What is polyploidy and what role does it play in the formation of species?

Polyploidy is a condition in which a normally diploid cell or organism acquires one or more additional sets of chromosomes. In other words, a polyploid cell or organism has three or more haploid chromosome numbers. Polyploidy occurs as a result of the complete inseparability of chromosomes during mitosis or meiosis.

Polyploidy is common among plants and, in fact, is the main source of speciation in angiosperms. Particularly important is allopolyploidy, which involves duplication of chromosomes in a hybrid plant.