Short Internal Branches

When a species tree has a short total height with numerous short internal branches, the gene trees that evolve conditionally on the species tree vary considerably across genetic loci. The short internal branches of the species tree give rise to considerable disagreement among gene trees, so that the species tree is difficult to infer from the gene trees.

Hence, in estimation procedures for species trees that possess short internal branches, the true species tree, is, like this itinerant bonsai truck, possible to find – but it is elusive.

Photo: Noah Rosenberg, October 3, 2021