Fig. 3.

Inferred phylogenetic history of $N_{\mathrm{e}}$ (left) and μ (right) across placental mammals (posterior mean estimate), based on an analysis of a concatenation of 18 genes randomly chosen among single-copy orthologs putatively under an exclusively purifying selection regime. $N_{\mathrm{e}}$ estimates are relative to the value of $N_{\mathrm{e}}$ at the root. The scale for μ is per nucleotide site and per total tree depth (i.e., total time from the most recent common ancestor to the present). If we assume the root to be 105 My old (Meredith et al. 2011; Kumar et al. 2017), the rescaled mutation rate per site per year in extant species is between $1.1\times {10}^{-10}$ and $7.8\times {10}^{-9}$. Icons are adapted from http://phylopic.org.