3.5 Selection: Change in gene- and genotype frequencies, and effect of population size

In all cells with initial values you can put data
You can put the fitness for each genotype.
Fitness = 1-s ->
Gene frequency p -> Graph indiv-1, or avr-0 ->
Gene frequency q -> Number of pop. ->
Pop. size -> "Generations ->
Set digit for print ->
Generation q Frequency Genetic load           ........Change of q over generations......

Click the Evaluate button. Put the fitness of the genotypes (relative or numbers) and you can run one generation at the time by pressing the button +1 generation!, or you can get a graph over gene frequency changes over 60 generations by pressing the Run button. The corresponding data you can extract over the clip board in the lower left window.
If you define population size (pop. size) you can simulate random changes in gene frequencies over time.
If you define more populations (number of pop.) you get an average estimate of the gene frequencies over generations and its standard error.
If you use large and many populations the simulation might take several minutes, start with few and small populations so you can have an impression of the time consumption on your computer.

For utilization of a deterministic model go to the program 3.4 and its explanation.


If you have a genetic system (Aa) with gene frequency q=.5. and you have random mating. How many populations out of ten would either have lost or fixed the gene a after 20 generations ? after 40 ? and after 60 generations ?

Put 10 in the pop size box, and pres Run 10 times recording loss or fixation of gene 'a' in each run.

Calculate the gene frequency in the first 60 generations of selection in the genetic system shown below with selection favouring the heterozygotes with s1 = 0.3 and s2 = 0.5 having a population size of 20.

Genotype         AA               Aa             aa       Total
Observed numbers 225		  157            43
Frequency        p2               2pq            q2       = 1,00
Fitness          1-s1              1            1-s2      
Proportion       p2(1-s1)         2pq           q2(1-s2)   = 1-p2s1 - q2s2
after selection

Will equilibrium within 0.02 units be reached ?

Back to theory, Back to theory (in Danish) or Back to the other programs