Grade Level: 9th - 12th; Type: Life Science
Student compares the biodiversity of ant populations in various locations.
- Do fire ants compete with native ants for resources?
- What is the impact of habitat destruction on insect biodiversity
- What foods do ants commonly consume?
- What is the ecological role of ants in the environment?
- What habitat types do ants prefer?
Biodiversity is the variety of organisms found in an area. Healthy ecosystems usually have biodiversity. Biodiversity can be measured in three different ways: Species Richness, Simpson’s Index, and the Shannon-Wiener Index. The Simpson’s index uses the richness and percentage of each subspecies to determine the biodiversity of an area. The formula for the Simpson’s index is:
N = total number of organisms in the survey
ni = the number of individuals for each species
When maximum diversity occurs, the value of the index is zero and when minimum diversity occurs, the value of the index is 1.
Ants are a group of organisms that may belong to one of many species, thus their biodiversity can be measured. By looking at a subset of organisms, one can make inferences about the biodiversity of the entire ecosystem. Threats to native ant biodiversity include the non-native invasive fire ants and ongoing development of the land by humans. In this experiment, the student will compare the biodiversity of ants in several locations. The student will choose locations of different ecosystem types. Ants will be baited and counted to obtain data with which to calculate the ant biodiversity of each chosen location.
- 1 pack of 3x5 inch index cards
- 1-2 cans of tuna fish packed in vegetable oil
- 1 bottle of corn syrup
- 1 spoon
- 1 can opener for tuna if necessary
- Choose three nearby locations to compare ant biodiversity. Forests, fields, lawns, and areas near parking lots are all good choices. The best time to conduct this experiment is on a warm, sunny day when insects are active in your area. Create a hypothesis as to which location you believe will have the greatest ant biodiversity and why.
- At each location, put a spoonful of tuna onto each of 5 index cards. Place the cards at least three meters apart from each other. Squirt an equivalent amount (as the tuna) of corn syrup on each of 5 cards. Place a corn syrup card beside each tuna card. Repeat this procedure at each chosen location.
- Leave the cards for at least one hour. Come back and check for ant activity. If there is ample ant activity, count the number of each ant type. If you wish to attempt to identify the ants using a field guide, you may. However, by noting the different sizes and body types and counting the number of each type, you will be able to measure the biodiversity. If there is no ant activity, leave the cards and check them again every half hour for the next few hours. If there is still no activity, try another day or in different locations.
- Use your data to calculate the ant biodiversity of each location. The diversity index (D) is calculated as: D = sum ni(ni-1)/N(N-1) where N = total number of organisms in the survey and ni = the number of individuals for each species. So for example, if you count three different types of ants at one location, 10 of type 1, 5 of type 2, and 2 of type three, your equation would look like:
- 10(10-1) + 5(5-1) + 2(2-1) / 17(17-1) = 112/2032 = 0.055
- This diversity index value would be considered more diverse than a value of 0.25 but less diverse than a value of 0.025. Create a table or bar graph to illustrate your results. Draw conclusions concerning reasons for the differences in ant biodiversity at your locations.
Terms/Concepts: Biodiversity; Species Richness; Simpson’s Index; Shannon-Wiener Index; Ant Species; Types of Ants; Fire ant impacts; Habitat destruction
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