Oxygen Consumption in the Lizard Uta Stansburiana

Roberts, L. A.

doi:10.2307/1936532

Cited by 72 publications

(23 citation statements)

References 16 publications

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“…These differences probably result from circadian metabolic fluctuations, which can produce decrements as great as 50% in lizards (Roberts, 1968;Bennett, unpublished data). The low thermal dependence of resting metabolism of Dipsosaurus from 35-40~ C (Fig.…”

Section: Discussionmentioning

confidence: 99%

Aerobic and anaerobic metabolism during activity in the lizardDipsosaurus dorsalis

1972

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Summary. 1. Oxygen consumption and lactate content of the lizard Dipsosaurus 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 cm a 02/(g• occurred at 40~ (Figs. 2, 4). The increase in oxygen consumption during activity at the various temperatures between 25 ~ and 45~ represented 7-to 17-fold of corresponding resting levels.3. Lactate content of resting Dipsosaurus is independent of temperature and averages 0.25 mg/g body weight. Maximal lactate production during the activity induced by a 2-rain period of electrical stimulation occurred at 40~ (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 amount of energy mobilized by Dipsosaurus in the activity induced by a 2-min period of electrical stimulation was maximal at 40~ (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.

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Section: Discussionmentioning

confidence: 99%

Aerobic and anaerobic metabolism during activity in the lizardDipsosaurus dorsalis

1972

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“…It is well known that metabolic rate cycles dramatically over the course of the day during the active season in lizards (Kramer 1934;Roberts 1968;Songdahl and Hutchison 1972;Mautz and Case 1974;Rismiller and Heldmaier 1991;Klein et al 2006). While lizards also demonstrate circadian rhythms in thermal preference and locomotor activity, metabolic rates in many still show circadian cycles even when temperature and activity remain constant (Kramer 1934;Roberts 1968;Rismiller and Heldmaier 1991).…”

Section: Seasonal Changes In Daily Metabolic Patterns Of Tegu Lizardsmentioning

confidence: 99%

“…While lizards also demonstrate circadian rhythms in thermal preference and locomotor activity, metabolic rates in many still show circadian cycles even when temperature and activity remain constant (Kramer 1934;Roberts 1968;Rismiller and Heldmaier 1991). Tegu lizards appear to be no exception (Klein et al 2006).…”

Section: Seasonal Changes In Daily Metabolic Patterns Of Tegu Lizardsmentioning

confidence: 99%

“…While some species show metabolic acclimation/acclimatization to compensate for seasonal changes in temperature (Roberts 1968), other species downregulate physiological and biochemical processes and become dormant. The metabolic rate of tegus, like other lizards in this latter group, measured at a constant temperature falls progressively from summer to winter, and the magnitude of this fall is proportionately less at lower temperatures (Weigmann 1932;Moberly 1963;Mayhew 1965;Gelineo 1967;Bennett and Dawson 1976;Abe 1983Abe , 1993Abe , 1995de Souza et al 2004).…”

Section: Seasonal Changes In Daily Metabolic Patterns Of Tegu Lizardsmentioning

confidence: 99%

“…Much of this variation, however, is due to diel variations in body temperature and activity (Kramer 1934;Roberts 1968;Songdahl and Hutchison 1972;Mautz and Case 1974;Bennett and Dawson 1976;Rismiller and Heldmaier 1991;Klein et al 2006). However, metabolic rates may still show circadian cycles even when temperature and activity remain constant, Figure 4.…”

Section: Circadian Rhythms In the Rate Of Oxygen Consumptionmentioning

confidence: 99%

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Seasonal Changes in Daily Metabolic Patterns of Tegu Lizards (Tupinambis merianae) Placed in the Cold (17°C) and Dark

Milsom

Andrade²,

Brito³

et al. 2008

Physiological and Biochemical Zoology

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. ABSTRACTOxygen consumption rate was measured continuously in young tegu lizards Tupinambis merianae exposed to 4 d at 25ЊC followed by 7-10 d at 17ЊC in constant dark at five different times of the year. Under these conditions, circadian rhythms in the rate of oxygen consumption persisted for anywhere from 1 d to the entire 2 wk in different individuals in all seasons except the winter. We also saw a progressive decline in standard oxygen consumption rate (at highly variable rates in different individuals) to a very low rate that was seasonally independent (ranging from to mL kg Ϫ1 h Ϫ1 across seasons). 19.1 ‫ע‬ 6.2 27.7 ‫ע‬ 0.2 Although this degree of reduction appeared to take longer to invoke when starting from higher metabolic rates, tegu lizards reduced their metabolism to the low rates seen in winter dormancy at all times of the year when given sufficient time in the cold and dark. In the spring and summer, tegus reduced their standard metabolic rate (SMR) by 80%-90% over the experimental run, but only roughly 20%-30% of the total fall was due to the reduction in temperature; 70%-80% of the total fall occurred at constant temperature. By autumn, when the starting SMR on the first night at 25ЊC was already reduced by 59%-81% (early and late autumn, respectively) from peak summer values, virtually all of the fall (63%-83%) in metabolism was due to the reduction in temperature. This suggests that the temperature-independent reduction of metabolism was already in place by autumn before the tegus had entered winter dormancy.

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