Unit 7 Concept 3- Population Ecology

Population

A group of organisms of the same species living in the same place.

Population Density

Measures the number of individual organisms living in a defined space.

Survivorship Curve

A graphic representation of mortality patterns.

Type I Survivorship Curve

Late loss; heavy parental care; Ex. Humans.

Type II Survivorship Curve

Constant loss; mortality unaffected by age; Ex. Some birds, rodents.

Type III Survivorship Curve

Early loss; produce lots of offspring at once and many die right away; Ex. fish, mosquitoes.

Population Dispersion

The spatial distribution of organisms in a population.

3 types of dispersion

clumped, uniform/even, random

Population Growth

The increase in the number of individuals in a population.

Exponential Growth

Population grows without limit. ex: humans

Logistic Growth

Population grows quickly at first and then levels off. ex: most natural species (fish, rabbits, trees)

Carrying Capacity

The theoretical maximum population that a given environment could support.

Limiting Factors

Aspects of the environment that limit the size a population can reach.

Density-Dependent Limiting Factors

Factors that have a bigger impact on more dense populations. Factors that are triggered by an increase in population size.

Density-Independent Limiting Factors

Factors that regulate population growth regardless of its size or density. All species are affected equally.

Examples of Density-Dependent Factors

Competition, Predation, Parasitism, Disease.

Examples of Density-Independent Factors

Weather changes, pollution, natural disasters.

Biotic Limiting Factors

Living factors that limit population size. ex: predators, food supply

Abiotic Limiting Factors

Nonliving factors that limit population size. weather, temperature

What affects population density?

birth and immigration (high density), death and emigration (low density)