The COI gene as an indicator of mitochondrial adaptation to hypoxic high altitude environments in birds

ESTALLES, CECILIA; TUBARO, PABLO L.; LAVINIA, PABLO D.; LIJTMAER, DARÍO A.; VILACOBA, ELISABET

Congreso; 8th International Barcode of Life Conference; 2019

Background: Birds that inhabit highland environments tolerate hypoxia due to physiological and morphological adaptations. Even though mitochondrial genes participate in the cellular respiratory process, their role in the adaptation to hypoxia has been poorly studied and analyses are needed to establish general patterns of mitochondrial adaptation to high altitude. In this context, we studied the adaptation of COI to hypoxia. The choice of this gene is based on two main reasons: 1) it catalyzes the last reduction of oxygen in the electron transport chain, and 2) large-scale sequence libraries of a portion of this gene are available due to the Barcode of Life project. Over 22,000 sequences of the COI barcode region were retrieved from around 2,000 avian species from the American Continent. We classified 155 pairs of sister species into highland-lowland, highland-highland, and lowland-lowland species pairs to compare their COI barcode region sequences. Also, because the COI barcode region represents only a portion of this gene, we sequenced the complete gene for a reduced set of 28 sister species pairs. Results: Analyses based on the COI barcode region pointed towards more changes in amino acids when at least one of the species of the pair was a highland species, however, results did not show a clear trend towards more significant modifications or a stronger effect on the protein in high altitude species. For the smaller dataset, results were clearer with the entire protein, showing more changes between species when at least one of them inhabited highland environments and also indicating that changes were more significant for the protein function in highland species. Significance This is the first large-scale analysis of mitochondrial differentiation in high altitude species in any taxonomic group and it suggests that the mitochondrial genome is involved in the adaptation to high, hypoxic environments in birds.