Evolution: a different method, polyploidy (Introduction)

by David Turell , Monday, May 11, 2015, 01:16 (3266 days ago) @ David Turell
edited by David Turell, Monday, May 11, 2015, 01:21

No one knows how it works, but some plants and some animals double up on DNA:-"It was a particularly rare find given hybrid plants of its kind are normally infertile. Instead, it doubled the amount of DNA in its cells and evolved to form a new species in a process known as polyploidisation, the same mechanism by which Wheat, Cotton and Tobacco originated."-http://www.sciencedaily.com/releases/2015/05/150506120527.htm-Here's the abstract:-"Whole genome duplication (polyploidisation) is a mechanism of “instantaneous” species formation that has played a major role in the evolutionary history of plants. Much of what we know about the early evolution of polyploids is based upon studies of a handful of recently formed species. A new polyploid hybrid (allopolyploid) species Mimulus peregrinus, formed within the last 140 years, was recently discovered on the Scottish mainland and corroborated by chromosome counts. Here, using targeted, high-depth sequencing of 1200 genic regions, we confirm the parental origins of this new species from M. x robertsii, a sterile triploid hybrid between the two introduced species M. guttatus and M. luteus that are naturalised and widespread in the United Kingdom. We also report a new population of M. peregrinus on the Orkney Islands and demonstrate that populations on the Scottish mainland and Orkney Islands arose independently via genome duplication from local populations of M. x robertsii. Our data raise the possibility that some alleles are already being lost in the evolving M. peregrinus genomes. The recent origins of a new species of the ecological model genus Mimulus via allopolyploidisation provide a powerful opportunity to explore the early stages of hybridisation and genome duplication in naturally evolved lineages. (paywall) - Mario Vallejo-Marín, Richard J. A. Buggs, Arielle M. Cooley, Joshua R. Puzey. Speciation by genome duplication: Repeated origins and genomic composition of the recently formed allopolyploid speciesMimulus peregrinus. Evolution, 2015; DOI: 10.1111/evo.12678"-Another article on the subject:-http://blogs.scientificamerican.com/artful-amoeba/2013/05/19/for-plants-polyploidy-is-not-a-four-letter-word/-Only two cases of successful polyploidy are known among birds, and only one among mammals: the South American red viscacha rat (which is much cuter than it sounds). It has four copies of its genome, which makes it tetraploid.-"Polyploidy is slightly more common among other animals. A few hundred cases of polyploidy are known in insects, reptiles, amphibians, crustaceans, fish, and other “lower” animals."