A Simple Experiment

A Simple Experiment

A Simple Experiment

November 14, 2011

This week, my student, Justin Baraboo, and I, will try a simple experiment that may shed some light on whether or not, for Paramecium aurelia, the rate of change of the rate of change of the population is something that is important in understanding how the population changes with time. (Justin is an undergraduate physics major at Truman State University. Unlike Justin, Paramecium aurelia is a one celled organism shaped kind of like a piece of rice. Because Paramecia divide every four to twelve hours, they make a good system for studying population dynamics.

What we are going to do is take some Paramecia and stress half of them by starving them for two days. Then, we will take ten of the stressed Paramecia and ten of the unstressed Paramecia, and put them in separate identical containers with plenty of food, and monitor their populations for about 36 hours. If the population dynamics depend mostly on the rate of change of the population, then, after about four to ten hours (very roughy: one generation), the growth rates of the two samples should be statistically the same. If, however, the growth rates are significantly different after that time period, that would be evidence that the population dynamics depend on the rate of change of the rate of change of the population in an important way. We’ll see how it turns out!

2 responses to “A Simple Experiment”

  1. Anna H. says:

    I’m trying to replicate your experiment but I don’t know how to starve the paramecium. How did you do it?

  2. prolnick says:

    Hi Anna. There are two ways that we stressed the Paramecia, in two different experiments. One is: grow them in medium which has been diluted by half twice. The other is to take Paramecia that have been growing without having their medium changed for about a week and a half (so their environment is pretty toxic), and then filtering out the Paramecium using Whatman #1 filter paper, and using the resulting liquid as the stressful environment.

    I will email you a summary of our procedure for each experiment.

    By the way, though the jury is not out yet, it looks like we are not seeing much of a maternal effect.

    Good luck!

    Peter