polyploïdie

Polyploïdie is a condition where an organism has more than two complete sets of chromosomes. In most sexually reproducing organisms, individuals are diploid, meaning they have two sets of chromosomes, one inherited from each parent. Polyploïdie occurs when an organism possesses three or more sets of chromosomes. This can arise from errors during meiosis, the process of cell division that produces gametes, or through genome duplication events.

There are several types of polyploïdie. Autopolyploïdy occurs when an organism has multiple sets of chromosomes that are all derived from the same species. For example, an autotetraploid has four sets of chromosomes, all from the same parent species. Allopolyploïdy, on the other hand, involves the combination of chromosome sets from different species, typically through hybridization followed by chromosome doubling.

Polyploïdie is common in plants, where it has played a significant role in their evolution and diversification. Many cultivated crops, such as wheat, cotton, and potatoes, are polyploid. In animals, polyploïdie is less common but is found in some invertebrates, fish, and amphibians. The consequences of polyploïdie can vary. In some cases, it can lead to increased vigor, size, or altered characteristics. In others, it can result in infertility or developmental abnormalities. The mechanisms and implications of polyploïdie continue to be an active area of research in genetics and evolutionary biology.