Figure 3.

Nested calibrations iterator. The calibrated clades are N (green), M (blue) and L (red), with, respectively, $n+2$, $n+2+m+1$ and $l+2$ taxa. In addition, we have $r$ “free” taxa in orange, which can coalesce between themselves and with the roots of M and L. There are four levels associated with the three calibration nodes, separated by the root ages of the calibrated clades.