Table 1. Parameters and prior distributions.

Parameter	Description	Prior distribution
θanc,l	Scaled ancestral mutation rate at locus l, 4Neu	${\text{log}}_{10}\left({\theta }_{\text{anc},l}\right)\sim N\left({\mu }_{{\theta }_{\text{anc}}},{\sigma }_{{\theta }_{\text{anc}}}^2\right)$a
${\mu }_{{\theta }_{\text{anc}}}$	Mean across loci of θanc,l (on log10-scale)	${\mu }_{{\theta }_{\text{anc}}}\sim N\left(0.5,1\right)$
${\sigma }_{{\theta }_{\text{anc}}}$	Standard deviation across loci of θanc,l (on log10-scale)	${\sigma }_{{\theta }_{\text{anc}}}\sim {\text{log}}_{10}$-uniform in [0.01, 1]
ω	Proportion of mature males with access to matings	ω ∼ log10-uniform in [0.01, 1]
${\tilde{m}}_{i,j}$b	Forward migration rate per year from deme i to deme j	${\tilde{m}}_{i,j}\sim {\text{log}}_{10}$-uniform in [10−3.5, 10−0.5]

^aN(μ, σ²), normal distribution with mean μ and variance σ².

^bAlthough migration rates are not estimated here, they are drawn from the prior in all simulations (see main text).