PS 47-134: Teaching ecology through original student research
Joseph L. Fail Jr., Demetrius Hawkins, and Douglas Lawrence. Johnson C. Smith University
Background/Question/Methods Ecology offers a very wide range of affordable, time and user friendly research themes for general biology students. Sophomore biology students at Johnson C. Smith University are required to design, execute, interpret, and formally write-up original ecological research efforts. These students have just come from a previous year of laboratory work that is tightly monitored but that also requires data interpretation and formal write-ups. The sophomore students are first presented with basic principles of general ecology accompanied by field trips to forests and to facilities of urban ecological interest. These field laboratories are written up as story narratives, and are accompanied also by summaries and critiques of several refereed ecology articles so that students get a feel for field research and the methods of reporting findings. The second half of the semester is devoted in large part to work on student projects. Here we report on the results of two of these efforts. Fire ants (Solenopsis invicta) are aggressively invasive ants that have found a new niche in the Southeastern United States. We wondered about their reactions to environmental and competitive stressors. To test this Hawkins placed varying numbers of ants in plastic vials and measured weight loss over time. He then subjected the ants to temperature stressors to test the hypothesis that reaction rates (respiration) doubles for every 10 degree C increase in temperature. He then went on to test interaction effects of environmental and competition stress factors. Engelmann in 1882 discovered the relationship between light wavelength and photosynthesis. He did this by observing the reactions of bacterial heterotrophs in the presence of algae exposed to the spectral wavelengths (colors) of light. Lawrence verified his experiment by counting protistan populations in aquatic microcosms of blue-green algae exposed respectively to either red, green, or blue light for 48 hours. Results/Conclusions Hawkins found a 5-fold loss of mass (due to CO2 evolution) in ant populations subjected to 20 degree C higher temperature than a control set. He also found a 4-fold loss of mass in crowded microcosms vs 2½ times less loss in less crowded microcosms. We concluded that both temperature and population stressors increased respiration rates in ant populations. Lawrence found that there were 3-fold more protista (heterotrophs) found in the red light than in the green light, and 2-fold more found in the blue light than in the green. He concluded that Engelmann’s findings on chlorophyll action spectra were verified.