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Background

Throughout the past century, hybridization and polyploidization have variously been viewed as drivers of biodiversity (eg Arnold, 1997) or evolutionary noise, unimportant to the main processes of evolution (eg Stebbins, 1950; Wagner, 1970). Wagner (1970) argued that while polyploids have always existed, they have never diversified or played a major role in the evolution of plants, and that the study of polyploidy (as well as inbreeding, apomixis, and hybridization) has led researchers to be ‘carried away with side branches and blind alleys that go nowhere’. However, the use of molecular tools revolutionized the study of polyploidy, revealing that a given polyploid species often forms multiple times (reviewed in Soltis & Soltis, 1993, 1999, 2000, 2009). The realization that recurrent polyploidization from genetically differentiated parents is the rule that shattered the earlier perceptions of polyploids as …