Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4.
J Exp Biol. 2019 Apr 1;222(Pt 7):jeb198622. doi: 10.1242/jeb.198622.
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 in total ventilation and pulmonary O extraction. O consumption rates were maintained or increased slightly in acute hypoxia, despite ∼1-2°C reductions in body temperature in most species. Two high-altitude taxa - yellow-billed pintail and torrent duck - exhibited higher total ventilation than their low-altitude counterparts, and yellow-billed pintail exhibited greater increases in pulmonary O extraction in severe hypoxia. In contrast, three other high-altitude taxa - Andean ruddy duck, Andean cinnamon teal and speckled teal - had similar or slightly reduced total ventilation and pulmonary O extraction compared with low-altitude relatives. Arterial O saturation ( ) was elevated in yellow-billed pintails at moderate levels of hypoxia, but there were no differences in in other high-altitude taxa compared with their close relatives. This finding suggests that improvements in in hypoxia can require increases in both breathing and haemoglobin-O affinity, because the yellow-billed pintail was the only high-altitude duck with concurrent increases in both traits compared with its low-altitude relative. Overall, our results suggest that distinct physiological strategies for coping with hypoxia can exist across different high-altitude lineages, even among those inhabiting very similar high-altitude habitats.
我们研究了 6 种独立适应安第斯高地的高海拔鸭的呼吸控制和呼吸气体交换。我们比较了秘鲁高海拔地区（海拔约 3800 米的的的喀喀湖；海拔 3000-4100 米的昌凯河）的鸭与来自低海拔地区的近缘种群或物种。在原生海拔处，我们在捕获后不久测量了低氧通气反应。一般来说，鸭子对急性缺氧的反应是总通气量和肺 O 摄取量显著增加。尽管大多数物种的体温降低了 1-2°C，但 O 消耗率在急性缺氧时仍保持或略有增加。两种高海拔鸭类 - 黄嘴鸭和激流鸭 - 的总通气量高于其低海拔对应种，而黄嘴鸭在严重缺氧时肺 O 摄取量的增加更大。相比之下，另外三种高海拔鸭类 - 安第斯红鸭、安第斯肉桂鸭和斑点鸭 - 的总通气量和肺 O 摄取量与低海拔亲缘种相似或略有降低。黄嘴鸭在中度缺氧时动脉血氧饱和度（ ）升高，但与近亲相比，其他高海拔鸭类的 没有差异。这一发现表明，在低氧条件下改善 可能需要增加呼吸和血红蛋白-O 亲和力，因为黄嘴鸭是唯一一种与低海拔亲缘种相比同时增加这两个特征的高海拔鸭。总的来说，我们的结果表明，即使在栖息于非常相似的高海拔生境的物种中，不同的高海拔血统之间也可能存在不同的应对低氧的生理策略。
