The phenotypic result is different constellations of phenotypes. Euploidy Examples of euploidy are given in the section on speciation, where the significance of the euploidy to the process of species formation is discussed. The information given here supplements that discussion with information on the genetic basis of euploidy. Mitotic failure in sex organ, doubling the number of chromosomes in the organ and changing the number of gametic chromosomes. Failure of meiosis to produce a diploid gamete instead of haploid one.
Sterility occurs in almost all sexually reproducing organisms with odd-numbered sets of chromosomes.
Nonetheless, all homologous chromosomes of autopolyploids align together on the meiotic spindle, and in the case of an autotetraploid, the quadrivalents need not segregate in pairs. Thus, the gametes receive unbalanced chromosomal complements, and the autopolyploids are often sterile. The formation of a polyploid by hybridization of genetically differentiated diploid populations through the hybridization of different species. Allopolyploidy is common among plants, but not among animals. This is due to the XY sex determination mechanism, which is easily upset when chromosome sets are duplicated.