Polyploidy is whole genome duplication, when all the chromosomes and so, all the genes, of an organism double. In plants, it is very common; easily 3/4 of plants are polyploid.
an Oenothera |
Because polyploidy is a genetic effect that takes place inside the cell's nucleus, it is not casually observed. But botanists discovered polyploidy as soon as they had microscopes to look at the contents of the nucleus and when they tried crossing polyploids and got results that didn't make sense based on diploid genetics. (Diploid = 2 copies of the genome, polyploidy = numbers over 2, like 3, 4, and 6 see previous posts in this series link link). Study of polyploidy began in the early 1900s.