| [effect of monoamines on acth secretion by dispersed perfused cells from the adenohypophysis of barcino chico duck (anas flavirostris)]. | we have pursued with the characterization of acth secretagogues from the avian corticomelanotrophic (cm) cell, by testing the acth-releasing activity of various monoamines and related drugs, using an in vitro system which uses dispersed perfused duck pituitary cells. the substances used were: noradrenaline (na), adrenaline (a), dopamine (da), serotonin (5-ht), phenylephrine (phe), and isoproterenol (ip). the responses obtained with the substances assayed were compared with those obtained with di ... | 1986 | 2886008 |
| 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 ... | 2011 | 21887236 |
| 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 ... | 2013 | 24367536 |
| 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 ... | 2020 | 32173858 |
| 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 ... | 2020 | 32041807 |
| 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 ... | 2019 | 30846536 |
| 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 ... | 2020 | 32164026 |
| migration-selection balance drives genetic differentiation in genes associated with high-altitude function in the speckled teal (anas flavirostris) in the andes. | local adaptation frequently occurs across populations as a result of migration-selection balance between divergent selective pressures and gene flow associated with life in heterogeneous landscapes. studying the effects of selection and gene flow on the adaptation process can be achieved in systems that have recently colonized extreme environments. this study utilizes an endemic south american duck species, the speckled teal (anas flavirostris), which has both high- and low-altitude populations. ... | 2018 | 29211852 |