Lecture 19. Population Growth

Populations change due to…

Births, migration, ageing, & death

B

Births

D

Deaths

r

Per capita growth rateC

K

Carrying capacity

E

Emigration

I

Immigration

N

Population size

r equation

B - D

Exponential growth rate example

European rabbit population in Australia

Exponential growth equation

rN

Exponential growth model assumes…

Ideal environment with unlimited resources

Logistic growth equation

rN((K-N)/K)

Carrying capacity (K)

Maximum average population size that can be sustained by limited resources of an environment

Logistic growth example

Two species of paramecia

Logistic growth model

Limiting factors eventually slow population growth

Competition is very slow when…

Population size is small

Limiting factors

Factors that limit population growth

Carrying capacity can increase for a population if…

Resources increase - may lead to range expansion