Functional Studies on Nine Different Haemoglobins with High Oxygen Affinity

David, O; Ivaldi, Giovanni Battista; Rabino-Massa, Emma; Ricco, G

doi:10.1159/000064702

Cited by 7 publications

(1 citation statement)

References 16 publications

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“…However, duck muscle is known to exhibit higher venous oxygen tension than mammalian red muscle tissue (Grubb 1981), and high-altitude flight may impose more stringent selection pressure on O 2 binding and delivery. A variety of disorders associated with mutations that increase hemoglobin O 2 affinity also are known to occur in humans inhabiting lowland regions (David et al 2002;Hardison et al 2002;Wajcman and Galacteros 2005). In summary, there are numerous possible mechanisms that might cause the hemoglobins of these highland populations to be less fit in the lowlands or vice versa.…”

Section: Discussionmentioning

confidence: 99%

Signatures of High‐Altitude Adaptation in the Major Hemoglobin of Five Species of Andean Dabbling Ducks

McCracken

Barger

Bulgarella

et al. 2009

The American Naturalist

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Hypoxia is one of the most important factors affecting survival at high altitude, and the major hemoglobin protein is a likely target of selection. We compared population genetic structure in the alphaA and betaA hemoglobin subunits (HBA2 and HBB) of five paired lowland and highland populations of Andean dabbling ducks to unlinked reference loci. In the hemoglobin genes, parallel amino acid replacements were overrepresented in highland lineages, and one to five derived substitutions occurred at external solvent-accessible positions on the alpha and beta subunits, at alpha(1)beta(1) intersubunit contacts, or in close proximity to inositolpentaphosphate (IPP) binding sites. Coalescent analyses incorporating the stochasticity of drift and mutation indicated that hemoglobin alleles were less likely to be transferred between highland and lowland populations than unlinked alleles at five other loci. Amino acid replacements that were overrepresented in the highlands were rarely found within lowland populations, suggesting that alleles segregating at high frequency in the highlands may be maladaptive in the lowlands and vice versa. Most highland populations are probably nonmigratory and locally adapted to the Altiplano, but gene flow for several species may be sufficiently high to retard divergence at unlinked loci. Heterozygosity was elevated in the alphaA or betaA subunits of highland populations exhibiting high gene flow between the southern lowlands and the highlands and in highland species that disperse seasonally downslope to midelevation environments from the central Andean plateau. However, elevated heterozygosity occurred more frequently in the alphaA subunit but not simultaneously in both subunits, suggesting that selection may be more constrained by epistasis in the betaA subunit. Concordant patterns among multiple species with different evolutionary histories and depths of historical divergence and gene flow suggest that the major hemoglobin genes of these five dabbling duck species have evolved adaptively in response to high-altitude hypoxia in the Andes.

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