Figure 5
From: Ancient horizontal gene transfer and the last common ancestors
Hypnologs. HGT from ancient lineages that diverge before LUCA into the ancestors of extant lineages produce a unique phylogenetic signal within gene families. Species trees (blue) become pruned over time via extinction, while gene ancestry (red) from extinct lineages can be preserved by the HGT event, resulting in a gene ancestor predating the LUCA species ancestor.