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. 2020 Oct 27;216(4):985–994. doi: 10.1534/genetics.120.303680

Figure 1.

Figure 1

The variance of genetic relatedness between grandoffspring and grandparent, calculated from the possible segregation patterns of a single parental meiosis. In the figure, the positions of crossovers in a maternal meiosis (and the chromatids involved) are specified, but the segregation pattern in the resulting egg (and therefore offspring) is not. Averaging across the four segregation patterns, we find E[IBDgrand]=(l1+l2+l3+l4+l5)/4=1/4, and, from Equation 1 in Veller et al. (2019b), r¯=(l1+l3+l4)(l2+l5)+(l2+l4)(l1+l3+l5). Across the four possible segregation patterns, E[IBDgrand]=1/4 and Var(IBDgrand)=E[IBDgrand2](E[IBDgrand])2=14[14(l1+l3+l5)2+14(l1+l3+l4)2+14(l2+l4)2+14(l2+l5)2]116=11618[(l1+l3+l4)(l2+l5)+(l2+l4)(l1+l3+l5)]=18(12r¯),which is Equation 2.