Figure 1
From: Reconciliation and local gene tree rearrangement can be of mutual profit
Example of subdivision of a species tree. The subdivision S′ is obtained from the species tree S by splitting some of its edges thanks to additional artificial nodes (∘), i.e. nodes with a single child. These nodes are added on edges at the precise date a node appears somewhere else in S. For instance here, the artificial node s1 is placed at the same date as the node s2 of S, while s4 and s5 are placed at the same date as s3.