The respiratory system influences flight mechanics in soaring birds

• 成果类型: Article
• 署名作者: Schachner, Emma R.; Moore, Andrew J.; Martinez, Aracely; Diaz, Raul E., Jr.; Echols, M. Scott; Atterholt, Jessie; Kissane, Roger W. P.; Hedrick, Brandon P.; Bates, Karl T.
• 署名单位: State University System of Florida; University of Florida; State University of New York (SUNY) System; Stony Brook University; Stony Brook University Hospital; Louisiana State University System; Louisiana State University Health Sciences Center New Orleans; California State University System; California State University Los Angeles; Western University of Health Sciences; University of Liverpool; Cornell University
• 刊物名称: Nature
• ISSN/ISSBN: 0028-5800
• DOI: 10.1038/s41586-024-07485-y
• 发表日期: 2024-06-20
• 页码: 671-+
• 关键词: air sacs; FLOW; EVOLUTION; discrete; DYNAMICS

摘要

The subpectoral diverticulum (SPD) is an extension of the respiratory system in birds that is located between the primary muscles responsible for flapping the wing(1,2). Here we survey the pulmonary apparatus in 68 avian species, and show that the SPD was present in virtually all of the soaring taxa investigated but absent in non-soarers. We find that this structure evolved independently with soaring flight at least seven times, which indicates that the diverticulum might have a functional and adaptive relationship with this flight style. Using the soaring hawks Buteo jamaicensis and Buteo swainsoni as models, we show that the SPD is not integral for ventilation, that an inflated SPD can increase the moment arm of cranial parts of the pectoralis, and that pectoralis muscle fascicles are significantly shorter in soaring hawks than in non-soaring birds. This coupling of an SPD-mediated increase in pectoralis leverage with force-specialized muscle architecture produces a pneumatic system that is adapted for the isometric contractile conditions expected in soaring flight. The discovery of a mechanical role for the respiratory system in avian locomotion underscores the functional complexity and heterogeneity of this organ system, and suggests that pulmonary diverticula are likely to have other undiscovered secondary functions. These data provide a mechanistic explanation for the repeated appearance of the SPD in soaring lineages and show that the respiratory system can be co-opted to provide biomechanical solutions to the challenges of flight and thereby influence the evolution of avian volancy.