

is called a is called a

k-selected life k-selected life

strategystrategy

How Density Relates to FactorsHow Density Relates to Factors Density Dependent FactorsDensity Dependent Factors

– Factors that come into effect with population Factors that come into effect with population sizesize

Populations will grow to their capacity but are Populations will grow to their capacity but are dependent upon outside factorsdependent upon outside factors

– Food, water, space, sunlightFood, water, space, sunlight

Density Independent FactorsDensity Independent Factors– Factors that come into play regardless of Factors that come into play regardless of

population sizepopulation size Natural disasters (hurricane, flood, volcano) warNatural disasters (hurricane, flood, volcano) war

Where would disease fit? Where would disease fit?

Life History PatternsLife History Patterns Type IType I

– Humans / ElephantsHumans / Elephants– Few offspring/life longerFew offspring/life longer

Type IIType II– Jellyfish / BirdsJellyfish / Birds– Constant Death rateConstant Death rate

Type IIIType III– Oysters / Plants / InsectsOysters / Plants / Insects– High offspring-few live to High offspring-few live to

reproducereproduce

How did we get so big?How did we get so big?

What will happen in the future?What will happen in the future?

Density Dependent Factors?Density Dependent Factors?

Density Independent?Density Independent?