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Transmission genetics with two loci

I'm going to construct a reduced version of a mating table to see how gamete frequencies change from one generation to the next. There are ten different two-locus genotypes (if we distinguish coupling, $A_1B_1/A_2B_2$, from repulsion, $A_1B_2/A_2B_1$, heterozygotes as we must for these purposes). So a full mating table would have 100 rows. If we assume all the conditions necessary for genotypes to be in Hardy-Weinberg proportions apply, however, we can get away with just calculating the frequency with which any one genotype will produce a particular gamete.3

    Gametes
Genotype Frequency $A_1B_1$ $A_1B_2$ $A_2B_1$ $A_2B_2$
$A_1B_1/A_1B_1$ $x_{11}^2$ 1 0 0 0
$A_1B_1/A_1B_2$ $2x_{11}x_{12}$ $\frac{1}{2}$ $\frac{1}{2}$ 0 0
$A_1B_1/A_2B_1$ $2x_{11}x_{21}$ $\frac{1}{2}$ 0 $\frac{1}{2}$ 0  
$A_1B_1/A_2B_2$ $2x_{11}x_{22}$ $\frac{1-r}{2}$ $\frac{r}{2}$ $\frac{r}{2}$ $\frac{1-r}{2}$
$A_1B_2/A_1B_2$ $x_{12}^2$ 0 1 0 0
$A_1B_2/A_2B_1$ $2x_{12}x_{21}$ $\frac{r}{2}$ $\frac{1-r}{2}$ $\frac{1-r}{2}$ $\frac{r}{2}$
$A_1B_2/A_2B_2$ $2x_{12}x_{22}$ 0 $\frac{1}{2}$ 0 $\frac{1}{2}$
$A_2B_1/A_2B_1$ $x_{21}^2$ 0 0 1 0
$A_2B_1/A_2B_2$ $2x_{21}x_{22}$ 0 0 $\frac{1}{2}$ $\frac{1}{2}$
$A_2B_2/A_2B_2$ $x_{22}^2$ 0 0 0 1



Subsections
next up previous
Next: Where do and come Up: Two-locus population genetics Previous: A little diversion
Kent Holsinger 2008-08-19