Population Ecology

Population Group of individuals of a single species that occupy the same general area. Population density = number of individuals unit area The number of oak trees per square kilometer in a forest. The number of earthworms per cubic meter in forest soil.

Dispersion patterns Way individuals in a population are spaced within an area. Clumped Uniform Random

Clumped dispersion individuals are grouped in patches. Most common dispersion patter. Result of need for resources.

Uniform dispersion individuals are equally spaced in the environment Result of territorial behavior.

Random dispersion individuals in a population are spaced in an unpredictable way Least common dispersion pattern.

Survivorship curve A plot of the proportion of individuals alive at each age. Type I Type II Type III

Type I Survive to old age. Humans, large mammals Produce few offspring & provides good care.

Type II Likelihood of death constant throughout life. Lizards, rodents, birds.

Type III Low survival rate for the very young. Oysters, invertebrates, seed plants Produce large numbers of offspring, & little care.

Exponential Growth Model Gives an idealized picture of unregulated population growth. Bacteria, humans, rabbits

Limiting Factors Environmental factors that restrict population growth. Food, competition, space, predation