Instructor's Presentation Notes- Natural Selection Demonstration Program
 

Natural Selection- The process by which nature (limiting factors) selects those individuals adapted for a particular environment at a particular time.

This program requires the random generation of alpha-numeric characters produced by either manual keyboard entry (select Mode/Human) or by computer-generated random characters (select Mode/Computer).  As these random characters are entered by either mode, a background program called "natural selection" is running which "selects" for the correct sequence of characters to produce the Shakespearean phrase "To be or not to be, that is the question".  The "natural selection" program deletes entries made in the incorrect sequence and saves the correct character entries.  In other words, the program, like nature, saves the successes and eliminates the mistakes.  The "natural selection" program continues to save or delete characters until the phrase "To be or not to be, that is the question" is achieved.

When introducing this program to students, it is important to explain that the computer program "natural selection" acts upon a series of randomly generated characters.  The comparison should be made to nature's role (limiting factors) acting upon the complete randomness of genetic variation.
Students commonly misunderstand the process of natural selection by concluding that natural selection is a completely random process when in fact they should understand that genetic variation is a completely random process but acting upon this randomly produced gene pool is the very non-random process of natural selection.

This program demonstrates this process of selection acting upon a randomly generated "gene pool" (of characters).  The computer program "natural selection" establishes the environmental parameters in which this selection will take place (the correct character generated in the correct sequence).  Just like natural environments have limiting factors such as predation, competition and drought that select for or against certain characteristics (genes), this computer program establishes similar artificial environmental parameters.  Therefore the "natural selection" program serves as the environment in which this selection will take place. 

When using this program with students, it is of paramount importance to emphasize that natural selection and therefore evolution is NOT goal-oriented.  However, it might be suggested that this program is goal-oriented in that it selects for a pre-determined phrase ("To be or not to be.....").  It should be pointed out to your students that: 1) the "natural selection" program is only goal-oriented in that it pre-establishes the parameters of the environment (limiting factors) by which selection will take place and 2) the program is a simulation to demonstrate how  a randomly produced "gene pool" is acted upon by a non-random process (natural selection) to produce outcomes (species) that would be an improbable outcome of random genetic variation alone.  This program is not intended to meet all of the actual dynamic contingencies that occur in natural environments.  It is merely a demonstration of how randomness (genetic variation) is acted upon by non-random processes (natural selection) in natural environments.

The learning outcome for this exercise is for students to understand that random genetic variation produces a genetically diverse gene pool.  Acting upon this randomly produced gene pool is a very non-random process called natural selection.

Instructions
1.  Choose your mode of character entry.  From "Mode" choose either "Human" or "Computer".  If "Computer" is chosen, the program will begin the random generation of characters.  If "Human" is chosen, begin the manual entry of characters.

2. When "To be or not to be, that is the question" is achieved, the program will stop and the phrase "Got it!" will appear.  The "Computer" mode will take between 6-9 minutes to complete the phrase.  As the character generation is random, the completion time will vary each time the program is run.

3.  To replay the program and clear the clock, choose "File/Reset".

4.  To close program, either close window or choose "File/Exit".