Polyploidy—having more than two copies of each chromosome—is lethal in most animals, but not an uncommon phenomemon in plants. In fact, all angiosperm species is believed to have undergone one or more polyploidization events in their lifetime. Allopolyploidy—when the genomes of two different species merge and hybrids arize—can result in higher capacity for adaptation, but what are the drivers and how are the polyploid plants distributed globally?
Reconstructing a complete angiosperm phylogeny while gathering data on chromosome numbers and GBIF-mediated occurrences, this study maps the global distribution of polyploid frequency among nearly 135,000 plant species. The resulting maps show a clear latitudinal pattern with polyploidy increasing towards the poles. At the biome-level, most polyploid plant are found in tundras. Most ecoregions show the same patterns as their biomes—with some notable polyploid-rich tropical ecoregions, such as the Andes and Hawaii.
Exploring possible environmental drivers, the authors show that polyploidy is corelated with temperature, prevailing in cooler climates. The effect, however, appears predominantly mediated indirectly through its effect on the floral composition of ecoregions.