Learning Exercise

PREDATOR - PREY

The Ecosimulator programme allows you to simulate the development of populations and some interspecific relationships in ecosystems, as well as some aspect of Natural Selection.

This time we will study the interspecific relationship of predation.

Open the programme or the ECOSIMULATOR website. Go to Simulate > Data Entry.

In Standard Simulations choose "Predator/Prey", or enter data by hand:

Generations (sweeps) to graph:  50

Time for the grass to grow:  1

RABBITS: Initial number=64  ; Maximum life=5  ; Points to eat=5  ; Moving distance=8  ;

FOXES : Initial number=64  ; Maximum life=5  ; Points to eat=8  ; Moving distance=8;

Speed=average

Click "Start" and observe the populations development.

When the number of chosen sweeps is reached, click "Graph".

QUESTIONS to choose for your teacher:

1.      Draw in your notebook the graph obtained. And write down all the events or details that you find interesting.

2.      Describe in your own words the graph obtained. Do both species survive? Who is the predator? Who is the prey?

3.            a) What happens to the number of predators when the number of preys increases.

            b) What happens to the number of predators when the number of preys decreases.

c) What happens to the number of preys when the number of predators increases.

      d) What happens to the number of preys when the number of predators decreases.

4.      Do you know of any examples in which this type of graph is produced or could be produced?

5.      Search on the Internet "Lotka-Volterra equations." What are those equations for? Search on the Internet for graphs that are produced with these equations. What do those graphs look like?

6.      Search and explain the case of sold skins of lynxes and hares by the Hudson's Bay Company  between 1845 and 1935.

7.      Try to modify the simulation data and view the results.