We often get asked to pick the biggest discoveries in our fields. To me, this is only a part of what we are trying to do, but big things are worth crowing about. So this is something I consider a big discovery that for reasons I do not fully understand has never got the recognition it deserved. I may not be remembering the details with complete accuracy, but this is a story about discovering a new family and an adaptive radiation at the same time.
Back in 2000, Tom Schulenberg, who is now at the Cornell Lab of Ornithology, was working for our Environmental and Conservation Programs. To me, he’s the person at the center of the discovery. At the University of Chicago, Tom did his doctoral work on Vangas, gathering DNA sequence data to better understand evolution of this well known and ecologically diverse radiation of Malagasy birds. But I am not writing about Vangas here, although they are an interesting story in their own right, Tom and others have just published a new phylogeny of vangas. No, I’m talking about the discovery of the family Bernieridae.
Tom is both a skilled ornithologist and a birder, so while he was in Madagascar, not surprisingly, he did all he could to get to know all the birds of the island. He also collected specimens and tissue samples of many of those species. So did Field Biologist Steve Goodman, as he and Malagasy colleagues worked to document diversity around the country. As collection manager, Dave Willard would send subsamples of these tissues (we call them tissue loans, but the subsamples generally get used up) to qualified researches making requests to include them into their gene sequencing projects to document parts of the evolutionary tree of songbirds. Tom has always taken an active interest in what such projects were uncovering.
Madagascar has a number of brown, green and gray insectivorous perching birds, and what had always been most interesting about them is that they were morphologically and behaviorly similar to birds from Africa and Asia. So similar, that some were placed in the same genera with African species. The Madagascar birds included species placed in the same genus Phyllastrephus, as some African greenbuls (Pycnonotidae). Others small insectivores were placed in the Old World warblers, the Sylviidae. Still others that were larger and brown were placed with the Bulbuls (Timaliidae). Madagascar is full of mysteries, but these relationships made sense and had been accepted for over 100 years (with the exception of a couple of authors whose hypotheses had been ignored). That is until Tom started to think about this and knew that several people had gathered DNA sequence data for separate family-level projects on Greenbuls, Old World Warblers, and bulbuls. He contacted Alice Cibois, one of these researchers, who at the time was a post-doctoral fellow at the American Museum of Natural History. He suggested that she should get sequences of the Madagascar species placed in these three families and do a combined analysis with non-Malagasy birds. Basically, Tom had a hunch, and Alice’s subsequent analyses proved him right.
The citation for their paper is:
Cibois, A., Slikas, B., Schulenberg, T.S., & Pasquet, E. (2001) An endemic radiation of Malagasy songbirds is revealed by mitochondrial DNA sequence data. Evolution, 55, 1198–1206.
Top to bottom: Cryptic Warbler (Crytposylvicola randrianasoloi) placed originally in Sylviidae, Long-billed Tetraka (Bernieria madagascariensis) placed originally in the Pycnonotidae (genus Phyllastrephus), White-throated Oxylabes (Oxylabes madagacariensis) placed orginally in the Timaliidae. The 2001 paper of Cibois et al. used genetic data to document that all three are part of a radiation of birds endemic to Madagascar.
These Malagasy birds formerly spread across three different families were each other’s closest relatives. They formed a monophyletic group, a group endemic to Madagascar and a radiation of 11 species. Thus an adaptive radiation of species that were ecologically convergent on, but evolutionarily unrelated to greenbuls, warblers and bulbuls from Africa and Asia was "discovered." There have been lots of really exciting ornithological discoveries made using genetic data, but to find a new family and discover a new adaptive radiation at the same timehas to be on of the list of the most exciting things anyone has found in ornithology in the last 25 years.