After 10,000 years of inbreeding, Rakiura/Stewart Island kākāpō have been found to be in surprisingly good genetic health.
Stella-2-B is a juvenile from the bumper 2019 kākāpō breeding season. Photo: CC BY-NC-SA 2.0 Jake Osborne / DOC
A major international study has revealed the kākāpō have lost harmful mutations due to inbreeding.
University of Otago Professor Bruce Robertson has been studying kākāpō genes for 25 years, and said the purging of mutations was believed to have been through natural selection.
"We looked at whole genomes of the Stewart Island birds and also the historical samples from the mainland and what we found was that the Stewart Island birds have actually lost a lot of the harmful mutations and typically in a small population they should actually be accumulating," he said.
"We think it's due to natural selection ... purging some of these harmful mutations."
He said it was good news for kākāpō and for other endangered species.
"Many of these harmful mutations can cause genetic diseases, so it means that they've got fewer of them [than might be expected].
"It's good news for other species as well because kākāpō have been at this sort of bottleneck for a long period of time, since about 10,000 years, so it suggests that populations can persist over a long period of time."
He said the research could be applied to other endangered species with small populations.
However, the research also raised some complex problems conservationists would need to confront.
"We do need to be mindful that inbreeding is still a problem, and poor hatching success - and only about 50 percent of eggs hatch in kākāpō - probably has a genetic basis.
"The other thing that for kākāpō we need to be mindful of is we have the genes from one - richard henry, the last Fiordland kākāpō - and we have to now think how we're going to get his genes into the gene pool because he actually has good genes but he also has these harmful mutations so we have to consider how to do that."