Extended Bayesian skyline plots (EBSPs) for Columbia and Snake River groups (A) and rate of reduction in Nef indicated in the associated EBSP (B).

<p>Mean effective population size is indicated with solid black line, median with dashed line, and 95% highest posterior density (HPD) in shaded grey. Contrasting patterns are present for the two groups; the Columbia River groups visually indicates a reduction in mean effective population size while no such reduction is present for Snake River samples.