Avian malaria has decimated native bird populations in Hawaiʻi, bringing some species, like the ʻakikiki, to the brink of extinction. But some Hawaiʻi ʻamakihi appear to have evolved a resistance against the disease.
Gabrielle Names is an evolutionary ecologist. She's trying to determine what's behind the ʻamakihi's evolutionary edge. Names suspects that it has to do with how much exposure to the disease each population of ʻamakihi has. And unlikeʻiʻiwi orʻakiapōlāʻau, ʻamakihi have contained territories, which allows more genetic difference to develop within a population.
"The ʻamakihi on Hawaiʻi Island are all the same species. So you may see some down in Puna, you may see some all the way up on Maunakea. But... these populations are distinct," says Names. "100% of the low elevation birds on the wet side down in the Puna area were infected with avian malaria, whereas on the dry side, only about 30% of birds were infected."
Names observed that bird populations with higher average infection rates had higher levels of natural antibodies levels as well.
"So that's another reason why it's special to study for this type of project because we really have a natural experiment on Hawaiʻi, we have populations at high elevation that have never been exposed to avian malaria, and then populations that low elevation that have experienced a really strong selection by the disease," says Names.
While the ʻamakihi's resistance offers a ray of hope, Names isn't betting on evolution as a conservation strategy. "While it is important to understand what's going on in the ʻamakihi, understanding what it's doing may not be the answer to conserve all of the Hawaiian honeycreepers because they have different behaviors and characteristics that can affect whether evolution could act on them in the same way," say Names.
"We know that this isn't the last disease that's going to be introduced to to Hawaiʻi. Unfortunately, that's just the globalized world we're in. More diseases will eventually probably get to the Hawaiian Islands the same way that COVID has spread across the world."
