Predictable convergence in hemoglobin function has unpredictable molecular underpinnings

Authors

Chandrasekhar Natarajan, University of Nebraska-LincolnFollow
Federico G. Hoffmann, University of Nebraska - LincolnFollow
Roy E. Weber, Aarhus UniversityFollow
Angela Fago, Aarhus University, DenmarkFollow
Christopher C. Witt, University of New MexicoFollow
Jay F. Storz, University of Nebraska - LincolnFollow

Date of this Version

10-2016

Citation

Science 21 Oct 2016: Vol. 354, Issue 6310, pp. 336-339
DOI: 10.1126/science.aaf9070

Comments

Copyright 2016 AAAS

Abstract

To investigate the predictability of genetic adaptation, we examined the molecular basis of convergence in hemoglobin function in comparisons involving 56 avian taxa that have contrasting altitudinal range limits. Convergent increases in hemoglobin-oxygen affinity were pervasive among high-altitude taxa, but few such changes were attributable to parallel amino acid substitutions at key residues.Thus, predictable changes in biochemical phenotype do not have a predictable molecular basis. Experiments involving resurrected ancestral proteins revealed that historical substitutions have context-dependent effects, indicating that possible adaptive solutions are contingent on prior history. Mutations that produce an adaptive change in one species may represent precluded possibilities in other species because of differences in genetic background.