Lesson 4Biotic Interactions

3.1 Predation

Use a higher textbook (available in M4) or your memory to:

1. Describe a predator prey interaction2. Describe how these interactions have a

stabilising effect on diversity

4. Explain density dependent regulation of population sizes.

5. Explain density independent regulation of population sizes.

6. Give an example of use of biological control of pests.

3. Explain what the carrying capacity of a habitat is.

What You Should Know

Predator-Prey InteractionsPredators and prey will show population cycles

that are linked. To show a true interaction the following criteria must be met:

1. The predator is totally dependent on the prey for food

2. The prey have an unlimited food source

3. There is no other threat to prey

In reality it is almost impossible for these criteria to be met in nature. The closest and most studied example of this is the interaction between Snowshoe Hare and Lynx.

Snowshoe Hare and Lynx

Produce a report on the interactions between snowshoe hare and lynx. This report must include:

1. Background on the habitat and feeding strategies of the 2 species.

2. An A4 sized graph of the population data (Pg43)

3. Answers to Q5 –Q8

4. Analysis of Paramecium and bacterium interactions from the graph on page 42 (copy of graph not required)

Predation promotes natural selection

• it provides a selective pressure

• co-evolution of prey and predators

What’s so good about predation?

What to do (a summary)

1. Working on your own or in groups, plan, write up and carry out the ‘mesh size’ investigation. This completed write up will be due in the spring.

2. Complete notes on “What you should know” for Tues Oct 21st.

3. Report on Snowshow Hare and Lynx due Tuesday Oct 21st.

4. Prepare for your quiz on Pages 1 -14 on Tuesday Oct 21st .