In a classic experiment on competition between species for a common food source, the Russi...

In a classic experiment on competition between species for a common food source, the Russian microbiologist G. F. Gause grew populations of different species of ciliated protozoans separately and together in an artificial culture medium. He counted the number of cells of each species and plotted the total volume of each population. The organisms were Paramecium caudatum and its close relative, Paramecium aurelia. He plotted the aggregate volume of cells rather than the total number in each population because P. caudatum is much larger than P. aurelia (this size difference allowed him to distinguish between them in a mixed culture). The graphs in this box show the experimental results. As we mentioned earlier in the text, this was one of the first experimental demonstrations of the principle of competitive exclusion. After studying these graphs, answer the following questions.

How do you read these graphs? What is shown in the top and bottom panels?