Fig. 2
From: In the light of deep coalescence: revisiting trees within networks
a The genealogy of a gene (blue lines) within the branches of a phylogenetic network. In this scenario, the two lineages from B and C failed to coalesce prior to the reticulation node (evolution is viewed backward in time, from the leaves toward the root). The resulting genealogy in this case is ((a,b),(c,d)) and neither of the two trees in the set \(\mathcal {U}(\psi)\) (shown in Fig. 1) capture this scenario. The length in coalescent units of the branch between the reticulation node and the MRCA of B and C is y. b An abstract representation of the network, assuming both reticulation edges have the same length w