How do communities change over time? Population Growth How do communities change over time?

Say Something… Groups of 2, 3, or 4…spread out…face each other! Chunk/Divide up the text. Decide how to read (Independently? Aloud? Take turns?) Begin. When it’s your turn to “say something” do one of the flowing using the discussion stems provide: Make a prediction Ask a question Clarify something you misunderstood Make a comment Make a connection Say Something…

Population growth called EXPONENTIAL GROWTH Populations will grow until they reach their biotic potential, unless they are limited by factors in the environment This type of growth is known as a J-curve

Exponential Growth (J-curve) As a population gets larger it also grows faster. Resources (food, water, space) are unlimited and plentiful.

Population growth called LOGISTIC GROWTH As resources (called limiting factors) become scares, the population growth will slow. This type of growth is known as a S-curve.

Logistic Growth (S-curve) Population growth eventually slows/stops and stabilizes when it reaches its carrying capacity Resources (food, water, space) are scarce and in limited supply.

Logistic Growth Occurs when a population’s growth slows or stops following a period of exponential growth As resources become less available, the growth of a population slows or stops

Population growth Carrying capacity is defined as the number of individuals an environment can support.

Population growth Limiting factors in the environment help to maintain ecosystem stability by allowing populations to fluctuate around the carrying capacity. This is called dynamic equilibrium.

What is the CARRYING CAPACITY of the deer on WallaWalla Island?

LIMITING FACTORS A limiting factor is a factor that causes population growth to decrease. 2 TYPES: Density-Independent Density-Dependent

DENSITY – DEPENDENT LIMITING FACTORS DDLFs are resources that have greater effects as the population size/density increases.  Affects larger population sizes/densities

EXAMPLES of DENSITY – DEPENDENT LIMITING FACTORS Availability of Food Availability of Water Availability of Space Competition Disease Predation Migration

DENSITY – INDEPENDENT LIMITING FACTORS Resources/factors that affect all populations, regardless of the population density (size).

DENSITY – INDEPENDENT LIMITING FACTORS Resources/factors that affect all populations, regardless of the population density (size). Affects all population sizes/densities.

EXAMPLES of DENSITY – INDEPENDENT LIMITING FACTORS Natural Disasters (floods, hurricanes, earthquakes, tornadoes, forest fires, etc.) War and Human Activities Weather (drought) Temperature (frost)

Practice! Complete the practice worksheet (both sides). Finish for Homework