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):

http://asu.info.apple.com/swupdates.nsf/artnum/n11572

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.

Evolutionary Genetics: Two-Locus

Selection at multiple loci can have considerably more complicated dynamics than selection at one locus. However, if the loci are independent with regards to selection, then multi-locus genotype frequencies will behave the same as they would in a one-locus system. Two-locus genotype frequencies can be found, for example, by multiplying the corresponding one-locus genotype frequencies.

For example, suppose that f(AA) in the next generation was calculated to be 0.4 and f(Bb) was calculated to be 0.3. Then the frequency of the two-locus genotype, f(AABb) would be 0.4*0.3=0.12.

When the two loci are not independent of each other, complications arise (for example, linkage disequilibrium can result). See the section on linkage equilibrium for more information.

Evolutionary Genetics: Two-Locus

Adjust the initial allelic frequencies and the fitness values to the right:

For best results, begin by setting the fitness values to 1.0, and initial allelic frequencies to 0.5. Then, decrease one or more of the fitness values by a small amount.

The initial allelic and genotypic frequencies are displayed below the graph whereas the run-time frequencies are displayed above the graph.

In this simulaiton, two loci are subjected to independent selection pressures in a population of 5000 individuals. Because the two loci in this simulation are independent with respect to selection gene frequencies at each locus will be identical to the case of one-locus selection.Two-locus genotype frequencies can be found by multiplying the two corresponding one-locus genotype frequencies.