Table A1 The transition matrix approach used to study the influence of genetic background on the impact of a new mutation (either with increasing or decreasing effect) on the proportion of additive variance (VA) in the genotypic variance (VG)
Mutation b → BMutation B → b
No selection VA/VGSelection VA/VGNo selection VA/VGSelection VA/VG
Positive interaction [aa] = a0.9650.9680.9810.988
Negative interaction [aa] = −a0.9230.9040.7930.742
  • The variation is caused by two interacting loci. A haploid population of size 40 is first iterated for 100 generations with or without selection to reach a steady state on one locus and the impact of mutation (either to decreasing b or increasing B allele) at the other locus is estimated after another 100 generations with or without selection, respectively. Selection intensity applied was 0.29.