共查询到20条相似文献,搜索用时 62 毫秒
1.
C. R. Brown G. G. Foster 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(7):658-664
Summary The effect of clustering behaviour on metabolism, body temperature, thermal conductance and evaporative water loss was investigated in speckled mousebirds at temperatures between 5 and 36°C. Within the thermal neutral zone (approximately 30–35 °C) basal metabolic rate of clusters of two birds (32.5 J·g-1·h-1) and four birds (28.5 J·g-1·h-1) was significantly lower by about 11% and 22%, respectively, than that of individuals (36.4 J·g-1·h-1). Similarly, below the lower critical temperature, the metabolism of clusters of two and four birds was about 14% and 31% lower, respectively, than for individual birds as a result of significantly lower total thermal conductance in clustered birds. Body temperature ranged from about 36 to 41°C and was positively correlated with ambient temperature in both individuals and clusters, but was less variable in clusters. Total evaporative water loss was similar in individuals and clusters and averaged 5–6% of body weight per day below 30°C in individuals and below 25°C in clusters. Above these temperatures total evaporative water loss increased and mousebirds could dissipate between 80 and 90% of their metabolic heat production at ambient temperatures between 36 and 39°C. Mousebirds not only clustered to sleep between sunset and sunrise but were also observed to cluster during the day, even at high ambient temperature. Whereas clustering at night and during cold, wet weather serves a thermoregulatory function, in that it allows the brrds to maintain body temperature at a reduced metabolic cost, clustering during the day is probably related to maintenance of social bonds within the flock.Abbreviations BMR
basal metabolic rate
- bw
body weight
-
C
totab
total thermal conductance
- EWI
evaporative water loss
-
M
metabolism
- RH
relative humidity
-
T
a
ambient temperature
-
T
b
body temperature
-
T
ch
chamber temperature
-
T
cl
cluster temperature
- TEWL
total evaporative water loss
- LCT
lower critical temperature
- TNZ
thermal neutral zone 相似文献
2.
G. C. Whittow T. N. Pettit R. A. Ackerman C. V. Paganelli 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1987,157(5):607-614
Summary At low air temperatures (2.3–13.9°C), Wedge-tailed Shearwaters (Puffinus pacificus) shivered and their oxygen consumption increased to as much as 283% of the mean value (0.77 ml O2/g·h) within the thermoneutral zone of air temperature (23–34°C). The minimal thermal conductance of the tissues and plumage was similar to the value predicted from the body mass (320.5 g). The oxygen consumption of the birds within their thermoneutral zone was lower than predictions based on body mass. At elevated air temperatures, the shearwaters panted at respiratory frequencies as high as 260 respirations/min; maximal respiratory frequencies were not invoked until the birds had become hyperthermic. During exposure to a hot environment, the oxygen consumption of the birds increased and in most instances the shearwaters were not able to lose heat equivalent to their concurrent metabolic heat production.Symbols and abbreviations
BMR
basal metabolic rate
-
C
total
total thermal conductance
-
f
respiratory frequency
-
TEWL
total evaporative water loss
-
T
st
stomach temperature
-
T
re
rectal temperature 相似文献
3.
A. Haim A. Rubal J. Harari 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(7):602-607
Thermoregulatory abilities, which may play a role in physiological adaptations, were compared between two field mouse species (Apodemus mystacinus and A. hermonensis) from Mount Hermon. While A. hermonensis is common at altitudes above 2100 m, A. mystacinus is common at 1650 m. The following variables were compared in mice acclimated to an ambient temperature of 24°C with a photoperiod of 12L:12D, body temperature during exposure to 4°C for 6 h, O2 consumption and body temperature at various ambient temperature, non-shivering thermogenesis measured as a response to a noradrenaline injection, and the daily rhythm of body temperature. Both species could regulate their body temperature at ambient temperatures between 6 and 34°C. The thermoneutral zone for A. mystacinus lies between 28 and 32°C, while for A. hermonensis a thermoneutral point is noted at 28°C. Both species increased O2 consumption and body temperature as a response to noradrenalin. However, maximal VO
2 consumption as an response to noradrenaline and non-shivering thermogenesis capacity were higher in A. mystacinus, even though A. hermonensis is half the size of A. mystacinus. The body temperature rhythm in A. hermonensis has a clear daily pattern, while A. mystacinus can be considered arhythmic. The results suggest that A. hermonensis is adapted to its environment by an increase in resting metabolic rate but also depends on behavioural thermoregulation. A. mystacinus depends more on an increased non-shivering thermogenesis capacity.Abbreviations C
thermal conductance
- NA
noradrenaline
- NST
non-shivering thermogenesis
- OTC
overall thermal conductance
- RMR
resting metabolic rate
- STPD
standard temperature and pressure dry
-
T
a
ambient temperature
-
T
b
body temperature
-
I
b
Min minimal T
b
, measured before NA iniection
-
T
b
NA
maximal
-
T
b
as a response to NA injection
-
T
lc
lower critical point
- TNP
thermoneutral point
- TNZ
thermoneutral zone
-
VO2
O2 consumption
-
VO2 Min
minimal VO2 measured before NA injection
-
VO2NA
maximal VO2, as a response to NA injection 相似文献
4.
J. T. Pearson 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1994,164(6):415-424
Oxygen consumption rates were measured in chicks (0–7 days of age), and in non-brooding and brooding adults. Brooded chicks maintained a constant oxygen consumption rate at a chamber ambient temperature of 10–35°C (0–5 days of age: 2.95ml O2·g-1·h-1 and 6–17 days of age: 5.80 ml O2·g-1·h-1) while unbrooded chicks increased oxygen consumption rate at ambient temperature below 30°C to double the brooded oxygen consumption rate at 25 and 15°C for chicks < 5 days of age and>5 days of age, respectively. The massspecific oxygen consumption rate of breeding male and females (non-brooding) were significantly elevated within the thermoneutral zone thermal neutral zone (28–35°C) in comparison to non-breeding adults. Below the thermal neutral zone, oxygen consumption rate was not significantly different. The elevation in oxygen consumption rate of breeding quail was not correlated with the presence of broodpatches, which developed only in females, but is a seasonal adjustment in metabolism. Male and females that actively brooded one to five chicks had significantly higher oxygen consumption rate than non-brooding quail at ambient temperature below 30°C. Brooding oxygen consumption rate was constant during day and night, indicating a temporary suppression of the circadian rhythm of metabolism. Brooding oxygen consumption rate increased significantly with brood number, but neither adult body mass nor adult sex were significant factors in the relationship between brooding oxygen consumption rate and ambient temperature. The proportion of daylight hours that chicks were brooded by parents was negatively correlated with ambient temperature. After chicks were 5 days old brooding time was reduced but brooding oxygen consumption rate was unchanged. Heat from the brooding parent appeared to originate mainly from the apteria under the wings and legs rather than the broodpatch. The parental heat contribution to chick temperature regulation below the chicks' thermal neutral zone is achieved by increasing parental thermal conductance by a feedback control similar to that suggested for the control of egg temperature via the brood-patch. It is concluded that the brooding period is an energetic burden to parent quail, and the magnitude of the cost increases directly with brood number and inversely with ambient temperature during this period. The oxygen consumption rate of brooding parents was 5.80–6.90 ml O2·g-1·h-1 (ambient temperature 10–15°C) at night and up to 5.10 ml O2·g-1·h-1 (ambient temperature 18°C) during the day, which are 100 and 40% higher than non-brooding birds, respectively.Abbreviations bm
body mass
- SMR
standard metabolic rate
-
T
a
ambient temperature
-
T
b
body temperature
- I/O2
oxygen consumption rate
-
C
wet
wet thermal conductance
- TNZ
thermal neutral zone
- ANOVA
analysis of variance
- ANCOVA
analysis of covariance 相似文献
5.
Willis CK Turbill C Geiser F 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2005,175(7):479-486
Data on thermal energetics for vespertilionid bats are under-represented in the literature relative to their abundance, as
are data for bats of very small body mass. Therefore, we studied torpor use and thermal energetics in one of the smallest
(4 g) Australian vespertilionids, Vespadelus vulturnus. We used open-flow respirometry to quantify temporal patterns of torpor use, upper and lower critical temperatures (T
uc and T
lc) of the thermoneutral zone (TNZ), basal metabolic rate (BMR), resting metabolic rate (RMR), torpid metabolic rate (TMR),
and wet thermal conductance (C
wet) over a range of ambient temperatures (T
a). We also measured body temperature (T
b) during torpor and normothermia. Bats showed a high proclivity for torpor and typically aroused only for brief periods. The
TNZ ranged from 27.6°C to 33.3°C. Within the TNZ T
b was 33.3±0.4°C and BMR was 1.02±0.29 mlO2 g−1 h−1 (5.60±1.65 mW g−1) at a mean body mass of 4.0±0.69 g, which is 55 % of that predicted for a 4 g bat. Minimum TMR of torpid bats was 0.014±0.006 mlO2 g−1 h−1 (0.079±0.032 mW g−1) at T
a=4.6±0.4°C and T
b=7.5±1.9. T
lc and C
wet of normothermic bats were both lower than that predicted for a 4 g bat, which indicates that V. vulturnus is adapted to minimising heat loss at low T
a. Our findings support the hypothesis that vespertilionid bats have evolved energy-conserving physiological traits, such as
low BMR and proclivity for torpor. 相似文献
6.
P. I. Webb G. C. Hays J. R. Speakman P. A. Racey 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(2):144-147
Summary Mean oxygen consumption and simultaneous ventilation frequency of nine non-reproductive brown long-eared bats (body mass 8.53–13.33 g) were measured on 159 occasions. Ambient (chamber) temperature at which the measurements were made ranged from 10.8 to 41.1°C. Apneic ventilation occurred in 22 of the 59 measurements made when mean oxygen consumption was less than 0.5 ml·min-1. No records of apneic ventilation were obtained when it was over 0.5 ml·min-1. The relationship between ventilation frequency and mean oxygen consumption depended on whether ventilation was apneic or non-apneic. When ventilation was non-apneic the relationship was positive and log-linear. When ventilation was apneic the relationship was log-log. Within the thermoneutral zone ventilation frequency was not significantly different from that predicted from allometric equations for a terrestrial mammal of equivalent body mass, but was significantly greater than that predicted for a bird. A reduction in the amount of oxygen consumed per breath occurred at ambient temperatures above the upper critical temperature (39°C).Abbreviations RH
relative humidity
-
T
a
chamber temperature
- vf
ventilation frequency
-
VO2
oxygen consumption 相似文献
7.
Roland Prinzinger 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1988,157(6):801-806
Summary Breathing frequencyF
r of resting blue-naped mousebirdsUrocolius macrourus lies between 50–70 per min and correlates directly with ambient temperatureT
a and energy metabolismM. The nocturnal mean energy intake per breath varies between 5.6–17.7 mJ/g. At highT
a the birds show gular fluttering with a relatively constantF
r of about 460 min–1.M shows a constant absolute day-night difference of 25 J/g·h; the relative differences areT
a-dependent between 36–168% (lower values at lowerT
a). Thermal conductance is 2.10–2.15 J/g·h·°C (predicted 2.67), indicating a good insulation. Basal metabolic rate BMR is reduced by 63% compared to predicted values. At aT
a-range of +8–36 °C the birds are normothermic. Below this range nocturnalT
b andM decrease slightly with fallingT
a. The birds show partial heterothermia (shallow hypothermia). Clustering is an effective energy saving strategy which allows loweringM with keeping highT
b even at lowT
a.Oxygen-intake is controlled byF
r as well as by tidal volumeV
t inT
a-dependent changing portions.V
T can vary between 0.29–0.91 ml (mean value 49.7 ml).Abbreviations
T
a
ambient temperature
-
T
b
body temperature
-
M
energy metabolism
-
F
r
breathing frequency
-
V
T
tidal volume
- BMR
basal metabolic rate
- TNP
thermoneutral point 相似文献
8.
S. Marhold A. Nagel 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1995,164(8):636-645
Body temperature, oxygen consumption, respiratory and cardiac activity and body mass loss were measured in six females and four males of the subterranean Zambian mole rat Cryptomys sp. (karyotype 2 n=68), at ambient temperatures between 10 and 35°C. Mean body temperature ranged between 36.1 and 33.2°C at ambient temperatures of 32.5–10°C and was lower in females (32.7°C) than in males (33.9°C) at ambient temperatures of 10°C but dit not differ at thermoneutrality (32.5°C). Except for body temperature, mean values of all other parameters were lowest at thermoneutrality. Mean basal oxygen consumption of 0.76 ml O2·g-1· h-1 was significantly lower than expected according to allometric equations and was different in the two sexes (females: 0.82 ml O2·g-1·h-1, males: 0.68 ml O2·g1·h-1) but was not correlated with body mass within the sexes. Basal respiratory rate of 74·min-1 (females: 66·min1, males: 87·min-1) and basal heart rate of 200·min-1 (females: 190·min-1, males: 216·min-1) were almost 30% lower than predicted, and the calculated thermal conductance of 0.144 ml O2·g-1·h1·°C-1 (females; 0.153 ml O2·g-1·h-1·°C-1, males: 0.131 ml O2·g-1·h-1·°C-1) was significantly higher than expected. The body mass loss in resting mole rats of 8.6–14.1%·day-1 was high and in percentages higher in females than in males. Oxygen consumption and body mass loss as well as respiratory and cardiac activity increased at higher and lower than thermoneutral temperatures. The regulatory increase in O2 demand below thermoneutrality was mainly saturated by increasing tidal volume but at ambient temperatures <15°C, the additional oxygen consumption was regulated by increasing frequency with slightly decreasing tidal volume. Likewise, the additional blood transport capacity was mainly effected by an increasing stroke volume while there was only a slight increase of heart frequency. In an additional field study, temperatures and humidity in different burrow systems have been determined and compared to environmental conditions above ground. Constant temperatures in the nest area 70 cm below ground between 26 and 28°C facilitate low resting metabolic rates, and high relative humidity minimizes evaporative water loss but both cause thermoregulatory problems such as overheating while digging. In 13–16 cm deep foraging tunnels, temperature fluctuations were higher following the above ground fluctuations with a time lag. Dominant breeding females had remarkably low body temperatures of 31.5–32.3°C at ambient temperatures of 20°C and appeared to be torpid. This reversible hypothermy and particular social structure involving division of labour are discussed as a strategy reducing energy expenditure in these eusocial subterranean animals with high foraging costs.Abbreviations BMR
basal metabolic rate
- br
breath
-
C
thermal conductance
- HR
neart rate
- LD
light/dark
-
M
b
body mass
- MR
metabolic rate
- OP
oxygen pulse
- PCO2
partial pressure of carbon dioxide
- PO2
partial pressure of oxygen
- RMR
resting metabolic rate
- RR
respiratory rate
-
T
a
ambient temperature
-
T
b
body temperature
- TNZ
thermal neural zone
-
O2
oxygen consumption 相似文献
9.
E. Król 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1994,164(6):503-507
Body temperature and oxygen consumption were measured in the eastern hedgehog,Erinaceus concolor Martin 1838, during summer at ambient temperatures (T
a) between-6.0 and 35.6°C.E. concolor has a relatively low basal metabolic rate (0.422 ml O2·g-1·h-1), amounting to 80% of that predicted from its body mass (822.7 g). Between 26.5 and 1.2°C, the resting metabolic rate increases with decreasing ambient temperature according to the equation: RMR=1.980-0.057T
a. The minimal heat transfer coefficient (0.057 ml O2·g-1·h-1·°C-1) is higher than expected in other eutherian mammals, which may result from partial conversion of hair into spines. At lower ambient temperature (from-4.6 to-6.0° C) there is a drop in body temperature (from 35.2 to 31.4° C) and a decrease in oxygen consumption (1.530 ml O2·g-1·h-1) even though the potential thermoregulation capabilities of this species are significantly higher. This is evidenced by the high maximum noradrenaline-induced non-shivering thermogenesis (2.370 ml O2·g-1·h-1), amounting to 124% of the value predicted. The active metabolic rate at ambient temperatures between 31.0 and 14.5° C averages 1.064 ml O2·g-1·h-1; at ambient temperatures between 14.5 and 2.0° C AMR=3.228-0.140T
a.Abbreviations AMR
active metabolic rate
- bm
body mass
- BMR
basal metabolic rate
-
h
heat transfer coefficient
- NA
noradrenaline
- NST
non-shivering thermogenesis
- NSTmax
maximum rate of NA-induced non-shivering thermogenesis
- RMR
resting metabolic rate
- RQ
respiratory quotient
- STPD
standard temperature and pressure (25°C, 1 ATM)
-
T
a
ambient temperature
-
T
b
body temperature 相似文献
10.
Theresa L. Bucher 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1985,155(3):269-276
Summary The BMR (6.00 ml O2·min–1) and thermal conductance (0.235 ml O2·min–1·°C–1) ofAmazona viridigenalis, a medium sized parrot, are close to allometrically predicted values for nonpasserine birds, but theT
1c of 26.5 °C is 8.5 °C higher than predicted (Fig. 1). Minimal respiratory frequencies measured in four species of birds average 60% of the rate predicted by a previous equation and yield the relationship, breaths·min–1= 10.3 kg–0.32. Frequencies are very dependent upon the methods used to obtain the data (Fig. 3). Resting values of respiratory parameters are poorly defined in the existing literature, and there are no single resting values within the TNZ analogous to a BMR. Rather values change within, as well as below and above, the TNZ. Minimal values of different parameters occur at differentT
a's, not necessarily within the TNZ (Figs. 2, 4, 5). For clarity, resting respiratory parameters should be reported as standard values, analogous to standard metabolic rates, withT
a specified. In birds the pattern of ventilation (f andV
T) changes asT
a changes resulting in different extraction efficiencies at a given minute volume (Figs. 6, 7). This facilitates adjustment to both changing oxygen demands and changing thermoregulatory needs.Abbreviations and symbols
BMR
basal metabolic rate
-
TNZ
thermoneutral zone
-
T
a
ambient temperature
-
SMR
standard metabolic rate
-
R.H.
relative humidity
-
f
respiratory frequency
-
br
breath
-
T
b
body temperature
-
T
lc
lower critical temperature
-
Tuc
upper critical temperature
-
T
Rlc
respiratory lower critical temperature
-
RQ
respiratory quotient
-
extraction efficiency
-
V
T
tidal volume
-
minute volume (=V
T
xf) 相似文献
11.
E. Tęgowska E. Wasilewska 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(4):327-330
Summary The effects of ambient temperatures of 10°C and 30°C and of E. coli endotoxin on brain temperature and plasma iron level were investigated in unrestrained wild house mice, Mus musculus. In control animals (i.p. saline-injected) exposed to cold environmenta the brain temperature decreased and plasma iron levels were lower than those observed under thermoneutral conditions (30°C). Animals injected i.p. with endotoxin (0.5 g·kg-1) and placed at 30°C showed a drop in plasma iron level during the fever episode. The results provide strong evidence for a relationship between brain temperature and plasma iron level in control mice under thermoneutral conditions, and show that during cold exposure or after injection of endotoxin, there is no linear correlation between brain temperature and plasma iron. Moreover, it was found that cold stress influences plasma iron level and that this influence is not mediated by changes in brain temperature.Abbreviations EP
endotoxin pyrogen
-
T
A
ambient temperature
-
T
Br
brain temperature
- T
Br
change in T
Br in relation to its initial value in feverish or control mice
- T
Br
difference between T
Br in feverish and control mice 相似文献
12.
Effect of temperature and humidity on evaporative water loss in Anna's hummingbird (Calypte anna) 总被引:1,自引:0,他引:1
Donald R. Powers 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(1):74-84
Summary Evaporative water loss (EWL), oxygen concumption
, and body temperature (Tb) of Anna's Hummingbirds (Calypte anna; ca. 4.5g) were measured at combinations of ambient temperature (Ta) and water vapor density (va) ranging from 20 to 37 °C and 2 to 27 g·m-3, respectively. The EWL decreased linearly with increasing va at all temperatures. The slopes of least squares regression lines relating EWL to va at different temperatures were not significantly different and averaged-0.50 mg H2O·m-3·g-2·h-1 (range:-0.39 to-0.61). Increased va restricted EWL in C. anna more than has been reported for other endotherms in dry air. The percent of metabolic heat production dissipated by evaporation (
) was lower than that of other birds in dry air, but higher than that for other birds at high humidity when Ta 33 °C. When Ta>33 °C the effect of humidity on
was similar to that in other birds. Calypte anna might become slightly hyperthermic at Ta>37 °C, which could augment heat transfer by increasing the Tb-Ta gradient. Body temperature for C. anna in this study was 43 °C (intramuscular) at Tas between 25 and 35 °C, which is above average for birds. It is estimated that field EWL is less than 30% of daily water loss in C. anna under mild temperature conditions (<35 °C).Abbreviations BMR
basal metabolic rate
- EWL
evaporative water loss
-
percent of metabolic heat production dissipated by evaporation
-
ambient water vapor density
-
body surface water vapor density
- RMR
resting metabolic rate
- Ta
ambient-temperature
- Tb
body temperature
- Td
dew-point temperature
- TNZ
thermoneutral zone
- Ts
body surface temperature
-
carbon dioxide production
-
oxygen consumption 相似文献
13.
Proper adjustment of thermoregulatory mechanisms ensures the survival of mammals when they are subjected to seasonal changes in their natural environment. To understand the physiological and ecological adaptations of Eothenomys olitor, we measured their metabolic rate, thermal conductance, body temperature (Tb) and evaporative water loss at a temperature range of 5–30 °C in summer. The thermal neutral zone (TNZ) of E. olitor was 20–27.5 °C, and the mean body temperature was 35.81±0.15 °C. Basal metabolic rate (BMR) was 2.81±0.11 ml O2/g h and mean minimum thermal conductance (Cm) was 0.18±0.01 ml O2/g h °C. Evaporative water loss (EWL) in E. olitor increased when the ambient temperature increased. The maximal evaporative water loss was 6.74±0.19 mg H2O/g h at 30 °C. These results indicated that E. olitor have relatively high BMR, low body temperature, low lower critical temperature, and normal thermal conductance. EWL plays an inportant role in temperature regulation. These characteristics are closely related to the living habitat of the species, and represent its adaptive strategy to the climate of the Yunnan-Kweichow Plateau, a low-latitude, high-altitude region where annual temperature fluctuations are small, but daily temperature fluctuations are greater. 相似文献
14.
We examined the thermoregulatory behaviour (TRB) of roosting Humboldt penguins (Spheniscus humboldti) in north central Chile during summer and winter, when ambient temperatures (Ta) are most extreme. Each body posture was considered to represent a particular TRB, which was ranked in a sequence that reflected different degrees of thermal load and was assigned an arbitrary thermoregulatory score. During summer, birds exhibited eight different TRBs, mainly oriented to heat dissipation, and experienced a wide range of Ta (from 14 to 31°C), occasionally above their thermoneutral zone (TNZ, from 2 to 30°C), this being evident by observations of extreme thermoregulatory responses such as panting. In winter, birds exhibited only three TRBs, mainly oriented to heat retention, and experienced a smaller range of Ta (from 11 to 18°C), always within the TNZ, even at night. The components of behavioural responses increased directly with the heat load which explains the broader behavioural repertoire observed in summer. Since penguins are primarily adapted in morphology and physiology to cope with low water temperatures, our results suggest that behavioural thermoregulation may be important in the maintenance of the thermal balance in Humboldt penguins while on land. 相似文献
15.
Seasonal variations in ambient temperature (Ta) require changes in thermoregulatory responses of endotherms. These responses vary according to several factors including taxon and energy constraints. Despite a plethora of studies on chiropteran variations in thermoregulation, few have examined African species. In this study, we used the Wahlberg's epauletted fruit bat (Epomophorus wahlbergi, body mass≈115 g) to determine how the thermoregulatory abilities of an Afrotropical chiropteran respond to seasonal changes in Ta. Mass specific Resting Metabolic Rates (RMRTa) and basal metabolic rate (BMR) were significantly higher in winter than in summer. Furthermore, winter body mass was significantly higher than summer body mass. A broad thermoneutral zone (TNZ) was observed in winter (15–35 °C) compared with summer (25–30 °C). This species exhibited heterothermy (rectal and core body temperature) during the photophase (bats' rest-phase) particularly at lower Tas and had a low tolerance of high Tas. Overall, there was a significant seasonal variation in the thermoregulatory abilities of E. wahlbergi. The relative paucity of data relating to the seasonal thermoregulatory abilities of Afrotropical bats suggest further work is needed for comparison and possible effects of climate change, particularly extreme hot days. 相似文献
16.
S. Saarela B. Klapper G. Heldmaier 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1995,165(5):366-376
The oxygen consumption of European finches, the siskin (Carduelis spinus), the brambling (Fringilla montifringilla), the bullfinch (Pyrhulla pyrhulla), the greenfinch (Carduelis chloris) and the hawfinch (Coccothraustes coccothraustes), was recorded continuously while ambient temperature was decreased stepwise from +30 down to-75°C. The oxygen consumption, body temperature (telemetrically), and shivering (integrated pectoral electromyography) of greenfinches were measured simultaneously at ambient temperatures between +30 and-75°C. Maximum heat production, cold limit, lower critical temperature, basal metabolic rate and thermal conductance (of the greenfinch) were determined. The diurnal variation of oxygen consumption of siskins and greenfinches was recorded at thermoneutrality and below the thermoneutral zone in winter- and summer-acclimatized birds. The diurnal variation of body temperature and thermal conductance of greenfinches were also determined. The diurnal variation of heat production was not seasonal or temperature dependent in the siskin and in the greenfinch. Nocturnal reduction of oxygen consumption saved 15–33% energy in the siskin and greenfinch. Body temperature of the greenfinch was lowered by 2.5–3.4°C. The nocturnal reduction of thermal conductance in the greenfinch was 39–48%. The basal metabolic rate was lowest in the largest bird (hawfinch) and highest in the smallest bird (siskin). The values were in the expected range. The heat production capacity of finches in winter was 4.7 times basal metabolic rate in the siskin, 4.2 times in the brambling, 3.5 times in the greenfinch and 2.9 times in the bullfinch and hawfinch. The heat production capacity of the siskin and greenfinch was not significantly lower in summer. The cold limit temperatures (°C) in winter were-61.2 in the siskin,-41.3 in the greenfinch,-37.0 in the bullfinch,-35.7 in the brambling and-28.9 in the hawfinch. The cold limit was 14.3°C higher in summer than in winter in the siskin and 8.7°C in the greenfinch. Thermal insulation of the greenfinch was significantly better in winter than in summer. The shivering of the greenfinch increased linearly when ambient temperature was decreased down to-40°C. Maintenance of shivering was coincident with season. In severe cold integrated pectoral electromyography did not correlate with oxygen consumption as expected. The possible existence of non-shivering thermogenesis in birds is discussed. It is concluded that the acclimatization of European finches is primarily metabolic and only secondly affected by insulation.Abbreviations
AAT
avian adipose tissue
-
bm
body mass
-
BMR
basal metabolic rate
-
C
t
thermal conductance
-
EMG
electromyogram
-
HP
heat production
-
HP
max
maximum heat production
-
MR
metabolic rate
-
NST
non-shivering thermogenesis
-
RMR
resting metabolic rate
-
RQ
respiratory quotient
-
T
a
ambient temperature
-
T
b
body temperature
-
T
c
colonic temperature
-
T
1c
lower critical temperature
-
TNZ
thermoneutral zone
-
T
st
shivering threshold temperature
-
V
oxygen consumption 相似文献
17.
C. Traeholt 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1995,165(2):125-131
Eight water monitor lizards, Varanus s. salvator, were captured; four individuals from an oil palm estate on the Malayan peninsula, and four from fresh water-deficient Tulai island 65 km off-shore in the South China Sea. They were fitted with a radio transmitter attached to a thermistor which was inserted into the cloaca of the animals and released. The heating rate during basking was measured as 0.117 and 0.118 °C·min-1 while the daily cloacal temperature fluctuated between 29.5–37.3 °C. Cloacal temperature was measured on other individuals caught at random times during the day, which revealed a considerable daily and individual variation. The average cloacal temperature during activity was 30.4 °C. The peak activity appeared when body temperature was 31 °C. Thermoregulation by behavioural means included cooling in water and reducing heat loss at night by sleeping in burrows. The cooling rate for two individuals when submerged in 29 °C water was 0.308 and 0.340 °C·min-1. There appeared to be a strong correlation between ambient temperature and cloacal temperature.Abbreviations bw
body weight
-
T
a
ambient temperature
-
T
a
body temperature
-
T
c
cloacal temperature
- TOP
Timor Oil Palm Estate
- TUL
Tulai Island 相似文献
18.
Doucette LI Geiser F 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2008,151(4):615-620
Many birds living in regions with seasonal fluctuations in ambient temperatures (Ta) typically respond to cold by increasing insulation and adjusting metabolic rate. Seasonal variation in thermal physiology has not been studied for the Caprimulgiformes, an order of birds that generally have basal metabolic rates (BMR) lower than predicted for their body mass. We measured the metabolic rate and thermal conductance of Australian owlet-nightjars (Aegotheles cristatus) during summer and winter using open-flow respirometry. Within the thermoneutral zone (TNZ; 31.3 to 34.8 °C), there was no seasonal difference in BMR or thermal conductance (C), but body temperature was higher in summer- (38.2 ± 0.3 °C) than winter-acclimatized (37.1 ± 0.5 °C) birds. Below the TNZ, resting metabolic rate (RMR) increased linearly with decreasing Ta, and RMR and C were higher for summer- than winter-acclimatized birds. The mean mass-specific BMR of owlet-nightjars (1.27 mL O2 g− 1 h− 1) was close to the allometrically predicted value for a 45 g Caprimulgiformes, but well below that predicted for birds overall. These results suggest that owlet-nightjars increase plumage insulation to cope with low winter Ta, which is reflected in the seasonal difference in RMR and C below the TNZ, rather than adjusting BMR. 相似文献
19.
Cooper CE Withers PC 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2004,174(2):107-111
This study examines the ventilatory physiology of the numbat (Myrmecobius fasciatus), a small to medium-sized (550 g) termitivorous marsupial. Ventilatory parameters at thermoneutrality reflect the slightly low (83% of predicted) basal metabolic rate of the numbat, with ventilation frequency (ƒR; 30.6±3.65 breaths min–1), tidal volume [VT; 6.0±0.66 ml at body temperature and pressure, saturated (BTPS)] and consequently minute volume (VI; 117.7±15.22 ml min–1; BTPS) all being 80–87% of that expected for a marsupial of similar body mass. Oxygen extraction was 27.7±1.37% in the thermoneutral zone. As is typical of marsupials, numbats accommodated increased oxygen consumption rates at ambient temperatures (T
a) below the thermoneutral zone by increasing minute volume (up to 411.2±43.98 ml min–1; BTPS at T
a=10 °C) rather than oxygen extraction. Minute volume at 10 °C increased more by changes in ventilation frequency (up to 45.5±4.85 breaths min–1) than tidal volume (9.4±1.03 ml, BTPS), as is also typical for a small-medium sized marsupial.Abbreviations
BMR
basal metabolic rate
-
BTPS
body temperature and pressure, saturated
-
EO
2
oxygen extraction
-
ƒ
R
ventilation frequency
-
STPD
standard temperature and pressure, dry
-
T
a
ambient temperature
-
T
b
body temperature
-
TNZ
thermoneutral zone
-
V
I
minute volume
-
V
T
tidal volume
-
O
2
oxygen consumption rate
Communicated by I.D. Hume 相似文献
20.
D. A. Croll E. McLaren 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(2):160-166
The diving and thermoregulatory metabolic rates of two species of diving seabrid, common (Uria aalge) and thick-billed murres (U. lomvia), were studied in the laboratory. Post-absorptive resting metabolic rates were similar in both species, averaging 7.8 W·kg-1, and were not different in air or water (15–20°C). These values were 1.5–2 times higher than values predicted from published allometric equations. Feeding led to increases of 36 and 49%, diving caused increases of 82 and 140%, and preening led to increases of 107 and 196% above measured resting metabolic rates in common and thick-billed murres, respectively. Metabolic rates of both species increased linearly with decreasing water temperature; lower critical temperature was 15°C in common murres and 16°C in thick-billed murres. Conductance (assuming a constant body temperature) did not change with decreasing temperature, and was calculated at 3.59 W·m-2·oC-1 and 4.68 W·m-2·oC-1 in common and thick-billed murres, respectively. Murres spend a considerable amount of time in cold water which poses a significant thermal challenge to these relatively small seabirds. If thermal conductance does not change with decreasing water temperature, murres most likely rely upon increasing metabolism to maintain body temperature. The birds probably employ activities such as preening, diving, or food-induced thermogenesis to meet this challenge.Abbreviations ADL
aerobic dive limit
- BMR
basal metabolic rate
- FIT
food-induced thermogenesis
- MHP
metabolic heat production
- MR
metabolic rate
- PARR
post-absorption resting rate
- RMR
resting metabolic rate
- RQ
respiratory quotient
- SA
surface area
- STPD
standard temperature and pressure (25°C, 1 ATM)
-
T
a
ambient temperature
-
T
b
body temperature
-
T
IC
Iower critical temperatiure
- TC
thermal conductance
-
V
oxygen consumption rate
-
W
body mass 相似文献