Fig 4. Interactions between A^Bd and A^dB.

a, The edge weights in the chunks A^Bd (red) and A^dB (blue) are shown as a function of t (here t ≫ 1 is large). The connecting edge has weight 1/t³, all other edges with endpoint u have total weight 1/t and all other edges with endpoint v have total weight 1. For each of two versions of the Moran process, the rates at which the offspring migrate from u to v and from v to u can be calculated and are listed in the table. b, Under Birth-death updating, the migration rate p_{u → v} from u to v is roughly t× larger than the migration rate p_{v → u} from v to u, so the chunk A^Bd is upstream of the chunk A^dB, and a mutant who has fixated over A^dB is likely to fixate over A^Bd too. c, In contrast, under death-Birth updating we have p_{v → u} ≈ t ⋅ p_{u → v}, hence the chunk A^dB is upstream of A^Bd.