Model experiment 2. Study of the genetic structure of the population under the influence of natural selection
- In column 2 for the parent generation P, we introduce the number of pairs of two-body gene alleles (in other words, the number of individuals).
- We determine the ratio of the dominant (A) and recessive (a) alleles and select the required number of chips, such as 70 red and 30 white.
- We put the selected number of chips in an opaque package, mix.
- We get 2 chips and put it into one of three packs: in the first one - a pair of one color, red (AA), in the other - a pair of different colors, red and white (Aa), in the third - a pair of the second color, white ( aa) This is how the parent population is modeled.
- We count the number of pairs of chips in each pile.
- The results are entered in the row P: in column 3 - the number of AA, in column 5 - Aa, in column 7 - aa.
- Click the "Calculate" button.
- We collect the chips for the package, mix and repeat steps number 6 and 7, filling the line for the first (F1) daughter generation, columns 3, 5, 7. At the same time, stack the chips from the third pile (aa) and do not include them in the total number of individuals of the next generation. This is how we remove recessive homozygotes from the population, while realizing that recessive homozygous genotypes are formed, but not viable. That is, collect the chips in a package of the first two pile.
- We carry out the action number 8 5 more times each time putting the chips from the third heap, filling the lines for the second (F2) - the sixth (F6) daughter generations, columns 3, 5, 7.
- Click the "Calculate" button opposite the lines F1 - F6.
- Click on the "Show Graphs" button.
- Based on the analysis of the obtained graphs and diagrams, formulate the conclusions of the plan:
- Change in the frequency of genotypes in generations;
- Change in the ratio of gene frequencies in generations;
- The direction of evolutionary changes in the population.
Table 3. Genetic structure of the population under the influence of natural selection
Note: Gene frequencies are calculated automatically by the method of extracting the square root from the frequency of dominant homozygotes for the dominant allele A and finding the frequency of the recessive allele a from the heterozygote frequency, namely from the product 2 x p x q (2 x A x a).