allotetraploidi

Allotetraploidy is a form of polyploidy where an organism has two or more complete sets of chromosomes, and these sets originated from different species. This contrasts with autotetraploidy, where all chromosome sets come from the same species. Allotetraploidy typically arises through hybridization between two different species, followed by chromosome doubling. For example, if species A with 2n=2x chromosomes hybridizes with species B with 2n=2y chromosomes, the initial hybrid offspring would be an allodiploid with n=x+y chromosomes. If the chromosome number of this hybrid then doubles, the resulting allotetraploid would have 2n=2(x+y) chromosomes, with two sets from species A and two sets from species B.

This phenomenon is significant in plant evolution and agriculture. Many important crop plants, such as wheat, cotton, and tobacco, are allotetraploids. Allotetraploidy can lead to novel gene combinations, potentially resulting in new traits or increased vigor, a phenomenon known as hybrid vigor or heterosis. The presence of multiple sets of chromosomes can also provide genetic redundancy, which may help buffer against deleterious mutations. However, allotetraploids can sometimes experience challenges in meiosis due to the presence of non-homologous chromosome sets, which can lead to reduced fertility if proper pairing and segregation do not occur. Despite these challenges, allotetraploidy has been a major driver of speciation and the evolution of biodiversity.