Figure 2 – Potential outcomes of a triploid F1 backcrossing to the parental species. In both panels, the schematic follows that of Figure 1a. Interrupted lines indicate backcrosses to parental species. In a the triploid F1 hybrid produces reduced gametes that combine with reduced gametes from the diploid male parent. In b there are two pathways to produce a tetraploid F1 backcross: firstly the unreduced gametes from the triploid F1 can combine with reduced gametes from the female tetraploid parent, secondly the unreduced gametes from the triploid F1 can combine with unreduced gametes from the diploid male parent. Figure generated with graphviz (Ellson et al., 2002).