Originally, the Eudyptula genus included two different species of penguin, the little penguin ("E. minor") and the fairy penguin ("E. undina"). In 1976, scientists combined these two species into one species ("E. minor") with six subspecies. However, new research on the penguins' mitochondrial DNA shows that the DNA of populations in the Australia and southern New Zealand region are very different from those of little penguins in northern New Zealand. Because of those discoveries, some researchers still argue about whether these two populations should be divided into two different species. Another common argument is over the classification of the white-flippered penguin. While most believe the white-flippered penguin is a subspecies of the little penguin, some argue that it is a different species. Others argue that it is not a subspecies at all, but a morph that just has different colors.