Tetraploidization

Tetraploidization is a genetic process where an organism acquires an additional set of chromosomes, resulting in four complete sets rather than the usual two. This condition is known as tetraploidy, and the organism is called a tetraploid. It is a type of polyploidy, which encompasses any condition with more than two sets of chromosomes. Tetraploidization can occur naturally through errors in cell division, specifically during meiosis when gametes (sperm or egg cells) are formed, or during mitosis. If a cell fails to divide properly after its chromosomes have duplicated, it can end up with twice the normal number of chromosomes. When these cells participate in reproduction, they can lead to tetraploid offspring.

In plants, tetraploidization is relatively common and can lead to significant changes in morphology, such as larger flowers, fruits, or seeds, and increased vigor. Many cultivated crops, including wheat, cotton, and potatoes, are naturally or artificially tetraploid. This phenomenon has been extensively utilized in plant breeding to develop desirable traits. In animals, tetraploidy is much rarer and often lethal, particularly in mammals. However, some invertebrates and fish can tolerate or even thrive as tetraploids. The genetic consequences of tetraploidization are substantial, as it doubles the gene dosage for all genes and can lead to the evolution of new gene functions through gene duplication and subsequent divergence.