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High altitude adaptation and anaerobiosis in sceloporine lizards
Abstract
Abstract-1.The duration of maximal activity and the intensity of anaerobic metabolismwere measured in lowland Sceloporus occidentalis at low (200 ft) and high (10,150 ft) elevations and compared to those of resident S. occidentalis and S. graciosus at high altitude. 2.The duration of maximal activity is independent of altitude: all groups of S. occidentalis had the same stamina, regardless of the altitude of experimentation or prior residence. 3.The amount of lactate formed during activity is also independent of altitude or prior residence.
... 0031-935X/82/5 504-8139$02.00 367 (Bullock 1955). Comparisons of low altitude and high-altitude vertebrates are especially common (Bartlett 1970;Bennett and Ruben 1975;Jameson, Heusner, and Arbogast 1976;Snyder and Weathers 1977). ...
... 367 (Bullock 1955). Comparisons of low altitude and high-altitude vertebrates are especially common (Bartlett 1970;Bennett and Ruben 1975;Jameson, Heusner, and Arbogast 1976;Snyder and Weathers 1977). Similar comparisons involving ter restrial invertebrates are rare (Scholander et al. 1953). ...
... 367 (Bullock 1955). Comparisons of low altitude and high-altitude vertebrates are especially common (Bartlett 1970;Bennett and Ruben 1975;Jameson, Heusner, and Arbogast 1976;Snyder and Weathers 1977). Similar comparisons involving ter restrial invertebrates are rare (Scholander et al. 1953). ...
The oxygen consumption rates at 30 C and the temperature sensitivity of the rates were compared for member groups (larvae, pupae, callows, workers, females, and males) of three species of harvester ants which occur at different altitudes in southern California. Developmental changes in both rates and temperature sensitivity were found. There is an abrupt doubling or tripling of the respiratory rates of males prior to the mating flights. No similar changes were found in the respiratory rates of the females. The males are dimorphic, with each size having different respiratory rates. In general, Pogonomyrmex montanus MacKay, the harvester ant from the highest altitude, had the highest respiratory rates and demonstrated the greatest temperature sensitivity. The mid-altitude species, P. subnitidus Emery, had intermediate respiratory rates. The lowest-altitude species, P. rugosus Emery, had the lowest respiratory rates and demonstrated the least temperature sensitivity. These differences are important as the ants are exposed to different temperature ranges; the higheraltitude species are exposed to lower temperatures. This physiological adaptation may be necessary to allow each of the species to be active at similar rates in the three different habitats. Although a physiological adaptation involving higher respiratory rates in ants from higher altitudes was determined in the three species investigated, it may not be a general phenomenon in ants. It is suggested that further investigation is needed to determine the parameters which have an effect on the important physiological process of respiration and to provide ecological interpretations for the differences observed.
... We recorded tail displays in both males and females and examined correlations between tail display behavior and metabolic enzyme concentration (lactate dehydrogenase, LDH) and blood lactate concentration as markers of anaerobic metabolism. The LDH activity mostly reflects the individual capacity of anaerobic metabolism (Bertram et al. 2011;Mowles 2014;Thomson et al. 2014), while the blood lactate concentration mostly indicates the intensity of recent anaerobic metabolic activity (Bennett & Ruben 1975). We also examined another metabolic enzyme CS activity as indictor of individual aerobic metabolic capacity, and investigated whether different display component correlates with different metabolic pathway, and whether the correlations between display variation and energy metabolism varies with sexes. ...
... Bennett and Licht (1972) found that anaerobic metabolism pathways comprise 80-90% of total energy expenditure for initial vigorous activity, and suggested that anaerobic metabolism was less associated with thermal regulation, which likely permits high levels of activity in lizards without effect of body temperature. Lizards'activity in the genus Sceloprus, at high altitudes, are highly dependent on anaerobic metabolism (Bennett & Ruben 1975). Bennett and George (1981) investigated anaerobic metabolism in Anolis bonairensis, and found that anaerobic metabolism could considerably extend individual behavioral variations. ...
Understanding the mechanism underlying signal variation is an important goal in the study of animal communication. Several potential causes have been proposed for signal variation, including environmental noise (e.g. wind, sound), energy limitation, and predation risk, among others, but the physiological control of many signals are often unclear. Here, we examined the correlation between tail display signal variation and energy metabolic activity using an Asian agamid lizard Phrynocephalus vlangalii. Individual tail display signals were observed in the field, and blood lactate concentration as well as two energy metabolic enzymes were assayed. Our results showed that average tail coil speed was positively associated with blood lactate concentration, while tail coil duration was negatively associated with LDH activity. We also found that average tail lash speed was positively associated with blood lactate concentration, suggesting that the tail display behavior of P. vlangalii was regulated by anaerobic metabolism. Furthermore, the correlation between tail display behavior and energy metabolism was not sex‐dependent. Taken together, our research provides insight into the physiological mechanisms underlying tail display variation in lizards, and suggests that tail display variation likely transmits important information on individual body condition and resource holding potential.
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... Some studies have shown little or no correlation between blood values (i.e., Erc, Hct, [Hb]) in lizards and altitudinal distribution (Dawson and Poulson 1962;Dessauer 1970;Biswas et al. 1981, Ruiz et al. 1983, 1993Weber 2007;He et al. 2013). For example, Mexican spiny lizards of the genus Sceloporus Wiegmann, 1828 found at lowlands (61 m above sea level (asl)) and highlands (3100 m asl) have shown no differences in lactate levels, which suggests that they both exhibit similar patterns of anaerobic activity (Bennett and Ruben 1975). Others have reported increased hematological values (Hb, Erc, Hct, etc.) in highland lizards (Vinegar and Hillyard 1972;Weathers and White 1972;Engbretson and Hutchinson 1976;Newlin and Ballinger 1976). ...
... It has been shown that hypoxic environments lead to an increase in blood lactate (see Lundby et al. 2000). Because lactate production provides most of the energy generation during rapid activity, lactate is associated with anaerobic activity (Bennett and Ruben 1975). In our results, highland lizards showed higher lactate levels than lowland lizards. ...
This study examined changes of some different hematological parameters in a reptilian model naturally exposed to altitude-associated hypoxia. Four populations of the Mexican lizard Sceloporus torquatus (Wiegmann 1828) from different altitudes were sampled to evaluate erythrocyte count (Erc), hematocrit (Hct), mean corpuscular hemoglobin concentration (MCHC) and erythrocyte size (Ers). Blood was also assayed to determine hemoglobin ([Hb]), glucose, lactate and electrolytes concentration. Erc was performed using a Neubauer hemocytometer. Hct was calculated as per cent packed cell volume by centrifuging blood samples. [Hb] was determined using a Bausch and Lomb Spectronic Colorimeter. MCHC was calculated with 100 x [Hb]/Hct. Erythrocyte size (Ers) was calculated from blood smear micro-photographs analyzed with the Sigma Scan Pro software. Serum electrolytes (Na+, K+ and Ca2+), pH, glucose, and lactate values from blood samples were obtained through a blood electrolyte analyzer. Highland populations of Sceloporus torquatus exhibited a significant increase in erythrocyte count, hematocrit, erythrocyte size, and hemoglobin concentration. In contrast, MCHC showed no correlation with altitude. Additionally, significant differences in lactate, sodium, potassium and calcium were observed in highland populations. In general, we found that most hematological parameters were significantly different among lizard populations from different altitudes. This is the first study to report changes in erythrocyte size in relation to altitude, which could be a physiological response to hypoxia.
... Some studies have shown little or no correlation between blood values (i.e., Erc, Hct, [Hb]) in lizards and altitudinal distribution (Dawson and Poulson 1962;Dessauer 1970;Biswas et al. 1981, Ruiz et al. 1983, 1993Weber 2007;He et al. 2013). For example, Mexican spiny lizards of the genus Sceloporus Wiegmann, 1828 found at lowlands (61 m above sea level (asl)) and highlands (3100 m asl) have shown no differences in lactate levels, which suggests that they both exhibit similar patterns of anaerobic activity (Bennett and Ruben 1975). Others have reported increased hematological values (Hb, Erc, Hct, etc.) in highland lizards (Vinegar and Hillyard 1972;Weathers and White 1972;Engbretson and Hutchinson 1976;Newlin and Ballinger 1976). ...
... It has been shown that hypoxic environments lead to an increase in blood lactate (see Lundby et al. 2000). Because lactate production provides most of the energy generation during rapid activity, lactate is associated with anaerobic activity (Bennett and Ruben 1975). In our results, highland lizards showed higher lactate levels than lowland lizards. ...
This study examined changes in certain hematological parameters in a reptilian model naturally exposed to altitude-associated hypoxia. Four populations of the Mexican lizard Sceloporus torquatus Wiegmann, 1828 (Wiegmann’s Torquate Lizard) from different altitudes were sampled to evaluate erythrocyte count (Erc), hematocrit (Hct), mean corpuscular hemoglobin concentration (MCHC), and erythrocyte size (Ers). Blood was also assayed to determine hemoglobin ([Hb]), glucose, lactate, and electrolyte concentrations. Erc was performed using a Neubauer hemocytometer. Hct was calculated as percentage of packed cell volume by centrifuging blood samples. [Hb] was determined using a Bausch and Lomb Spectronic colorimeter. MCHC was calculated with the formula 100 × [Hb]/Hct. Ers was calculated from blood smear microphotographs analyzed with the Sigma Scan Pro software. Values of serum electrolytes (sodium (Na⁺), potassium (K⁺), and calcium (Ca²⁺)), pH, glucose, and lactate from blood samples were obtained through a blood electrolyte analyzer. Highland populations of S.torquatus exhibited a significant increase in Erc, Hct, Ers, and [Hb]. In contrast, MCHC showed no correlation with altitude. Additionally, significant differences in lactate, Na⁺, K⁺, and Ca²⁺ were observed in highland populations. In general, we found that most hematological parameters were significantly different among lizard populations from different altitudes. This is the first study to report changes in Ers in relation to altitude, which could be a physiological response to hypoxia.
... Some lizards endure more than 4000 m, for instance, Phrynocephalus vlangalli occurs at 4500 m on the Tibetan Plateau and Liolaemus tacnae occurs at 5000 m in Peru (He et al., 2013;Cerdeña et al., 2021). Highaltitude lizards (species living above 2000 m) show elevated values of blood traits such as hemoglobin concentration or hematocrit (Vinegar and Hillyard, 1972;Bennett and Ruben, 1975;He et al., 2013;González-Morales et al., 2015;Megía-Palma et al., 2020). This physiological variation along altitudinal gradients allows them to maintain an adequate oxygen supply, so blood gas pressures may not differ along an altitudinal gradient . ...
Ecogeographical patterns describe predictable variation in phenotypic traits between ecological communities. For example, high-altitude animals are expected to show elevated hematological values as an adaptation to the lower oxygen pressure. Mountains act like ecological islands and therefore are considered natural laboratories. However, the majority of ecophysiological studies on blood traits lack replication that would allow us to infer if the pattern reported is a local event or whether it is a widespread pattern resulting from larger-scale ecological processes. In lizards, in fact, the increase of hematological values at high altitudes has received mixed support. Here, for the first time, we compare blood traits in lizards along elevational gradients with replication. We tested the repeatability of blood traits in mesquite lizards between different elevations in three different mountains from the Trans-Mexican Volcanic Belt. We measured hematocrit, hemoglobin concentration, mean corpuscular hemoglobin concentration, and erythrocyte size in blood samples of low, medium, and high-elevation lizards. We obtained similar elevational patterns between mountains, but the blood traits differed among mountains. Middle-altitude populations had greater oxygen-carrying capacity than lizards from low and high altitudes. The differences found between mountain systems could be the result of phenotypic plasticity or genetic differentiation as a consequence of abiotic factors not considered.
... We hope that this report will encourage future research into the physiological mechanisms that allow these animals to live at such extremely high elevations through adaptations to low temperatures and low oxygen availability (e.g. Bennett and Ruben 1975;Lu et al. 2015;Cordero et al. 2017;Gangloff et al. 2019). ...
Life at high altitudes is particularly challenging for ectothermic animals like reptiles and involves the evolution of specialised adaptations to deal with low temperatures, hypoxia and intense UV radiation. As a result, only very few reptile taxa are able to survive above 5,000 m elevation and herpetological observations from these altitudes are exceedingly rare. We report here an exceptional observation of a lizard population (Liolaemus aff. tacnae; Reptilia, Squamata) from the high Andes of Peru. During an ascent of Chachani mountain (6,054 m, 16°11'S, 71°32'W), we observed and documented photographically this species living between 5,000 and 5,400 m above sea level. Following a review of literature, we show that this is the highest known record of a reptile species.
... and highlands (3100 m elevation.) showed no differences in lactate levels, which suggest that they both exhibit similar anaerobic activity patterns (Bennett & Ruben, 1975). Others have reported increased hematological values in highland lizards (Engbretson & Hutchison, 1976;González-Morales et al., 2015;Newlin & Ballinger, 1976;Vinegar & Hillyard, 1972;Weathers & White, 1972). ...
Heloderma horridum is one of the few known venomous lizards in the world. Their populations are in decline due to habitat destruction and capture for the pet trade. In México, many zoos have decided to take care of this species, most of them at altitudes greater than the natural altitudinal distribution. However, we know little about the capacity of the reptiles to face high-altitude environments. The objective of this study was to compare hematological traits of H. horridum in captivity in high and low altitude environments. Our findings show that H. horridum does not respond to hypoxic environments, at least in blood traits, and that the organisms appear to be in homeostasis. Although we cannot know if individual H. horridum housed in high-altitude environments are completely comfortable, it appears hypoxia can be avoid without modifications of blood parameters. We suggest that future work should address changes in metabolic rates and in behavioral aspects to understand how to maintain the health and comfort of the reptiles native to low altitude when they are housed in high-altitude environments.
... Emergence levels of lactate for the two species of Sceloporus we studied are similar to resting values measured in the laboratory for other species of Sceloporus and for other genera of small iguanid lizards (Bennett and Dawson 1972;Bennett and Ruben 1975;Bennett and Gleeson 1976;Bennett, Gleeson, and Gorman 1981;Gleeson 1982). This correspondence of lactate concentrations of lizards under natural conditions with those of lizards observed in the laboratory is gratifying because it suggests that ecological and behavioral inferences can be drawn from laboratory studies of whole-body lactate concentrations of lizards at rest and during exercise. ...
We measured whole-body lactic acid concentrations of two species of iguanid lizards and two species of teiids in the field during routine and experimentally manipulated activities. Lactate concentrations were lowest when lizards first emerged in the morning. Routine foraging behavior produced small increases in lactate concentrations for all species. The teiids (Cnemidophorus exsanguis and C. sonorae) had significantly higher lactate concentrations at emergence and during routine activity than did the iguanids (Sceloporus virgatus and S. jarrovi). For S. virgatus lactate concentration during routine activity was positively correlated with the distance a lizard moved (0-16 m) during the half-hour period of observation before capture. Subduing and swallowing grasshoppers increased lactate concentrations of S. virgatus by an average of .121 mg/g, which was an increase of 40% over the average for routine activity. The magnitude of the increase was positively correlated with the size of the prey (.09-.48 g) but not with the time required (<1-35 min). Territorial defense by S. jarrovi doubled the average lactate concentration from .309 mg/g during routine activity to .653 mg/g after combat. Intensity of combat (measured as bites per minute by the resident lizard) was positively correlated with lactate concentration, but the duration of an agonistic encounter (1-15 min) was not. These data suggest that anaerobic metabolism can be an important pathway of energy input for lizards under natural conditions and support the hypothesis that physiological constraints can limit the behaviors available to a species of lizard.
... The influence of cold and low PO 2 on the metabolism of lizards living at high altitude remains relatively unexplored, since lizards are not abundantly distributed at altitudes above 4000 m [23][24][25][26]. However, some viviparous toad-headed lizards are widely distributed on the Tibetan plateau from altitudes of 2500 m to 4800 m [27]. ...
... The influence of cold and low PO 2 on the metabolism of lizards living at high altitude remains relatively unexplored, since lizards are not abundantly distributed at altitudes above 4000 m [23][24][25][26]. However, some viviparous toad-headed lizards are widely distributed on the Tibetan plateau from altitudes of 2500 m to 4800 m [27]. ...
Metabolic response to high altitude remains poorly explored in reptiles. In the present study, the metabolic characteristics of Phrynocephaluserythrurus (Lacertilia: Agamidae), which inhabits high altitudes (4500 m) and Phrynocephalusprzewalskii (Lacertilia: Agamidae), which inhabits low altitudes, were analysed to explore the metabolic regulatory strategies for lizards living at high-altitude environments. The results indicated that the mitochondrial respiratory rates of P. erythrurus were significantly lower than those of P. przewalskii, and that proton leak accounts for 74~79% of state 4 and 7~8% of state3 in P. erythrurus vs. 43~48% of state 4 and 24~26% of state3 in P. przewalskii. Lactate dehydrogenase (LDH) activity in P. erythrurus was lower than in P. przewalskii, indicating that at high altitude the former does not, relatively, have a greater reliance on anaerobic metabolism. A higher activity related to β-hydroxyacyl coenzyme A dehydrogenase (HOAD) and the HOAD/citrate synthase (CS) ratio suggested there was a possible higher utilization of fat in P. erythrurus. The lower expression of PGC-1α and PPAR-γ in P. erythrurus suggested their expression was not influenced by cold and low PO2 at high altitude. These distinct characteristics of P. erythrurus are considered to be necessary strategies in metabolic regulation for living at high altitude and may effectively compensate for the negative influence of cold and low PO2.
... Closely related reptiles often show differences in aerobic metabolism correlated with their behaviour or thermal experience (e.g. Hailey and Davies, 1986), while anaerobic glycolysis seems to be rather invariable (Bennett and Licht, 1972; Bennett and Ruben, 1975). A possible reason for this lack of variation is that anaerobic glycolysis is most useful in intense exercise such as escaping predators, which usually involves similar behaviour in related animals, although some lactate does accumulate in less intense activities (Pough and Andrews, 1985). ...
1. 1. Whole-body lactate production during intense activity was insensitive to body temperature Tb from 25 to 35°C in the lizard Podarcis taurica. 2. 2. Whole-body lactate removal during recovery was more sensitive to Tb from 15 to 35°C and was two orders of magnitude slower than production. 3. 3. At 30°C a significant oxygen debt persisted for a similar period to elevated lactate. 4. 4. Lizards recovering in refuges at 25 or 35°C emerged later than unexercised lizards, while, at 15°C they emerged after a short period and speeded recovery by basking.
... Neither duration of maximal activity nor amount of lactate formed differs between two populations of S . occidentalis from different elevations (23). Population differences in locomotor performance occur in garter snakes (36, 37). ...
... Neither duration of maximal activity nor amount of lactate formed differs between two populations of S . occidentalis from different elevations (23). Population differences in locomotor performance occur in garter snakes (36, 37). ...
Although studies of geographic variation are relatively common, the vast majority have dealt with morphometric or meristic traits
(13, 120, 297, 327), allozymes (150, 233, 327), or most recently, mitochondrial DNA (9). The relative rarity of studies of geographic variation in physiological traits (see 4 2, 245, 312 for reviews of early studies) is somewhat surprising, considering that a major focus within vertebrate "physiological ecology," "comparative physiology," "environmental physiology," and "biophysical ecology" is the study of adaptation (14,15, 44, 75, 102, 112, 156, 181, 244, 246, 298, 299). Of course, populations may show differentiation on other than large geographic scales, such as "microgeographic"
(150, 188, 213, 233, 290), temporal (164, 165, 213, 253, 278,
Armitage, this volume) or altitudinal; the last has received considerable attention from vertebrate physiologists.
Why are population differences in physiology not studied more often? We suggest four reasons: (i) Physiological measurements require living organisms. Collecting from multiple populations is formidable enough without the: additional difficulty of making physiological measurements. "Expeditionary physiology" is possible, but requisite equipment often is considerably less portable than that needed for sampling tissues or for obtaining study skins or skeletons. Moreover, physiological measurements can be quite time-consuming and require maintaining animals in a healthy state, sometimes for weeks or months, to achieve a common state of acclimation. (ii) Physiologists and evolutionary biologists often share little in the way of training, interests, perspectives, techniques, and study organisms. Population geneticists routinely study Drosophila because they are small and so can be bred in large numbers. Physiological ecologists rarely study Drosophila because they are small and hence intractable for most physiological measurements (but see 63, 137, 158, 166). Nonetheless, some studies of population differentiation in physiological traits have been done. Many involve invertebrates, including Drosophila (42, 63, 137, 158, 223, 233, 245, 312 refs. therein). Another cohort of researchers has come from a background in population genetics, having moved toward physiology in an attempt to discover the adaptive significance of population differences in allozymes (104, 137, 191, 223, 224, 243, refs. therein). (iii) To increase the likelihood of finding differences and exemplary cases of adaptation, comparative physiologists have tended to focus on species expected to display extremes in physiological function (102, 255). Recognizing problems introduced by rampant acclimatization, physiologists may have been inhibited from searching for relatively small population differences. Consequently, the focus on proximate mechanisms of coping with environmental change (i.e. acclimatization) drew more attention than the possibility of genetic differentiation among populations. (iv) "Typological thinking" still exists among many physiologists (102). (The coexistence of typological thinking and ardent adaptationism is somewhat surprising!)
... The selection of the Western Fence Lizard, Sceloporus occidentalis, was primarily made because of the wealth of background information on its energy production (Dawson and Bartholomew, 1956;Francis and Brooks, 1970;Bennett and Ruben, 1975;Bartlett, 1976;Bennett and Gleeson, 1976). Sceloporus oceidentalis spend much of their "active" time basking in the sun and can be observed sitting alert but motionless for periods greater than an hour. ...
The effects of training and captivity on the running performance and selected metabolic and biochemical variables were investigated in the lizardSceloporus occidentalis (Sauria: Iguanidae) in two studies of 6 and 8 weeks duration. Resting and maximal oxygen consumption, lactate concentration of the blood and whole body, and enzyme activities in skeletal muscle were compared among trained and untrained-captive animals taken recently from the field. No significant changes in these metabolic and biochemical measurements occurred as a result of training or of captivity. Distance run to exhaustion and the running endurance of these animals also failed to change in a way attributable to the experimental treatments. Training and captivity appear incapable of altering the maximal rates or the components of metabolic energy production inS. occidentalis. This inflexibility is in contrast to the adaptability and plastic nature of the metabolic capacities exhibited by captive and domestic mammals subjected to varying amounts of chronic activity.
... Accordingly, there is no evidence for increases in glycolytic pathways in rats acclimated to 5500 m (Ou and Leiter, 2004) and in Andean coots (Fulia americana peruviana) native to high altitude (4200 m) (Leon-Velarde et al., 1993) compared to their sea-level counterparts. Similarly, lizards (Sleroporus) that are acclimated to, or residents of, lowland (61 m) and highland (3100 m) habitats show no differences in lactate levels or maximal activity -indicating that their basically anaerobic activity patterns 'preadapt' these animals to colonize high altitudes (Bennett and Ruben, 1975). ...
Vertebrates at high altitude are subjected to hypoxic conditions that challenge aerobic metabolism. O(2) transport from the respiratory surfaces to tissues requires matching between the O(2) loading and unloading tensions and the O(2)-affinity of blood, which is an integrated function of hemoglobin's intrinsic O(2)-affinity and its allosteric interaction with cellular effectors (organic phosphates, protons and chloride). Whereas short-term altitudinal adaptations predominantly involve adjustments in allosteric interactions, long-term, genetically-coded adaptations typically involve changes in the structure of the haemoglobin molecules. The latter commonly comprise substitutions of amino acid residues at the effector binding sites, the heme-protein contacts, or at intersubunit contacts that stabilize either the low-affinity ('Tense') or the high-affinity ('Relaxed') structures of the molecules. Molecular heterogeneity (multiple isoHbs with differentiated oxygenation properties) can further broaden the range of physico-chemical conditions where Hb functions under altitudinal hypoxia. This treatise reviews the molecular and cellular mechanisms that adapt haemoglobin-oxygen affinities in mammals, birds and ectothermic vertebrates at high altitude.
High-altitude organisms exhibit hematological adaptations to augment blood transport of oxygen. One common mechanism is through increased values of blood traits such as erythrocyte count, hematocrit, and hemoglobin concentration. However, a positive relationship between altitude and blood traits is not observed in all high-altitude systems. To understand how organisms adapt to high altitudes, it is important to document physiological patterns related to hypoxia gradients from a greater variety of species. Here, we present an extensive hematological description for three populations of Sceloporus grammicus living at 2,500, 3,400, and 4,300 m. We did not find a linear increase with altitude for any of the blood traits we measured. Instead, we found nonlinear relationships between altitude and the blood traits erythrocyte number, erythrocyte size, hematocrit, and hemoglobin concentration. Erythrocyte number and hematocrit leveled off as altitude increased, whereas hemoglobin concentration and erythrocyte size were highest at intermediate altitude. Additionally, lizards from our three study populations are similar in blood pH, serum electrolytes, glucose, and lactate.Given that the highest-altitude population did not show the highest levels of the variables we measured, we suggest these lizards may be using different adaptations to cope with hypoxia than lizards at low or intermediate altitudes. We discuss future directions that research could take to investigate such potential adaptations.
Four adult male chorus frogs were collected from each of 22 breeding congregations situated along an altitudinal gradient from 1500 m in the piedmont of N-central Colorado to ca. 3000 m in the Front Range of the Rocky Mountains. The concentration of hemoglobin in the blood of these frogs did not vary with altitude of the collecting site, but was positively correlated with body weight of the animals. The equation describing the relationship between blood hemoglobin concentration (Hb) and body weight (w) of chorus frogs is Hb = 7.62 W0.165.
The sections in this article are:
Lactate removal and glycogen replenishment were studied in the lizardSceloporus occidentalis following exhaustion at 35C. Whole body lactate concentrations and oxygen consumption were measured inSceloporus at rest, after 2 min vigorous exercise and at intervals during a 150 min recovery period. Lactate concentrations peaked at 2.2 mg/g (24 mM) after exercise and returned to resting levels after 90 min. Oxygen consumption returned to resting rates after 66 min. In a second set of experiments, glycogen and lactate concentrations of liver, hindlimb and trunk musculature were measured over the same time periods of exercise and recovery. The decrease in muscle glycogen following exercise was identical (mg/g) to the increase in muscle lactate, and the stoichiometric and temporal relationships between lactate removal and glycogen replenishment during the recovery period were also similar. Glycogen replenishment was rapid (within 150 min) and complete in fastedSceloporus. Dietary supplement of carbohydrate during 48 h of recovery led to supercompensation of glycogen stores in the muscle (+66%) and liver (+800%). The changes were similar to the seasonal differences measured inSceloporus from the field.
Resting rates of O2 consumption
[(V)\dot]O2 \dot V_{O_2 }
against
PO2 P_{O_2 }
, exercise endurance times and
[(V)\dot]O2 \dot V_{O_2 }
during recovery from vigorous exercise were measured inSceloporus occidentalis captured near sea level and inS. graciosus captured above 2850 m. Oxygen consumption against
PO2 P_{O_2 }
was also measured inS. occidentalis captured above 2850 m. When
[(V)\dot]O2 \dot V_{O_2 }
was recorded continuously, as ambient
PO2 P_{O_2 }
was slowly reduced from 155 Torr, it became directly dependent upon ambient
PO2 P_{O_2 }
between 110 and 120 Torr. The critical
PO2 P_{O_2 }
for the high altitude lizards was lower than that for the lowland lizards, which enabled the former to maintain relatively higher
[(V)\dot]O2 \dot V_{O_2 }
's when ambient
PO2 P_{O_2 }
was reduced below 120 Torr. The high altitude lizards also had significantly greater endurance when stimulated to exercise at 1600 m (
PO2 P_{O_2 }
[(V)\dot]O2 \dot V_{O_2 }
under hypoxia and the greater endurance roughly parallel a significantly greater maximum
[(V)\dot]O2 \dot V_{O_2 }
in the high altitude lizards. At a simulated altitude of 3600 m (
PO2 P_{O_2 }
[(V)\dot]O2 \dot V_{O_2 }
and rate of recovery of the O2 debt calculated from post active
[(V)\dot]O2 \dot V_{O_2 }
were significantly reduced in the lowland but not the high altitude lizards. The effects of simulated altitude conditions on the lowland but not the mountaine animals indicate adaptations to altitude in these sceloporine lizards. We did not find any consistent relationship between organ/body weight ratios or hematocrit and our measures of
[(V)\dot]O2 \dot V_{O_2 }
endurance or the altitude at which the lizards were captured.
1.1. Blood indices were measured in 27 species of lizard from Chile and Argentina occurring at different altitudes ranging from sea-level up to 4600 m.2.2. Contrary to amphibians, none of the hematological values of these lizards, such as hematocrit, hemoglobin concentration, red cell count, mean cell volume, mean cell hemoglobin and mean cell hemoglobin concentration, were found to be correlated with their altitudinal distribution.3.3. Intrageneric comparison of blood values in Liolaemus lizards (seven highland species living above 3000m and 12 lowland species) showed a similar degree of independence from their altitudinal site of capture or from their upper limit of distribution.4.4. As reported for other vertebrate taxa, an inverse correlation between size and number of red blood cells was also found in the studied reptiles.
Standard and maximal levels of oxygen consumption, and lactate production during burst activity were determined in the Galapagos marine iguana, Amblyrhynchus cristatus. This semiaquatic lizard sustains vigorous activity at relatively low body temperatures during underwater feeding (<25°C). Intense activity can be sustained only briefly, 90% of the response occurring within 2 min. The amount of activity elicited by stimulation is independent of body temperature. Standard oxygen consumption has a strong temperature dependence (Q10=2.9) over the range studied (24.8-41.6°C). Oxygen consumption during activity is maximal at 30-40°C. Aerobic scope is maximal at 35°C, the basking temperature of the species. The rate of increase of oxygen consumption during activity is temperature dependent. High concentrations of lactic acid appear in the blood after maximal activity. An estimated 97-99% of the carbohydrate catabolized during maximal activity enters anaerobic pathways; 71-92% of the ATP produced is derived anaerobically. Despite its atypical thermal regime and energetically demanding mode of feeding, Amblyrhynchus displays a metabolic pattern similar to that of more terrestrial species in the same family (Iguanidae).
Histochemical studies on the activities of alpha-GPDH, LDH, SDH and MDH in liver have been carried out during the different phases of tail regeneration in the lizard, Hemidactylus flaviviridis. Changes in the metabolic activities of the liver during regeneration indicate that during the initial phases of regeneration (namely, wound healing and blastema formation) the energetics of the hepatic tissue are anaerobically oriented, but later (i.e. during the growth phase) the TCA cycle appears to be predominant.
Oxygen consumption and lactate production above resting levels, and selected body temperatures, were measured in the lizard Agama stellio. Active and resting VO2 have low Q10 (1.7, 2.0) in the activity range 30-37 degrees C and higher Q10 (3.8, 4.0) below this. A correlation was found between published resting and active VO2 of lizards, and between VO2 and lifestyle. Four types were recognized, in order of increasing VO2: (a) fossorial; (b) sit-and-wait (including A. stellio); (c) cruising, and (d) widely foraging. A. stellio has a high capacity for lactate production, correlated with its short but rapid bursts of activity. This accounts for 80-90% of the energy used during 30 sec maximal activity.
1. Lactate production and physical performance during intense activity were measured in Lacerta vivipara, Podarcis muralis and Podarcis hispanica, temperate lizards from progressively lower latitudes. 2. Rates of lactate production during the initial 30 sec of bursts of activity (means = 1.75 mg g-1) and their Q10S (means = 1.36) are similar to previously obtained values for lizards. 3. Maximal anaerobic scope at activity body temperatures is lowest in Lacerta vivipara, which correlates with a tendency to less strenuous behaviour than that of the Podarcis species and may reflect the need for energy economy. 4. Q10S of maximal performance are lower in Lacerta vivipara and Podarcis muralis than Podarcis hispanica, a difference having no demonstrated metabolic basis but which is thermally adaptive for these cooler climate species.
1.1. Oxygen affinity of blood of five lizard species was measured at 25, 35 and 40°C and pCO2's of 38 and 76 mm Hg.2.2. At its activity temperature each species had a P50 of 68–72 mm Hg. Oxygen affinity was also related to body size.3.3. There was a seasonal shift in oxygen affinity in Dipsosaurus dorsalis.4.4. There was no difference in oxygen affinity of blood of Sceloporus occidentalis from sea level and from 6000 ft.5.5. There was no correlation between sensitivity to CO2 and fossorial habits.6.6. An anguid (Gerrhonotus multicarinatus) showed less sensitivity to changes in temperature and pCO2 than iguanids.
The oxygen capacity of bloods from nineteen species of lizards representing eight genera and three families were determined. Mean values obtained for these species ranged from 7.7 to 12.6 vol %. Oxygen capacity was found to be uncorrelated with the extent of heat resistance characterizing the various species. Likewise no correlation was evident between oxygen capacity and the altitude at which the lizards had existed prior to study, whether the analysis was concerned with populations within a single species (Sceloporus jarrovi), species within a single genus (Sceloporus), or with the entire array of species studied. The values reported for this study fall within the general range previously established for reptiles by other authors. The upper portion of this range overlaps the lower portion of that for oxygen capacities of birds and mammals. This overlap suggests that the demands upon respiratory transport created with the intensification of metabolism in the evolution of homeothermy have been met primarily through such means as augmentation of cardiac output rather than through any major increase in the transport capacities of the blood.
Hemoglobin and hematocrit values, and erythrocyte shapes and sizes were compared in the three subspecies of the side-blotched lizard, Uta stansburiana. Significantly higher hemoglobin values and corresponding hematocrits were found for the Colorado population, U. s. stansburiana. The lowest values were found in the Arizona-Mexico population, U. s. stejnegeri, while intermediate values were obtained from the California population, U. s. hesperis. Erythrocyte measurements were similar in all the populations sampled. The Uta blood values are within the ranges for other iguanid lizards. Variation in hemoglobin parallels altitudinal differences in the populations.
1. 1. In the iguana, standard metabolism increased with temperature with a Q10 of 2·24. Metabolic scope was greatest at 32°C, decreasing above and below this temperature. Resting and post-activity heart rates varied with temperatures with Q10's of 2·0.2 and 1·84, respectively. 2. 2. Energy produced anaerobically by the production of lactic acid was shown to provide at least three-fourths of the total energy used during activity. 3. 3. Glycogen reserves in the muscle were adequate to account for the production of lactate during activity. 4. 4. The rapidity with which an iguana could remove an accumulated oxygen debt was temperature-dependent, and appeared to be greatest at the temperature where the metabolic scope was greatest.
in o q g e n consumption during activity at the various temperatures between 25'and 45'C reprcscnted 7-to 17-fold of corresponding resting levels. 3.Lactate content of resting Dipsosaurus is independent of temperature and avenges 025 mg/g body weight. Xaximal lactate production during the activity induced by a 2-min period of electrical sti~nulation occurred a t 40掳 C (Fig. 3). The capacity of Dipsosaurus for anaerobic metabolism exceeds that of other lizards investigated, both in its magnitude and in its thermal dependence. 4.The total amouuL of euci-gy mobilized by Dip8osaurus in the nctivity induced by a Zmin period of electrical stimulation \\-as maximal a t 40掳 C (Fig. 4). An-aerobiosis accounts for a minimum of 58-S3?A of the total energetic expenditure. 5.It It. postulated that the principal physiological adaptations to preferred thermal levels in reptiles have in~olved energy mobilization during and rapid recovery after activity.
A summary of body temperatures of reptiles has been made on the basis of some 9000 body, air, soil, and water temperatures taken or recorded in the literature for 161 species of reptiles. The range and mean body temperature for the various groups of reptiles are: turtles: 8.0 to 37.8, mean: 28.4; Sphenodon: 6.2 to 18.0, mean: 12.5; American alligator 26-37, mean: between 32 and 35; snakes: 9.0 to 38.0, mean: 25.6, lizards: 11.0 to 46.4, mean 29.1. There are often specific, generic, and family differences in thermal tolerances and preferences, though some reptiles show wide ranges of thermal tolerance with no "preferred" body temperature, while others have narrow activity ranges and preferences. With an increase in thermal preference, there is usually an associated increase in the critical thermal maximum. Forms with low thermal preference usually have low critical minima and are usually found in colder areas and in colder seasons than those with high thermal preferences. In terms of their thermoregulatory behavior, reptiles can be grouped into: burrowing forms; aquatic forms not selecting temperatures; aquatic forms selecting temperatures; aquatic forms which bask at surface or on shore; nocturnal thigmothermic forms; nocturnal thigmothermic forms that occasionally bask; diurnal, primarily thigmothermic forms that occasionally bask and become crepuscular or nocturnal as hot seasons develop; diurnal non-baskers; diurnal limited baskers; and true heliothermic baskers. Thermoregulation in reptiles is both behavioral (emergence, retreat, selection of temperatures, basking, orientation, postural changes, etc.) and physiological (evaporative cooling, vasomotor responses affecting rates of heating and cooling, and limited heat production in brooding female Indian pythons).
1.
Oxygen consumption and lactate content of the lizardDipsosaurus
dorsalis were determined under standard conditions and for a bout of maximal activity induced by a 2-min period of electrical stimulation. Observations were made between 25 and 45 C.
2.
Maximal aerobic scope, 2.27 cm3 O2/(g hr), occurred at 40 C (Figs. 2, 4). The increase in oxygen consumption during activity at the various temperatures between 25 and 45 C represented 7- to 17-fold of corresponding resting levels.
3.
Lactate content of restingDipsosaurus is independent of temperature and averages 0.25 mg/g body weight. Maximal lactate production during the activity induced by a 2-min period of electrical stimulation occurred at 40 C (Fig. 3). The capacity ofDipsosaurus for anaerobic metabolism exceeds that of other lizards investigated, both in its magnitude and in its thermal dependence.
4.
The total amount of energy mobilized byDipsosaurus in the activity induced by a 2-min period of electrical stimulation was maximal at 40 C (Fig. 4). Anaerobiosis accounts for a minimum of 58–83% of the total energetic expenditure.
5.
It is postulated that the principal physiological adaptations to preferred thermal levels in reptiles have involved energy mobilization during and rapid recovery after activity.
A new technique developed for the determination of total lactate production in small animals was used to evaluate the role of anaerobiosis during activity at different temperatures in lizards. Measurements on six species of small lizards indicate little interspecific variation or thermal effect in resting lactate levels (0.35 mg lactate/g body weight) or maximal lactate levels achieved at exhaustion (1.4 mg lactate/g). Normally activeAnolis in captivity had a lactate content of 0.5 mg lactate/g. Rates of lactate formation were most rapid during the first 30 sec of activity and had a low thermal dependence (Q10=1.1–1.3 above 20 C). The lactate formed during activity persists for long periods; e.g., for 30 to 60 min between 20 and 37 C inAnolis carolinensis (Fig. 1). Recovery rate generally increases with temperature. Muscle lactate concentrations peak at the end of activity, but liver and blood lactate are not maximal until 10 and 30 min, respectively, after activity (Fig. 2). The decrease in the blood lactate is shown to be a poor estimator of total recovery. An estimated 80–90% of the total energy utilized during initial vigorous activity comes from anaerobic sources. Because of its low thermal dependence, anaerobiosis permits high levels of activity in lizards at all body temperatures without requiring high levels of aerobic resting metabolism.
1.1. Strictly aerobic metabolism in Iguana iguana during walking was highly temperature-dependent, as was the maximum rate of walking without the incurrence of an oxygen debt. The absolute maximum rate of walking aerobically correlated with the temperature of the maximum metabolic scope.2.2. The energetic cost of walking did not increase with temperature, but rose curvilinearly with speed, the efficiency being greatest at the higher rates of walking.3.3. Diving iguanas could remain submerged for up to hr, tolerating blood lactate levels as high as 320 mg per cent.4.4. Blood pH dropped as low as 6·9 during a dive.
Thesis (Ph. D.)--University of California, Riverside. Includes bibliographical references (leaves 54-57).
1.1. Red blood cell counts and hemoglobin content were determined for blood samples from Sceloporus jarrovi collected at altitudes of 5100, 6000 and 8600 ft.2.2. Oxygen capacity was determined for blood samples from Sceloporusoccidentalis collected at altitudes of 500, 4000, 6000 and 7000 ft.3.3. Oxygen-binding parameters of blood from both species showed significant differences for populations from 6000 ft and above as compared with lower altitude populations. These differences are attributed to the more restricted annual heat budget of the higher altitude lizards.
1.1. Desert iguanas acclimated to a simulated altitude of 5500 m (18,000 ft) for 4 weeks had hematocrits and hemoglobin concentrations which averaged 22 and 19 per cent higher, respectively, than values for sea level controls.2.2. Erythrocyte count was increased 21 per cent by acclimation to altitude.3.3. Exposure to chronic hypoxia had no effect on mean corpuscular hemoglobin, heart-body weight ratio or total body water content.
Seasonal and elevational compari-sons of oxygen consumption rates in the lizard Scelo-porus occidentalis b955) Effects of hypoxia rBENNETT Aerobic and anaerobic metabolism during activity in the lizard Dipsosaurus dorsalis
- P N P D Riverside
- Parker
B A R T L ~ P. N. (1970) Seasonal and elevational compari-sons of oxygen consumption rates in the lizard Scelo-porus occidentalis. Ph.D. dissertation, University of California, Riverside. P. D. & PARKER M. b955) Effects of hypoxia rBENNETT A. F. & DAWSON W. R. (1972) Aerobic and anaerobic metabolism during activity in the lizard Dipsosaurus dorsalis. J. comp. Physiol. 81, 289-299
Hematologicat observations on populations of the lizard Seeloporus occidentalis from sea level and altitude. Herpetolo[ztca 28, 172-175 Key Word Index--Activity; altitude; anaerobiosis; exercise; lactic acid; lizard; reptile
- W W Weaa
- F N White
WEAa'r~RS W. W. & WHITE F. N. (1972) Hematologicat observations on populations of the lizard Seeloporus occidentalis from sea level and altitude. Herpetolo[ztca 28, 172-175 Key Word Index--Activity; altitude; anaerobiosis; exercise; lactic acid; lizard; reptile; Sceloporus.
Anerobic metabolism during activity in lizards
- A F B~nnet
- P L~c~rr
B~NNeT'r A. F. & L~c~rr P. (1972) Anerobic metabolism during activity in lizards. 3". eomp. Physiol. 81, 277-288.
Aerobic and anaerobic meta-bolism during activity in the turtles Pseudemys scripta and Terrapene ornata Intraspecific comparisons of the blood properties of the side-blotched lizard, Uta stansburiana
- Gatten R E Jr
GATTEN R. E., JR. (1973) Aerobic and anaerobic meta-bolism during activity in the turtles Pseudemys scripta and Terrapene ornata. :Ph.D. dissertation, University of Michigan, Ann Arbor. HADLEY N. F. & BURNS T. A. (1968) Intraspecific comparisons of the blood properties of the side-blotched lizard, Uta stansburiana. Copeia 1968, 737-740.
Body temperatures of reptiles Oxygen capacity of lizard bloods
- B H Bratrstrom
- R Dawson
BRATrSTROM B. H. (1965) Body temperatures of reptiles. Am. Midl. Nat. 73, 376-422 DAWSON W R. & Por-~soN T. L. (1962) Oxygen capacity of lizard bloods. Am. Mtdl. Nat. 68, 154-164.
The effects of altitude on oxygen-binding parameters of the blood of the iguanid lizards, Sceloporus jarrovi and Sceloporus occidentalis
- C Stebbins R
STEBBINS R. C. (1954) Amphibians and Reptiles of Western
North America, pp. 240-244. McGraw-Hill, New York.
VINEGAR A. & HILLYARD S. D. (1972) The effects of
altitude on oxygen-binding parameters of the blood of
the iguanid lizards, Sceloporus jarrovi and Sceloporus
occidentalis. Comp. Biochem. Physiol. 43A, 317-320.
Effects of hypoxia upon the box turtle Seasonal and elevational comparisons of oxygen consumption rates in the lizard Sceloporus occidentalis
- Altland P D Parker M
ALTLAND P. D. & PARKER M. b955) Effects of hypoxia
upon the box turtle. Am. J. Physiol. 180,421427.
B A R T L ~
P. N. (1970) Seasonal and elevational comparisons of oxygen consumption rates in the lizard Sceloporus occidentalis. Ph.D. dissertation, University of
California, Riverside.