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Graham AM, Lavretsky P, Wilson RE, McCracken KG. High-altitude adaptation is accompanied by strong signatures of purifying selection in the mitochondrial genomes of three Andean waterfowl. PLoS One 2024; 19:e0294842. [PMID: 38170710 PMCID: PMC10763953 DOI: 10.1371/journal.pone.0294842] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 11/09/2023] [Indexed: 01/05/2024] Open
Abstract
Evidence from a variety of organisms points to convergent evolution on the mitochondria associated with a physiological response to oxygen deprivation or temperature stress, including mechanisms for high-altitude adaptation. Here, we examine whether demography and/or selection explains standing mitogenome nucleotide diversity in high-altitude adapted populations of three Andean waterfowl species: yellow-billed pintail (Anas georgica), speckled teal (Anas flavirostris), and cinnamon teal (Spatula cyanoptera). We compared a total of 60 mitogenomes from each of these three duck species (n = 20 per species) across low and high altitudes and tested whether part(s) or all of the mitogenome exhibited expected signatures of purifying selection within the high-altitude populations of these species. Historical effective population sizes (Ne) were inferred to be similar between high- and low-altitude populations of each species, suggesting that selection rather than genetic drift best explains the reduced genetic variation found in mitochondrial genes of high-altitude populations compared to low-altitude populations of the same species. Specifically, we provide evidence that establishment of these three Andean waterfowl species in the high-altitude environment, coincided at least in part with a persistent pattern of negative purifying selection acting on oxidative phosphorylation (OXPHOS) function of the mitochondria. Our results further reveal that the extent of gene-specific purifying selection has been greatest in the speckled teal, the species with the longest history of high-altitude occupancy.
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Affiliation(s)
- Allie M. Graham
- Eccles Institute for Human Genetics, University of Utah, Salt Lake City, UT, United States of America
| | - Philip Lavretsky
- Department of Biological Sciences, University of Texas at El Paso, El Paso, TX, United States of America
| | - Robert E. Wilson
- School of Natural Resources and Nebraska State Museum, University of Nebraska–Lincoln, Lincoln, NE, United States of America
| | - Kevin G. McCracken
- Department of Biology, University of Miami, Coral Gables, FL, United States of America
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, Miami, FL, United States of America
- Human Genetics and Genomics, University of Miami Miller School of Medicine, Miami, FL, United States of America
- University of Alaska Museum, University of Alaska Fairbanks, Fairbanks, AK, United States of America
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2
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Palacios C, Wang P, Wang N, Brown MA, Capatosto L, Du J, Jiang J, Zhang Q, Dahal N, Lamichhaney S. Genomic Variation, Population History, and Long-Term Genetic Adaptation to High Altitudes in Tibetan Partridge (Perdix hodgsoniae). Mol Biol Evol 2023; 40:msad214. [PMID: 37768198 PMCID: PMC10583571 DOI: 10.1093/molbev/msad214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 09/09/2023] [Accepted: 09/25/2023] [Indexed: 09/29/2023] Open
Abstract
Species residing across elevational gradients display adaptations in response to environmental changes such as oxygen availability, ultraviolet radiation, and temperature. Here, we study genomic variation, gene expression, and long-term adaptation in Tibetan Partridge (Perdix hodgsoniae) populations residing across the elevational gradient of the Tibetan Plateau. We generated a high-quality draft genome and used it to carry out downstream population genomic and transcriptomic analysis. The P. hodgsoniae populations residing across various elevations were genetically distinct, and their phylogenetic clustering was consistent with their geographic distribution. We identified possible evidence of gene flow between populations residing in <3,000 and >4,200 m elevation that is consistent with known habitat expansion of high-altitude populations of P. hodgsoniae to a lower elevation. We identified a 60 kb haplotype encompassing the Estrogen Receptor 1 (ESR1) gene, showing strong genetic divergence between populations of P. hodgsoniae. We identified six single nucleotide polymorphisms within the ESR1 gene fixed for derived alleles in high-altitude populations that are strongly conserved across vertebrates. We also compared blood transcriptome profiles and identified differentially expressed genes (such as GAPDH, LDHA, and ALDOC) that correlated with differences in altitude among populations of P. hodgsoniae. These candidate genes from population genomics and transcriptomics analysis were enriched for neutrophil degranulation and glycolysis pathways, which are known to respond to hypoxia and hence may contribute to long-term adaptation to high altitudes in P. hodgsoniae. Our results highlight Tibetan Partridges as a useful model to study molecular mechanisms underlying long-term adaptation to high altitudes.
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Affiliation(s)
- Catalina Palacios
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Pengcheng Wang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, P. R. China
| | - Nan Wang
- School of Ecology and Nature Conservation, Beijing Forestry University, Beijing 100083, P. R. China
| | - Megan A Brown
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Lukas Capatosto
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Juan Du
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Jiahu Jiang
- School of Ecology and Nature Conservation, Beijing Forestry University, Beijing 100083, P. R. China
| | - Qingze Zhang
- School of Ecology and Nature Conservation, Beijing Forestry University, Beijing 100083, P. R. China
| | - Nishma Dahal
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, HP 176061, India
| | - Sangeet Lamichhaney
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
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3
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Ivy CM, Guglielmo CG. Migratory songbirds exhibit seasonal modulation of the oxygen cascade. J Exp Biol 2023; 226:jeb245975. [PMID: 37534524 PMCID: PMC10482389 DOI: 10.1242/jeb.245975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 07/31/2023] [Indexed: 08/04/2023]
Abstract
Migratory flight requires birds to maintain intensive aerobic exercise for many hours or days. Maintaining O2 supply to flight muscles is therefore important during migration, especially since migratory songbirds have been documented flying at altitudes greater than 5000 m above sea level, where O2 is limited. Whether songbirds exhibit seasonal plasticity of the O2 cascade to maintain O2 uptake and transport during migratory flight is not well understood. We investigated changes in the hypoxic ventilatory response, haematology and pectoralis (flight) muscle phenotype of 6 songbird species from 3 families during migratory and non-migratory conditions. Songbirds were captured during southbound migration in southern Ontario, Canada. Half of the birds were assessed during migration, and the rest were transitioned onto a winter photoperiod to induce a non-migratory phenotype and measured. All species exhibited seasonal plasticity at various stages along the O2 cascade, but not all species exhibited the same responses. Songbirds tended to be more hypoxia tolerant during migration, withstanding 5 kPa O2 and breathed more effectively through slower, deeper breaths. Warblers had a stronger haemoglobin-O2 affinity during autumn migration (decrease of ∼4.7 Torr), while the opposite was observed in thrushes (increase of ∼2.6 Torr). In the flight muscle there was an ∼1.2-fold increase in the abundance of muscle fibres with smaller fibre transverse areas during autumn migration, but no changes in capillary:fibre ratio. These adjustments would enhance O2 uptake and transport to the flight muscle. Our findings demonstrate that in the O2 cascade there is no ideal migratory phenotype for all songbirds.
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Affiliation(s)
- Catherine M. Ivy
- Department of Biology, Advanced Facility for Avian Research, Western University, London, ON, Canada, N6A 3K7
| | - Christopher G. Guglielmo
- Department of Biology, Advanced Facility for Avian Research, Western University, London, ON, Canada, N6A 3K7
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4
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Dawson NJ, Alza L, Nandal G, Scott GR, McCracken KG. Convergent changes in muscle metabolism depend on duration of high-altitude ancestry across Andean waterfowl. eLife 2020; 9:e56259. [PMID: 32729830 PMCID: PMC7494360 DOI: 10.7554/elife.56259] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/23/2020] [Indexed: 01/07/2023] Open
Abstract
High-altitude environments require that animals meet the metabolic O2 demands for locomotion and thermogenesis in O2-thin air, but the degree to which convergent metabolic changes have arisen across independent high-altitude lineages or the speed at which such changes arise is unclear. We examined seven high-altitude waterfowl that have inhabited the Andes (3812-4806 m elevation) over varying evolutionary time scales, to elucidate changes in biochemical pathways of energy metabolism in flight muscle relative to low-altitude sister taxa. Convergent changes across high-altitude taxa included increased hydroxyacyl-coA dehydrogenase and succinate dehydrogenase activities, decreased lactate dehydrogenase, pyruvate kinase, creatine kinase, and cytochrome c oxidase activities, and increased myoglobin content. ATP synthase activity increased in only the longest established high-altitude taxa, whereas hexokinase activity increased in only newly established taxa. Therefore, changes in pathways of lipid oxidation, glycolysis, and mitochondrial oxidative phosphorylation are common strategies to cope with high-altitude hypoxia, but some changes require longer evolutionary time to arise.
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Affiliation(s)
- Neal J Dawson
- Department of Biology, McMaster UniversityHamiltonCanada
- Department of Biology University of MiamiCoral GablesUnited States
| | - Luis Alza
- Department of Biology University of MiamiCoral GablesUnited States
- University of Alaska Museum and Institute of Arctic Biology, University of Alaska FairbanksFairbanksUnited States
- Centro de Ornitología y Biodiversidad - CORBIDILimaPeru
| | | | - Graham R Scott
- Department of Biology, McMaster UniversityHamiltonCanada
| | - Kevin G McCracken
- Department of Biology University of MiamiCoral GablesUnited States
- University of Alaska Museum and Institute of Arctic Biology, University of Alaska FairbanksFairbanksUnited States
- Centro de Ornitología y Biodiversidad - CORBIDILimaPeru
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of MiamiMiamiUnited States
- Human Genetics and Genomics, Hussman Institute for Human Genomics, University of Miami Miller School of MedicineMiamiUnited States
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5
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Bakkeren C, Smith E, York JM, Chua B, McCracken KG, Milsom WK. A morphometric analysis of the lungs of high-altitude ducks and geese. J Anat 2020; 237:188-196. [PMID: 32173858 PMCID: PMC7309286 DOI: 10.1111/joa.13180] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/12/2020] [Accepted: 02/18/2020] [Indexed: 02/06/2023] Open
Abstract
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 determined the relationship between mass-specific lung volume, the volume densities of the component parts of the lung, and previously reported hypoxia-induced increases in pulmonary O2 extraction. We found that the mass-specific lung volumes and the mass-specific volume of the exchange tissue were larger in the lungs of high-altitude resident birds. The bar-headed goose had a mass-specific lung volume that fell between those of the low-altitude species and the high-altitude residents, but a mass-specific volume of exchange tissue that was not significantly different than that of the high-altitude residents. The data suggest that the mass-specific volume of the lung may increase with evolutionary time spent at altitude. We found an inverse relationship between the percentage increase in pulmonary O2 extraction and the percentage increase in ventilation across species that was independent of the volume density of the exchange tissue, at least for the resident Andean birds.
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Affiliation(s)
- Ciska Bakkeren
- Department of ZoologyUniversity of British ColumbiaVancouverBCCanada
| | - Emily Smith
- Department of ZoologyUniversity of British ColumbiaVancouverBCCanada
| | - Julia M. York
- Department of Integrative BiologyUniversity of Texas at AustinAustinTXUSA
| | - Beverly Chua
- Department of ZoologyUniversity of British ColumbiaVancouverBCCanada
| | - Kevin G. McCracken
- Department of BiologyRosenstiel School of Marine and Atmospheric SciencesUniversity of MiamiCoral GablesFLUSA
- Department of Marine Biology and EcologyRosenstiel School of Marine and Atmospheric SciencesUniversity of MiamiCoral GablesFLUSA
- Human Genetics and GenomicsUniversity of Miami Miller School of MedicineUniversity of MiamiCoral GablesFLUSA
- University of Alaska Museum and Institute of Arctic BiologyUniversity of Alaska FairbanksFairbanksAKUSA
| | - William K. Milsom
- Department of ZoologyUniversity of British ColumbiaVancouverBCCanada
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6
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Lague SL, Ivy CM, York JM, Chua BA, Alza L, Cheek R, Dawson NJ, Frappell PB, Farrell AP, McCracken KG, Scott GR, Milsom WK. Cardiovascular responses to progressive hypoxia in ducks native to high altitude in the Andes. J Exp Biol 2020:jeb.211250. [PMID: 34005543 DOI: 10.1242/jeb.211250] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 02/02/2020] [Indexed: 02/24/2024]
Abstract
The cardiovascular system is critical for delivering O2 to tissues. Here we examine the cardiovascular responses to progressive hypoxia in four high-altitude Andean duck species compared to 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 concentration [Hb]. We calculated O2 pulse (the product of stroke volume and the arterial-venous O2 content difference), blood O2 concentration, and heart rate variability. Regardless of altitude, all eight populations maintained O2 consumption rate with minimal change in heart rate or O2 pulse, indicating that O2 consumption was maintained by either a constant arterial-venous O2 content difference (an increase in the relative O2 extracted from arterial blood) or by a combination of changes in stroke volume and the arterial-venous O2 content difference. Three high-altitude taxa (yellow-billed pintails, cinnamon teal, and speckled teal) had higher Hct and [Hb], increasing the O2 content of arterial blood, and potentially providing a greater reserve for enhancing O2 delivery during hypoxia. Hct and [Hb] between low- and high-altitude populations of ruddy duck were similar, representing a potential adaptation to diving life. Heart rate variability was generally lower in high-altitude ducks, concurrent with similar or lower heart rates than low-altitude ducks, suggesting a reduction in vagal and sympathetic tone. These unique features of the Andean ducks differ from previous observations in both Andean geese and bar-headed geese, neither of which exhibit significant elevations in Hct or [Hb] compared to their low-altitude relatives, revealing yet another avian strategy for coping with high altitude.
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Affiliation(s)
- Sabine L Lague
- Department of Zoology, University of British Columbia, BC, Canada
| | | | - Julia M York
- Department of Zoology, University of British Columbia, BC, Canada
- Department of Integrative Biology, University of Texas at Austin, TX, USA
| | - Beverly A Chua
- Department of Zoology, University of British Columbia, BC, Canada
| | - Luis Alza
- Department of Biology and Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, FL, USA
- Division of Ornithology, Centro de Ornitologia y Biodiversidad, Peru
- Institute of Arctic Biology and University of Alaska Museum, University of Alaska Fairbanks, AK, USA
| | - Rebecca Cheek
- Institute of Arctic Biology and University of Alaska Museum, University of Alaska Fairbanks, AK, USA
| | - Neal J Dawson
- Department of Biology, McMaster University, ON, Canada
- Department of Biology and Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, FL, USA
| | - Peter B Frappell
- Institute for Marine and Antarctic Studies, University of Tasmania, Tasmania, Australia
| | | | - Kevin G McCracken
- Department of Biology and Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, FL, USA
- Division of Ornithology, Centro de Ornitologia y Biodiversidad, Peru
- Institute of Arctic Biology and University of Alaska Museum, University of Alaska Fairbanks, AK, USA
| | | | - William K Milsom
- Department of Zoology, University of British Columbia, BC, Canada
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7
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Origin of Elevational Replacements in a Clade of Nearly Flightless Birds: Most Diversity in Tropical Mountains Accumulates via Secondary Contact Following Allopatric Speciation. NEOTROPICAL DIVERSIFICATION: PATTERNS AND PROCESSES 2020. [DOI: 10.1007/978-3-030-31167-4_23] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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8
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Postnatal changes in O2 and CO2 sensitivity in rodents. Respir Physiol Neurobiol 2020; 272:103313. [DOI: 10.1016/j.resp.2019.103313] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 08/31/2019] [Accepted: 10/02/2019] [Indexed: 02/06/2023]
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9
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Parr N, Wilkes M, Hawkes LA. Natural Climbers: Insights from Avian Physiology at High Altitude. High Alt Med Biol 2019; 20:427-437. [DOI: 10.1089/ham.2019.0032] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Nicole Parr
- College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Cornwall, United Kingdom
| | - Matt Wilkes
- Centre for Altitude Space and Extreme Environment Medicine, Institute of Sport, Exercise and Health, London, United Kingdom
| | - Lucy Alice Hawkes
- Hatherly Laboratories, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
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10
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Ivy CM, Lague SL, York JM, Chua BA, Alza L, Cheek R, Dawson NJ, Frappell PB, McCracken KG, Milsom WK, Scott GR. Control of breathing and respiratory gas exchange in high-altitude ducks native to the Andes. ACTA ACUST UNITED AC 2019; 222:jeb.198622. [PMID: 30846536 DOI: 10.1242/jeb.198622] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/03/2019] [Indexed: 11/20/2022]
Abstract
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 O2 extraction. O2 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 O2 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 O2 extraction compared with low-altitude relatives. Arterial O2 saturation (S aO2 ) was elevated in yellow-billed pintails at moderate levels of hypoxia, but there were no differences in S aO2 in other high-altitude taxa compared with their close relatives. This finding suggests that improvements in S aO2 in hypoxia can require increases in both breathing and haemoglobin-O2 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.
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Affiliation(s)
- Catherine M Ivy
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
| | - Sabine L Lague
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - Julia M York
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4.,Department of Integrative Biology, University of Texas at Austin, TX 78712, USA
| | - Beverly A Chua
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - Luis Alza
- Department of Biology and Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Coral Gables, FL 33146, USA.,Division of Ornithology, Centro de Ornitologia y Biodiversidad, Lima 33, Peru.,Department of Biology and Wildlife, Institute of Arctic Biology and University of Alaska Museum, University of Alaska Fairbanks, AK 99755, USA
| | - Rebecca Cheek
- Department of Biology and Wildlife, Institute of Arctic Biology and University of Alaska Museum, University of Alaska Fairbanks, AK 99755, USA
| | - Neal J Dawson
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
| | - Peter B Frappell
- Zoology Department, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Kevin G McCracken
- Department of Biology and Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Coral Gables, FL 33146, USA.,Division of Ornithology, Centro de Ornitologia y Biodiversidad, Lima 33, Peru.,Department of Biology and Wildlife, Institute of Arctic Biology and University of Alaska Museum, University of Alaska Fairbanks, AK 99755, USA.,Human Genetics and Genomics, University of Miller School of Medicine, Miami, FL 33136, USA
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - Graham R Scott
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
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11
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York JM, Scadeng M, McCracken KG, Milsom WK. Respiratory mechanics and morphology of Tibetan and Andean high-altitude geese with divergent life histories. ACTA ACUST UNITED AC 2018; 221:jeb.170738. [PMID: 29180602 DOI: 10.1242/jeb.170738] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 11/21/2017] [Indexed: 12/31/2022]
Abstract
High-altitude bar-headed geese (Anser indicus) and Andean geese (Chloephaga melanoptera) have been shown to preferentially increase tidal volume over breathing frequency when increasing ventilation during exposure to hypoxia. Increasing tidal volume is a more effective breathing strategy but is also thought to be more mechanically and metabolically expensive. We asked whether there might be differences in the mechanics or morphology of the respiratory systems of high-altitude transient bar-headed geese and high-altitude resident Andean geese that could minimize the cost of breathing more deeply. We compared these two species with a low-altitude migratory species, the barnacle goose (Branta leucopsis). We ventilated anesthetized birds to measure mechanical properties of the respiratory system and used CT scans to quantify respiratory morphology. We found that the respiratory system of Andean geese was disproportionately larger than that of the other two species, allowing use of a deeper breathing strategy for the same energetic cost. The relative size of the respiratory system, especially the caudal air sacs, of bar-headed geese was also larger than that of barnacle geese. However, when normalized to respiratory system size, the mechanical cost of breathing did not differ significantly among these three species, indicating that deeper breathing is enabled by morphological but not mechanical differences between species. The metabolic cost of breathing was estimated to be <1% of basal metabolic rate at rest in normoxia. Because of differences in the magnitude of the ventilatory response, the cost of breathing was estimated to increase 7- to 10-fold in bar-headed and barnacle geese in severe hypoxia, but less than 1-fold in Andean geese exposed to the same low atmospheric PO2.
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Affiliation(s)
- Julia M York
- University of British Columbia, Department of Zoology, 6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4
| | - Miriam Scadeng
- University of California San Diego, Department of Radiology, Center for Functional MRI, 9500 Gilman Drive 0677, La Jolla, CA, USA 92093
| | - Kevin G McCracken
- University of Miami, Department of Biology, Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, and Human Genetics and Genomics - Miller School of Medicine, Coral Gables, FL, 33146, USA
| | - William K Milsom
- University of British Columbia, Department of Zoology, 6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4
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12
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Ivy CM, Scott GR. Control of breathing and ventilatory acclimatization to hypoxia in deer mice native to high altitudes. Acta Physiol (Oxf) 2017. [PMID: 28640969 DOI: 10.1111/apha.12912] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
AIM We compared the control of breathing and heart rate by hypoxia between high- and low-altitude populations of Peromyscus mice, to help elucidate the physiological specializations that help high-altitude natives cope with O2 limitation. METHODS Deer mice (Peromyscus maniculatus) native to high altitude and congeneric mice native to low altitude (Peromyscus leucopus) were bred in captivity at sea level. The F1 progeny of each population were raised to adulthood and then acclimated to normoxia or hypobaric hypoxia (12 kPa, simulating hypoxia at ~4300 m) for 5 months. Responses to acute hypoxia were then measured during stepwise reductions in inspired O2 fraction. RESULTS Lowlanders exhibited ventilatory acclimatization to hypoxia (VAH), in which hypoxia acclimation enhanced the hypoxic ventilatory response, made breathing pattern more effective (higher tidal volumes and lower breathing frequencies at a given total ventilation), increased arterial O2 saturation and heart rate during acute hypoxia, augmented respiratory water loss and led to significant growth of the carotid body. In contrast, highlanders did not exhibit VAH - exhibiting a fixed increase in breathing that was similar to hypoxia-acclimated lowlanders - and they maintained even higher arterial O2 saturations in hypoxia. However, the carotid bodies of highlanders were not enlarged by hypoxia acclimation and were similar in size to those of normoxic lowlanders. Highlanders also maintained consistently higher heart rates than lowlanders during acute hypoxia. CONCLUSIONS Our results suggest that highland deer mice have evolved high rates of alveolar ventilation and respiratory O2 uptake without the significant enlargement of the carotid bodies that is typical of VAH in lowlanders, possibly to adjust the hypoxic chemoreflex for life in high-altitude hypoxia.
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Affiliation(s)
- C. M. Ivy
- Department of Biology; McMaster University; Hamilton ON Canada
| | - G. R. Scott
- Department of Biology; McMaster University; Hamilton ON Canada
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13
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Laguë SL. High-altitude champions: birds that live and migrate at altitude. J Appl Physiol (1985) 2017; 123:942-950. [PMID: 28839002 DOI: 10.1152/japplphysiol.00110.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 08/09/2017] [Accepted: 08/14/2017] [Indexed: 11/22/2022] Open
Abstract
High altitude is physiologically challenging for vertebrate life for many reasons, including hypoxia (low environmental oxygen); yet, many birds thrive at altitude. Compared with mammals, birds have additional enhancements to their oxygen transport cascade, the conceptual series of steps responsible for acquiring oxygen from the environment and transporting it to the mitochondria. These adaptations have allowed them to inhabit a number of high-altitude regions. Waterfowl are a taxon prolific at altitude. This minireview explores the physiological responses of high-altitude waterfowl (geese and ducks), comparing the strategies of lifelong high-altitude residents to those of transient high-altitude performers, providing insight into how birds champion high-altitude life. In particular, this review highlights and contrasts the physiological hypoxia responses of bar-headed geese (Anser indicus), birds that migrate biannually through the Himalayas (4,500-6,500 m), and Andean geese (Chloephaga melanoptera), lifelong residents of the Andes (4,000-5,500 m). These two species exhibit markedly different ventilatory and cardiovascular strategies for coping with hypoxia: bar-headed geese robustly increase convective oxygen transport elements (i.e., heart rate and total ventilation) whereas Andean geese rely predominantly on enhancements that are likely morphological in origin (i.e., increases in lung oxygen diffusion and cardiac stroke volume). The minireview compares the short- and long-term cardiovascular and ventilatory trade-offs of these different physiological strategies and offers hypotheses surrounding their origins. It also draws parallels to high-altitude human physiology and research, and identifies a number of areas of further research. The field of high-altitude avian physiology offers a unique and broadly applicable insight into physiological enhancements in hypoxia.
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Knight K. Birds do not work harder to breathe. J Exp Biol 2017; 220:955. [DOI: 10.1242/jeb.158675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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