This applets simulates a world where three types of unicellular forms exist - Red, Blue & Green.
Each cell starts its life at a random place and moves in a predestined path. Every now and then, it might encounter a another cell type could be its predator or prey. Red eats blue, Blue eats green and Green feeds on red. When a cell eats another cell, its size grows a bit while over a period of time, each cell undergoes slight shrinkage till death.
If a cell reaches a certain maximum size (based on its rate of shrinkage and eating), it splits into two daughter cells that inherit all the qualities of the mother cell. The daughter cells also start their lives from random positions. As you would expect, if there is only one cell type left in the world, they will eventually shrink and die in absence of food.
Suggested Experiment You can try out any scenario you can imagine but may I suggest a couple of them. Click on the 'Blue' button 20 times to introduce 20 blue cells. You will notice that they eventually shrink and die out. Again get 20 blue cells on the screen. Now press the 'Red' button once. It will introduce one predator red cell. Just see how fast the competitive advantage of red cells wipes out the blue population. You can also press the 'All color' button 10 times and see what happens. Each time, one species will emerge supreme.
Buttons : All color - Generates 3 cells of different color simultaneously ; Freeze - Pauses the applet [press again to cont.] ; Color Buttons - Generates cell of that color.
Refresh the browser to reinitialize applets and avoid the temptation of loading million cells unless you have a superfast CPU :)
This applet is pretty much like the above applet in terms of having a world with three different cell types - Red , Blue & Green.The main difference is that when a cell divides, it generates two daughter cells which are predatory on the 'mother' cell type. For example red cells eat blue cells. But when they divide, they will give rise to two green daughter cells that feed on red cell types. Of'course it appears ridiculous that a particular species would evolve to give birth to its predators. But we must remember here that evolution operates at multiple levels. Though this phenomena may not be best suited for one species, but it works extremely well for the survival of the 'total population'. It is advantageous at the species level also as it guards against the total extinction of any one cell type. In this type of world, you would notice that it is very hard for any cell type to completely dominate the world or completely become extinct. If you repeat the suggested experiment for applet 1 above that requires pressing 'all color' button 10 times, you would notice that a nice equilibrium is established and it lasts way longer than that for applet 1.
Buttons : All color - Generates 3 cells of different color simultaneously ; Freeze - Pauses the applet [press again to cont.] ; Color Buttons - Generates cell of that color.
Refresh the browser to reinitialize applets and avoid the temptation of loading million cells unless you have a superfast CPU :)
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For sending any suggestions, criticism or reporting bugs, please mail to shantanu01@cmu.edu ___________________________________