Chapter 5

 Determined by ◦ Births ◦ Deaths ◦ Migration

 Under ideal conditions populations grow exponentially.

 Under real conditions populations experience logistic growth.  Limiting factors cause a population to maintain a certain size = carrying capacity

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

Growth of Aphids Exponential growth Steady population size Peak population size Rapid decline Steady population size Section 5-2 A Density-Dependent Limiting Factor Competition

 Still exponential.  Advances in agriculture, medicine, industry and sanitation have improved survival rates.

Agriculture begins Plowing and irrigation Bubonic plague Industrial Revolution begins Section 5-3 Human Population Growth

 Estimated to be 9 billion.  What will happen when we reach earth’s carrying capacity? ◦ War, famine, pandemics  ck.php ck.php