Initializing the simulation sets up 20 parents, 10 female and 10 male. The 10 females are shown with different mitochondrial genotypes. This is shown by 10 different color patterns, but there is no meaning to the patterns - all that is important is that there are 10 different ones. This information is presented in the text box named "pnumb" and labelled "maternal mitochondrial genotypes".
10 males are also shown, but they are all shown as gray because their mitochondria will not be passed the next generation.
The button "Produce Offspring Generation" then samples 10 male and 10 female offspring from the parental generation to produce the Offspring. The mitochondrial genotypes of all of the offspring are shown, but only the number of different female mitochondrial genotypes is presented in the text box named "onumb" and labelled "female mitochondrial genotypes". Most often, because of random sampling, there will be fewer than 10 different female mitochondrial genotypes in the first generation of offspring.
Note that the number of different female mitochrondial genotypes can only stay the same or go down. It can not ever increase because the simulation doesn't include mutation. The process, from generation to generation, is recorded in the last text box named "record". The first column is the number of the generation (the parents are the 0th generation) and the second column records the number of different female mitochondrial genotypes in that generation. What isn't recorded is how many there are of each mitochondrial genotype. Typically these numbers vary, and there is more chance of "losing" a genotype that is present in only one or two parents than losing one present in three or more parents.
To produce another generation, the button ""Promote Offspring to Parental Generation" is clicked - this moves the offspring to the position of being parents of the succeeding generation, and then the button "Produce Offspring Generation" is clicked once again.
Typically, the student will go through the simulation several times. Each time sufficient generations will be generated to reach "fixation" on one mitochondrial genotype.
Here is an example of the record for one run through the simulation
until fixation is reached:
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Copyright © 2006 by Henry E. Schaffer
I appreciate the support of the NCSU Genetics Dept. and the Information Technology Division