High altitude, adaptation

Alpine waters are sensitive ecosystems with unique features and resources. Extreme environmental conditions (altitude, gradient, low nutrients, duration of snow cover) shape special habitats that are only suitable for highly-adapted fishes. Only cold stenothermic species can inhabit Alpine waters. During spawning and the period of egg development, water temperature is low and can reach 0°C. Therefore, only a few of the native fishes were able to colonize and inhabit Alpine waters. In the last decades, non-native cold water resistant fish appeared in many Alpine waters. Nonnative species have inhabited alpine lakes since the late 19th century Salvelinus namaycush were stocked in 1886 in small alpine lakes in the Swiss Alps [92]) and started to reproduce in many lakes. Over the last decades in many Alpine streams, non-native, cold stenothermic species have established self-reproducing populations and appear well-adapted to the harsh environmental conditions. 

Holden, J. E., C. Stone, W.D. Brown, R.J. Nickels, C. Stanley, C.M. Clark, and P.W. Hochachka (1995). Enhanced cardiac metabolism of plasma glucose in high altitude natives Adaptations against chronic hypoxia. J. Appl. Physiol. 79 222-228. 

Figure 5.45. Correlations of NOy with N2O concentrations measured from ATMOS aboard the Space Shuttle and instruments aboard the ER-2 high altitude aircraft. Adapted from Chang et al. (1996).

Immediate treatment of altitude sickness includes hydration, rest, and if necessary, descending to a lower altitude. The adaptation to lowered oxygen levels requires about 10 days. During this time the bone marrow increases red blood cell production, providing more red blood cells and more hemoglobin. A person living at a high altitude can have 50% more red blood cells than someone at sea level. This... 

Body iron content is the principal factor in the regulation of iron absorption (Marx,1979a,b). However, other physiological variables, such as erythropoietic rate (Bothwell, 1968), hypoxia (Raja et ah, 1988) and inflammation (Weber et ah, 1988) also influence iron absorption. In normal individuals, if the rate of erythropoiesis is stimulated by blood loss, dyserythropoiesis or acute haemolysis, iron absorption is increased. Conversely, if erythropoiesis is inhibited by hypertransfusion, starvation or descent from high altitude to sea level, then iron absorption decreases. The adaptive response of iron absorption to increased erythropoiesis, stimulated... 

BPG levels are elevated In the RBCs of persons who have adapted to high altitude conditions, enhancing dissociation of02 In tissues to compensate for reduced O2 saturation of hemoglobin. 

But even at the thin atmosphere at high altitudes, atmospheric distortion limits the ability of telescopes to discern faint objects. Adaptive optics helps by sensing this distortion and instantly adjusting the optical properties of the instrument to counteract the harmful effects. The process must operate continually since air moves around, and the extent and nature of atmospheric distortion changes rapidly. 

Fig. 2 Stations used in measurements of aerosol number size distributions. Black symbols are EUSAAR stations, white GUAN (MPZ was in both networks). Triangles denote high-altitude mountain stations (over 1,000 m from mean sea level). Figure adapted from figure published in [18], which also has more details on the locations and types of the stations...

High Altitude An Exploration of Human Adaptation, edited by... 

When the ancestors of man left the oceans and started to live on the dry land, their most critical acquisition was the capacity to adapt to a continuously changing dry gaseous environment. Humans live not only in hot deserts but also in cold Alaska, in the high altitudes of Tibet and the low altitudes of the Dead Sea. They stay alive in summer and winter. Some humans gratuitously add to the adaptation task of their skin by uselessly washing and perfuming themselves several times a day. This accounts... 

ADAPTABLE TRAITS AND A HIGH-ALTITUDE PHYSIOLOGICAL PHENOTYPE... 

Compared to acute or acclimatory adjustments, these longer term (phylogenetic) adaptations appear to compensate quite well for 02 deficits caused by hypoxia, but the advantage appears to be gained at the cost of some attenuation of maximum aerobic and anaerobic metabolic capacities. On balance the picture emerging so far is that of a high altitude phy-... 

Figure 5.6. A diagrammatic summary of adjusted hypoxia response systems (the AHRS) proposed as the ancestral physiological phenotype and as a phylogenetic adaptation to hypobaric hypoxia. Summary based largely upon studies of Quechuas and Sherpas. Essentially all of the characteristics summarized here are also expressed in individuals well adapted for endurance performance. In the latter, the main modification involves an upwards regulation of mitochondrial volume densities at the working tissues (altered expression of mitochondrial metabolic enzymes and metabolite transporters above), which is why this is referred to as a high-capacity version of the lower capacity high-altitude phenotype. See text for further details. (Modified from Hochachka et al., 1999.)...

Hochachka, P.W. (1992). Muscle enzymatic composition and metabolic regulation in high altitude adapted natives. Int. J. Sport Med. 13 S89-S91... 

---