Hibernation in the horned lizard, Phrynosoma m'calli

Mayhew, Wilbur W.

doi:10.1016/0010-406x(65)90167-2

Cited by 84 publications

(31 citation statements)

References 31 publications

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“…By autumn, the starting SMR on the first night at 25ЊC was already reduced by 59%-81% (early and late autumn, respectively) from peak summer values, and now virtually all of the fall (63%-83%) in metabolism over the experimental run was due to the reduction in temperature; only 17%-37% of the total fall occurred at constant temperature. The observation that, by autumn, the temperature-independent reduction of metabolism was already in place is consistent with several previous studies (Mayhew 1965;Abe 1983Abe , 1993Abe , 1995de Souza et al 2004;Toledo et al 2008). However, our data further suggest that a metabolic decrease equivalent to that induced by seasonal change can also occur in spring and summer if animals are confined in the dark.…”

Section: Is This Metabolic Suppression?supporting

confidence: 93%

“…In Phrynosoma, dormancy was reported to develop in response to decreased photoperiod, while metabolic depression was largely dependent on falls in temperature (Mayhew 1965). This was also true for our autumn animals.…”

Section: Is This Metabolic Suppression?supporting

confidence: 73%

“…4). Many studies have documented such seasonal declines in oxygen consumption rate at constant temperature (Moberly 1963;Mayhew 1965;Rismiller and Heldmaier 1991;Zari 1999), and several studies have documented this trend specifically in tegu lizards at 17ЊC (Abe 1983(Abe , 1993(Abe , 1995de Souza et al 2004;Fig. 6).…”

Section: Constant Dark At 17њcmentioning

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). As a consequence, the effect of temperature on metabolic rate (the Q 10 effect) is progressively reduced from summer to winter, and thus the metabolic rate of dormant lizards is much less temperature dependent (Abe 1983(Abe , 1993(Abe , 1995de Souza et al 2004).…”

Section: Seasonal Changes In Daily Metabolic Patterns Of Tegu Lizardsmentioning

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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Section: Is This Metabolic Suppression?supporting

confidence: 93%

Section: Is This Metabolic Suppression?supporting

confidence: 73%

Section: Constant Dark At 17њcmentioning

confidence: 99%

Section: Seasonal Changes In Daily Metabolic Patterns Of Tegu Lizardsmentioning

confidence: 99%

See 2 more Smart Citations

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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“…Temperate reptiles, including red-eared sliders, often undergo active metabolic suppression, when metabolism ), breaths per episode, instantaneous breathing frequency (breaths min -1 in an episode) and percentage time spent in apnea of turtles breathing a hypoxic-hypercapnic gas (H-H) and air (Reyes and Milsom, 2009) and exposed to seasonal conditions (see Table 1 cannot be sustained under winter environmental conditions (Mayhew, 1965;Bennett and Dawson, 1976;Gregory, 1982;Ultsch, 1989;Zari, 1999). Toads and bullfrogs also show reduced metabolism and a lower ventilatory response to hypoxia [toads (Bicego-Nahas et al, 2001)] and hypercapnia [bullfrogs (BicegoNahas and Branco, 1999)] in the winter.…”

Section: Seasonal Rhythms In Ventilatory Sensitivitymentioning

confidence: 99%

Daily and seasonal rhythms in the respiratory sensitivity of red-eared sliders (Trachemys scripta elegans)

Reyes

Milsom

2009

Journal of Experimental Biology

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SUMMARYThe purpose of the present study was to determine whether the daily and seasonal changes in ventilation and breathing pattern previously documented in red-eared sliders resulted solely from daily and seasonal oscillations in metabolism or also from changes in chemoreflex sensitivity. Turtles were exposed to natural environmental conditions over a one year period. In each season, oxygen consumption, ventilation and breathing pattern were measured continuously for 24 h while turtles were breathing air and for 24 h while they were breathing a hypoxic-hypercapnic gas mixture (H-H). We found that oxygen consumption was reduced equally during the day and night under H-H in all seasons except spring. Ventilation was stimulated by H-H but the magnitude of the response was always less at night. On average, it was also less in the winter and greater in the reproductive season. The data indicate that the day-night differences in ventilation and breathing pattern seen previously resulted from daily changes in chemoreflex sensitivity whereas the seasonal changes were strictly due to changes in metabolism. Regardless of mechanism, the changes resulted in longer apneas at night and in the winter at any given level of total ventilation, facilitating longer submergence at times of the day and year when turtles are most vulnerable.

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Obligatory hibernation for completion of vitellogenesis in the lizard Lacerta vivipara J.

Gavaud¹

1983

J. Exp. Zool.

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Hibernation in Lacerta uiuipara from Massif Central (1,000-1,200 m) lasts 6-7 months and is immediately followed by vitellogenesis, gestation, and parturition within a short period of time (May-August). Suppression of hibernation by maintaining females in active life (food and high temperatures) inhibits the resumption of ovarian growth in spring; i.e., the reproductive system remains indefinitely refractory to high temperatures. In order for vitellogenesis to be completed, females need to hibernate below 8-10 "C with sufficient duration ("amount of cold" threshold). The prolongation of the exposure of females to low temperature beyond the minimal stay gradually improves their ability to complete vitellogenesis: The number of females responding increases, and the heat requirement for the onset of ovarian growth decreases.

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Hibernation in the horned lizard, Phrynosoma m'calli

Cited by 84 publications

References 31 publications

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

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

Daily and seasonal rhythms in the respiratory sensitivity of red-eared sliders (Trachemys scripta elegans)

Obligatory hibernation for completion of vitellogenesis in the lizard Lacerta vivipara J.

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