for the three modes of reproduction are coloured Red: asexual reproduction; Blue: sexual reproduction with free recombination; and Green: sexual reproduction with segregation alone. The x-axes vary the “ridge length”,

(Panels (a) and (c)), or the genomic deleterious mutation rate,

(Panels (b) and (d)). Panels (a) and (b) show the equilibrium mean fitness of the populations,

. Points show exact numerical results, and solid lines show analytical approximations from . These solid lines become dashed in regions of parameter space in which hidden epistasis is not predicted (), and so where the normal approximations might not apply. Panels (c) and (d) represent the genetic constitution of the populations, with points showing the mean number of mutations carried,

, and error bars delimiting 99.75% of the population (corresponding to 3 standard deviations of the normal distribution). Coloured areas show the analytical approximations for

(). The thick dashed black line shows

, and so populations who do not overlap with this line are said to exhibit hidden epistasis. Dashed coloured lines, and lighter shading denote the parameter regimes where hidden epistasis is not predicted (). The vertical light-green dotted lines shows the transition between the two possible parameter regimes for sex with segregation alone (

).

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