A hypothetical reconstruction of evolutionary history is called a phylogeny. Creating accurate phylogenies, which are essentially family trees that show how different species are related through evolution, can be done with different types of data. Some phylogenies are based on morphology, which refers to the study of the physical characteristics and structures of organisms, like their shape, size, and specific body parts. Other phylogenies rely on analysis of DNA sequences, which contain the molecular instructions for building and maintaining living things.

Each type of data provides a different piece of the overall evolutionary puzzle. By taking each into account, scientists get a more complete and more accurate picture of how life on Earth has evolved. It’s like using both photos and genetic tests to trace your family tree—each provides valuable insights that, together, give a fuller story.

The first phylogeny of the honeycreepers (Fig. 1) was published in 1903 by Robert C. L. Perkins, a naturalist who, together with Darwin and Wallace, laid the groundwork for understanding how biological diversity evolves on islands. He used morphological data, since the presence and role of DNA had yet to be discovered. According to Perkins, all the honeycreepers are united by tubular tongues (for sipping nectar) and a peculiar odor. He separates them into two main lineages by plumage and vocalizations, dividing the “red” or “black” group (Melanodrepanine) from counterparts in the “green” group (Chlorodrepanine).

Unlike some other ornithologists of his day who reasoned that the spectacular diversity of honeycreepers could only be explained by the establishment of multiple immigrant species, Perkins believed that the wide array of forms arose from a single ancestral species. He was less certain, however, of the origin and identity of that ancestral population.

In 2011, more than a hundred years later, a team of scientists led by Dr. Robert Fleischer set about trying to identify that ancestral species. They published another honeycreeper phylogeny based on analysis of DNA, both mitochondrial and nuclear (Fig. 2). Using similarities and differences in the DNA sequences, they assessed the relationships among 19 species of Hawaiian honeycreepers, 18 extant and one extinct. To uncover what kind of bird gave rise to the honeycreepers, they needed to compare the honeycreeper sequences to DNA taken from other birds around the world. But there are over 10,000 species of birds worldwide. Time and cost prohibited comparing the honeycreepers to all of them, so the team relied on the expertise of Dr. Helen James, a paleontologist and curator of birds at the Smithsonian’s National Museum of Natural History. She used her extensive knowledge of avian morphology to identify living species whose physical characteristics and structure were closest to the Hawaiian honeycreepers.

The results of their analyses were quite surprising. Rather than being closely related to birds in North and South America, as widely theorized, the Hawaiian honeycreepers’ closest living relatives were rosefinches (Carpodacus sp.) from Asia.

Also surprising was the estimated timing of their arrival. Using the geologic history of the Islands as a source of known values, Fleischer’s postdoc, Dr. Heather Lerner, calibrated their phylogeny and estimated that the ancestral rosefinches arrived in the Hawaiian Islands sometime between 7.2 and 5.8 million years ago (mya). This would have been a surprisingly recent arrival to Perkins, who theorized that the extreme diversity exhibited by the honeycreepers would have required a very, very long time to develop. He believed the honeycreepers’ ancestor must have arrived before that of another, much less diverse group of native Hawaiian forest birds, the Mohoidae family, which included four species of ʻōʻō and two species of kioea. However, we know from a study published in 2008, that the ancestor of the Mohoidae (waxwings, silky flycatchers, and palmchats) arrived between 14 and 17 mya, long before the rosefinches that were underwent such drastic changes.

At the end of their publication, Fleischer’s team suggested that a natural follow-up to their research would be to incorporate DNA sequences from more of the extinct honeycreeper species, thereby providing a more robust dataset. Now that molecular techniques have been refined, it is practicable to extract and amplify DNA from very old museum study skins and even ancient bones! Work is underway at Smithsonian’s National Zoo and Conservation Biology Institute (NZCBI) to publish an updated phylogeny, with many of the samples provided by Bishop Museum’s Vertebrate Zoology collection.

In this video, Dr. Robert Fleischer, director of NZCBI, discusses his work and the importance of natural history collections, like those at Bishop Museum, as a means of revealing the evolutionary history of the honeycreepers.