Polyploid

Polyploidy is a condition in which the cells of an organism have more than two paired (homologous) sets of chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two homologous sets of chromosomes, one set inherited from each parent. However, polyploidy is found in some organisms and is especially common in plants.

Causes

Polyploidy may occur due to abnormal cell division, either during mitosis, or commonly during meiosis. Polyploids are classified according to the number of chromosome sets in the nucleus. The types of polyploidy are triploid (3x), tetraploid (4x), pentaploid (5x), hexaploid (6x), heptaploid or septaploid (7x), octaploid (8x), nonaploid (9x), decaploid (10x), undecaploid (11x), dodecaploid (12x), tridecaploid (13x), tetradecaploid (14x), pentadecaploid (15x), hexadecaploid (16x), heptadecaploid (17x), octadecaploid (18x), enneadecaploid (19x), and icosaploid (20x).

Effects

Polyploidy can be beneficial to organisms by enabling them to become larger or more complex. Polyploidy can lead to increased genetic diversity, which can increase the ability of the organism to survive and adapt to varying environments. However, polyploidy can also have negative effects, such as reduced fertility and increased susceptibility to certain diseases.

In plants

Polyploidy is common in plants and can result in new species. For example, the wheat genome is a result of two plant species with two different genomes undergoing fertilization to produce a tetraploid. This new species was then able to undergo normal sexual reproduction to become a stable, reproducing species.

In animals

Polyploidy is much less common in animals than in plants. It is most commonly found in amphibians and reptiles, although it can also occur in mammals and birds. In animals, polyploidy can lead to sterility.

See also

• Endopolyploidy
• Monoploid
• Haploid
• Diploid
• Triploid
• Tetraploid
• Pentaploid
• Hexaploid
• Heptaploid
• Octaploid

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