The New Zealand flightless parrot Kakapo is critically endangered. Detailed genetic data should now help to make the protection efforts even more effective. To do this, the researchers sequenced the genomes of a large proportion of the specimens that were still alive. By comparing them with information about the individual individuals, they were also able to link the genetic characteristics with traits relevant to breeding, including reproductive success, growth and susceptibility to disease. The method could also be applied to other endangered species.
The cacaopo (Strigops habroptilus) is the only living representative of flightless parrots. The nocturnal animals, which are up to 60 centimeters tall, can live up to 90 years and rarely reproduce. Native to New Zealand, they once had almost no natural enemies. However, predators introduced by humans almost wiped out the population until only 51 individuals remained in 1995. As part of the kakapo protection program introduced at the time, the remaining animals were taken to five New Zealand islands, which were freed from predators. Through targeted mating, it was possible to increase the population again to 252 individuals by 2022.
Basis for resettlement and protection
In order to make protection efforts even more effective in the future, a team led by Joseph Guhlin from the University of Otago in New Zealand has completely sequenced the genomes of a total of 169 individuals. On the one hand, these include all 125 animals that were alive at the start of the survey in 2015. On the other hand, genome data from 44 individuals from previous generations were also included in the study. “We combined this genetic data with an extensive, cross-generational data set on the characteristics and life history of the individuals,” reports the team.
In this way, the researchers were able to identify genetic variants that are crucial for the survival of the species. “We found associations for growth, disease susceptibility, clutch size and egg fertility,” they report. The data can help to specifically relocate individuals with particularly useful genetic characteristics in order to bring them into contact with other possible reproductive partners. It can also be estimated in which cases individuals and their offspring are more susceptible to illness, so that they can receive targeted veterinary care.
Genetic diversity despite small population
“Kakapos suffer from disease and low reproductive performance,” explains co-author Andrew Digby from the Kakapo Conservation Program. A major threat to kakapos, for example, is the fungal disease aspergillosis. A 2019 outbreak killed nine individuals. “Once we understand the genetic causes of these problems, we can now mitigate them. This will allow us to predict things like the growth of kakapo chicks and their susceptibility to disease, which will change our management practices locally and help improve survival rates.”
Overall, the team of authors comes to the conclusion that active management of the endangered species has maintained healthy genetic diversity despite the very small population size, which offers a good starting point for future breeding. Thanks to the genetic information, this can now be made even more effective.
“The study highlights the benefits of investing in genomic data for the conservation of endangered species,” writes Rebecca Taylor of Environment and Climate Change Canada, who was not involved in the study, in an accompanying commentary, also published in the journal Nature Ecology and Evolution was published. “The approach can also be applied to other threatened species (which often have naturally low numbers of individuals and low diversity), providing an exceptional level of information for better species recovery.”
Source: Joseph Guhlin (University of Otago, Dunedin, New Zealand) et al., Nature Ecology and Evolution, doi: 10.1038/s41559-023-02165-y