polyploidyzacj

Polyploidization, referred to in Polish as polyploidyzacja, is the process by which an organism gains one or more complete sets of chromosomes, increasing its ploidy beyond the diploid state. It is especially common in plants and can lead to instant speciation, since polyploid individuals may be reproductively isolated from their diploid ancestors. Polyploidization can arise by autopolyploidy, where chromosome duplication occurs within a single species, or by allopolyploidy, where two different species hybridize and the resulting genome doubles to restore fertility.

Autopolyploidy results from errors in meiosis or mitotic chromosome doubling that produce unreduced gametes; when such gametes fuse, offspring with doubled chromosome numbers occur. Allopolyploidy involves hybridization between species followed by chromosome doubling, allowing homologous chromosomes from the two parental genomes to pair during meiosis and enabling fertility. There are also segmental forms and, in some contexts, endopolyploidy, where certain tissues or cells become polyploid without the whole organism’s ploidy changing.

Plants show the greatest natural and agricultural significance of polyploidization. Wheat is a hexaploid crop (six chromosome sets), and certain cotton species are allotetraploids. Polyploidization can confer advantages such as larger cell and organ size, genetic redundancy, and novel traits, but can also cause meiotic irregularities and fertility challenges. In animals, polyploidy is rarer but occurs in some fish and amphibians.

Detection and study rely on cytogenetic methods, flow cytometry to estimate genome size, and genomic sequencing. Endopolyploidy, a related phenomenon, involves polyploid cells within otherwise diploid tissues, such as liver or certain insect glands, rather than organism-wide polyploidy.