Fig. 1

Example trees with suspicious long branches. a An unfiltered gene tree of a Plant dataset [23] with an obvious outlier leaf; b a gene tree in a mammalian dataset with a hard to detect outlier branch [36]. Outgroups are shown in blue and the suspicious long branches in the red. Dashed green line: the tree diameter after removal of red branches. Detecting the red branch is easy on the left but hard on the right