Ancient polyploidization predating divergence of the cereals
The parental genomes of most Andropogoneae polyploids diverged in the Late Miocene coincident with the expansion of the major C4 grasslands that dominate the earth today. Branch colors indicate Bayesian posterior probability with red highest, green lowest.
The role of polyploidy, particularly allopolyploidy, in plant diversification is a subject of debate. The pattern apparently indicates a rapid radiation.
The parental genomes of most Andropogoneae polyploids diverged in the Late Miocene coincident with the expansion of the major CPolyploidy (whole-genome duplication) is often linked with the acquisition of new traits and subsequent species diversification, particularly in plants (1, 2).
This number is a minimum, and the actual frequency could be considerably higher.
Studies of naturally occurring and synthetic polyploids find changes in gene expression, gene loss, release of transposons, and changes in morphology and physiology immediately after polyploidy (4, 8–12).
Good mechanistic reasons support such a hypothesis.
Whole-genome duplications precede the origins of many major clades (e.g., angiosperms, Brassicaceae, Poaceae), suggesting that polyploidy drives diversification. One reason for the difficulty of resolving the phylogeny may be a failure to account for polyploidy.