autopolyploidization

Autopolyploidization is the process by which polyploids arise from chromosome duplication within a single species, producing individuals with more than two complete sets of homologous chromosomes derived from the same genome. This contrasts with allopolyploidy, where chromosome sets come from different species through hybridization followed by genome doubling.

Autopolyploidy can occur through several pathways. Nondisjunction during meiosis can generate unreduced gametes that contain a full diploid chromosome set, which when fertilized yields an autotetraploid. Somatic doubling of chromosomes in a meristem or endoreduplication can also produce autopolyploid lineages. In plant breeding, chemical treatments such as colchicine or oryzalin are commonly used to induce genome doubling and create autotetraploid or higher-level polyploid lines.

Genetic and reproductive consequences accompany autopolyploidy. Chromosome pairing during meiosis often involves multivalents, leading to polysomic inheritance and sometimes reduced fertility in the first generations. Over time, chromosomal rearrangements and selection can stabilize pairing and fertility. In addition, autopolyploids tend to have larger cells, which can affect morphology and physiology. Gene dosage and dosage balance influence expression patterns, contributing to phenotypic variation.

Occurrence and significance extend across many plants and, to a lesser extent, animals. Autopolyploidization has been an important driver of plant diversification and speciation. A well-known agricultural example is the autotetraploid potato (Solanum tuberosum). Breeders exploit autopolyploidy to develop vigorous lines or sterile cultivars, while natural autopolyploid events contribute to evolutionary novelty in various plant groups. In animals, such events are rarer but have been observed under specific circumstances.