In 1928, the Russian plant geneticist Karpechenko produced a new species by crossing a cabbage with a radish. Fusion of these gametes produced vigorous, fully-fertile, polyploid plants with 36 chromosomes. These plants could breed with each other but not with either the cabbage or radish ancestors, so Karpechenko had produced a new species. The process also occurs in nature. Modern wheat and perhaps some of the other plants listed in the table above have probably evolved in a similar way.
Polyploidy is much rarer in animals.
It is found in some insects, amphibians, and reptiles. Until recently, no polyploid mammal was known. The liver cells of the Argentinian rat are larger than those of its diploid relatives, and its sperm are huge in comparison.