Natural Selection prevents deleterious mutations from spreading throughout a population while fostering the spread of beneficial mutations.

One can get populations to do many things with this simulator. Just remember, if your parameters are not realistic, your solution will not represent reality.

To download the Population Simulator go to:
http://www.mediafire.com/?z2p2ydew1id

To download this video go to:
http://www.mediafire.com/?zqmzezllkyv

If you wish to translate this video you can download the PowerPoint file from:
http://www.mediafire.com/?yexml12mkgi

Predator evolution is simulated by scaling the populations mean survival probability back to the attrition rate. Example. If the Attrition rate is 0.9 and every member of the population has a number of beneficial mutations then the mean probability of death may be 0.8. If the predators were allowed to evolve (as they would in nature) that would scale the mean death probability back to 0.9. This is known as the Red Queen Hypothesis. The organisms have to keep evolving just to stand still. Without predator evolution enough beneficial mutations can pile up to lower the death probability to 0 (or nearly so). This would stop selection as every member would live to mate.

Error: I stated that without selection, evolution stops. This is not entirely true. Genetic drift operates in the absence of selection. It is one mechanism by which neutral mutations can become fixed in a populations.

Think about it. (less info)