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Researchers have sequenced the genomes of a large proportion of the kākāpō population, providing new tools to help the critically endangered bird survive.
The work also shows that conservation management of the species has kept inbreeding to a minimum, and maintained genetic diversity.
Methods developed by Dr Joseph Guhlin, from the University of Otago, and an international team had revealed important aspects of kākāpō biology, Genetics Aotearoa – an alliance of some New Zealand universities and crown research institutes – said in a media release.
Department of Conservation’s science adviser for kākāpō recovery Dr Andrew Digby, said the genetic tools provided by the project would make an immense difference to kākāpō conservation.
“Kākāpō suffer from disease and low reproductive output, so by understanding the genetic reasons for these problems, we can now help mitigate them,” Digby said.
“It gives us the ability to predict things like kākāpō chick growth and susceptibility to disease, which changes our on-the-ground management practices and will help improve survival rates.”
The researchers analysed whole-genome sequence data for nearly all kākāpō living in 2018, when the population was 149 birds. Genomes from some dead birds from earlier generations were also sequenced. Altogether, 169 birds were sequenced.
Jake Osborne/Supplied
Bunker the kakapo, one of the four kākāpō moved in July to Sanctuary Mountain Maungatautari, near Cambridge, from Whenua Hou.
For intensively managed species, the ultimate goal was to minimise the loss of genetic diversity to maintain long-term evolutionary potential, a paper on the research, published in Nature Ecology & Evolution, reported.
A large, nocturnal flightless parrot, kākāpō were thought to have been functionally extinct by 1976, with fewer than 15 males known to be surviving in Fiordland.
But the discovery of a population including females on Rakiura/Stewart Island in 1977 rekindled conservation efforts, with most known birds relocated to predator-free offshore islands.
By August 2022, the population had grown to 252 kākāpō, derived from a population of 51 in 1995, which was when the formal Kākāpō Recovery Programme began, the report said.
Kākāpō had a low reproductive rate for various reasons, including high hatching failure attributed to inbreeding, reduced egg fertility and embryo failure, irregular breeding synchronised with mass-fruiting (masting) of certain tree species, the long time taken to reach sexual maturity, the ratio between adult males and females, and some aspects of captive rearing.
The researchers found associations within regions of genes for growth, disease susceptibility, clutch size and egg fertility.
John Hawkins/Fairfax NZ
KÄkÄpÅ chicks at a hand-rearing facility in Invercargill in 2016.
In a commentary on the work, Rebecca Taylor, who studies genomic diversity in wildlife in Canada, said the researchers involved in the project had been able to identify the genetic basis of key fitness traits – those traits that enable survival and reproduction.
The results made important contributions for kākāpō management, Taylor said.
It would help in choosing which birds to move to new homes, as well as enable better monitoring of birds with a high disease risk.
That was beneficial, given that 9 kākāpō died in 2019 from the respiratory disease aspergillosis on Whenua Hou/Codfish Island.
The sequencing also showed that a kākāpō known as Richard Henry – the only male from the remnant Fiordland population to have descendants – had increased fitness and fertility in some traits, Taylor said.
“The unique genetic variation that he has contributed to living kākāpō may be valuable for the species in the long term, despite his potentially high mutational load.”
The approaches used in the kākāpō project could be applied to other managed species, adding an exceptional level of information for improved species recovery.
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