Dr. Peter Houde was part of an international team that resolved the relationships of the adzebill, a large flightless extinct bird from New Zealand. More than just a curiosity of nature, the adzebill was the focus of contention regarding the age of bird lineages. Proponents of a very early origin of birds cited a hypothesis that the adzebill was most closely related to another flightless bird, the kagu, which is endemic to New Caledonia, a land mass that was united with New Zealand in the supercontinent Gondwana before the extinction of the dinosaurs. These researchers were unswayed by a study of adzebill ancient DNA conducted by Houde at NMSU in 1996 that instead found the adzebill to have evolved more recently from rails. Rails are notorious for losing their powers of flight after colonizing remote Pacific islands devoid of predators. Using ancient DNA once again, the new collaborative team sequenced the complete mitochondrial genomes of the adzebill, ten prospective relatives, and 98 of the 148 species of living rails. The study conclusively shows that adzebills diverged recently from small rail-relatives of Madagascar, not the kagu. Coincidentally, New Zealand’s kiwi also recently diverged from Madagascan endemics, and is among a group of flightless ‘ratite’ birds of southern landmasses similarly championed in evidence of the early origins hypothesis based on the now-discredited Gondwanan origin of that group. The new results were published on Feb. 15th in a special issue on avian genomic evolution in the journal Diversity, of which Houde is also Guest Editor.
