Resolution:
## Figure 1.
Predicted extinction times of the Amazon molly. Muller's ratchet might cause extinctions of the unisexual Amazon molly due to the
accumulation of slightly deleterious mutations. (A) analytical results only, (B) analytical results and simulations combined. The upper bar denotes the assumed age
of the line (70 Ky, min 40 Ky, max 100 Ky). The lower bar marks the border to neutrality
for the effective population sizes (N_{e}) used by spanning the selection coefficients from N_{e}s = 1 for the largest (10^{7 }females) to the smallest conceivable N_{e }(10^{4 }females). The lines represent the analytic predictions of the extinction time for
different deleterious genomic mutation rates (U_{sdm}) with N_{e }= 316,000, generation time T_{gen }= 1 year and maximal reproductive capacity R_{max }= 500 offspring/generation. Our current best overall estimate for U_{sdm }is 0.4 critically deleterious mutations/diploid genome/generation. Our upper limit
is close to U_{sdm }= 1. The dashed lines indicate the variability of the extinction time estimates for
a value that is close to our lowest credible mutation rate estimate (U_{sdm }= 0.05, green diamantes) using the corresponding upper and lower limits of N_{e}, T_{gen }and R_{max}; variability in extinction time is similar for other U_{sdm}. Large symbols denote valid extinction time estimates from simulations with at least
2 observed clicks of Muller's ratchet (usually many more, up to 500). Small symbols
denote lower limits for extinction times from simulations without observed clicks,
based on the (usually wrong) assumption that the ratchet would have clicked just after
stopping the simulation. Each symbol denotes an independent simulation with a different
random seed and assumes the same mean T_{gen }and R_{max }as analytic predictions (different N_{e }have been plotted on top of each other to avoid a series of similar plots). This plot
contains 24,251 simulations with a total of 14.78 years of computing time. See main
text for a discussion of parameter combinations and Loewe [7] for an in-depth explanation
of the U-shaped plot shown here. The location of the wall of background selection for a particular parameter combination is approximately given by the vertical part
of the corresponding line: all mutations with effects larger than the location of
this wall are removed deterministically.
Loewe and Lamatsch |