Figure 3

Rarefaction analyses of modern and ancient koala mtDNA haplotypes. Panel A shows the expected number of haplotypes based on random sampling of the modern koala dataset. Based on the Houlden et al. [8] dataset, one would expect that a random sample of 14 modern koalas would carry 4 unique haplotypes. The set of 14 museum samples for which mtDNA could be sequenced also carried 4 unique haplotypes (blue diamond), completely consistent with expectations based on modern mtDNA diversity. Panel B models mtDNA haplotype data based on random sampling of modern koalas, ancient koalas and a conjectural dataset. The solid blue curve represents the rarefied number of mtDNA haplotypes for modern koalas, showing the number of unique mtDNA haplotypes expected given sample sizes of up to 14. The overlapping red dotted line indicates the number of mtDNA haplotypes for museum koalas. The overlap between curves representing modern and ancient koalas indicates that koala mtDNA diversity was not substantially higher in the museum samples than the modern samples. The green solid line represents rarefaction analysis of a conjectural population with twice the number of mtDNA haplotypes as modern koalas. The curve for the conjectural dataset deviates substantially from the curves drawn from modern and museum data, even at small sample sizes.