Figure 1.

Schematic diagram showing how nodes are used to define species on a hypothetical gene tree. Black diamonds indicate the MRCA nodes that define species in a particular delimitation. Branches in dashed and solid lines represent speciation and coalescent branches, respectively. Bars next to the tips represent two alternative delimitations. Solid bars indicate the delimitation defined by the MRCA nodes shown on the tree. Dashed black bars indicate an alternative delimitation (i.e., splitting the top species into two) that could be assigned by the multiple-threshold method but not by the single-threshold method. Dashed gray vertical lines show the waiting times ×1, ×2, etc. that are used in the GMYC likelihood model.