Ancient whole genome duplications, novelty and diversification: the WGD Radiation Lag-Time Model.

Many large and economically important plant groups (e.g. Brassicaceae, Poaceae, Asteraceae, Fabaceae and Solanaceae) have had ancient whole genome duplications (WGDs) occurring near or at the time of their origins, suggesting that WGD contributed to the origin of novel key traits and drove species diversification. However, these large clades show phylogenetic asymmetries with a species-rich crown group and a species-poor sister clade, suggesting significant 'lag-times' between WGDs and radiations. The species-poor sister groups share many key traits, but are often restricted to the hypothesized center of origin for the larger clade. Thus, the ultimate success of the crown group does not only involve the WGD and novel key traits, but largely subsequent evolutionary phenomena including later migration events, changing environmental conditions and/or differential extinction rates.