Fig 2. Possible locations for the whole genome duplication uncovered for Encephalartos natalensis and Ginkgo biloba.

Cycad and ginkgo share a common ancestor and are sister to the ancestor of Gnetales and conifers [17, 30, 34, 35, 37, 39]: the inferred polyploidy event could have occurred in the common ancestor of the cycad and gingko lineages (red square), the gymnosperm ancestor (green square), or in the seed plant ancestor (blue square). Note that the position of Gnetales remains uncertain (see text for details).