Fig. 2.

$P_{Mut}$ (black lines), P ₁ (red lines), and P _con (blue lines) for resistant cost-free mutations. a Probabilities $P_1$ and P _Mut increase with increasing uN ₀, for R _m = 6 and m = 0.95 (solid lines) or R _m = 12 and m = 0.98 (dotted lines). b All probabilities increase with increasing R _m, for m = 0.95 (solid lines) and $m=0.98$ (dotted lines), with uN ₀ = 1. Curves only extend as far as R _m = 1/[2(1 − m)(1 − u)] (see Additional file 1: end of Section A1.1b) above which the strength of Y drive m < m _crit and population elimination does not occur. c Probabilities decrease with increasing $m$ (strength of Y drive), for R _m = 6, uN ₀ = 1. d Probabilities increase with increasing mutant fitness parameter w, for $R_m=6,m=0.95$ (solid lines) and $R_m=12,m=0.98$ (dotted lines), and $u{N}_0=1$. The deterministic model shows that the population will be eliminated for w ≤ 0.563 for m = 0.95, and for $w\le 0.452$ for m = 0.98. For all plots, h ₀ = 0.05. Error bars at low $R_m,w$ and high m show the standard error for simulations (averaged over ${10}^6$ runs, N ₀ = 10⁶), when the branching process model does not apply; if not shown, error is within thickness of plot line