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Most instances of autopolyploidy result from the fusion of unreduced (2n) gametes, which results in either triploid (n + 2n = 3n) or tetraploid (2n + 2n = 4n) offspring. [21] Triploid offspring are typically sterile (as in the phenomenon of triploid block ), but in some cases they may produce high proportions of unreduced gametes and thus aid ...
There are two major divisions of polyploidy, allopolyploidy and autopolyploidy. Allopolyploids arise as a result of the hybridization of two related species, while autopolyploids arise from the duplication of a species' genome as a result of hybridization of two conspecific parents, [ 25 ] or somatic doubling in reproductive tissue of a parent.
The so-called Brassica triangle is an example of allopolyploidy, where three different parent species have hybridized in all possible pair combinations to produce three new species. [40] Polyploidy occurs commonly in plants, but rarely in animals.
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.
Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution.It can be defined as any duplication of a region of DNA that contains a gene.
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Hybrid speciation by spontaneous allopolyploidy. As Karpechenko realized, this process had created a new species, and it could justifiably be called a new genus, and proposed the name Raphanobrassica for them, but the earlier name Brassicoraphanus has priority. Plants of this parentage are now known as radicole. [4]
[1] [2] This phenomenon usually happens when autopolyploidy occurs in diploid plants. Triploid blocks lead to reproductive isolation. The triploid block effects have been explained as possibly due to genomic imprinting in the endosperm. [1] Triploid block can be partially ovecome by chemical treatment with 5-Azacytidine. [3]