Population+Growth+Curves

= = = Amazing 5.1 Growth Curves = = = =Exponential Growth=

 **Exponential Growth** []
 * ======Exponential growth occurs when the individuals in a population reproduce at a constant rate. C.B. ======
 * If an animal has enough space, food and is protected then organisms in that population will multiply. C.B.
 * If bacteria constantly reproduced at its rate of 20 minutes each time then it would cover the planet in only a few days. C.B.
 * The exponential growth pattern is in the shape of a j like the picture below. C.B.
 * Accelerated birth rate and slowed death rate is the main factors that control exponential growth. E.S.
 * As a population grows, there are more organisms to reproduce so the population grows exponentially. E.S.


 * Example:** If a population of mice lived in an area with plentiful food, space, and no predators they would keep reproducing at a steady rate and the population would increase dramatically. C.B.

For a Youtube video on exponential growth click on the link below. It has a good overview of all the important information on Exponential growth. C.B.

[|http://www.youtube.com/watch?v=W2rTQpdyCFQ]

exponential growth below []

= Logistic Growth =


 * Logistic Growth**
 * It occurs when a population's growth slows or stops following a period of exponential growth. After a while, exponential growth in the population begins to slow down but not necessarily stop. C.B.
 * As resources in a population become less available the growth of the population slows or stops. C.B.
 * Population growth may slow down when birth rate decreases or the death rate increases. It may also occur when immigration decreases. C.B.
 * Even when the population growth is said to stop it still raises and lowers. C.B.


 * Example:** As the population of a group of deer grows, there will be less food in the area and there will be more competition. Because of this, the birth rate will decrease and the death rate will increase. J.A.

When exponential growth occurs, the organisms are not killed by disease or starvation. Although, in most populations, food and disease become an issue when there are too many organisms in that population. There is a limit to the number of organisms the environment can support. Ecologists refer to this as the **carrying capacity** of the environment. Logistic growth is often found in this kind of environment. J.A.

[]

logistic growth below [] > == = = =Carrying Capacity=

> > = = 
 * the max pop. size the environment can support without damage to the ecosystem.**
 * Carrying Capacity**
 * There are many factors in the world that can slow down the growth of a population. C.B.
 * Based on the Lotka-Volterra equation, predator populations can shrink due to famine. E.S. [|see model of Lotka-Volterra equation]
 * <span style="color: rgb(0,128,0);">When there are more predators, there are less prey and vice-versa. E.S.
 * <span style="color: rgb(0,128,0);">The amount of life the land can support is its carrying capacity usually determined by resources such as food. E.S.
 * Example:** If there is a large population of people in one area, there will only be enough food and other resources for a certain amount of people to survive. The amount of people that an environment can support is called its carrying capacity. J.A.

carrying capacity below Purple reflects realistic population count, Blue is ideal. [|http://carrier.pbwiki.com/f/carrying%20capacity.gif]

Group Members: Chris Blanchard: Book souce Eric Shi, Jeremy Adams: Out of book sources.