Under-Dominance Constrains the Evolution of Negative Autoregulation in Diploids
Figure 2
Invasibility of autoregulatory binding sites.
The response time of mutant (a) homozygotes and (b) heterozygotes are shown. Different values of the binding strength of the resident allele, in units of (x-axis), are plotted against mutations to binding site strength
of different size (y-axis). Thus the graphs compare a resident allele,
with a mutant allele,
. Mutations falling into white region result in decreased response time in the carrier compared to resident genotype and are favoured by selection; mutations falling into the gray region result in increased response time and are not favoured by selection. Weak binding occurs when
[1], [2]. Response times were calculated by numerically integrating Eq. 1 from zero protein concentration to 90% of the equilibrium. The optimal binding strength in these graphs is
, corresponding to a background transcription rate
.