The kakapo, New Zealand’s adorable flightless parrot, is one of the most endangered birds in the world. Back in 1995 there were just 51 animals remaining, with 50 being isolated on tiny Stewart Island to the south of the South Island, and a lone male, named Richard Henry, being the last remaining bird on the mainland.
Thanks to recent conservation efforts those numbers have climbed back up to around 200, but the species still remains critically endangered.
Now, a collaboration carried out by researchers based in New Zealand and Sweden has found that all is not lost for the quirky, waddling bird. The team's genetic analysis shows that, despite their small gene pool and isolation, they have lost a number of potentially harmful mutations rather than accumulating them as previous theories suggested.
“Even though the kakapo is one of the most inbred and endangered bird species in the world, it has many fewer harmful mutations than expected,” said Dr Nicolas Dussex, a researcher at the Center for Palaeogenetics and Stockholm University.
“Our data shows that the surviving population on Stewart Island has been isolated for approximately 10,000 years and that during this time, harmful mutations have been removed by natural selection in a process called ‘purging’ and that inbreeding may have facilitated it.”
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To make the discovery, the team conducted the first ever detailed analysis of 49 kakapo genomes – 35 taken from living birds on Stewart Island and 14 from the functionally extinct mainland population.
As well as indicating that the picture may not be as bleak as was once thought for the kakapo, the study could also be used to select the birds most suitable for breeding future populations, the researchers say.
For example, Richard Henry, the single male survivor from the mainland, was found to have more harmful mutations than the Stewart Island birds. However, despite this he may prove to be the best candidate thanks to being genetically distinct from the other birds.
“While the species is still critically endangered, this result is encouraging as it shows that a large number of genetic defects have been lost over time and that high inbreeding alone may not necessarily mean that the species is doomed to extinction,” said Dussex.
“It thus gives us some hope for the long-term survival of the kakapo as well as other species with a similar population history.”
The team now plan to investigate the genomes of other extremely inbred mammals and birds in order to determine whether the kakapo is a special case.