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Polyploid plants can arise spontaneously in nature by several mechanisms, including meiotic or mitotic failures, and fusion of unreduced (2n) gametes. [41] Both autopolyploids (e.g. potato [ 75 ] ) and allopolyploids (such as canola, wheat and cotton) can be found among both wild and domesticated plant species.
Polyploidy is important to wheat classification for three reasons: Wheats within one ploidy level will be more closely related to each other. Ploidy level influences some plant characteristics. For example, higher levels of ploidy tend to be linked to larger cell size. Polyploidy brings new genomes into a species.
A study comparing the karyotypes of endangered or invasive plants with those of their relatives found that being polyploid as opposed to diploid is associated with a 14% lower risk of being endangered, and a 20% greater chance of being invasive. [60] Polyploidy may be associated with increased vigor and adaptability. [61]
The main goals of diploidization are: (1) To ensure proper gene dosage; and (2) to maintain stable cellular division processes. This process does not need to occur rapidly for all chromosomes in one or few steps. In recent polyploid events, segments of the genome may still remain in a tetraploid status.
Speciation via polyploidy: A diploid cell undergoes failed meiosis, producing diploid gametes, which self-fertilize to produce a tetraploid zygote.. Polyploidy is pervasive in plants and some estimates suggest that 30–80% of living plant species are polyploid, and many lineages show evidence of ancient polyploidy (paleopolyploidy) in their genomes.
Polyploid speciation is commonly observed in plants because their nature allows them to support genome duplications. Polyploids are considered a new species because the occurrence of a whole genome duplication imposes post-zygotic barriers, which enable reproductive isolation between parent populations and hybrid offspring.
A diagram that summarizes all well-known paleopolyploidization events. Ancient genome duplications are widespread throughout eukaryotic lineages, particularly in plants. . Studies suggest that the common ancestor of Poaceae, the grass family which includes important crop species such as maize, rice, wheat, and sugar cane, shared a whole genome duplication about
A polyploid complex, also called a diploid-polyploid complex, is a group of interrelated and interbreeding species that also have differing levels of ploidy that can allow interbreeding. A polyploid complex was described by E. B. Babcock and G. Ledyard Stebbins in their 1938 monograph The American Species of Crepis : their interrelationships ...