Explanations/Instructions

Probability that a potential mate is related: This parameter just means the likelihood that the mate you choose is actually related to you. Setting the probability to .5 means that every second person you consider as a mate is related to you to some degree, such as cousins, half-sibs, etc.

Mating threshold: This parameter specifies at which degree of relatedness you will no longer mate with someone.  If you set it to anyone, you will mate with anyone, including your relatives.  If you set it for first cousins, you will onlymate with people how are more distantly related than first cousins (or not related).

Avg. lethals/indiv.: This parameter specifies how many recessive lethal alleles each person has on average. For every gene locus (place on the chromosome) a person can have two different alleles (gene variants). Some of these alleles will express their phenotypic effects when the person has only a single copy (dominant alleles) whereas other alleles need to be present in a double dose to express their phenotypic effect (recessive alleles). Using this parameter you can specify how many of these recessive lethals a person has on average.

Yellow square form: This is the most common, wild type, of genome against which you want to compare the success of your mutant form, which is the "red diamond form".

Red diamond form frequency: This paramter lets you specify the frequency of the mutant genome in the population.
 
 

In answering all questions about simulations, you should run the simulator several times on the same setting.  Since there is an element of randomness in the simulation, you will get a better sense of the overall tendency at a given setting if you run the simulator several times at that setting.

Questions:

1) In the "wild," under which conditions do you think people are likely to encounter mates that are relatives?
 
 
 

2.) For your initial simulation set the probability that the potential mate is related at .5, the yellow diamond form (the most common) mating threshold as "anyone," the "red diamond form" (the mutant) mating threshold as "half sibling", the average number of lethals at 1, and the red frequency for .05.  Does this mutant become fixated? If so after how many generations?
 
 
 
 
 

3.) What happens if you set the yellow diamond form (the most common) mating threshold as "anyone" and the "red diamond form" (the mutant)  mating threshold as "first cousin" while keeping all other values at the levels in question 2?  It means you would mate with anyone except for those that are first cousins or closer related to you.  Does this mutant become fixated?  If so after how many generations?
 
 
 
 
 

4.) How does the result change when you increase the threshold for the red diamonds to exclude even 2nd cousins from your choice of mates.  Does it take longer or shorter time to reach to fixation?
 
 
 
 

5.) Now, reset all of the parameters to the values in question #2.  Raise the "avg. lethals/indiv" from 1 to 1.5.  How does this affect the rate of fixation compared with the previous parameters (in question 2) ?
 
 
 
 

6.) Now,  raise the "avg. lethals/indiv" from 1.5 to 2, leaving all other parameters the same.  How does this affect the rate of fixation compared with the previous parameters (in questions 2 and 5) ?
 
 
 
 
 

7.) Now, reset all the parameters to the levels in question 2.  Increase your red diamond form frequency from .05 to 0.5. That means, the mutant is already in every other person.  Can you think of a situation in which  our ancestors might have encountered where a "mutant" started out with a frequency of 0.5?   How do these affect the rate of fixation compared to the previous parameters (in questions 2) ?