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: Modes of Selection

There are three typical modes of selection:

Directional Selection occurs when selection favors one extreme trait value over the other extreme. This typically results in a change in the mean value of the trait under selection.

Disruptive Selection occurs when selection favors the extreme trait values over the intermediate trait values. In this case the variance increases as the population is divided into two distinct groups. Disruptive selection plays an important role in speciation.

Stabilizing Selection occurs when selection favors the intermediate trait value over the extreme values. Populations under this type of selection typically experience a decrease in the amount of additive genetic variation for the trait under selection.

Natural Selection: Modes of Selection

Choose a selection mode to the right: