Chapter 5 Populations 5-1 How Populations Grow page 119 Review Worksheet 5-1

Bell Work Review the two graphs in figure 5-3 on page 121 How are the graphs alike? How are the graphs different?

Bell Work Review Same- Both plot time on the Horizontal axis and the number of organisms on the Vertical axis. Both are J shaped Different- The size of the population hundreds of thousands vs. millions and time hours vs. years What do these differences indicate? Bacteria reproduce very rapidly in a short period of time while elephants reproduce much more slowly over a long period of time.

5-1 Key Concepts What characteristics are used to describe a population? What factors affect population size? What are exponential growth and logistic growth?

Characteristics of Populations Several terms can be used to describe a population in nature: The four main terms, or characteristics, of a population are a. geographic distribution b. density c. growth rate d. age-structure

Characteristics of Populations What is a population’s Geographic Distribution? Geographic Distribution describes the area inhabited by a population. Another term Is Range

Characteristics of Populations What is population density? It is the number of individuals per unit area Population Density = Number of Individuals --------------------------------------- Unit Area

Characteristics of Population Population Density

Population Growth Populations can grow rapidly Populations can decrease in size Populations may stay the same from year to year

Population Growth What are the three factors that can affect population growth? Number of births Number of deaths Number of individuals that enter or leave the population

Population Growth If more individuals are born than die in any period of time, how will the population change? Population will grow

Changes in Population Immigration – Population movement into an area Results in population growth They may immigrate to find a mate or find food

Changes in Population Emigration Movement of a Population Out of an Area EXIT Results in Population Decrease

Exponential Growth How will a population change if there is abundant space and food and if the population is protected from predators and disease? The organisms will multiply and the population size will increase

Exponential Growth When does exponential growth occur? When the individuals in a population reproduce at a constant rate Under ideal conditions Absence of Predation or Disease

Exponential Growth What are three ways that a growth rate may be stated, or expressed? It may be stated as doubling time, a birthrate per female, or a percentage of growth per year.

Exponential Growth

Logistic Growth Exponential Growth Does not continue in natural populations for very long When resources become less available, how does population growth change? It slows or stops

Logistic Growth When does logistic growth occur? When a populations growth slows or stops following a period of exponential growth A populations growth will slow down when: the birthrate and death rate are the same the rate of immigration and emigrate are equal

Logistic Growth A populations growth will slow down when The birth rate is ______________ down The death rate is ______________ up When immigration is ____________ When emigration is ______________

Carrying Capacity What is the carrying capacity of the environment for a particular species? It is the largest number of individuals that the given environment can support.

Population Growth J shape vs. S shape

Carrying Capacity Overshoot – What is the carrying capacity for this population?

Exit Ticket What factors might cause the carrying capacity of a population to change?