Laguë Sabine L, Ivy Catherine M, York Julia M, Dawson Neal J, Chua Beverly A, Alza Luis, Scott Graham R, McCracken Kevin G, Milsom William K
Department of Zoology, University of British Columbia, 4200-6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada.
Division of Pediatric Respirology, BC Children's Hospital, 1C31A-4480 Oak Street, Vancouver, British Columbia V6H 3V4, Canada.
Philos Trans R Soc Lond B Biol Sci. 2025 Feb 27;380(1920):20230424. doi: 10.1098/rstb.2023.0424.
High-altitude life poses physiological challenges to all animals due to decreased environmental oxygen (O) availability (hypoxia) and cold. Supporting high metabolic rates and body temperatures with limited O is challenging. Many birds, however, thrive at high altitudes. The O-transport cascade describes the pathway involved in moving O from the environment to the tissues encompassing: (i) ventilation, (ii) pulmonary O diffusion, (iii) circulation, (iv) tissue O diffusion, and (v) mitochondrial O use for ATP production. Shared avian traits such as rigid lungs with cross-current gas exchange and unidirectional airflow aid in O acquisition and transport in all birds. Many high-altitude birds, however, have evolved enhancements to some or all steps in the cascade. In this review, we summarize the current literature on gas exchange and O transport in high-altitude birds, providing an overview of the O-transport cascade that principally draws on the literature from high-altitude waterfowl, the most well-studied group of high-altitude birds. We close by discussing two important avenues for future research: distinguishing between the influences of plasticity and evolution and investigating whether the morphological and physiological differences discussed contribute to enhanced locomotor or thermogenic performance, a potential critical link to fitness.This article is part of the theme issue 'The biology of the avian respiratory system'.
由于环境氧气（O）可用性降低（缺氧）和寒冷，高海拔环境给所有动物带来了生理挑战。在有限的氧气条件下维持高代谢率和体温是一项挑战。然而，许多鸟类在高海拔地区茁壮成长。氧气运输级联描述了氧气从环境转移到组织所涉及的途径，包括：（i）通气，（ii）肺部氧气扩散，（iii）循环，（iv）组织氧气扩散，以及（v）线粒体利用氧气产生三磷酸腺苷（ATP）。鸟类共有的特征，如具有交叉流气体交换的刚性肺和单向气流，有助于所有鸟类获取和运输氧气。然而，许多高海拔鸟类在级联的某些或所有步骤中都进化出了增强功能。在这篇综述中，我们总结了当前关于高海拔鸟类气体交换和氧气运输的文献，主要借鉴了对高海拔水禽（研究最充分的高海拔鸟类群体）的文献，概述了氧气运输级联。我们最后讨论了未来研究的两个重要方向：区分可塑性和进化的影响，以及研究所讨论的形态和生理差异是否有助于提高运动或产热性能，这可能是与适应性的关键联系。本文是主题为“鸟类呼吸系统生物学”的一部分。
