Fig. 3

Demographic histories of N. australis and N. obscura populations. A Stairway plot reconstructions of demographic history. Inset stars indicate co-occurring populations which were further explored within a codemographic framework. Populations are arranged from westernmost to easternmost within each species. B Most likely individual demographic histories for co-occurring N. australis and N. obscura populations over the Pleistocene, simulated using FastSimCoal2. Thick dark lines indicate mean Ne over time, calculated based on the means of current Ne, rates of change and timing of switching rates (see Supplementary Material). Shaded areas indicate 95% confidence intervals based on the 97.5% and 2.5% probability estimates for the same parameters. C Bayes Factor matrix of the proportion of populations showing synchronised bottlenecks (ξ) within a co-demographic model using Multi-DICE. Each cell compares the model in the column with the model in the row, with brighter colours indicating greater support for the column. D Posterior distribution of mean bottleneck strength (ε) across all six populations. E Posterior distribution of dispersion index of bottleneck strength [Var(ε)/Mean(ε)] across all six populations. F Posterior distribution of the timing of the bottleneck event, in generations/years