While normal evolution takes generations of genetic distinction to produce a new species, evolution via polyploidy is instantaneous, according to WSU professor of botany Doug Soltis. It takes just one generation, and it doesn t require that the new species be spatially separated from the old, Soltis says. It appears to be the rule rather than the exception that polyploid species evolve more than one time, adds Soltis, who has found this to be the case in all polyploids tested. Polyploidy appears to involve an error in a plant s production of its pollen, or egg, which results in its containing too many copies of each chromosome. Thus the offspring of such a plant also have extra chromosomes.
Polyploidy can occur in two ways.
It can happen between individuals of two distinct plant species, a process termed allopolyploidy. Or it can happen between two individuals of the same species, a process termed autopolyploidy. The latter process was considered rare and maladaptive for many years, since it was thought autopolyploidy would result in a high proportion of sterile pollen. But Soltis, along with his wife and collaborator, Pam Soltis, also a professor of botany at WSU, have found through molecular methods such as enzyme and DNA analysis that autopolyploidy is more common than previously thought. These methods also indicate that autopolyploidy is not maladaptive, for autopolyploids have more genetic variability than their parent plants.