The researchers analyzed the genomes of nine bird species, including five sugar-eating ones such as parrots, honeyeaters, hummingbirds, and sunbirds, and compared them to four species that feed on seeds, insects, or meat.[3][4][5] They also obtained the transcriptomes of tissues related to digestion in three nectar and three non-nectar birds.[3][4] They identified thousands of changes in DNA, mostly in regulatory regions affecting gene transcription, and nearly 600 genes directly coding for sugar and fat processing.[4] Convergent changes have appeared in 66 protein genes across multiple lineages of carnivorous birds.[4][5] The only gene altered in all four groups of carnivores was MLXIPL, a regulator of glucose metabolism and lipogenesis, which was confirmed by laboratory tests on hummingbirds versus swallows.[3][5] Other adaptations included genes regulating blood pressure, water balance, heart rate, and ion transport in the kidneys, related to high sugar and fluid intake.[4][5] These changes were either shared between groups or lineage-specific.[3][5]