### Inbreeding at One Locus - Full Sib Lines

Starting with AA and aa, two inbred lines differing at a locus, an F1 is produced. It is composed of individuals with genotype Aa. From each of 50 crosses, two parents (one female, one male) are taken. This is shown as the Parental Generation in the histogram. Two full sibs are then taken and crossed, under the controls of the buttons below. In this way full-sib lines are produced, and are tallied in the histogram. After all of the full sib lines are reproduced, the resulting generation of 50 full sib-lines (a total 100 individuals) can be "promoted" to be the parents of the next generation. A record is kept of each generation in the box at the bottom.

Click on the buttons below to proceed:

 Parental Generation Offspring Generation
 Parent Parent Offspring Offspring Generation
When a full-sib line is chosen to reproduce, it is removed from the Parental Generation histogram. When full-sib offpring are produced, the genotypes are shown and the resulting line is added to the Offspring histogram. Click the "Run Continuously" button to get the effect of clicking the above buttons, in sequence, over and over until the all parental full sib-lines have produced offspring. Then the offspring need to be "Promoted" to produce the following offspring generation.
 To start all over again click: and then proceed as before.

#### Thought Questions

• What pattern of heterozygosity and homozygosity results from inbreeding?
• Is it exactly the same in each run of this exercise?
• How can the heterozygosity and homozygosity in each generation be described?
• Hint: what is F?
• What is the value of F when the population is in H-W proportions?
• Calculate F for each generation
• Graph F over at least 10 generations.
• This exercise starts with 100 individuals and continues with 100 individuals in each generation. (50 pairs of full sibs.) What would be different if:
• There were a different number at the start?
e.g. 50, or 500?
• There were a different number of offspring per parent?
e.g. 2, or 1/2 (on the average)
• Can you characterize variation within vs. between lines?