Washington: A new study has determined the evolutionary family tree of one of the most strikingly diverse and endangered bird families in the world.
Smithsonian scientists and collaborators have determined the evolutionary family tree of the Hawaiian honeycreepers using one of the largest DNA data sets for a group of birds and employing next-generation sequencing methods.
Not only did the researchers determine the types of finches that the honeycreeper family originally evolved from, but also linked the timing of that rapid evolution to the formation of the four main Hawaiian Islands.
“There were once more than 55 species of these colourful songbirds, and they are so diverse that historically it wasn’t even entirely clear that they were all part of the same group,” said Heather Lerner, assistant professor of biology at Earlham College, said.
“Some eat seeds, some eat fruit, some eat snails, some eat nectar. Some have the bills of parrots, others of warblers, while some are finch-like and others have straight, thin bills. So the question that we started with was how did this incredible diversity evolve over time,” Lerner said.
The researchers looked at the evolution of the Hawaiian honeycreepers after the formation of Kauai-Niihau, Oahu, Maui-Nui and Hawaii and found that each island that forms represents a blank slate for evolution, so as one honeycreeper species moves from one island to a new island, those birds encounter new habitat and ecological niches that may force them to adapt and branch off into distinct species.
“This radiation is one of the natural scientific treasures that the archipelago offers out in the middle of the Pacific,” Helen James, co-author of the paper, said.
“It was fascinating to be able to tie a biological system to geological formation and allowed us to become the first to offer a full picture of these birds’ adaptive history,” she said.
Using genetic data from 28 bird species that seemed similar to the honeycreepers morphologically, genetically or that shared geographic proximity, the researchers determined that the various honeycreeper species evolved from Eurasian rosefinches.
They also found that unlike most other ancestral bird species that came from North America and colonized the Hawaiian Islands, the rosefinch likely came from Asia.
“There is a perception that there are no species remaining that are actually native to Hawaii, but these are truly native birds that are scientifically valuable and play an important and unique ecological function,” Rob Fleischer, co-author of the paper, said.
The study will be published in the 8th November issue of Current Biology.