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Thermal Physiology (thermal + physiology)
Selected AbstractsInterplay between global patterns of environmental temperature and variation in nonshivering thermogenesis of rodent species across large spatial scalesGLOBAL CHANGE BIOLOGY, Issue 9 2009ENRIQUE RODRÍGUEZ-SERRANO Abstract The purpose of this study was to test for correlations of mass-independent nonshivering thermogenesis (NST) in rodent species with climatic factors such as maximum and minimum geographic temperature. We first analyzed whether the responses of rodents show a phylogenetic signal. If so, and if the NST over a broad geographical range is similar, then such responses probably reflect physiological evolutionary adaptation. Our results show that NST did not show phylogenetic signal, appears to be evolutionary labile and is negatively correlated with environmental temperature. We predicted that species evolved in cold climates will exhibit higher mass-independent NST than species from warmer habitats. Indeed, we observed that the relationships between mass-independent NST and minimum temperature (rs=,0.411, P=0.009) as well as between NST and maximum temperature (rs=,0.443, P=0.004) were both negatively and significantly correlated, thus supporting our predictions. Thus, thermal physiology may be a significant factor underlying the ecological and evolutionary success of animals. Finally we suggest that due to the pressing need to explain and predict the likely biological impact of climatic change, advances in this field are necessary. [source] Differences between young adults and elderly in thermal comfort, productivity, and thermal physiology in response to a moderate temperature drift and a steady-state conditionINDOOR AIR, Issue 4 2010L. Schellen Abstract, Results from naturally ventilated buildings show that allowing the indoor temperature to drift does not necessarily result in thermal discomfort and may allow for a reduction in energy use. However, for stationary conditions, several studies indicate that the thermal neutral temperature and optimum thermal condition differ between young adults and elderly. There is a lack of studies that describe the effect of aging on thermal comfort and productivity during a moderate temperature drift. In this study, the effect of a moderate temperature drift on physiological responses, thermal comfort, and productivity of eight young adults (age 22,25 year) and eight older subjects (age 67,73 year) was investigated. They were exposed to two different conditions: S1-a control condition; constant temperature of 21.5°C; duration: 8 h; and S2-a transient condition; temperature range: 17,25°C, duration: 8 h, temperature drift: first 4 h: +2 K/h, last 4 h: ,2 K/h. The results indicate that thermal sensation of the elderly was, in general, 0.5 scale units lower in comparison with their younger counterparts. Furthermore, the elderly showed more distal vasoconstriction during both conditions. Nevertheless, TS of the elderly was related to air temperature only, while TS of the younger adults also was related to skin temperature. During the constant temperature session, the elderly preferred a higher temperature in comparison with the young adults. Practical Implications ,Because the stock of fossil fuels is limited, energy savings play an important role. Thermal comfort is one of the most important performance indicators to successfully apply measures to reduce the energy need in buildings. Allowing drifts in indoor temperature is one of the options to reduce the energy demand. This study contributes to the knowledge concerning the effects of a moderate temperature drift and the age of the inhabitants on their thermal comfort. [source] What determines a species' geographical range?JOURNAL OF ANIMAL ECOLOGY, Issue 1 2010Thermal biology, latitudinal range size relationships in European diving beetles (Coleoptera: Dytiscidae) Summary 1.,The geographical range sizes of individual species vary considerably in extent, although the factors underlying this variation remain poorly understood, and could include a number of ecological and evolutionary processes. A favoured explanation for range size variation is that this result from differences in fundamental niche breadths, suggesting a key role for physiology in determining range size, although to date empirical tests of these ideas remain limited. 2.,Here we explore relationships between thermal physiology and biogeography, whilst controlling for possible differences in dispersal ability and phylogenetic relatedness, across 14 ecologically similar congeners which differ in geographical range extent; European diving beetles of the genus Deronectes Sharp (Coleoptera, Dytiscidae). Absolute upper and lower temperature tolerance and acclimatory abilities are determined for populations of each species, following acclimation in the laboratory. 3.,Absolute thermal tolerance range is the best predictor of both species' latitudinal range extent and position, differences in dispersal ability (based on wing size) apparently being less important in this group. In addition, species' northern and southern range limits are related to their tolerance of low and high temperatures respectively. In all cases, absolute temperature tolerances, rather than acclimatory abilities are the best predictors of range parameters, whilst the use of independent contrasts suggested that species' thermal acclimation abilities may also relate to biogeography, although increased acclimatory ability does not appear to be associated with increased range size. 4.,Our study is the first to provide empirical support for a relationship between thermal physiology and range size variation in widespread and restricted species, conducted using the same experimental design, within a phylogenetically and ecologically controlled framework. [source] Thermal tolerance and geographical range size in the Agabus brunneus group of European diving beetles (Coleoptera: Dytiscidae)JOURNAL OF BIOGEOGRAPHY, Issue 2 2008P. Calosi Abstract Aim, Within clades, most taxa are rare, whilst few are common, a general pattern for which the causes remain poorly understood. Here we investigate the relationship between thermal performance (tolerance and acclimation ability) and the size of a species' geographical range for an assemblage of four ecologically similar European diving beetles (the Agabus brunneus group) to examine whether thermal physiology relates to latitudinal range extent, and whether Brown's hypothesis and the environmental variability hypothesis apply to these taxa. Location, Europe. Methods, In order to determine the species tolerances to either low or high temperatures we measured the lethal thermal limits of adults, previously acclimated at one of two temperatures, by means of thermal ramping experiments (± 1°C min,1). These measures of upper and lower thermal tolerances (UTT and LTT respectively) were then used to estimate each species' thermal tolerance range, as total thermal tolerance polygons and marginal UTT and LTT thermal polygons. Results, Overall, widespread species have higher UTTs and lower LTTs than restricted ones. Mean upper lethal limits of the Agabus brunneus group (43 to 46°C), are similar to those of insects living at similar latitudes, whilst mean lower lethal limits (,6 to ,9°C) are relatively high, suggesting that this group is not particularly cold-hardy compared with other mid-temperate-latitude insects. Widespread species possess the largest thermal tolerance ranges and have a relatively symmetrical tolerance to both high and low temperatures, when compared with range-restricted relatives. Over the temperature range employed, adults did not acclimate to either high or low temperatures, contrasting with many insect groups, and suggesting that physiological plasticity has a limited role in shaping distribution. Main conclusions, Absolute thermal niche appears to be a good predictor of latitudinal range, supporting both Brown's hypothesis and the environmental variability hypothesis. Restricted-range species may be more susceptible to the direct effect of climate change than widespread species, notwithstanding the possibility that even ,thermally-hardy', widespread species may be influenced by the indirect effects of climate change such as reduction in habitat availability in Mediterranean areas. [source] The value of infrared thermography for research on mammals: previous applications and future directionsMAMMAL REVIEW, Issue 3 2007DOMINIC J. MCCAFFERTY ABSTRACT 1Infrared thermography (IRT) involves the precise measurement of infrared radiation which allows surface temperature to be determined according to simple physical laws. This review describes previous applications of IRT in studies of thermal physiology, veterinary diagnosis of disease or injury and population surveys on domestic and wild mammals. 2IRT is a useful technique because it is non-invasive and measurements can be made at distances of <1 m to examine specific sites of heat loss to >1000 m to count large mammals. Detailed measurements of surface temperature variation can be made where large numbers of temperature sensors would otherwise be required and where conventional solid sensors can give false readings on mammal coats. Studies need to take into account sources of error due to variation in emissivity, evaporative cooling and radiative heating of the coat. 3Recent advances in thermal imaging technology have produced lightweight, portable systems that store digital images with high temperature and spatial resolution. For these reasons, there are many further opportunities for IRT in studies of captive and wild mammals. [source] Circadian variation in resource quality: leaf water content and its relevance to eastern grey kangaroo Macropus giganteus and common wombat Vombatus ursinusAUSTRAL ECOLOGY, Issue 2 2010PETER J. JARMAN Abstract Green leaves of six grass species in temperate Australia showed considerable circadian variation (especially in summer) in water content, which peaked late in the night and fell from sunrise to an afternoon minimum. In summer, water content of a set of ,wetter' species (Axonopus affinis, Pennisetum clandestinum and Paspalum dilatatum) was consistently higher and varied less profoundly through the 24 h than that of a ,drier' set (Imperata cylindrica, Poa labillardieri and Themeda triandra). Hour-to-hour and day-to-day variation in leaf water content of P. dilatatum in summer partly but imperfectly reflected ambient temperature. Recognizing the risks for herbivores of visiting water sources, we considered leaf water content as a source of free water for leaf-grazing herbivores, eastern grey kangaroos Macropus giganteus and common wombats Vombatus ursinus. Using known field metabolic rates, energy requirements and digestive efficiencies, we calculated these two species' free-water intakes when satisfying their energy needs with these grasses but distributing their grazing in different schedules. Both species would obtain more free water by their observed foraging schedules than by random or daytime-only schedules. We calculated that the measured grasses could satisfy the water requirements of wombats but not always those of kangaroos, who would need to drink when forage water content was less than about 70%. Water content of grass leaf could rise above and fall below this value within a day, creating some scope for kangaroos to manage their need to visit water by adjusting foraging schedules or choice of grass species. In future studies, circadian variation in leaf water content should be considered as a factor (together with their thermal physiology) driving herbivores' activity scheduling, and affecting their dietary selection. [source] | ||||||||||