Download Diversity Index Lab

Diversity Index Lab
Introduction
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.
Materials
notebook paper
1 small bag of fruit candies of different colors
1 small bag of chocolate candies of different colors
2 dishes or plastic containers
Procedures
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.
Blue-B, Green-G, Yellow-Y, O-Orange, Brown-T, Red- R
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.
Chocolate candy: (M&M's) GGOOTOOGO
Fruit candy: (Skittles) GYBGGOBB
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.
m&m's - 3
Skittles- 2
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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)
m&m's- .33 , Skittles- .22
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.
Sample
Trial 1
Chocolate .33
Fruit
.22
Diversity Index Table
Trial 2
Trial 3
Avg.
.22
.11
.22
.22
.11
.18
Analysis
1. How did the diversity index values vary from the chocolate candies and fruit candies?
The m&m's were a tad more diverse than the skittles
2. Which habitat is the most diverse?
M&M'S
3. Why are populations that are more diverse usually more stable?
They are more diverse because the more their are the better chance of a bigger survival
if a disease hits them.
4. Why would a diverse population be more resistant to disease, predation, and invasion?
Since its very diverse, It has different levels of immunity of the species to diseases.
5. Assume two habitats have the same number of species. One habitat is predominantly one
species with just a few of the other species. The other habitat has equal numbers of all the
different species. Which will have the highest diversity index?
The one with an equal number of different species because its more stable.
© 2012 Connections Education LLC. All rights reserved.
6. Why do you think the process was repeated three times?
Its less accurate if you are dependent on just one try, its important to try many times to
get an accurate average
7. There are many human-caused losses of biodiversity, such as habitat destruction and
introduction of invasive species. Are there any natural events that could alter the
diversity index?
Yes, any natural disaster like a wildfire, a very bad storm, volcanic eruption, all affect.
8. How do invasive species change the diversity index?
Since invasive species are not native they may invade and reproduce adding more
species.
9. What do you think would happen to a habitat if the plant diversity declines?
Many species rely on plants for food, so if the plants decline, so do they.
© 2012 Connections Education LLC. All rights reserved.