Focus on polyploidy

Polyploidy (whole-genome duplication) has played a pervasive role in the evolution of fungi and animals, and is particularly prominent in plants (Wendel & Doyle, 2005; Cui et al., 2006; Otto, 2007; Wood et al., 2009). This important evolutionary phenomenon has attracted renewed and growing interest from the scientific community in the last decade since it was discovered that even the smallest plant genomes considered to be ‘diploid' (e.g. Arabidopsis thaliana, reviewed in Henry et al., 2006) have incurred at least one round of whole-genome duplication, possibly predating the origins of the angiosperms (Soltis et al., 2009). Polyploidy is an important speciation mechanism for all eukaryotes and has profound impacts on biodiversity dynamics and ecosystem functioning. Newly formed polyploids, and particularly those of hybrid origin (allopolyploids), frequently exhibit rapid range expansion (Ainouche et al., 2009), and over long periods of evolutionary time, polyploidy has increased morphological complexity and probably reduced the risk of species extinction (Fawcett et al., 2009). Last, but not least, genome duplication has often provided the raw material for plant domestication (e.g. wheat, Dubkovsky & Dvorak, 2007) and thus has had a major impact on human societies and the development of an agrarian lifestyle