Fig. 1
From: The link between orthology relations and gene trees: a correction perspective
A species tree S, a binary DS-tree G and a non-binary DS-tree \(G'\). In DS-trees, Dup nodes are indicated by squares. All other nodes are speciations nodes. Each leaf \(\alpha _i\) denotes a gene belonging to the genome \(\alpha\). G is a refinement of \(G'\) such that \({\mathcal O} (G) = {\mathcal O} (G')\) and \({\mathcal P} (G) = {\mathcal P} (G')\). Notice that, although in this example the gene trees contain exactly one gene copy from each genome, this is not a requirement. Another example with multiple gene copies in genome a is given in Fig. 2