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If I had to do this experiment myself, I would most likely demonstrate natural selection with bacteria because they are well-understood and replicate quickly.
Part one: I would choose 3 different strains of bacteria (bacteria #1, 2, 3), each of whom differ in their optimal temperature range, needed nutrition, whether they are aerobic or anaerobic, ect... (I think you get the idea here).
Part two: Then I would subject each of the three strains to the same environmental pressures (i.e temperature change, amount of O2 being exposed, change in pressure, various media containing a different nutrient/environmental composition (minimal, with glucose,acidic, with saline, complete media ect..).
Then after being subjected to these changes by themselves I would do the following:
Part three: I would repeat part two, but instead of having only one type of bacteria, I would do different combinations to show the effects competition, transfection, transduction, induced mutation, ect.
Combinations are as follows:
-Bacteria #1 &2
-Bacteria #2 & 3
-Bacteria #1&3
-Bacteria #1,2,&3
Note: it is important to keep all conditions constant when performing these experiments, you may also want to use controls to show comparison.
As for analysis: I would look for various mutation (for example, did any of the bacteria acquire a higher G:C ratio in their DNA after being exposed to high heat (G:C has three H-bonds and melts at a higher temperature, many extremophiles have higher G:C ratios because of this). Where there any other mutations (such as a F plasmid transfer via conjugation, ect..). What were the reproduction statistics?
I think this should be a good enough idea to get you going somewhere, whether or not you choose to use this for your assignment. Just make sure you do enough research on the organisms you choose to use, this way you make an educated model for your experiment.
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