The average pairwise distance for the control region between congeneric species has been reported 8.11% within a selection of bird genera. This corresponds to 89 substitutions for the control region length sequenced here. Nearest-neighbour distances between a large set of North American bird species’ COI regions average 4.3%. In contrast, the mean intraspecific distances for the same dataset average 0.23%. The former corresponds to 66 substitutions and the latter corresponds to 4 substitutions for the COI region length sequenced in this study. Low variation in the control region is generally unexpected. Potential causes of this low DNA sequence diversity might include a genetic bottleneck in the ancestral emu population or slow evolutionary or mutation rates. However, other ratites and birds show rates that are quite fast when compared to other animals. A likely cause for the minor divergence between both taxa is a very recent isolation of the King Island population from the modern Emu population. This scenario is based on the hypothesis that the King Island Emu were only recently isolated due to sea level changes in the Bass Strait,Batimastat as opposed to a founding emu lineage that diverged from modern Emu far earlier and has subsequently gone extinct on the mainland. Models of sea level change indicate that Tasmania, including King Island, was isolated from the Australian mainland around 14,000 years ago. Up to several thousand years later King Island was then separated from Tasmania. This scenario would suggest that initially a King Island/Tasmanian Emu population was isolated from the mainland taxon,Balsalazide disodium after which the King Island and Tasmanian populations were separated. This in turn indicates that the Tasmanian Emu is probably as closely related to the modern Emu as is the King Island Emu, with both the King Island and Tasmanian Emu being more closely related to each other. Fossil emu show an average size, between that of the dwarf and modern Emu taxa. Hence, modern Emu can be regarded as a large or gigantic form. It is remarkable that a lineage of this same group again evolved to a smaller form, within a short time span, possibly due to insular dwarfism as a result of phenotypic plasticity. The King Island Emu and the modern Emu show few morphological differences other than their significant difference in size. Additional traits that supposedly distinguish these taxa have previously been suggested to be plumage colour, the distal foramen of the tarsometatarsus, and the contour of the cranium. However, the distal foramen is known to be variable in the modern Emu showing particular diversity between juvenile and adult forms and is therefore taxonomically insignificant. The same is true of the contour of the cranium, which is more dome-shaped in the King Island Emu but is in fact also seen in juvenile modern Emu. Due to their close genetic/evolutionary relation- ship and similar morphology it seems inappropriate to suggest that King Island Emu should be given species-status. Other terrestrial animals that are restricted to King Island are not typically considered endemic or different species, but rather subspecies or the same species with regard to their relatives living on Tasmania and/or mainland Australia. This study also highlights the independence of processes governing morphological and neutral molecular evolution.