Figure 1.

Mechanisms of polyploid formation. For simplicity, the A and D genomes of the diploid species are represented by only two chromosomes, in white and black, respectively. An allopolyploid (AADD) may form as a result of hybridization of the two species (hybrid AD), followed by whole-genome duplication (WGD). Alternatively, the two diploid species may give rise directly to the allopolyploid by fusion of their unreduced gametes.

Pignatta and Comai Journal of Biology 2009 8:43   doi:10.1186/jbiol140
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