Hope for Hawaii’s Honeycreepers: Genetics, a Way to Beat Malaria
By Michelle Cowell
It’s hard to think of Hawai’i and not picture the colorful sights and sounds of the animals that exist there. Without our intervention, however, this could be the reality sooner than you think.
Hawai’i is home to a vast array of species, including the Hawaiian forest birds, one of the most threatened groups of forest-dependent birds in the world (Samuel et. al 2019). This group, which includes a variety of different honeycreeper species was once widely distributed among Hawai’ian forests, but now find themselves more and more limited to the highest elevations of these forests.
Why Have Honeycreepers Moved?
A deadly disease, avian malaria, has crept in and spread across Hawai’ian forests, causing honeycreeper populations to drop and even led to the extinctions of some of these beautiful and unique birds. The Southern House Mosquito, the carrier of avian malaria, has been limited to lower elevation areas where the warmer temperatures help it to thrive. The cooler temperatures in the higher elevation forests stop the mosquitoes from spreading upwards which has allowed for the remaining dwindling populations of honeycreepers to seek safety in these higher elevation forests.
The Looming Climate Change: What Does it Mean for Honeycreepers?
Although the Hawai’ian honeycreepers’ risk of malaria infection is currently limited by high elevation, there is a great deal of concern for what is to come as future climate change unfolds. As the earth continues to warm in the coming years, the temperature and rainfall in the higher elevation forests will become more tolerable to the Southern House Mosquito, expanding the range for avian malaria infection and leaving the Hawai’ian honeycreepers with nowhere left to run for safety, ultimately leading to more extinctions.
Making Way for New Solutions: Gene Editing
There are several proposed ideas to help save the honeycreepers and other tropical birds which have been successful in other places, such as controlling the mosquito population to stop the spread of avian malaria, but it never hurts to have more tools in the conservation toolbox. New ideas and strategies are being researched in order to give the honeycreepers a fighting chance as climate change threatens to bring them to extinction.
In a recent study, scientists researched the possibility of gene editing as a solution to the threat of malaria towards honeycreeper populations, a conservation strategy called facilitated adaptation. They proposed that by releasing birds that have been genetically engineered to be resistant to malaria they could strengthen the populations resistance to disease, which could potentially allow the population to recover (Samuel et al. 2019).
For this study, the researchers developed a simulation model capable of evaluating how effective releasing birds that had been gene-edited would be against malaria in preserving and reestablishing the species. They focused their study area around the Mauna Loa volcano of Hawaii in mid- and high-elevation forests where honeycreepers, such as the Iiwi are currently found.
What Did They Find?
Overall, the study found that gene editing was an effective way to recover honeycreeper populations in Hawaii’ effected by malaria. The researchers found that release of gene-edited malaria-resistant birds at mid- and low-range elevations was the most effective way for conserving and restoring populations, with populations eventually reaching stable numbers with the best chance for success.
Why is This Important?
It is estimated that as much as 40% of our living species may be effectively extinct by 2050 from climate warming (Samuel et al. 2019). In this rapidly changing world, it is so important to have more than one tool in our toolkit, more than one way to help conserve species, especially those less equipped to adapt to the changing climate.
In the case of the Hawaiian honeycreepers, perhaps for now, conservation for these wonderful birds could be met by just managing for mosquitos, but it is a very real possibility that we could need more than one way to help save this species. Looking for new solutions and methods like gene editing could provide us with backup plans when pest control and redistribution is no longer an option.
Using this method of gene editing with honeycreepers as a positive and successful example may lead a path for conserving other species in the future that may similarly benefit from gene editing.
Additionally, it is important to bring attention to new cutting-edge techniques and ideas like gene editing, as there are still many limitations to overcome with these types of approaches, such as cost, the need for technologies and research to advance, as well as the social implications that are likely to be controversial amongst the general public and scientific community. However, with better understanding of the options available to us to conserve species, we can begin to plan and prepare for the future ahead with all possible solutions available.
References:
Samuel, Michael D., et al. “Facilitated Adaptation for Conservation — Can Gene Editing Save Hawaii’s Endangered Birds from Climate Driven Avian Malaria?” Biological Conservation, Elsevier, 26 Dec. 2019, www.sciencedirect.com/science/article/pii/S0006320719310225.
