 DNA sequencing of both mitochondrial and nuclear genes yielded relationships quite different; the three New World pelicans formed one lineage, with the American white pelican sister to the two brown pelicans, and the five Old World species the other. The Dalmatian, pink-backed and spot-billed were all closely related to one another, while the Australian white pelican was their next-closest relative. The great white pelican also belonged to this lineage but was the first to diverge from the common ancestor of the other four species. This finding suggests that pelicans evolved in the Old World and spread into the Americas, and that preference for tree- or ground-nesting is more related to size than genetics.
