If you do not see an applet here, chances are that you are using Netscape with Mac OS. Not to worry you are only 8 clicks away from viewing this applet.

1. Please download the Apple Runtime for Java available for FREE at (if you already have the Apple Applet Viewer, skip to step 5):


2. Once the program has downloaded, click on the the MRJ2.2.2.smi icon on your desktop.

3. Click on the MRJ Install icon to install the applet viewer.

4. Open the Apple Applet Runner Folder

5. Click on the Apple Applet Runner Icon

6. In the file menu select Open location

5. Copy the URL of this page and paste it into the Location box of the Applet Runner window.

6. Click Open. The applet may take a moment or two to load.

It will be worth your time, I promise!

NOTE: You can also save the applet in your Apple Applet Viewer Favorites if you want to access it more quickly next time. Do the following:

When the applet is loaded, go to the applets menu and select add applet to list.

Natural Selection: Variation

Variation is important in determining the strength of natural selection. Populations with a large amount of variation can adapt quicker to changing environments. Populations with little variation change more slowly, and are more suseptable to extinction.

Natural selection may also effect the amount of variation in a population. For example, persistant selection in one direction (such as that seen to the right) can reduce the amount of variation in a population. This variation can only be replenished by mutation, which is the source of all new variation. Variance is a descriptive statistic which is a measurement of the amount of variation in a population.

Natural Selection: Variation

Adjust the amount of variation to the right:

Note that as the amount of variation increases, the rate of selection is greater. When there is no variation (variance = 0), no selection can occur.

The trait in question is the color of the individual, where selection is acting against purple and for green.