Fig. 3

Probability of crossing fitness threshold via accumulating mutations. A Histogram for DFE conducivity―the fraction of replicate populations (of size \(N={1000}\)) with the same DFE where the locus fitness goes on to cross the 0.1 threshold, at the absence of locus deletion (\(d=0\)). Bars indicate the number of DFE parameter sets (p, n, f, s) in a given conducivity bin (grey bars―high mutation rate regime, dull green bars―low mutation rate regime). This figure includes 108 DFE parameter sets for each of the low and high mutation rate regimes. Inset: Histograms for the fraction of conducive parameter sets with given values of parameters p, n, f, or s (blue bars― high mutation rate regime, and green bars―low mutation rate). B Trajectories of population averaged fitness in one of the replicate populations with DFE parameters indicated in the legend, and no locus deletion, \(d=0\), for a population with high (left) and low (right) mutation rates. This DFE is closest to the one reported for C reinhardtii in [18]. Black lines show average fitness with shading showing standard deviation. The red point in the left panel indicates the time step at which average fitness reached a minimum value. Each panel includes fitness values for \(N=1000\) individuals over 1000 time-steps. C, D Scatter plots showing the effect of locus deletion in 432 parameter sets (4 values of locus deletion rate d for each of 108 DFEs). The x-axis indicates the time at which minimum average fitness is achieved, where the average is over all populations with the same DFE parameters, p, n, f, s (with random jitter to make point density more apparent). The dotted red line indicates the time of minimum average fitness for DFE parameters close to C reinhardtii. C High mutation rate regime: black (blue) points represent parameter sets where \(\ge {50}{\%}\) (\(<{50}{\%}\)) of replicate populations cross the fitness threshold. All populations where the fitness threshold was crossed retain the locus. D Black (green) points represent parameter sets where \(\ge {50}{\%}\) (\(<{50}{\%}\)) of replicate populations cross the fitness threshold. Brown points represent parameter sets where the fitness threshold was crossed in \(\ge {50}{\%}\) of replicate populations, and the locus was subsequently lost in \(>{95}{\%}\) of the replicate populations