4.1- Population Dynamics [part 1]

SPI 2 Interpret the relationship between environmental factors and fluctuations in population size.

Goals: Understand how density, distribution, and range define populations, and become familiar with population limiting factors

Joke of the day

• Why don't aliens eat clowns?

Because they taste funny.

Population Attributes• Population Density:

– The number of organisms per unit of area.

Population Ranges

• Population Ranges– The range that populations of certain species

can live depends on their adaptability to the abiotic and biotic factors of other habitats.

Kiwi Bird in New Zealand Cows everywhere

Population Attributes

• Spatial Distribution:

– How a population is spread out over an area; where they can be found

• Random

• Uniform

• Clumped

Unpredictable b/c of resources: White-tailed Deer

Herds: Bison, Cows

Territorial animal: bear

Population Limiting Factors• Density-independent

– Any factor in the environment that DOES NOT depend on the population density• Usually abiotic Natural Disasters• Human Activity Dams, Clear-cutting, air

pollution

• Density-dependent

– Any factor that DOES depend on the population density

• Often biotic predation, competition, disease, parasites

• Predation…wolf and moose populations

• Competition…– When density increases, competition

increases as there is less resources to go around

– Food, space…etc.

• Disease…population density matters! How often have you gotten sick in the first few weeks back to school?

• Parasites- like disease, parasites spread easily in larger populations