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    Dating origins polyploidy events

    Identifying and characterizing plant paleopolyploidies is ongoing research.They are identified through whole genome comparisons using a combination of the data derived from genomic structure (e.g. As such, detecting these events and determining which lineages share what subset are continually changing.Stebbins and his contemporaries developed a model of polyploid evolution that persisted for nearly half a century.As new perspectives emerged in the 1980s and new genetic tools for addressing key aspects of polyploidy have become available, a new paradigm of polyploidy has replaced much of the Stebbinsian framework.We review that paradigm shift and emphasize those areas in which the ideas of Stebbins continue to propel the field forward, as well as those areas in which the field was held back; we also note new directions that plant geneticists and evolutionists are now exploring in polyploidy research.Perhaps the most important conclusion from recent and ongoing studies of polyploidy is that, following Levin and others, polyploidy may propel a population into a new adaptive sphere given the myriad changes that accompany genome doubling.Polyploidy, or whole genome duplication (WGD), is now recognized as a major evolutionary force not only in plants, but also in all eukaryotes (e.g., Mable, 2003; Gregory and Mable, 2005).

    Male bees and other Hymenoptera, for example, are monoploid.Hexaploidies can form in either one step (instant triplication of the genome) or two steps ( 1) tetraploidy, 2) a tetraploid gamete fuses with a diploid gamete creating a sterile triploid which then regains fertility by doubling its genome again, creating a hexaploid). Bread wheat is an excellent example of this process where most of the intermediate species still exist.Einkorn wheat is a diploid containing only the A genome.Polyploid cells and organisms are those containing more than two paired (homologous) sets of chromosomes.Most species whose cells have nuclei (Eukaryotes) are diploid, meaning they have two sets of chromosomes—one set inherited from each parent.

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