ADAPTIVE SIGNIFICANCE OF AMINO ACID POLYMORPHISMS IN HEMOGLOBIN GENES OF CRESTED DUCKS (_LOPHONETTA SPECULARIOIDES_)

BULGARELLA, MARIANA; BARGER, CHRISTOPHER P.; JOHNSON, KEVIN P.; KOPUCHIAN, CECILIA; VALQUI, THOMAS H.; WILSON, ROBERT E.; MCCRACKEN, KEVIN G.

Veracruz, México

Congreso; IV Congreso Norteamericano de Ornitología; 2006

American Ornithologists’ Union, Cooper Ornithological Society, Wilson Ornithological Society

Hemoglobins of high-altitude animals frequently display unusually high oxygen affinities, an adaptive trait because oxygen pressure declines sharply with altitude (at 4,000 meters is ~60% of sea level). One or a few mutations affecting key amino acid (AA) residues may be sufficient to modify the functional properties of hemoglobin for the severely hypoxic conditions of High Andes. The objective of this study is to identify the adaptive AA polymorphisms in hemoglobins exposed to high altitude respiration in Crested Duck (_Lophonetta specularioides_), a non-migratory duck species that comprises two subspecies occupying different altitudinal environments ranging from 5,000 meters in the Central High Andes to sea level in Patagonia and Malvinas Islands. Preliminary data indicate that alfa and beta hemoglobin of _Lophonetta_ possess derived AA polymorphisms that segregate by altitude and are locally adapted for oxygen binding and delivery in highland and lowland populations. Two AA substitutions in the alfa-A subunit and one in alfa-D subunit segregate by altitude between subspecies and show high levels of heterozygosity in the highland population. In contrast, the single AA replacement that segregates by altitude on the beta-A subunit is fixed for different alleles in the two populations. Fst values differ markedly, suggesting that the alfa and beta subunits are under different levels of selection.