Understanding Population Dynamics Chapter 19 Objectives Describe how populations are measured and how populations change Compare the exponential model and the logistic model of population growth. Explain how change in population density is affected by emigration, immigration, birth rate, and death rate

Properties of Populations Section 1 Understanding Populations Chapter 19 Properties of Populations Population- group of organisms that belong to the same species and live in a particular place at the same time. Populations can be measured in terms of: Size -Growth rate Density -Age Structure Dispersion -Survivorship

Chapter 19 Population Size Section 1 Understanding Populations Chapter 19 Population Size Population’s size = number of individuals in a population Population Density Population Density = how crowded the population is. High Density Low Density

Population Dynamics:How a population can be represented… Section 1 Understanding Populations Chapter 19 Population Dynamics:How a population can be represented… Age Structure A population’s age structure indicates the percentage of individuals at each age.

Population Growth Rate Section 2 Measuring Populations Chapter 19 Population Growth Rate Growth rate of a population is the amount by which a population’s size changes in a given time. Birth rate - death rate = growth rate Or find percentage….

Section 2 Measuring Populations Chapter 19 Objectives Compare the exponential model and the logistic model of population growth.

Chapter 19 The Exponential Model Section 2 Measuring Populations Chapter 19 The Exponential Model Exponential model= continual population growth at a steady rate The model assumes constant birth and death rates and no immigration or emigration. *Immigration=current individuals leave area ex.England to U.S.A *Emigration=new individuals move into area ex.U.S.A from England

Chapter 19 The Logistic Model Section 2 Measuring Populations Chapter 19 The Logistic Model Logistic model= birth rates fall and death rates climb as the population grows because the population reaches its carrying capacity. Carrying capacity = the number of individuals the environment can support is reached, population growth becomes stable.

Two Population Growth Models Section 2 Measuring Populations Chapter 19 Two Population Growth Models

Follow-Up: How do birth rate, death rate, emigration and immigration affect population density? Which model (exponential or logistic) does the human species follow? What do you think causes a population to reach its carrying capacity?