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1.
(1) The thermal capabilities of Australian silvereyes (Zosterops lateralis, 11 g) were investigated both at low and high ambient temperatures (Ta) during the photophase and scotophase. (2). The peak metabolic rate (PMR) induced by helium–oxygen (79:21 %, He–O2) exposure during the photophase was 15.64±1.55 mL O2 g−1 h−1 at an effective lower survival limit Ta (Tpmr) of −39.7±6.1°C. (3). Above the thermoneutral zone (TNZ), metabolic rate, body temperature (Tb), and thermal conductance increased steeply, but they were able to withstand a Ta of 39°C. (4). Our study shows that silvereyes are able to tolerate an impressive range of Ta from about −42°C to at least +39°C and are able to produce enough heat to maintain a thermal difference between Tb and Ta of up to 80°C.  相似文献   

2.
The respiration rate of the thermogenic inflorescences of Japanese skunk cabbage Symplocarpus renifolius can reach 300 nmol s?1 g?1, which is sufficient to raise spadix temperature (Ts) up to 15 ° C above ambient air temperature (Ta). Respiration rate is inversely related to Ta, such that the Ts achieves a degree of independence from Ta, an effect known as temperature regulation. Here, we measure oxygen consumption rate (?o 2) in air (21% O2 in mainly N2) and in heliox (21% O2 in He) to investigate the diffusive conductance of the network of gas‐filled spaces and the thermoregulatory response. When Ts was clamped at 15 ° C, the temperature that produces maximal ?o 2 in this species, exposure to high diffusivity heliox increased mean ?o 2 significantly from 137 ± 17 to 202 ± 43 nmol s?1 g?1 FW, indicating that respiration in air is normally limited by diffusion in the gas phase and some mitochondria are unsaturated. When Ta was clamped at 15 ° C and Ts was allowed to vary, exposure to heliox reduced Ts 1 ° C and increased ?o 2 significantly from 116 ± 10 to 137 ± 19 nmol s?1 g?1, indicating that enhanced heat loss by conduction and convection can elicit the thermoregulatory response.  相似文献   

3.
The functional response of a predator describes the rate at which it kills its prey at different prey densities and is, therefore, an important tool to determine the efficiency of a predator in regulating the population dynamics of a prey. We investigated the functional response of Coccinella septempunctata L. (Coleoptera: Coccinellidae) to varying densities of Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae). The results revealed that the linear coefficient, P1 in the reduced logistic model was found significantly negative for the 4th instar larvae and adult male and female of C. septempunctata (?0.002, ?0.004 and???0.002, respectively) indicating a type II functional response. The parameter estimates of adult male, female and 4thinstar larvae of C. septempunctata calculated through Holling's disc model revealed that the highest attack rate (a) (1.047?±?0.014), shortest handling time (Th) (0.0984?±?0.024?h) and largest maximum capture rate (T/Th) (243.902) was exhibited by female. Parameter estimates calculated through Rogers’s equation also showed the same sequence where maximum attack rate (a) of 0.00256?±?0.0003 was exhibited by female followed by 4th instar larvae (0.00251?±?0.0005). The shortest handling time (Th) (0.210?±?0.003?h) and highest maximum capture rate (T/Th) (114.17) was also exhibited by female. Comparison of functional response curves of adult male, female and 4th instar larvae revealed that maximum consumption of prey at all the densities offered was shown by female followed by 4thinstar larvae. The study manifested that C. septempunctata could be an efficient biocontrol agent of pea aphid, A. pisum.  相似文献   

4.
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   

5.
The red-tailed phascogale is a small arboreal dasyurid marsupial that inhabits semi-arid to arid regions of Western Australia's wheat belt. Its body mass (34.7 g) is only ~15% of that predicted based on its phylogenetic position among other dasyuromorphs; we interpret this as an adaptation to its scansorial and semi-arid/arid lifestyle. The standard physiology of this species at a thermoneutral ambient temperature of 30 °C conforms to that of other dasyurid marsupials; body temperature (34.7 ± 0.37 °C), basal metabolic rate (0.83 ± 0.076 mL O2 g?1 h?1), evaporative water loss (1.68 ± 0.218 mg H2O g?1 h?1) and wet thermal conductance (3.8 ± 0.26 J g?1 h?1 °C?1) all fall within the 95% predication limits for the respective allometric relationships for other dasyurid species. Thermolability confers an energy savings at low Ta and water savings at high Ta. Torpor, observed at low Ta, was found to be more beneficial for energy savings than for water economy. The red-tailed phascogale therefore has a physiology suitable for the challenges of arid environments without any obvious requirement for adaptations to its scansorial lifestyle, other than its considerably lower-than-expected body mass.  相似文献   

6.
Bats are among the most heterothermic mammals, with nearly all species investigated under free-ranging conditions to date exhibiting some degree of daily torpor and/or hibernation. We investigated thermoregulation during late winter by seven Nycteris thebaica in a warm, semi-arid habitat in northern South Africa, using temperature-sensitive transmitters to measure skin temperature (Tskin). Unexpectedly, we found no evidence for any expression of daily torpor or hibernation based on a total of 86 days of data from 7 bats (one male and six females), despite air temperatures as low as ~10 °C. Instead, daytime Tskin was distributed unimodally with most values in the 33–35 °C range, and a minimum Tskin of 28.4 °C at a roost temperature of 24.6 °C. There are several possible reasons why N. thebaica may avoid torpor, including predation in roosts, and the long nightly foraging periods of this species compared to many others.  相似文献   

7.
Basal metabolic rate (BMR) is thought to be a major hub in the network of physiological mechanisms connecting life history traits. Evaporative water loss (EWL) is a physiological indicator that is widely used to measure water relations in inter- or intraspecific studies of birds in different environments. In this study, we examined the physiological responses of summer-acclimatized Hwamei Garrulax canorus to temperature by measuring their body temperature (Tb), metabolic rate (MR) and EWL at ambient temperatures (Ta) between 5 and 40 °C. Overall, we found that mean body temperature was 42.4 °C and average minimum thermal conductance (C) was 0.15 ml O2 g−1 h−1 °C−1 measured between 5 and 20 °C. The thermal neutral zone (TNZ) was 31.8–35.3 °C and BMR was 181.83 ml O2 h−1. Below the lower critical temperature, MR increased linearly with decreasing Ta according to the relationship: MR (ml O2 h−1)=266.59–2.66 Ta. At Tas above the upper critical temperature, MR increased with Ta according to the relationship: MR (ml O2 h−1)=−271.26+12.85 Ta. EWL increased with Ta according to the relationship: EWL (mg H2O h−1)=−19.16+12.64 Ta and exceeded metabolic water production at Ta>14.0 °C. The high Tb and thermal conductance, low BMR, narrow TNZ, and high evaporative water production/metabolic water production (EWP/MWP) ratio in the Hwamei are consistent with the idea that this species is adapted to warm, mesic climates, where metabolic thermogenesis and water conservation are not strong selective pressures.  相似文献   

8.
High environmental temperatures pose significant physiological challenges related to energy and water balance for small endotherms. Although there is a growing literature on the effect of high temperatures on birds, comparable data are scarcer for bats. Those data that do exist suggest that roost microsite may predict tolerance of high air temperatures. To examine this possibility further, we quantified the upper limits to heat tolerance and evaporative cooling capacity in three southern African bat species inhabiting the same hot environment but using different roost types (crevice, foliage or cave). We used flow-through respirometry and compared heat tolerance limits (highest air temperature (Ta) tolerated before the onset of severe hyperthermia), body temperature (Tb), evaporative water loss, metabolic rate, and maximum cooling capacity (i.e., evaporative heat loss/metabolic heat production). Heat tolerance limits for the two bats roosting in more exposed sites, Taphozous mauritianus (foliage-roosting) and Eptesicus hottentotus (crevice-roosting), were Ta = ~44 °C and those individuals defended maximum Tb between 41 °C and 43 °C. The heat tolerance limit for the bat roosting in a more buffered site, Rousettus aegyptiacus (cave-roosting), was Ta = ~38 °C with a corresponding Tb of ~38 °C. These interspecific differences, together with a similar trend for higher evaporative cooling efficiency in species occupying warmer roost microsites, add further support to the notion that ecological factors like roost choice may have profound influences on physiological traits related to thermoregulation.  相似文献   

9.
Metabolic rate and evaporative water loss (EWL) were measured for a small, arid-zone marsupial, the stripe-faced dunnart (Sminthopsis macroura), when normothermic and torpid. Metabolic rate increased linearly with decreasing ambient temperature (Ta) for normothermic dunnarts, and calculated metabolic water production (MWP) ranged from 0.85±0.05 (Ta=30°C) to 3.13±0.22 mg H2O g–1 h–1 (Ta=11°C). Torpor at Ta=11 and 16°C reduced MWP to 24–36% of normothermic values. EWL increased with decreasing Ta, and ranged from 1.81±0.37 (Ta=30°C) to 5.26±0.86 mg H2O g–1 h–1 (Ta=11°C). Torpor significantly reduced absolute EWL to 23.5–42.3% of normothermic values, resulting in absolute water savings of 50–55 mg H2O h–1. The relative water economy (EWL/MWP) of the dunnarts was unfavourable, remaining >1 at all Ta investigated, and did not improve with torpor. Thus torpor in stripe-faced dunnarts results in absolute, but not relative, water savings.  相似文献   

10.
A functional response study of Chrysoperla carnea (Stephens) larvae to different densities of sugar cane whitefly Aleurolobus barodensis (Maskell) was conducted in test tubes at 26?±?2 °C, 65?±?5 % RH. Chrysoperla carnea showed two different types of functional response in larval instars. First instar exhibits type II. However, second and third larval instars revealed type III functional response. Based on modified Holling’s disk equation, the highest searching rates (a) of 0.82?±?0.0247 h?1 was found for first instar larva. For second and third larval instars, the attack coefficient (b) were 0.002?±?0.030 and 0.0025?±?0.0424 respectively. The shortest handling time (Th) per prey was observed at third instar stage (1.574?±?0.0568 h) followed by second and first instar with 1.72?±?0.0411 h and 1.919?±?0.0568 h respectively.  相似文献   

11.
Ventilation was measured directly in the hagfish, Myxine glutinosa L., by means of an electro-magnetic blood flowmeter. Ventilatory flow and frequency increased from 0.86 ± 0.27 ml·min?, and 18.2 ± 5.1·min?, respectively, at 7°C to 1.70 ± 0.20 ml·min?, and 70.1 ± 9.5·min? at 15 ·C.Standard oxygen consumption,V?O2, was measured in non-buried hagfish. V?O2 was 0.57 ± 0.17μl O2·g?1·min?1 at 7°C, and 0.85 ± 0.12μl O2·g?1·min?1 at 15°C.  相似文献   

12.
In this study, the hypothesis is tested that continuous increases in ambient temperature (Ta) during daytime would give elevated core and skin temperatures, and consequently better thermal sensation and comfort. Rectal temperature (Tre), skin temperatures and regional dry heat losses at 7 sites were continuously measured for 10 Japanese male subjects in three thermal conditions: cond. 1, stepwise increases in Ta from 26 °C at 9 h00 to 30 °C at 18 h00; cond. 2, steady Ta at 28 °C from 9 h00 to 18 h00 and cond. 3, stepwise decreases in Ta from 30 °C at 9 h00 to 26 °C at 18 h00. Oxygen consumption was measured and thermal sensation and comfort votes were monitored at 15 min intervals. Body weight loss was measured at 1 h intervals. While Tre increased continuously in the morning period in any condition, it increased to a significantly greater (p?<?0.05) 36.9?±?0.3 °C at 18 h00 in cond. 1 relative to 36.7?±?0.28 °C in Cond. 2 and 36.5?±?0.37 °C in cond. 3. Better thermal comfort was observed in the afternoon and the evening in Cond.1 as compared with the other 2 conditions. Thus, a progressive and appropriate increase in Ta may induce optimal cycle in core temperature during daytime, particularly for a resting person.  相似文献   

13.
  • 1.1. Brain (hypothalamic), skin and body temperatures were measured in hand-reared acclimated (Acc, n = 5) and non-acclimated (NAcc, n =7) rock pigeons (Columba livia, mean body mass 237 g) exposed to increasing ambient temperatures (Ta) (30–60°C) and low humidities.
  • 2.2. In non-panting Acc birds, brain temperature gradually increased from 40.1 ± 0.4°C at 30°C to 41.2 ± 0.4°C at 60°C Ta. A mean body temperature (Tb) of 41.2 ± 0.2°C was measured at Ta up to 50°C; an increase of 1.1°C was observed at 60°C (Tb 42.2 ±0.6°C).
  • 3.3. In Acc panting birds exposed for 2 hr to 60°C, Thy was 41.9 ± 0.8°C and Ts was somewhat (but insignificantly) higher, i.e., 42.2 ± 0.7°C. It looks as if both values were increased as a result of a slight hyperthermia that developed (Tb = 43.5 ± 0.9°C).
  • 4.4. The significance of the present results for evaluating neuronal thermoresponsiveness of birds' hypothalamus is discussed.
  相似文献   

14.
Rates of net photosynthesis and respiration were determined for Pithophora oedogonia (Mont.) Wittr. acclimatized to 56 combinations of light (7–1200 μE m?2 s?1) and temperature (5–35°C). Conditions for maximum net photosynthesis were estimated to be 26°C and 970 μE m?2 s?1. The rate of net photosyntheses varied considerably with temperature, with the maximum measured value (9.67 mg O2 h?1 g dry wt.?1) occurring at 25°C. Respiration rate increased with temperature and the light received just prior to measurement. The maximum respiration rate (7.05 mg O2 g?1 h?1) occurred at 30°C and 1200 μE m?2 s?1. Exposure of Pithophora to light levels of 600 or 1200 μE m?2 s?1 prior to determination of the respiration rate resulted in significantly elevated levels of oxygen consumption at temperatures ≥ 15°C. The relationship between light, temperature and photosynthesis and respiration were summarized as three-dimensional response surfaces.  相似文献   

15.
Different cultivars of aplant species can affect the foraging and efficiency of natural enemies, both directly through physical and biochemical properties or indirectly through the herbivore's diet. In this study, the parasitism capacity and functional response of Diaeretiella rapae McIntosh were determined on the cabbage aphid, Brevicoryne brassicae (L.) reared on susceptible (Opera) and resistant (Okapi) canola cultivars under laboratory conditions at 25?±?1?°C, 60?±?5% RH and a16:8?h L:D photoperiod. The parasitoid exhibited Type II and Type III functional responses on the resistant and susceptible cultivars, respectively. The estimated value of searching efficiency (a) was 0.1637?±?0.1095?h?1 on the resistant cultivar whereas its value was dependent on host density on the susceptible cultivar. The handling times (Th) on the susceptible and resistant canola cultivars were 0.108?±?0.040 and 0.320?±?0.048?h, respectively. The net parasitism rate (C0) of the parasitoid wasp varied from 128.09 hosts per parasitoid lifetime on the susceptible to 71.01hosts on the resistant canola cultivar. The transformation rate from host population to parasitoid offspring (Qp) was equal to 1 on both cultivars (C0?=?R0). The finite parasitism rate (ω) on the susceptible cultivar (0.819 hosts per parasitoid per day) was significantly higher than that on the resistant one (0.578 hosts per parasitoid per day). In conclusion, canola cultivars affected the performance of D. rapae in controlled small-scale laboratory experiments and compared with the susceptible cultivar, the resistant one had anadverseeffect on the efficiency of the parasitoid.  相似文献   

16.
Little is known about torpor in the tropics or torpor in megachiropteran species. We investigated thermoregulation, energetics and patterns of torpor in the northern blossom-bat Macroglossus minimus (16 g) to test whether physiological variables may explain why its range is limited to tropical regions. Normothermic bats showed a large variation in body temperature (T b) (33 to 37 °C) over a wide range of ambient temperatures (T as) and a relatively low basal metabolic rate (1.29 ml O2 g−1 h−1). Bats entered torpor frequently in the laboratory at T as between 14 and 25 °C. Entry into torpor always occurred when lights were switched on in the morning, independent of T a. MRs during torpor were reduced to about 20–40% of normothermic bats and T bs were regulated at a minimum of 23.1 ± 1.4 °C. The duration of torpor bouts increased with decreasing T a in non-thermoregulating bats, but generally terminated after 8 h in thermoregulating torpid bats. Both the mean minimum T b and MR of torpid M. minimus were higher than that predicted for a 16-g daily heterotherm and the T b was also about 5 °C higher than that of the common blossom-bat Syconycteris australis, which has a more subtropical distribution. These observations suggest that variables associated with torpor are affected by T a and that the restriction to tropical areas in M. minimus to some extent may be due to their ability to enter only very shallow daily torpor. Accepted: 22 September 1997  相似文献   

17.
The green-tide macroalga, Ulva prolifera, was tested in the laboratory to determine its nutrient uptake and photosynthesis under different conditions. In the nutrient concentration experiments U. prolifera showed a saturated uptake for nitrate but an escalating uptake in the tested range for phosphorus. Both N/P and NO3 ?/NH4 + ratios influenced nutrient uptake significantly (p?<?0.05) while the PSII quantum yield [Y(II)] (p?>?0.05) remained unaffected. The maximum N uptake rate (33.9?±?0.8 μmol g?1 DW h?1) and P uptake rate (11.1?±?4.7) was detected at N/P ratios of 7.5 and 2.2, respectively. U. prolifera preferred NH4 +-N to NO3 ?-N when the NO3 ?-N/NH4 +-N ratio was less than 2.2 (p?<?0.05). But between ratios of 2.2 and 12.9, the uptake of NO3 ?-N surpassed that of NH4 +-N. In the temperature experiments, the highest N uptake rate and [Y(II)] were observed at 20 °C, while the lowest rates were detected at 5 °C. P uptake rates were correlated with increasing temperature.  相似文献   

18.
A Gram-stain positive, aerobic, non-motile, endospore-forming and rod-shaped strain (THG-NT9T) was isolated from a green tea sample. Growth occurred at 20–45 °C (optimum 28–35 °C), at pH 6.0–8.0 (optimum 7.0) and at 0–2.0% NaCl (optimum 0%). Based on 16S rRNA gene sequence analysis, the near phylogenetic neighbours of strain THG-NT9T were identified as Scopulibacillus daqui DSM 28236T (98.6%), Scopulibacillus darangshiensis DSM 19377T (97.4%), Pullulanibacillus pueri CGMCC 1.12777T (96.7%) and Pullulanibacillus camelliae CGMCC 1.15371T (96.3%). The DNA G?+?C content of strain THG-NT9T was determined to be 47.5 mol %. DNA–DNA hybridization values between strain THG-NT9T and S. daqui DSM 28236T, S. darangshiensis DSM 19377T, P. pueri CGMCC 1.12777T, P. camelliae CGMCC 1.15371T and Pullulanibacillus naganoensis DSM 10191T were 41.3?±?0.1 (39.4?±?0.4% reciprocal analysis), 39.1?±?0.1 (37.3?±?0.1%), 21.4?±?0.7 (20.1?±?0.3%), 20.7?±?0.1 (20.1?±?0.4%) and 12.1?±?0.2% (8.3?±?0.2%). The polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and three unidentified lipids. The quinone was identified as MK-7. The major fatty acids were C18:3 ω7c, iso-C15:0, iso-C16:0, iso-C17:0 and anteiso-C17:0. The cell wall type was determined to be A1γ peptidoglycan with meso-diaminopimelic acid as the diagnostic diamino acid plus alanine and glutamic acid and glucose as the cell wall sugar. On the basis of the phylogenetic analysis, chemotaxonomic data, physiological characteristics, and DNA–DNA hybridization data, strain THG-NT9T represents a novel species of the genus Scopulibacillus, for which the name Scopulibacillus cellulosilyticus sp. nov. is proposed. The type strain is THG-NT9T (=?KCTC 33918T?=?CGMCC 1.16305T).  相似文献   

19.
The response of the photosynthetic capacity (Pmax) of microphytobenthos to short-term variations of temperature (in the range 5–35° C) was assessed on a seasonal basis. The relationship is described mathematically, and relevant physiological parameters are identified: PMAX, the maximum value of Pmax achieved at Topl, the optimum temperature. Estimated values of Topt do not change significantly throughout the year and remain close to 25° C. It is thus concluded that Topt is not influenced by seasonal variations in the daily range of mud surface temperature. Identical conclusions hold for Tmax (ca. 38° C), the thermal threshold beyond which no photosynthesis occurs. Conversely, PMA estimates exhibit substantial variability: PMAX (mean ± root mean square error) is highest in April (11.18 ± 0.42 [μg C · [μg Chl a]?1· h?1) during the beginning of the annual increase in temperature, photoperiod, and maximum irradiance and is lowest in December (3.04 ± 0.16 μg C · [μg Chl a]?1· h?l). From an ecological point of view, the short-term and seasonal variations of PMAX suggest that the microphytobenthic community takes advantage of the abiotic spring environmental conditions, allowing the onset of the bloom. Nevertheless, no “acclimation strategy” (i.e. shifts in Topt and Tmax that prevent temperature inhibition in summer or improve photosynthetic rates in winter) is apparent from our results.  相似文献   

20.
Oxygen consumption rates (QO2) of laboratory reared stage one zoeae of Pandalus borealis (Krøyer) at 1.5, 3, 4.5, 6, and 9°C were 1.5, 2.2, 2.6, 3.6 and 4.1μ O2 · mg?1 · h?1, respectively. These values of QO2 correspond to 0.26, 0.38, 0.44, 0.60, and 0.70 μl O2 · individual?1 · h?1. At 10.5 °C oxygen consumption rates decreased suggesting thermally induced respiratory stress.The equation log10QO2 = 0.55 log10T°C + 0.086 describes the relationship between QO2 (μl O2 · mg?1 · h?1) and sea-water temperature between 1.5 and 9°C. Corresponding values of QO2 for an individual (μl O2 · h?1) exhibited the relationship log10QO2 = 0.55 log10T°C ?0.686.The minimum daily metabolic caloric requirements for an individual zoea ranged from 0.04 at 3 °C to 0.07 calories per day at 8 °C. The number of calories ingested daily ranged from 0.4 to 0.5 at 3 to 8 °C.  相似文献   

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