Figure 3.

Evolutionary origin of gamma-derived Vitis paralogues. The branch labels along the backbone of the phylogenetic tree [total(no. with greater than 50% BS)] indicate the number of Vitis paralogues estimated to have arisen along the respective stem linages assuming strict tetraploidy events. Possible phylogenetic origins of the third subgenome via the two-step model of gamma hexaploidy are indicated by 1, 2 and 3. Scenarios in which a tetraploid is crossed with a close relative that branched off the core eudicot stem lineage (position 1) or off an older stem lineage (position 2) can be reconciled with our gene trees if extensive gene loss and/or extinction is invoked. The scenario of a wide cross between the core eudicot tetraploid and a species that branched off the stem lineage ‘below’ Buxales and Trochodendrales (position 3) is less complex evolutionarily.