Figure 5. The second principal component for the combined vaginal data, representing about 24 percent of the variance. Low-weight regions of the tree are excluded from the figure. The edges across which maximal between-sample heterogeneity is found are those between two different Lactobacillus clades: L. iners and L. crispatus. Thus, the second important ‘‘axis’’ appears to correspond to the relative levels of these two species. [Matsen & Evans 2013]