IAB Research Project Description
Studies of Hemoglobin Function in Andean Ducks
Male Torrent duck at left and female at right, in Urubamba, Tanzania. Photograph by Kevin McCracken, associate professor of biology, Institute of Arctic Biology, University of Alaska Fairbanks.
Torrent ducks (left to right: 2 males, 2 females, 1 males) in Urubamba, Tanzania. Photograph by Kevin McCracken, associate professor of biology, Institute of Arctic Biology, University of Alaska Fairbanks.
High-altitude regions are characterized by simple physiographic differences in environmental variables such as ambient pressure and temperature that vary across elevational gradients in well-defined ways. This makes the study of natural selection and its effects on genetic polymorphism simpler and less complicated than it might be for complex traits that have many environmental correlates. Hypoxia in particular is one of the most important factors influencing survival at high elevations, and biochemical changes in the blood protein hemoglobin (Hb) have been shown to mitigate the effects of chronic hypoxia in high-altitude adapted populations. Surveys of hemoglobin amino acid polymorphism in Andean waterfowl suggest that genotypic variants that are over-represented in high-altitude populations have different fitness rankings in different elevational zones and influence Hb-O2 affinity. Our studies have further revealed that parallel substitutions evolved in distantly related lineages and are concentrated in the same few regions of the protein. Experimental studies of Hb function and blood properties are being combined with mutli-locus population genetic analyses to study the mechanistic basis of these apparent adaptations. One question we aim to answer is whether the same or different mechanisms underlie parallel changes in replicate lineages that independently colonized the Andes and other high-altitude regions. Other questions focus on the role of phenotypic plasticity, and specifically how individuals modulate their Hb-O2 carrying capacity when they disperse across elevational gradients.
15 Jun 2010 – 31 May 2013
IAB Project #191
302A Irving I
University of Alaska Fairbanks
Fairbanks, AK 99775-7000