Large-scale assessment of COI adaptation to high altitude in birds

TUBARO PABLO LUIS; ESTALLES, CECILIA; LIJTMAER DARÍO A.; LAVINIA OBLANCA PABLO DAMIÁN

Kruger National Park

Congreso; 7th International Barcode of Life Conference; 2017

The African Centre for DNA Barcoding (ACDB) y University of Johannesburg (UJ)

Background: Adaptation to hypoxic highlands has been widely studied in diverse organisms, mainly by analyzing genetic and amino acidic changes in haemoglobin and their physiological consequences. In spite of the relevant role of mitochondrial genes in the cellular respiratory process, their adaptation to high altitude has been less studied. Moreover, contrasting results have been found, with apparent adaptation present only in some high-altitude species. Broad analyses are therefore needed to establish general patterns of mitochondrial adaptation to hypoxic environments. In this context, and taking advantage of the large-scale genetic library generated by the Barcode of Life project, we studied COI adaptation to high altitude in birds in the Americas. Results: Over 22 000 COI sequences from around 2000 avian species from the American Continent were retrieved from the Barcode of Life Data System (BOLD). Using a complete phylogeny of the birds of the World, we classified 155 pairs of sister species into highland?lowland, highland?highland, and lowland?lowland species pairs to compare their COI sequences (2300 sequences used in total). Even though we did not find evidence of a generalized adaptation to high altitude in COI, there was a tendency towards more changes in amino acids and a higher proportion of sister species with differences in their amino acids in highland?lowland and highland?highland species pairs than in lowland?lowland species pairs. We also analyzed the amino acids that did differ between highland and lowland species to assess their position and whether their properties differed to assess whether the modification could affect the protein structure and function. Significance: This is the first large-scale analysis of mitochondrial adaptation to high altitude in any taxonomic group, and the results suggest that the adaptation of COI to hypoxic highlands in birds is idiosyncratic. This study constitutes an example of how DNA barcode libraries allow diverse large-scale analyses beyond species identification and discovery.