Publications

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gene flow in the face of countervailing selection: adaptation to high-altitude hypoxia in the betaa hemoglobin subunit of yellow-billed pintails in the andes.when populations become locally adapted to contrasting environments, alleles that have high fitness in only one environment may be quickly eliminated in populations adapted to other environments, such that gene flow is partly restricted. the stronger the selection, the more rapidly immigrant alleles of lower fitness will be eliminated from the population. however, gene flow may continue to occur at unlinked loci, and adaptive divergence can proceed in the face of countervailing gene flow if sele ...200919151158
gene flow and hybridization between numerically imbalanced populations of two duck species in the falkland islands.interspecific hybridization is common in plants and animals, particularly in waterfowl (anatidae). one factor shown to contribute to hybridization is restricted mate choice, which can occur when two species occur in sympatry but one is rare. the hubbs principle, or "desperation hypothesis," states that under such circumstances the rarer species is more likely to mate with heterospecifics. here we report interspecific hybridization between two waterfowl species that coexist in broad sympatry and ...201121887236
a morphometric analysis of the lungs of high-altitude ducks and geese.we examined the morphology of the lungs of five species of high-altitude resident ducks from lake titicaca in the peruvian andes (yellow-billed pintail [anas georgica], cinnamon teal [anas cyanoptera orinomus], puna teal [anas puna], speckled teal [anas flavirostris oxyptera], and ruddy duck [oxyura jamaicensis ferruginea]) and compared them with those of the high-altitude migratory bar-headed goose (anser indicus) and the low-altitude migratory barnacle goose (branta leucopsis). we then determi ...202032173858
cardiovascular responses to progressive hypoxia in ducks native to high altitude in the andes.the cardiovascular system is critical for delivering o2 to tissues. here, we examined the cardiovascular responses to progressive hypoxia in four high-altitude andean duck species compared with four related low-altitude populations in north america, tested at their native altitude. ducks were exposed to stepwise decreases in inspired partial pressure of o2 while we monitored heart rate, o2 consumption rate, blood o2 saturation, haematocrit (hct) and blood haemoglobin (hb) concentration. we calcu ...202032041807
control of breathing and respiratory gas exchange in high-altitude ducks native to the andes.we examined the control of breathing and respiratory gas exchange in six species of high-altitude duck that independently colonized the high andes. we compared ducks from high-altitude populations in peru (lake titicaca at ∼3800 m above sea level; chancay river at ∼3000-4100 m) with closely related populations or species from low altitude. hypoxic ventilatory responses were measured shortly after capture at the native altitude. in general, ducks responded to acute hypoxia with robust increases i ...201930846536
haemosporidian parasites of chilean ducks: the importance of biogeography and nonpasserine hosts.biogeography is known to have shaped the diversity and evolutionary history of avian haemosporidian parasites across the neotropics. however, a paucity of information exists for the temperate neotropics and especially from nonpasserine hosts. to understand the effect of biogeography in the temperate neotropics on haemosporidians of nonpasserine hosts we screened ducks (anseriformes) from central chile for the presence of these parasites. forty-two individuals of 4 duck species (anas flavirostris ...202032164026
gene flow and hybridization between numerically imbalanced populations of two duck species on the subantarctic island of south georgia.hybridization is common between species of animals, particularly in waterfowl (anatidae). one factor shown to promote hybridization is restricted mate choice, which can occur when 2 species occur in sympatry but one is rare. according to the hubbs principle, or "desperation hypothesis," the rarer species is more likely to mate with heterospecifics. we report the second of 2 independent examples of hybridization between 2 species of ducks inhabiting island ecosystems in the subantarctic and south ...201324367536
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