In one laboratory experiment, bacteria exposed to high levels of pathogenic bacteria over several hundred generations eventually adapted "their progeny became dependent on having the formerly pathogenic bacteria in food vacuoles...(Jeon, 1991)" (Armstrong) There are several ways in which bacteria may subsume other bacteria, including ingesting them and maintaining them in food vacuoles as in the Jeon experiment, or they may become infected by bacteria that are acting as parasites. Mitochondria, for example, could have been parasitic and fed off the host at the same time that they proved useful to it. Chloroplasts, because they are significantly self-supporting, are more likely to have been introduced as food. This theory continues to suggest that after many generations of true symbiosis, the mitochondria and chloroplasts lost their independence. If the endosymbiosis theory was correct, there are many things which should hypothetically prove true in experimentation. For example, it should be evidenced that single-celled organisms can indeed subsume other organisms and become dependent upon them for survival, and that subsumed organisms can surrender their own DNA and become dependent. These have both been seen to be true. For example, Margulis and Swartz found "an anaerobic organism that has adapted...
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