Author Keywords: Insecta; Diptera; Asilidae; Machimus; thermal biology; basking; refuges 相似文献
1. 1.|The robber flies Machimus occidentalis and Machimus formosus are ambush predators that occur sympatrically in grassland habitats of southwestern Montana, U.S.A., although the former occurs earlier in the season.
2. 2.|Early in daily foraging periods, when ambient temperatures are relatively low, the two species exhibited similar behaviours. They perched in a crouched posture on fully insolated bare soil surfaces and oriented their longitudinal and dorsoventral axes to maximize the incident solar radiation intercepted by the broad lateral surface of the thorax. Measurements of operative body temperature of flies in different locations, orientations, and postures indicate that such basking can significantly raise body temperature.
3. 3.|Their thermoregulatory tactics diverged as daily temperatures and solar radiation loads rise.
4. 4.|Like previous grassland species studied, M. occidentalis moved upward onto vegetation, where crouched postures and orientation to the sun disappeared.
5. 5.|Machimus formosus, on the other hand, took refuge in the shaded portions of ground squirrel (Citellus sp.) and badger (Taxidea taxus) burrows.
6. 6.|In both cases, the vertical movements resulted in lower body temperatures than would occur if flies remained on the fully insolated soil surfaces.
7. 7.|We compare the tactics of these two species with those of previous grassland species studied.
1. 1.|Newly-released larvae of both E. modestus and B. balanoides show similar tolerances to steady temperature levels.
2. 2.|Both species show an ability to withstand a wider range of temperatures when subjected to cyclic thermal shocks.
3. 3.|E. modestus shows a greater tolerance to short-term thermal shocks than B. balanoides.
Author Keywords: Tolerance; cyclic temperautres; barnacles; larvae 相似文献
1. 1.|Mean supercooling points (SCP) of Anguispira alternata (Say) gradually declined in autumn and increased in spring. SCP also declined in autumn in Discus conrkhitei (Newcomb) and Gastrocopta armifera (Say).
2. 2.|Supercooling ability varied among the species, being the greatest in G. armifera.
3. 3.|Prolonged exposure of winter animals to high temperatures resulted in only a modest increase in SCP.
4. 4.|Low temperature survival of D. cronkhitei and G. armifera was slightly poorer than predicted by the mean SCP.
Author Keywords: Cold-hardiness; supercooling point; land snail; Pulmonata; Anguispira alternata; Discus cronkhitei; Gastrocopta armifera; Helicodiscus parallelus 相似文献
- 1. The influence of interspecific hybridization on temperature preferences and morphology was examined in newts, Triturus carnifex and Triturus dobrogicus, before and after metamorphosis.
2. Thermoregulatory behavior was measured in an aquatic thermal gradient (5–32.5 °C) during 24 h.
3. Hybrid temperature preferences were similar to preferences of maternal species in both premetamorphic larvae and recently metamorphosed individuals.
4. Hybrid morphology (i.e., forelimb length and axilla–groin distance) was intermediate relative to parental species.
5. The mismatch between morphology and thermal preference in hybrid phenotypes indicates potential hybrid disadvantage in both intermediate and parental habitats.
Keywords: Hybridization; Hybrid intermediacy; Preferred body temperature; Amphibians; Salamandridae; Metamorphosis; Larvae 相似文献
1. 1.Preferred temperature ranges were determined for workers of 5 species of Myrmecocystus in a temperature gradient on wet sand.
2. 2.Workers of the diurnally foraging species, M. mendax Wheeler, M romainei Cole, M. depilis Forel, and M. mimicus Wheeler, were distributed between 7 and 45°C, and workers of one nocturnal species, M. mexicanus Wesmael, were distributed between 5 and 35°C.
3. 3.Mean preferred temperatures of the 5 species increased as follows: mexicanus < mendax < romainei < depilis < mimicus.
4. 4.Preferred temperatures of M. romainei and M. mexicanus were higher in the summer than in the fall.
5. 5.After 2 h in the gradient on dry sand, workers of M. romainei were distributed similarly to those on wet sand, but after 8 h on dry sand, most workers were below 12°C where the air was saturated.
Author Keywords: Myrmecocystus romainei; Myrmecocystus depilis; Myrmecocystus mimicus; Myrmecocystus mendax; Myrmecocystus mexicanus; honey ants: preferred temperatures; temperature limits; desert adaptations: humidity responses 相似文献
1. 1.|The development times and reproduction were measured for Daphnia pulex and Daphnia magna from 5 to 30°C at 5°C increments.
2. 2.|The general trends for D. pulex and D. magna were for the duration of all juvenile instars to be less than that of adults and for the last juvenile (or adolescent) instar to be longer than all previous juvenile instars.
3. 3.|The number of juvenile instars both species pass through before adulthood is influenced by temperature with increasing numbers occurring at temperature extremes.
4. 4.|Duration of development time decreased over the entire range of increasing temperatures measured for D. pulex but increased for D. magna at 30°C in relation to 25°C.
5. 5.|Quadratic models were less desirable than simple linear logarithmic transformations of the form ln Y = ln a + b ln X for describing the temperature/development relationship.
6. 6.|The greatest young production occurs at 15 and 20°C with significant decreases occurring at temperatures above and below these.
7. 7.|The observed temperature-dependent phenomena an the ecological relationships for the two species are discussed.
Author Keywords: Daphnia; development; reproduction; zooplankton; temperature; thermal; crustacea; cladocera; productivity; stress 相似文献
1. 1.|Selected body temperatures (SBT) of adult male, female and subadult Lacerta vivipara from a Belgian population, were measured monthly in a laboratory thermogradient.
2. 2.|Monthly mean SBTs varied between 29.9 and 34.0°C and differed significantly among months in all three lizard groups, and among lizard groups in 4 out of 6 months.
3. 3.|Evidence for a positive relationship between monthly SBT and air temperature was found in the subadults, but not in the adult lizards.
4. 4.|Monthly mean SBTs measured in this study were consistently higher (mean difference = 2.0°C) than those obtained by Patterson and Davies (1978) in a similar study on Lacerta vivipara from southern England.
Author Keywords: Selected body temperature; behavioural thermoregulation; Lacerta vivipara; intraspecific variation in body temperature 相似文献
1. 1.|Gemmules of Ephydatia mülleri can withstand exposure to temperatures down to −80°C for 63 days without loss of hatchability.
2. 2.|Hatching is slowed following exposure to temperatures below −27°C.
3. 3.|There is a slight but significant relationship between gemmule size and the time to hatch.
4. 4.|This species can withstand long-term exposure to winter air temperatures occurring within its known geographic range.
Author Keywords: Porifera; Spongillidae; sponge; freshwater sponge; Ephydatia mülleri; gemmule; hatching; low temperature; cold exposure 相似文献
1. 1.Three month-old seedlings of Taxodium distichum, Nyssa aquatica, Cephalanthus occidentalis and cuttings of Salix nigra were acclimated to simulated natural swamp conditions (ambient temperature, saturated soil) and then used to assess direct high temperature injury of root tissue.
2. 2.Electrolyte leakage from excised root tissue exposed for 30 min to temperatures ranging from 30 to 66°C was used to assess cellular injury.
3. 3.The relationship between leakage and temperature was sigmoidal for each species.
4. 4.Inflection point temperatures on the response curves, ranged from 45.4 to 51.0°C, were species-specific, and indicated differences in thermal tolerance of root membranes.
5. 5.Root of C. occidentalis and N. aquatica were more heat tolerant than roots of T. distichum and S. nigra.
Author Keywords: Bald cypress; waver tupelo; button bush; black willow; direct heat injury; membrane heat tolerance 相似文献
1. 1.|Heat hardening in a transitory increase in heat tolerance following a sublethal exposure to lethal high temperatures.
2. 2.|Within 1–2 h of an initial exposure to the critical thermal maximum (CTM), the CTM of two species of amphibians and two species of fish had increased significantly above the initial level and then decreased to the initial level within 24 h.
3. 3.|Experiments with exposure to sub-CTM temperatures and multiple exposures to the CTM indicated that hardening requires exposure to the CTM and may be the maximum CTM attainable by the animal.
4. 4.|Diel and seasonal variation had significant effects on hardening ability.
5. 5.|Field evidence suggests that heat hardening is adaptive in that it provides an acute means of adjustment to extreme fluctuations in diurnal temperatures.
Author Keywords: Acclimation; critical thermal maxima; diel variation; fish; heat hardening; salamanders; seasonal variation; thermal tolerance; Notropis lutrenis; Pimephales promelas; Rana berlanieri; Notophalmus viridescens 相似文献
1. 1.Thermal parameter of the four Gerbillurus species measured in the laboratory were examined in relation to their micro-environments in a xeric habitat.
2. 2.Basal metabolic rates (BMR) were lower than predicted, while thermoneutral zonds (TNZ) were narrow and exceeded burrow temperatures.
3. 3.Body temperatures (Tb) were regulated over a range of ambient temperatures (Ta). Evaporative water loss was used as a short-term cooling mechanism to reduce hyperthermia above the TNZ.
4. 4.Conductance was low below the TNZ to reduce heat loss.
5. 5.Adaptation to low temperatures is important for gerbils when active at night.
6. 6.The adaptive significance of the thermal biology of Gerbillurus is discussed in relation to phylogeny, distribution, food availability and nocturnal activity.
Author Keywords: Gerbillurus; thermal preferences; temperature regulation; oxygen consumption; conductance; evaporative water loss; behavioural avoidance 相似文献
1. 1. In a diel cycle Procambarus clarkii has two preferred temperatures: 24.0 ± 0.15 SEM °C during the day and 26.7 ± 0.13 SEM °C at night.
2. 2. The preferred temperatures are independent from the weight of the organisms.
3. 3. In the photophase the animals are dispersed, in the scotophase they congregate.
4. 4. The crawfish seem to feed during the thermal interphases.
5. 5. Animals in a constantly dark condition maintain a diel preferendum of temperature.
Author Keywords: Diel thermoregulation; Procambarus clarkii 相似文献
1. Entomopathogenic nematodes penetrate and kill Galleria mellonella within 48 h at optimal temperatures.
2. Low temperature induces infection latency, preventing host death until optimal conditions resume.
3. Infected Galleria survived 25 days at 5°C. On transfer to 25°C, 100% and 12.5% of Steinernema carpocapsae and Steinernema riobravis infected larvae died within 72 h.
4. Infective juvenile penetration decreased with decreasing temperature; declining from 49.7 and 49.3 nematodes/host at 25°C to 6.3 and 0.25 nematodes/host at 5°C for S. carpocapsae and S. riobravis, respectively.
5. Latent infection occurs, albeit infrequently, due to low host penetration at low temperature.
Author Keywords: Nematode; Steinernema carpocapsae; Steinernema riobravis; Low temperature 相似文献
1. 1.|The metabolic role of the thyroid gland was studied in intact snakes, Naja naja and Ptyas korros treated with tri-iodo-thyronine (T3) and thyroxine (T4) and in thyroidectomized (Tx) N. naja kept at 21°C by analyzing tissue composition and glycogen phosphorylase a activity.
2. 2.|Liver weight was unaffected by thyroid hormone injection in both species but decreases in liver glycogen followed T3 or T4 injection, and there was an increase in liver glycogen in N. naja. These changes in liver glycogen were accompanied by a decrease in glycogen phosphorylase a activity with T3 injection. T3 decreased muscle glycogen in Ptyas and Tx increased it in N. naja.
3. 3.|T3 increased % liver lipid in Ptyas but not in Naja.
4. 4.|Between species, there were differences in liver weight, blood glucose level, cholesterol level and % muscle lipid.
5. 5.|The results showed that thyroid hormones affected carbohydrate and lipid metabolism at a low temperature of 21°C, although the significance is not known.
Author Keywords: Snake, metabolism; liver glycogen and lipid; low temperature; Naja naja; Ptyas korros 相似文献
1. 1.The changes in fatty acid composition of trout liver phosphatidyl-choline, when the environmental temperature was increased, resulted in modifications in the amounts of the different molecular species.
2. 2.In vivo, incorporation of 32P occurred more rapidly in the molecular species with high degree of unsaturation.Temperature acclimation did not modify the relative proportions of label shown in the five subfractions.
3. 3.In vitro incorporation of 14C-methyl-choline also occurred more rapidly in the most unsaturated molecular species. However, when the incubation temperature was raised, the proportion of label decreased in the unsaturated fractions.
Author Keywords: Acclimation; 14C-choline incorporation; environmental temperature; fatty acid; molecular species; 32P incorporation; phosphatidyl-choline; trout 相似文献