Dispersal response to climate change: scaling down to intraspecific variation

Range shift, a widespread response to climate change, will depend on species abilities to withstand warmer climates. However, these abilities may vary within species and such intraspecific variation can strongly impact species responses to climate change. Facing warmer climates, individuals should disperse according to their thermal optimum with consequences for species range shifts. Here, we studied individual dispersal of a reptile in response to climate warming and preferred temperature using a semi‐natural warming experiment. Individuals with low preferred temperatures dispersed more from warmer semi‐natural habitats, whereas individuals with higher preferred temperatures dispersed more from cooler habitats. These dispersal decisions partly matched phenotype‐dependent survival rates in the different thermal habitats, suggesting adaptive dispersal decisions. This process should result into a spatial segregation of thermal phenotypes along species moving ranges which should facilitate local adaptation to warming climates. We therefore call for range shift models including intraspecific variation in thermal phenotype and dispersal decision.     

Heart rates in the captive, free-ranging beaver

1. Heart rates of beaver (Castor canadensis) under free-ranging captive conditions for active behaviors and resting in water (approximately 121 beats/min) were significantly (P less than 0.01) higher than for resting on land (100 beats/min). 2. Although no transient recovery tachycardia was evident in swimming heart rates following diving, average swimming heart rates were higher (127 beats/min) after diving than after other precursor behaviors (123 beats/min). 3. Beaver exhibited bradycardia when sleeping (75 beats/min), diving (61 beats/min), and when threatened on land (57 beats/min). 4. The respiratory sinus arrhythmia indicated a respiratory rate of 15 breaths/min. 5. Cold temperatures (approximately 0 degree C) elicited higher heart rates than did warmer temperatures (approximately 20 degrees C) in active, non-diving behaviors (P less than 0.05).     

Holocene climate changes and warm man-made refugia may explain why a sixth of British butterflies possess unnatural early-successional habitats

Analyses of their habitats indicate that 18% of British butterfly species are restricted to the earliest seral stages of ecosystems, whereas the same species occupy later seral stages in central Europe, where spring and summer temperatures are warmer. The microclimates of their British habitats are exceptionally warm, compensating for the cooler climate. Most of these British habitats are also ephemeral, and have long depended on man for their creation and regeneration This poses the question of where these species lived before man created their habitats, roughly 6000 BP, I suggest that they are relics from a period when British summers were warmer than today, and that they avoided extinction when the climate cooled by moving into warm refugia created by prehistoric man within three types of ecosystem If summer temperatures become warmer, these species should return to later seral stages that are commoner and less dependent on man.     

Position of patient and respiratory function in immediate postoperative period.

Respiratory function was studied in 19 patients placed in both the supine and sitting positions in the early postoperative period. Although the sitting position was expected to improve respiratory function, no such advantage was found; instead, a small but statistically significant deterioration in arterial oxygenation was found in most patients when sitting up. It is concluded that no respiratory benefit should be expected from sitting patients up in the early postoperative period.     

Matter production processes ofReineckia carnea Kunth,an evergreen forest floor herb in the warm-temperate region of Japan

The growth and matter production were examined forReineckia carnea, an evergreen herb growing on the forest floor in a warm-temperate region. Seasonal change in the biomass of plants growing in the field was estimated from the harvested sample plants. Carbohydrate contents and respiration rates were measured for analysis of dry matter economy. Light intensity and temperature on the forest floor were periodically measured. In mid-spring the biomass reached a maximum which was about half again its minimum value, found in autumn. Two phases, the productive phase in cooler seasons and the developmental phase in warmer seasons, were distinguished from the annual growth pattern of this plant. In cooler seasons, positive net production was found without any morphological changes, resulting in active accumulation of reserves which were mainly soluble sugars. This high net production seems to be closely related to the favorable light conditions and low respiratory losses. In warmer seasons, though new organs were developed, net production remained low or was even negative. The morphological development of this plant in these seasons depended mostly on reserves previously accumulated. This characteristic feature of annual matter economy is considered to be common to evergreen plants on the forest floor in warm regions.     

Thermoregulation behaviour in codling moth larvae

Abstract. The thermoregulation behaviour of the codling moth, Cydia pomonella, is investigated in temperature gradient experiments with larvae feeding within apples, and with mature larvae searching for cocooning sites. Feeding larvae appear to prefer the apple hemisphere with a higher temperature (i.e. they build larger cavities in the radiated, warmer part of the fruit). The proportion of larval cavities in the warmer hemisphere is positively related to increasing apple temperature on that side, as well as to the temperature difference between the warm and the cool fruit hemisphere. The mechanism in feeding larvae can be termed as cryptic basking because, during microhabitat selection, the caterpillars exploit temperature differences that are caused explicitly by incident solar radiation. Fifth-instar larvae in search of cocooning sites show no temperature preference within the large gradient offered (9–29 °C), with no difference between males and females. During larval development, the insect changes its thermoregulation behaviour in response to a possible shift in benefits of an elevated body temperature with respect to environmental conditions. Both the thermoregulation behaviour and such a shift of behavioural response should be respected when simulating body temperatures of the species.     

Adenylate control contributes to thermal acclimation of sugar maple fine‐root respiration in experimentally warmed soil

We investigated the occurrence of and mechanisms responsible for acclimation of fine‐root respiration of mature sugar maple (Acer saccharum) after 3+ years of experimental soil warming (+4 to 5 °C) in a factorial combination with soil moisture addition. Potential mechanisms for thermal respiratory acclimation included changes in enzymatic capacity, as indicated by root N concentration; substrate limitation, assessed by examining nonstructural carbohydrates and effects of exogenous sugar additions; and adenylate control, examined as responses of root respiration to a respiratory uncoupling agent. Partial acclimation of fine‐root respiration occurred in response to soil warming, causing specific root respiration to increase to a much lesser degree (14% to 26%) than would be expected for a 4 to 5 °C temperature increase (approximately 55%). Acclimation was greatest when ambient soil temperature was warmer or soil moisture availability was low. We found no evidence that enzyme or substrate limitation caused acclimation but did find evidence supporting adenylate control. The uncoupling agent caused a 1.4 times greater stimulation of respiration in roots from warmed soil. Sugar maple fine‐root respiration in warmed soil was at least partially constrained by adenylate use, helping constrain respiration to that needed to support work being performed by the roots.     

Comparison of the effector mechanisms during endotoxin fever in the adult rabbit.

In unanaesthetized adult rabbits an intravenous dose of E. coli endotoxin evoked a febrile rise in colonic temperature at ambient temperatures of 9 to 31 degrees C. The rise in colonic temperature and oxygen consumption did not depend on the ambient temperature, while, among the heat loss effectors, in warmer environments only the depression of respiratory heat loss and in cooler environments only ear skin vasoconstriction contributed to the febrile rise in colonic temperature. In moderately warm environments the endotoxin first induced a maximum inhibition of respiratory frequency and this was followed by vasoconstriction. Later, a transient rise in oxygen consumption occurred. During defervescence the timing of the effectors was reversed. The results showed that a febrile response is not necessarily characterized by simultaneous changes in the thermoregulatory effector mechanisms.     

Acclimation of respiratory temperature responses in northern and southern populations of Pinus banksiana

Temperature acclimation of respiration may contribute to climatic adaptation and thus differ among populations from contrasting climates. Short-term temperature responses of foliar dark respiration were measured in 33-yr-old trees of jack pine (Pinus banksiana) in eight populations of wide-ranging origin (44-55 degrees N) grown in a common garden at 46.7 degrees N. It was tested whether seasonal adjustments in respiration and population differences in this regard resulted from changes in base respiration rate at 5 degrees C (R(5)) or Q(10) (temperature sensitivity) and covaried with nitrogen and soluble sugars. In all populations, acclimation was manifest primarily through shifts in R(5) rather than altered Q(10). R(5) was higher in cooler periods in late autumn and winter and lower in spring and summer, inversely tracking variation in ambient air temperature. Overall, R(5) covaried with sugars and not with nitrogen. Although acclimation was comparable among all populations, the observed seasonal ranges in R(5) and Q(10) were greater in populations originating from warmer than from colder sites. Population differences in respiratory traits appeared associated with autumnal cold hardening. Common patterns of respiratory temperature acclimation among biogeographically diverse populations provide a basis for predicting respiratory carbon fluxes in a wide-ranging species.     

Testing temperature effects on woodboring beetles associated with oak dieback

A warmer climate may potentially have a strong effect on the health status of European oak forests by weakening oak trees and facilitating mass reproduction of wood boring insects. We did a laboratory experiment in Slovakia to study the response of major pest beetles of oak and their parasitoids to different temperature regimes as background for predicting climatic effects and improving management tools of European oak forests. With higher temperatures the most important oak pest Scolytus intricatus emerged much earlier, which indicate that completion of a second generation and increased damage further north in European oak forests may be possible. Lower temperatures gave longer larval galleries and more offspring per parents but still lower beetle production due to semivoltine life cycle. For buprestids and longhorn beetles warmer temperatures resulted in more emerging offspring and a shift towards earlier emergence in the same season, but no emergence in the first season indicated that a change to univoltine populations is not likely. Reduced development success of parasitoids at the highest temperatures (25/30 °C) indicates a loss of population regulation for pest beetle populations. A warmer climate may lead to invasion of other population-regulating parasitoids, but also new serious pest may invade. With expected temperature increases it is recommended to use trap trees both in April and in June, and trap trees should be removed within 2 months instead 1 year as described in the current standard.     

Models projecting the fate of fish populations under climate change need to be based on valid physiological mechanisms

Some recent modelling papers projecting smaller fish sizes and catches in a warmer future are based on erroneous assumptions regarding (i) the scaling of gills with body mass and (ii) the energetic cost of ‘maintenance’. Assumption (i) posits that insurmountable geometric constraints prevent respiratory surface areas from growing as fast as body volume. It is argued that these constraints explain allometric scaling of energy metabolism, whereby larger fishes have relatively lower mass‐specific metabolic rates. Assumption (ii) concludes that when fishes reach a certain size, basal oxygen demands will not be met, because of assumption (i). We here demonstrate unequivocally, by applying accepted physiological principles with reference to the existing literature, that these assumptions are not valid. Gills are folded surfaces, where the scaling of surface area to volume is not constrained by spherical geometry. The gill surface area can, in fact, increase linearly in proportion to gill volume and body mass. We cite the large body of evidence demonstrating that respiratory surface areas in fishes reflect metabolic needs, not vice versa, which explains the large interspecific variation in scaling of gill surface areas. Finally, we point out that future studies basing their predictions on models should incorporate factors for scaling of metabolic rate and for temperature effects on metabolism, which agree with measured values, and should account for interspecific variation in scaling and temperature effects. It is possible that some fishes will become smaller in the future, but to make reliable predictions the underlying mechanisms need to be identified and sought elsewhere than in geometric constraints on gill surface area. Furthermore, to ensure that useful information is conveyed to the public and policymakers about the possible effects of climate change, it is necessary to improve communication and congruity between fish physiologists and fisheries scientists.     

Paradox: increased blood perfusion to the face <Emphasis Type="BoldItalic">enhances</Emphasis> protection against frostbite while it <Emphasis Type="BoldItalic">lowers</Emphasis> wind chill equivalent temperatures

A model of facial heat exchange in cold and windy environments is presented. The tissue is depicted as a hollow cylinder and the model includes heat conduction and heat transport by blood circulation from the warmer core. A steady-state solution facilitating the estimation of wind chill equivalent temperature (WCET) as a function of the effective wind velocity, air temperature and blood perfusion rate was obtained. The results quantify and demonstrate the elevation of skin temperatures caused by increased flow of warmer blood from the inner core to the face. Elevated facial temperatures, while enhancing protection against frostbite and other cold-related injuries, also increase heat loss to the colder environment. Paradoxically, such elevated facial temperatures cause WCETs, as estimated by the prevailing definition, to attain lower rather than higher values, indicating, in fact, increased risk of frostbite. The results of this study should be useful in understanding and quantifying the effects of blood perfusion in protection against cold-related injuries. They should also be considered in the re-evaluation and re-formulation of the concept of wind chill, which has been a useful cold weather indicator for decades.     

Electron microscopy of the spindle in locally heated cells

Individual living cells in metaphase were exposed to a steep temperature gradient by placing a microheater near one spindle pole. The cells were then fixed and the spindle was examined by electron microscopy. The structure of the warmer half-spindle differed from the cooler half-spindle in several ways. Kinetochore microtubules were nearly parallel in the warmer half-spindle but were divergent in the cooler. The total length of microtubules in the warmer half-spindle was 52 per cent greater and the number of kinetochore microtubules per kinetochore averaged 16 per cent higher than in the cooler half-spindle. The warmer half-spindle was longer than the cooler. These observations clearly demonstrate a locally enhanced assembly of microtubules in the warmer half-spindle. The electron microscope study makes still clearer the unusual character of chromosome movement in the differentially heated cells: the structure of the warmer half-spindle is hard to distinguish from that in normal cells, yet chromosome movement there is far slower than normal (Nicklas, 1979).     

Facilitative interactions do not wane with warming at high elevations in the Andes

Positive interactions between species are known to play an important role in the structure and dynamics of alpine plant communities. The balance between negative and positive interactions is known to shift along spatial and temporal gradients, with positive effects prevailing over negative ones as the environmental stress increases. Thus, this balance is likely to be affected by climate change. We hypothesized that increases in temperature (a global warming scenario) should decrease the importance of positive interactions for the survival and growth of alpine plant species. To test this hypothesis, we selected individuals of the native grass species Hordeum comosum growing within the nurse cushion species Azorella madreporica at 3,600 m.a.s.l. in Los Andes (Chile), and performed nurse removal and seedling survival experiments under natural and warmer conditions. For warmer conditions, we used open-top chambers, which increased the temperature by 4 °C. After two growing seasons, we compared the effect of nurse removal on the survival, biomass, and photochemical efficiency of H. comosum individuals under warmer and natural conditions. Nurse removal significantly decreased the survival, biomass, and photochemical efficiency of H. comosum, demonstrating the facilitative effects of nurse cushions. Seedling survival was also enhanced by cushions, even under warmer conditions. However, warmer conditions only partially mitigated the negative effects of nurse removal, suggesting that facilitative effects of cushions do not wane under warmer conditions. Thus, facilitative interactions are vital to the performance and survival of alpine species, and these positive interactions will continue to be important in the warmer conditions of the future in high-alpine habitats.     

Thermal history influences lesion recovery of the threatened Caribbean staghorn coral Acropora cervicornis under heat stress

Anthropogenic climate change is the biggest threat to coral reefs, but reef restoration efforts are buying time for these ecosystems. Lesion recovery, which can be a determinant of colony survival, is particularly important for restored species. Here, we evaluate lesion recovery of 18 genets of Acropora cervicornis from Florida reefs with different thermal regimes in a temperature challenge experiment. Genets demonstrated significant variability in healing, which greatly slowed under heat stress. Only 35% of fragments healed at 31.5 °C compared to 99% at 28 °C. Donor reef thermal regime significantly influenced lesion recovery under heat stress with corals from warmer reefs demonstrating greater healing than corals from cooler reefs, but did not influence recovery under ambient conditions. These findings should encourage practitioners to utilize rapidly healing genets, avoid fragmentation in high temperatures, and incorporate assisted relocation by moving corals from warmer to cooler reefs, where they might succeed under future climate conditions.

     

Latitudinal compensation in oyster ciliary activity

1. Theories of latitudinal compensation predict that individuals living in colder temperature regimes should physiologically compensate for the slowing of standard physiological rates, owing to the relatively low temperature of their local environments, by increasing their metabolic rate in colder water temperatures relative to individuals living in warmer water temperature regimes.
2. This hypothesis was tested with oyster strains originally from geographically separated populations that were raised in a common environment for seven generations. The physiological parameter measured was ciliary activity across a temperature gradient.
3. Support for the latitudinal compensation hypothesis was found: the strain originally from the colder temperature regime had more active cilia at lower experimental temperatures than individuals originally from the warmer temperature regime. Ciliary activity of the more northern Long Island Sound oysters was significantly greater than activity in the more southern Delaware Bay oysters at temperatures of –1, 2 and 6 °C.
4. These results suggest that there is genetically based physiological differentiation between these populations of oysters consistent with the latitudinal compensation for local temperature regime.     

EPINEPHRINE HAND NEBULIZER IN ASTHMA—Technique of Use,Clinical Aspects

It behooves the physician seeking relief for asthmatic patients not to be casual about the epinephrine hand nebulizer and the manner in which it is used. Patients who claim to get no relief from the nebulizer should be asked to demonstrate their technique. If the nebulizer produces a hardly visible mist, it should be discarded. For many patients, the goal in spraying by hand must be the production of more or less continuous and voluminous aerosol, regardless of the phase of respiration, in order to effect relief. If the respiratory pattern has not deviated too far from normal in rate and depth, inhalations may be carried out in courses or cycles of about a half-minute duration and spaced a few minutes apart. If the respiratory pattern is abnormal during the act of spraying, it must be corrected.Inhaled epinephrine aerosols as constituted today appear to be somewhat irritating to the mouth, throat, and upper portion of the pulmonary tract of some persons, but it has not been convincingly demonstrated that serious and permanent damage to the lower respiratory tract of humans can occur from long-continued use of inhaled epinephrine.     

Epinephrine hand nebulizer in asthma; technique of use,clinical aspects

It behooves the physician seeking relief for asthmatic patients not to be casual about the epinephrine hand nebulizer and the manner in which it is used. Patients who claim to get no relief from the nebulizer should be asked to demonstrate their technique. If the nebulizer produces a hardly visible mist, it should be discarded. For many patients, the goal in spraying by hand must be the production of more or less continuous and voluminous aerosol, regardless of the phase of respiration, in order to effect relief. If the respiratory pattern has not deviated too far from normal in rate and depth, inhalations may be carried out in courses or cycles of about a half-minute duration and spaced a few minutes apart. If the respiratory pattern is abnormal during the act of spraying, it must be corrected. Inhaled epinephrine aerosols as constituted today appear to be somewhat irritating to the mouth, throat, and upper portion of the pulmonary tract of some persons, but it has not been convincingly demonstrated that serious and permanent damage to the lower respiratory tract of humans can occur from long-continued use of inhaled epinephrine.     

Decreased structural defence of an invasive thistle under warming

Plant structural defences play a key role in preventing fitness loss due to herbivory. However, how structural defences are affected by potential climate change is rarely examined. We examined how leaf morphological traits that relate to the structural defence of an invasive thistle, Carduus nutans, change in a warmer climate. We manipulated warming using open-top chambers (OTCs) and examined the morphology of leaves at three different positions (the 5th, 10th and 15th leaves, counted from the top of the plant) in two destructive summer censuses. We found that structural defence traits were different under ambient versus warmed conditions. Prickle densities (both the number of prickles per leaf area and the number of prickles per leaf mass) were significantly lower in plants grown in a warmer climate. Our results suggest that plant structural defences may be reduced under warming, and therefore should be considered when examining species' responses to climate change.     

Dynamic thermal responses of five commercially available infant radiant warmer systems

Five commercially available infant radiant warmer systems were characterized through radiant-energy measurements at the mattress surface under identical environmental conditions. Average irradiance levels for each warmer were then calculated. In addition, all systems were thermally evaluated for warm-up time using the International IEC standard black anodized aluminum disk simulator. Warm-up time and radiant-energy bed mapping tests were conducted in manual mode. To assess thermal performance under dynamic conditions, skin and core temperatures were measured using a patient simulator test-load device. Dynamic patient simulator response-time data and side-wall temperature data are provided. The radiative heat contribution from the warmer side walls on patient simulator core and skin temperatures was demonstrated. Extreme differences in warmer performances and energy to the mattress surface are documented. Differences in infant radiant warmer performances are principally due to heater-element composition, reflector design, and heater-to-mattress distance.