Biophysical Fitness Landscapes for Transcription Factor Binding Sites
Figure 2
The monomorphic limit and steady state of a Wright-Fisher model of population genetics.
In (A)–(C) we show results from simulations at various mutation rates, using a fitness function with ,
, and
. Each mutation rate data point is an average over
independent runs, as described in Methods. Colors from green to orange correspond to increasing mutation rates. (A) Observed steady-state distributions
for various mutation rates. The steady state
predicted using Eq. 3 is shown in gray. (B) Fitness functions
predicted using observed distributions
in Eq. 8. The exact fitness function is shown in gray. Inferred fitness functions are matched to the exact one by using the known population size
, and setting the maximum fitness to 1.0 for each curve. (C) For each mutation rate, the total variation distance (TVD)
between
and
, and the average number of unique sequences in the population
(the degree of polymorphism) are shown. The predicted bound
on mutation rate required for monomorphism is shown as a dashed line. In (D)–(F) we show simulations in the monomorphic regime which have not reached steady state, with the same parameters as in (A)–(C) and
. Colors from blue to red correspond to the increasing number of generations.