PopulationsChapter 5

Determined by◦ Births◦ Deaths◦ Migration

Population Growth

Under ideal conditions populations grow exponentially.

Exponential Growth

Under real conditions populations experience logistic growth.

Limiting factors cause a population to maintain a certain size = carrying capacity

Logistic Growth

Both biotic and abiotic factors limit the growth of populations.◦ Competition◦ Predation◦ Parasitism and disease◦ Unusual weather◦ Natural disasters◦ Seasonal cycles◦ Human activities

Limits to Growth

Growth of Aphids

Exponential growth

Steady populationsize

Peak populationsize

Rapid decline

Steady populationsize

Section 5-2

A Density-Dependent Limiting Factor

Competition

Predation

Still exponential. Advances in agriculture, medicine, industry

and sanitation have improved survival rates.

Human Population Growth

Agriculturebegins

Plowingand irrigation

Bubonicplague

IndustrialRevolutionbegins

Section 5-3

Human Population Growth

Human Population Growth

Estimated to be 9 billion. What will happen when we reach earth’s

carrying capacity?◦ War, famine, pandemics

http://www.peterrussell.com/Odds/WorldClock.php

Earth’s Carrying Capacity