Galahs are the pink and grey cockatoos that are one of the most familiar of all Australian birds. They’ve have been at the centre of a curious debate: what should their scientific name really be?
It’s a tale that spans centuries and continents, and has clues hidden in museums, diaries of 19th century travellers and evolution’s own diary of DNA sequences.
When biologists formally publish a scientific description of a new species, they give it a unique scientific name that is forever linked to a single, preserved specimen in a natural history collection. This specimen is known as the holotype.
The galah’s scientific name is Eolophus roseicapilla. Its holotype was collected in Australia in 1801 by biologists on the Expedition led by France’s Nicolas Baudin and is held in the Musée National d’Histoire Naturelle, in Paris.
East and west
Much later, Australian ornithologists realised galahs in the continent’s west look very different from galahs in the east.
Eastern galahs became known as the subspecies Eolophus roseicapilla roseicapilla, the holotype of that name automatically being the original held in Paris because it was assumed to have been collected in the east.
The subspecies in the west was named Eolophus roseicapilla assimilis and that name was also linked to a new holotype, a bird from the west.
But was the bird collected back in 1801 really from the east? The name roseicapilla means pink or rosy “hair” and so refers to the general pink colour of the species. It does not refer to the dark-pink headed galahs from the west as distinct from the pale-pink almost whitish-headed galahs from the east.
In the late 1980s, Dr Richard Schodde, then the Director of CSIRO’s Australian National Wildlife Collection, realised the route of the Baudin Expedition wouldn’t have passed anywhere near where eastern galahs occurred at that time.
Galahs were originally birds of arid, inland Australia, only expanding into their present, vast range in the early- to mid-20th century.
The biologists of the Baudin Expedition were more likely to have encountered galahs around Shark Bay in Western Australia. The holotype was more likely a western bird, Schodde reasoned.
Schodde further reasoned that if the holotype in Paris was a western galah, its name, Eolophus roseicapilla roseicapilla, actually belonged to the western galahs. This left the eastern galahs, one of the most familiar birds in all of Australia, without a scientific name.
Schodde named them Eolophus roseicapilla albiceps and designated a holotype that was collected in Canberra and is held in CSIRO’s Australian National Wildlife Collection.
His detective work at that time didn’t settle the debate. Simple examination of the holotype in Paris should reveal whether it is an eastern or western bird. But the specimen is more than 200 years old and not in great shape.
Nevertheless, two recent papers published by Australian ornithologists, including a further one by Richard Schodde, and another by our team, have argued that despite the specimen’s condition it is identifiable as a western bird.
What the DNA says
Enter DNA to solve the mystery. Australian natural history collections contain hundreds of specimens of galahs from across their modern range.
If these specimens show detectable genetic differences between eastern and western subspecies, and if we can get a DNA result from the Paris holotype, we could find out whether it belongs to the eastern or western group.
With a colleague in Germany, Thomas Wilke, we mapped genetic diversity of galahs from 192 museum specimens. We found that galahs were likely isolated during the last several hundred thousand years into western, northern and eastern subpopulations.
Even today, with the modern range expansions, any galah can be assigned to either of these three genetic groups regardless of where it occurs.
Colleagues at the Musée National d’Histoire Naturelle kindly allowed us to snip some skin from the toe pads of the holotype. One of us (Jeremy Austin) obtained DNA sequences and dropped them into our analysis.
Et voila! The Paris holotype is identical in its DNA sequence to the most common variant found in western birds.
Schodde’s theory holds. Galahs in the west should indeed be named Eolophus roseicapilla roseicapilla and those in the east Eolophus roseicapilla albiceps.
There is a third, northern variant but it is not part of our story here.
And what of the original scientific name for the western galahs, Eolophus roseicapilla assimilis? That name is not currently necessary but if anyone ever finds differences within the western birds, it may still be needed.
Leo Joseph, Research Director and Curator, Australian National Wildlife Collection, CSIRO and Jeremy Austin, Deputy Director and ARC Future Fellow, Australian Centre for Ancient DNA, University of Adelaide