The measure of the biodiversity of organisms in a given area is known as the diversity index. The diversity index values will vary between 0, which would indicate no diversity, and 1, which is very diverse. Any values above 0.5 usually indicate a relatively diverse population. For example, a healthy forest or woodland should have a diversity index of 0.7. An area that is not very diverse, like a cornfield, might have a diversity index of 0.02 or less.
In this investigation, each bag of candy represents a different habitat. Each color represents a different plant in the habitat.
1 small bag of fruit candies
1 small bag of chocolate candies
2 dishes or plastic containers
1. Pour each bag of candy into a separate container or dish so you can see all the colors in each bag. Assign a letter to each color of chocolate candies and fruit candies and record your key.
2. Without looking, randomly choose nine candies from each container one at a time. Using the letter symbols, record each candy as it is removed. Record the results in a single line like this: RBGGYYGBB.
3. Count the number of runs in the sample. A run is a group of letters that are the same. A run can be as small as one. The example RBGGYYGBB has six runs.
4. Calculate the Diversity Index of both the bag of chocolate candies and fruit candies using the following formula: Diversity Index = number of runs/number of plants surveyed (in the example 6/9 = 0.67)
5. Repeat the process two more times to verify your results. Make sure you replace the candy back into the container after each trial. Record the Diversity Index after each trial in the table. Calculate the average from the three trials.
Diversity Index Table
|Sample |Trial 1 |Trial 2 |Trial 3 |Avg. |