scholarly journals Life Ascending: Mechanism and Process in Physiological Adaptation to High-Altitude Hypoxia

2019 ◽  
Vol 50 (1) ◽  
pp. 503-526 ◽  
Author(s):  
Jay F. Storz ◽  
Graham R. Scott
Keyword(s):  
High Altitude ◽  
Environmental Conditions ◽  
Physiological Adaptation ◽  
Aerobic Performance ◽  
Cardiorespiratory System ◽  
Transport Pathway ◽  
Altitudinal Variation ◽  
Air Breathing ◽  
High Altitude Natives ◽  
Low Altitude

To cope with the reduced availability of O2 at high altitude, air-breathing vertebrates have evolved myriad adjustments in the cardiorespiratory system to match tissue O2 delivery with metabolic O2 demand. We explain how changes at interacting steps of the O2 transport pathway contribute to plastic and evolved changes in whole-animal aerobic performance under hypoxia. In vertebrates native to high altitude, enhancements of aerobic performance under hypoxia are attributable to a combination of environmentally induced and evolved changes in multiple steps of the pathway. Additionally, evidence suggests that many high-altitude natives have evolved mechanisms for attenuating maladaptive acclimatization responses to hypoxia, resulting in counter-gradient patterns of altitudinal variation for key physiological phenotypes. For traits that exhibit counteracting environmental and genetic effects, evolved changes in phenotype may be cryptic under field conditions and can only be revealed by rearing representatives of high- and low-altitude populations under standardized environmental conditions to control for plasticity.

scholarly journals Morphological variation in Leptorhynchos squamatus (Gnaphalieae: Asteraceae)

2002 ◽  
Vol 15 (2) ◽  
pp. 205 ◽  
Author(s):  
Christina Flann ◽  
Pauline Y. Ladiges ◽  
Neville G. Walsh
Keyword(s):  
High Altitude ◽  
Morphological Variation ◽  
Environmental Conditions ◽  
Leaf Size ◽  
Alpine Plants ◽  
The Other ◽  
Herbarium Specimens ◽  
South Eastern ◽  
Eastern Australia ◽  
Low Altitude

A study of morphological variation in Leptorhynchos squamatus (Labill.) Less. across its range in south-eastern Australia was undertaken to test the hypothesis that L. squamatus includes two taxa. Phenetic pattern analyses of both field-collected and herbarium specimens on the basis of morphology confirmed two major groups. Bract, cypsela, pappus bristle and leaf characters were particularly important in separating the two groups. The taxa are separated by altitude differences with one being a low-altitude plant found in many habitats and the other being a high-altitude taxon that is a major component of alpine meadows. Lowland plants have dark bract tips, fewer and wider pappus bristles than alpine plants, papillae on the cypselas and more linear leaves. A somewhat intermediate population from the Major Mitchell Plateau in the Grampians shows some alpine and some lowland characters but is included in the lowland taxon. Seeds from five populations (two alpine, two lowland and Major Mitchell) were germinated and plants grown for 18 weeks under four controlled sets of environmental conditions. The experiment showed that leaf size and some other characters are affected by environmental conditions, but that there are underlying genetic differences between the lowland and alpine forms. Leptorhynchos squamatus subsp. alpinus Flann is described here to accommodate the highland taxon.

A Single High-Altitude Training Bout Improves High-Altitude Aerobic Performance Following 1 Week of Low-Altitude Training

2011 ◽  
Vol 43 (Suppl 1) ◽  
pp. 284
Author(s):  
Brady D. Andersen ◽  
Daniel E. Turk ◽  
Robert W. Gotshall ◽  
Matthew S. Hickey ◽  
Richard G. Israel ◽  
...  
Keyword(s):  
High Altitude ◽  
Aerobic Performance ◽  
Altitude Training ◽  
Low Altitude

Evolved Mechanisms of Aerobic Performance and Hypoxia Resistance in High-Altitude Natives

2019 ◽  
Vol 81 (1) ◽  
pp. 561-583 ◽  
Author(s):  
Grant B. McClelland ◽  
Graham R. Scott
Keyword(s):  
Gene Expression ◽  
High Altitude ◽  
Aerobic Capacity ◽  
Metabolic Pathways ◽  
Chronic Hypoxia ◽  
Aerobic Performance ◽  
Comparative Physiology ◽  
Functional Changes ◽  
High Altitude Natives ◽  
Underlying Mechanisms

Comparative physiology studies of high-altitude species provide an exceptional opportunity to understand naturally evolved mechanisms of hypoxia resistance. Aerobic capacity (VO2max) is a critical performance trait under positive selection in some high-altitude taxa, and several high-altitude natives have evolved to resist the depressive effects of hypoxia on VO2max. This is associated with enhanced flux capacity through the O2transport cascade and attenuation of the maladaptive responses to chronic hypoxia that can impair O2transport. Some highlanders exhibit elevated rates of carbohydrate oxidation during exercise, taking advantage of its high ATP yield per mole of O2. Certain highland native animals have also evolved more oxidative muscles and can sustain high rates of lipid oxidation to support thermogenesis. The underlying mechanisms include regulatory adjustments of metabolic pathways and to gene expression networks. Therefore, the evolution of hypoxia resistance in high-altitude natives involves integrated functional changes in the pathways for O2and substrate delivery and utilization by mitochondria.

Regression of Body Density on Skinfold Thicknesses in High Altitude Natives: Decline in the Predictive Efficiency on De-Acclimatisation to Low Altitude

1995 ◽  
Vol 45 (3) ◽  
pp. 237-242 ◽  
Author(s):  
H. Bharadwaj ◽  
T. Zachariah ◽  
S. Kishnani ◽  
S. N. Pramanik ◽  
J. Prasad ◽  
...  
Keyword(s):  
High Altitude ◽  
Body Density ◽  
High Altitude Natives ◽  
Low Altitude ◽  
Predictive Efficiency

scholarly journals High serum testosterone levels are associated with excessive erythrocytosis of chronic mountain sickness in men

2009 ◽  
Vol 296 (6) ◽  
pp. E1319-E1325 ◽  
Author(s):  
Gustavo F. Gonzales ◽  
Manuel Gasco ◽  
Vilma Tapia ◽  
Cynthia Gonzales-Castañeda
Keyword(s):  
Thyroid Hormones ◽  
High Altitude ◽  
Serum Testosterone ◽  
High Serum ◽  
Chronic Mountain Sickness ◽  
Testosterone Levels ◽  
High Altitude Natives ◽  
Mountain Sickness ◽  
Low Altitude ◽  
Cerro De Pasco

Chronic mountain sickness (CMS) is characterized by excessive erythrocytosis (EE) secondary to hypoventilation. Erythropoietin (Epo) and testosterone regulate erythrocyte production. Low thyroid hormone levels are also associated to hypoventilation. Hence, these hormones can play a role in etiopathogeny of EE. The purpose of this study was to elucidate the effect of sexual and thyroid hormones and Epo in residents from Lima (150 m) and Cerro de Pasco (4,340 m), Peru, and the response to human chorionic gonadotrophin stimulation (hCG). Three groups, one at low altitude and two at high altitude [1 with hemoglobin values >16–21 g/dl and the second with Hb ≥21 g/dl (EE)], were studied. hCG was administered intramuscularly in a single dose (1,000 IU), and blood samples were obtained at 0, 6, 12, 24, 48, and 72 h after injection. High-altitude natives present similar levels of gonadotropins and thyroid hormones but lower dehydroepiandrosterone sulphate (DHEAS) levels ( P < 0.01) and greater Epo ( P < 0.01), 17α-hydroxyprogesterone ( P < 0.01), and testosterone levels ( P < 0.01) than those at 150 m. Serum testosterone levels (524.13 ± 55.91 μg/dl vs. 328.14 ± 53.23 ng/dl, means ± SE; P < 0.05) and testosterone/DHEAS ratios are higher (7.98 ± 1.1 vs. 3.65 ± 1.1; P < 0.01) and DHEAS levels lower in the EE group (83.85 ± 14.60 μg/dl vs. 148.95 ± 19.11 ug/dl; P < 0.05), whereas Epo was not further affected. Testosterone levels were highest and DHEAS levels lowest in the EE group at all times after hCG stimulation. In conclusion, high androgen activity could be involved in the etiopathogeny of CMS. This evidence provides an opportunity to develop new therapeutic strategies.

scholarly journals Down Feather Structure Varies Between Low- and High-Altitude Torrent Ducks (Merganetta Armata) in the Andes

2017 ◽  
Author(s):  
Rebecca G. Cheek ◽  
Luis Alza ◽  
Kevin G. McCracken
Keyword(s):  
High Altitude ◽  
Environmental Conditions ◽  
Critical Role ◽  
Ambient Temperatures ◽  
The Andes ◽  
Significant Difference ◽  
General Constraints ◽  
Low Altitude ◽  
High Elevations ◽  
Two Populations

AbstractFeathers are one of the defining characteristics of birds and serve a critical role in thermal insulation and physical protection against the environment. Feather structure is known to vary among individuals, and it has been suggested that populations exposed to different environmental conditions may exhibit different patterns in feather structure. We examined both down and contour feathers from two populations of male Torrent Ducks (Merganetta armata) from Lima, Peru, including one high-altitude population from the Chancay-Huaral River at approximately 3500 meters (m) elevation and one low-altitude population from the Chillón River at approximately 1500 m. Down feather structure differed significantly between the two populations. Ducks from the high-altitude population had longer, denser down compared with low-altitude individuals. Contour feather structure varied greatly among individuals but showed no significant difference between populations. These results suggest that the innermost, insulative layer of plumage (the down), may have developed in response to lower ambient temperatures at high elevations. The lack of observable differences in the contour feathers may be due to the general constraints of the waterproofing capability of this outer plumage layer.ResumenEl plumaje es una característica que define a las aves y cumple roles críticos en el aislamiento térmico y protección física del ambiente. Se sabe que la estructura de las plumas varía ente individuos, y se ha sugerido que poblaciones expuestas a diferentes condiciones ambientales pueden exhibir diferentes patrones en la estructura de las plumas. En este estudio se examinaron tanto el plumón como las plumas de contorno de machos adultos del Pato de los Torrentes (Merganetta armata) de dos poblaciones, una en el río Chancay-Huaral a 3,500 msnm y otra en el río Chillón a 1,500 msnm, ubicadas en Lima, Perú. La estructura de los plumones difiere significativamente entre las dos poblaciones. Los patos de la población a grandes elevaciones tienen plumones largos, y densos comparados con los individuos de las partes bajas. La estructura de las plumas de contorno varía ampliamente entre individuos pero no muestra diferencias significativas entre poblaciones. Estos resultados sugieren que las diferencias entre las capas interiores de aislamiento del plumaje (plumón), haberse desarrollado como respuesta en ambientes de bajas temperaturas a grandes elevaciones. En cambio la falta de detectables diferencias en las plumas de contorno puede ser debido a la constante selección en la capacidad impermeable de la capa de plumas exteriores.

scholarly journals Coordinated changes across the O 2 transport pathway underlie adaptive increases in thermogenic capacity in high-altitude deer mice

2020 ◽  
Vol 287 (1927) ◽  
pp. 20192750 ◽  
Author(s):  
Kevin B. Tate ◽  
Oliver H. Wearing ◽  
Catherine M. Ivy ◽  
Zachary A. Cheviron ◽  
Jay F. Storz ◽  
...  
Keyword(s):  
High Altitude ◽  
Complex Traits ◽  
Deer Mice ◽  
Transport Pathway ◽  
Physiological Mechanisms ◽  
Critical Determinant ◽  
In Captivity ◽  
Low Altitude ◽  
Hypoxia Acclimation ◽  
Thermogenic Capacity

Animals native to the hypoxic and cold environment at high altitude provide an excellent opportunity to elucidate the integrative mechanisms underlying the adaptive evolution and plasticity of complex traits. The capacity for aerobic thermogenesis can be a critical determinant of survival for small mammals at high altitude, but the physiological mechanisms underlying the evolution of this performance trait remain unresolved. We examined this issue by comparing high-altitude deer mice ( Peromyscus maniculatus ) with low-altitude deer mice and white-footed mice ( P. leucopus ). Mice were bred in captivity and adults were acclimated to each of four treatments: warm (25°C) normoxia, warm hypoxia (12 kPa O 2 ), cold (5°C) normoxia or cold hypoxia. Acclimation to hypoxia and/or cold increased thermogenic capacity in deer mice, but hypoxia acclimation led to much greater increases in thermogenic capacity in highlanders than in lowlanders. The high thermogenic capacity of highlanders was associated with increases in pulmonary O 2 extraction, arterial O 2 saturation, cardiac output and arterial–venous O 2 difference. Mechanisms underlying the evolution of enhanced thermogenic capacity in highlanders were partially distinct from those underlying the ancestral acclimation responses of lowlanders. Environmental adaptation has thus enhanced phenotypic plasticity and expanded the physiological toolkit for coping with the challenges at high altitude.

Selected Contribution: High-altitude natives living at sea level acclimatize to high altitude like sea-level natives

2003 ◽  
Vol 94 (3) ◽  
pp. 1263-1268 ◽  
Author(s):  
Maria Rivera-Ch ◽  
Alfredo Gamboa ◽  
Fabiola León-Velarde ◽  
Jose-Antonio Palacios ◽  
David F. O'Connor ◽  
...  
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Time Course ◽  
Ventilatory Response ◽  
Air Breathing ◽  
High Altitude Natives ◽  
End Tidal ◽  
Ventilatory Response To Hypoxia

Sea-level (SL) natives acclimatizing to high altitude (HA) increase their acute ventilatory response to hypoxia (AHVR), but HA natives have values for AHVR below those for SL natives at SL (blunting). HA natives who live at SL retain some blunting of AHVR and have more marked blunting to sustained (20-min) hypoxia. This study addressed the question of what happens when HA natives resident at SL return to HA: do they acclimatize like SL natives or revert to the characteristics of HA natives? Fifteen HA natives resident at SL were studied, together with 15 SL natives as controls. Air-breathing end-tidal Pco 2 and AHVR were determined at SL. Subjects were then transported to 4,300 m, where these measurements were repeated on each of the following 5 days. There were no significant differences in the magnitude or time course of the changes in end-tidal Pco 2 and AHVR between the two groups. We conclude that HA natives normally resident at SL undergo ventilatory acclimatization to HA in the same manner as SL natives.

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