Ch 8 Populations Limits to Growth Identify density-dependent and density-independent limiting factors that affect populations in an ecosystem.

Video clip on Limiting Factors First, we are going to watch this quick video on limiting factors! Pay attention  http://www.youtube.com/watch?v=CuwrZUTeEqM

Limiting Factors Definition- A factor that causes population growth to DECREASE A resource base that is limited can also affect the long-term survival of a species Examples?

Density-Dependent Factors A limiting factor that depends on population size is called a density-dependent limiting factor. In general, density-dependent factors are biological factors Some examples of this include competition, predation, parasitism, and also disease

Density- Independent Factors Definition- This is when all populations are affected in similar ways, regardless of the population size. Examples? Unusual weather, natural disasters, seasonal cycles, and certain human activities—such as damming rivers and clear cutting forests

Activity- Application Get in groups on 3 or 4 for this activity Read the passage “Yellow Perch in Lake Winnepig” aloud (each student should follow along throughout the passage) Answer the questions that follow in your group on your OWN SHEET OF PAPER (everyone must have their own sheet to turn in)

Activity Questions 1 & 2 1) Explain the difference between density independent and density dependent limiting factors. 2) From the previous article “Yellow Perch in Lake Winnipeg”, identify and describe as many limiting factors as possible and classify them as density independent or density dependent. Density Independent Density Dependent

Activity Question 3 3) Each of the statements below involves a situation that will affect the growth of a population. Classify each of the statements as DD (density dependent) or DI (density independent) and give a reason for your choice. (18 marks - 2 each) a. Rainbow smelt and yellow perch attempt to occupy the same area. The more aggressive smelt survive; the perch do not. b. A severe flood brings a lot of sediment and silt into Lake Winnipeg. The turbidity of the lake increases greatly. c. A drought decreases the water level in Lake Winnipeg. The carrying capacity of the lake decreases.

Activity Question 3 d. Due to the introduction of rainbow smelt, Lake Winnipeg becomes crowded and some fish species do not survive. e. Since northern pike prey on yellow perch, an increase in the perch population causes an increase in the pike population. f. Many fish die due to an increase in water temperature. g. Due to over-fishing, the number of walleye in Lake Winnipeg decreases. h. A population is growing quickly when parasites cause disease to spread quickly. i. Since lake sturgeon migrate long distances to spawn, many do not survive the trip.