SEE-U 2000: Exercise 14

## Exercise 14: Crazy Ants and Species Extirpation
Module 14: Exotic Species Introduction

### Your Questions

How does the presence of a successful and widespread exotic species influence the other organisms in the community and can we predict where large infestations of the exotic usually will occur?

### Background

Throughout Biosphere 2 and in the surrounding desert, a single ant, Paratrechina longicornis, has taken over. The ant is colloquially as the crazy ant for reasons that will be clear once you are familiar with them, relating to their movement patterns.

Paratrechina longicornis was one of the nine ant species that were introduced at essentially equal abundance levels into the Biosphere 2 before the domes were first infused with life and sealed in 1991. Shortly thereafter, P. longicornis began to dominate all other ant species. This same trend continued in subsequent years, such that during a trapping survey by J. Wetterer in 1996, he collected 28,827 ants from 174 bait stations. All but one of these ants were P. longicornis.

Crazy ants are found nearly everywhere throughout B2C and in the surrounding desert. Some have suggested that these ants are one of the very few organisms that enter and exit Biosphere 2 regularly, although this has been neither tested nor demonstrated.

### Your Assignment

This assignment involves completing four tasks.

- Design of field experiment = 1 hour
- Data collection for field experiment = 4 hours
- Data analysis and write-up = 3 hours
- Presentation = 1 hour

To complete these tasks, you should proceed through the following steps. First, you and your lab group should design a field experiment that would test some aspect of the effect of crazy ant presence on the biodiversity of communities. Some possible applications of the above main question that you could address include the following:

1. Setting aside the question of the affect of the ants on other species, are there ecological correlates that can be used to predict the probability of establishment of crazy ant colonies?
2. Do crazy ants affect the community diversity of plants and insects living nearby in areas where the ants have many colonies relative to others where they are absent?
3. Do the crazy ants most strongly affect those species with which they directly interact relative to others in the community?
4. Another question of your own design that is related to the main question.

Be certain to control for environmental differences, including moisture, topography, sunlight, temperature, slope orientation, etc., when determining which sites are appropriate to compare.

Second, you should determine how to identify Paratrechina longicornis, where the ants are present inside Biosphere 2, and where in the surrounding desert outside of Biosphere 2 that they are found.

Third, you should collect the data that you will need for your study, analyze it, and then present it after dinner.

You will have to finish all of this assignment today, taking no more than a total of NINE hours from conceptualization to presentation. As with previous activities, the quality of the data from the field experiment and the rapidity with which you are able to complete the task both will be enhanced if multiple lab pairs cooperate to collect data for the same study. Ask around to other groups to find others who are interested in addressing similar questions. Also as with previous activities, you will be graded not only on your experimental design, execution, and outcome, but also on how well you work together and on the final oral presentation.

### Objectives

1. Grasp that accidental introductions of pest species by humans are one of the main contributors to habitat degradation.
2. Recognition that reductions in biodiversity and ecosystem processing often accompany the introduction of exotic species.
3. Basic understanding of how insect pest species spread and interact with other ecological community members.
4. Knowledge of the basic biology and ecology of the crazy ant, where they live, and the species with which they directly interact, including scientific names.
5. Improved grasp of scientific methodology principles.
6. Improved understanding how to create a set of hypotheses to test a question.
7. Familiarity with the origins of measurement error and how to minimize it.

### Key Skills

1. Facility in conducting insect community surveys.
2. Familiarity with how to conduct a systematic survey for a single species
3. Skill in interpreting ecological correlates included in georeferenced community survey data.
4. Ability to estimate community diversity indices.
5. Dexterity in comparing diversity indices between sites and ecological conditions.
6. Skill at designing equal sampling efforts between heterogeneous sites.
7. Improved ability to present work orally.
8. Greater facility with GPS and GIS data processing.

### Timetable

1. Total elapsed time to perform the experiment : One day
   - Design of field experiment, implementation of field experiment, insect censusing, mapping, statistical analyses, write-up and oral presentation should all be done in one day
2. Total elapsed hands-on time: approximately Nine hours
   - Design of field experiment = 1 hour
   - Data collection for field experiment = 4 hours
   - Data analysis and write-up = 3 hours
   - Presentation = 1 hour

### Procedural Notes

1. The degree to which students in the class collaborate will determine which question they should be encouraged to answer
   - If the entire class is interested in one of the Community Diversity questions, then it would be possible to answer that question. The methodology outlined above is very time consuming and would require a large work effort—this is too much work for a small group
   - However, if only a subset of the class is interested in the Community Diversity questions then one group should be encouraged to answer the Ecological Correlates question and another group could answer another question of their own design.
2. Because this exercise could be performed inside of the Biosphere, a few correlates come with it
   - We need to get permission to go into the B2C immediately
   - It is fairly portable and can be performed in a number of locations and during a variety of days. If it is too hot outside to go out we can stay inside the B2C and not plan the day around the heat of the day.
3. This experiment could be reapplied to other modules
   - It could also be fitted into Community Ecology (Module 5) or Disturbances (Module 12) portions
   - However both of these modules are before the proposed Exotics (Module 14) module and therefore this reapplication may not be possible

### Materials Needed

1. GPS unit
2. Insect collecting equipment—determined by students
3. Clipboards & paper or notebooks, and writing implements
4. Soil moisture and texture evaluation methods and equipment
5. Slope measuring tool (two yardsticks attached at end with a level on one and a protractor)
6. Thermometer
7. Compound microscopes
8. Sorting trays, forceps, alcohol
9. Computer with Excel, Word, SPSS, and eBiome loaded