Diurnal Temperature Fluctuations Research Articles

'Dual-reference' method for high-precision infrared measurement of leaf surface temperature under field conditions.

Temperature is a key control over biological activities from the cellular to the ecosystem scales. However, direct, high-precision measurements of surface temperature of small objects, such as leaves, under field conditions with large variations in ambient conditions remain rare. Contact methods, such as thermocouples, are prone to large errors. The use of noncontact remote-sensing methods, such as thermal infrared measurements, provides an ideal solution, but their accuracy has been low (c. 2°C) owing to the necessity for corrections for material emissivity and fluctuations in background radiation Lbg . A novel 'dual-reference' method was developed to increase the accuracy of infrared needle-leaf surface temperature measurements in the field. It accounts for variations in Lbg and corrects for the systematic camera offset using two reference plates. We accurately captured surface temperature and leaf-to-air temperature differences of needle-leaves in a forest ecosystem with large diurnal and seasonal temperature fluctuations with an uncertainty of ± 0.23°C and ± 0.28°C, respectively. Routine high-precision leaf temperature measurements even under harsh field conditions, such as demonstrated here, opens the way for investigating a wide range of leaf-scale processes and their dynamics.

A Research Method for Semi-Automated Large-Scale Cultivation of Maize to Full Maturity in an Artificial Environment

There are unique advantages and disadvantages to using the field, greenhouse, growth chamber, and media-less techniques for growing maize (Zea mays L.) for research purposes. Soil-buffered nutrients such as phosphorus (P) do not allow for precise control of solution concentrations in the field, while greenhouses, growth chambers, and hydroponics provide limiting conditions. The objectives of this study were to develop a practical technique for productively cultivating several maize plants from seed to physiological maturity (R6) in a grow room environment, with precise control of nutrient availability and timing, and evaluate its utility for the purpose of measuring plant responses to variations in nutrient concentrations. The construction and testing of a semi-automated grow room for conducting nutrient studies on 96 maize plants utilizing simulated or artificial conditions are described. Plant growth response to a range of solution phosphorus (P) concentrations was tested to evaluate the utility of the technique. Maize yield components were measured and compared to values for field-grown plants. Due to ideal conditions and successful simulation of light intensity, diurnal fluctuations in temperature and RH, and changing photoperiod, grain yield and tissue nutrient concentrations were comparable to field-grown maize, although with greater shoot biomass. Plants responded positively to increased P concentrations in fertigation. The technique can be used for large-scale plant nutrient studies that require precise control of bioavailability and timing as well as manipulation of light intensity and photoperiod duration.

Diurnal and seasonal fluctuations in cloacal temperature in helmeted guinea-fowl (Numida meleagris) and the effect of ascorbic acid

ABSTRACT The study evaluated ascorbic acid (AA) effects on diurnal fluctuations in cloacal temperature (CT) in guinea-fowls. Twenty guinea-fowls were each assigned to two groups: Group I was administered with distilled water and Group II was treated daily with AA (50 mg/kg) orally. Measurements of dry-bulb temperature (DBT) and relative humidity (RH), to obtain temperature-humidity index (THI), and CT of each guinea-fowl were taken concurrently in the pen thrice a day for 3 days, 1 week apart, during the rainy, cold-dry (harmattan) and hot-dry seasons. Values of THI during the rainy (26.16 ± 0.36) and hot-dry (28.50 ± 1.11) seasons were above the thermoneutral zone for avian species (21), indicating that the guinea-fowls were exposed to heat stress in the seasons. Values of CT were higher (P < 0.05) in controls than experimental guinea-fowls (rainy, 42.17 ± 0.06 vs 42.04 ± 0.08; hot-dry, 42.78 ± 0.11 vs 42.52 ± 0.04°C) and were outside the normal range for avian species. Administration of AA modulated CT fluctuations by decreasing the values in hot-dry season. In conclusion, the hot-dry season was the most stressful for guinea-fowls, and AA modulated considerably CT fluctuations during the season.

ASSESSMENT OF SOME METEOROLOGY DATA OF AVERAGE MONTHLY AIR TEMPERATURE OVER MONGOLIA USING DIGITAL ELEVATION MODEL (DEM) AND GIS TECHNIQUES

Abstract. The climate of Mongolia is a harsh continental climate with four distinctive seasons, high annual and diurnal temperature fluctuations, and low rainfall. Because of the country’s high altitude, it is generally colder than that of other countries in the same latitude. This study focuses on evaluating the suitability of two interpolation methods in terms of their accuracy at the air temperature data in Mongolia. Four data sets of air temperature from 1982 to 2019 in 60 meteorological stations located in Mongolia and elaborated from a 90 m resolution digital elevation model (DEM), latitude and longitude using two interpolation methods. ArcGIS is used to produce the spatially distributed air temperature data by using IDW and ordinary kriging. Three statistical methods are multiple regression, RMSE and bias, which showed that the IDW the best for this data from other methods by the results that have been obtained. Statistics on the latitude, longitude and surface elevation of each of the 37 years in Mongolia at 60 meteorological stations have been statistically valid with dependent coefficients at 95–99.9%. As the average air temperature, recorded at the meteorological stations, had a statistical correlation of −0.606 with latitude, 0.295 with longitude, and −0.432 with altitude, a multiple regression equation was developed and a highly accurate map for long terms air temperature covering 1982–2019 using interpolation IDW and Kriging method. Also, the highest RMSE value for maps used IDW was 1.38 while the lowest and average values were 0.03 and 0.44, respectively, and the highest bias was 1.21, lowest 0.95, and average 1.01. As opposed to, highest RMSE value for maps that used Kriging, was 6.16, lowest 0.27 and average 1.08 while highest bias was 1.29 and lowest was 0.85, with 1.01 as average. This demonstrates that IDW offers much better accuracy as opposed to Kriging and shows less bias errors. When the air temperature map that used the IDW method is compared against the meteorological station data the significance was 0.98 and when compared against ERA5 model results, significance was 0.95 showing strong statistical significance. Also, a comparison of air temperature map, processed by Kriging method and the meteorological station data shows 0.97 statistical significance, and comparison with ERA5 model shows (validation) 0.94 significance, which is very high. The mean value of the calculated temperature regression model in Mongolia and the root mean square error 0.02–0.09 for each station indicates that the estimation method is good and can be used in the future.

Genetic and agro-climatic variability in seed fatty acid profiles of Akebia trifoliata (Lardizabalaceae) in China

This study first systematically investigated the differences and correlations of seed oil content, fatty acid (FA) composition and regional agro-climate conditions of Akebia trifoliata from 25 representative distribution areas throughout China. A. trifoliata seeds were rich in oil (30.2 %–48.8 %), but significant (P < 0.01) variations were detected among their FA profiles. Ten major FAs, dominated by oleic acid (OA, 155.9-261.5 mg g−1, 36.6 %–45.2 %), linoleic acid (LA, 113.8–156.4 mg g−1, 23.5 %–30.8 %) and palmitic acid (PA, 101.8–149.1 mg g−1, 20.3 %–25.7 %), were detected and quantified by GC–MS. Noticeably, their ratios of saturated: monounsaturated: polyunsaturated FAs were 1:1.5:1, which was in line with the World Health Organization's recommendation. Latitude, temperature and moisture were the core factors affecting oil accumulation in A. trifoliata. Opposite to PA and LA, the OA and oil content were strongly negatively correlated with high temperature and precipitation, and were higher in northern and eastern seeds. According to the results of correlation and cluster analysis, A. trifoliata germplasms and agro-climate characters of six regions (from cluster III) around latitude 35 °N, where were much colder and drier, and with larger diurnal temperature fluctuations than other regions, were more desirable for commercial cultivation of A. trifoliata for oil processing and for breeding of improved cultivars.

Monthly averages of diurnal temperature variation from meteor radar at Cachoeira Paulista (22.7°S, 45°W), Brazil

Monthly averages of the superposed values of decay times of meteor echoes from underdense meteor trails obtained by meteor radar observations at Cachoeira Paulista (22.7°S, 45°W), Brazil, have been employed to estimate temperature and to study the diurnal temperature fluctuations in the upper mesosphere and lower thermosphere region. The monthly diurnal amplitudes and phases in meteor radar temperatures at Cachoeira Paulista are comparable to those of the westward migrating diurnal tide, with zonal wave number 1, found in the reported temperatures obtained from SABER data, when the observations were obtained during the same period. The diurnal amplitudes in the temperature do not show the semiannual oscillation present in those of the diurnal tide in zonal and meridional winds. The diurnal temperature peaks 4 to 5 h ahead of diurnal tide in the zonal winds and is in anti-phase with the diurnal tide in the meridional winds. The semidiurnal amplitudes of the radar temperature fluctuations also are comparable with SABER westward migrating semidiurnal tide, with zonal wave number 2, and do not present a defined seasonal behavior, while their phases undergo small changes. They lead the semidiurnal tide in the zonal winds by about 4 h during austral summer, but it remains in-phase for the other months, and lead in meridional winds by about 5 to 8 h.

Within- and Trans-Generational Life History Responses to Diurnal Temperature Amplitudes of the Pupal Stage in the Diamondback Moth

Diurnal temperature fluctuations in nature can have a significant effect on many ectodermic traits. However, studies on the effects of diurnal temperature fluctuations on organisms, especially the effects on specific life stages, are still limited. We examined the immediate effects of the same average temperature (25°C) and different temperature amplitudes (±4, ±6, ±8, ±10, ±12°C) on the development and survival of Plutella xylostella (Lepidoptera: Plutellidae). We also assessed carry-over effects on adult longevity, reproduction, development, and survival of offspring across generations. The effect of moderate temperature amplitudes was similar to that of constant temperature. Wide temperature amplitudes inhibited the development of pupae, reduced total reproduction, lowered intrinsic rates of population growth, and slowed the development and survival of eggs on the first day, but the proportion of females ovipositing on the first three days increased. Insects coped with the adverse effects of wide temperature amplitudes by laying eggs as soon as possible. Our results confirmed that a logistic model based on daily average temperature cannot predict development rates under wide temperature amplitudes. These findings highlight the effect of environmental temperature fluctuations at the pupal stage on the development and oviposition patterns of P. xylostella and should be fully considered when predicting field occurrence.

Protein expression plasticity contributes to heat and drought tolerance of date palm

Climate change is increasing the frequency and intensity of warming and drought periods around the globe, currently representing a threat to many plant species. Understanding the resistance and resilience of plants to climate change is, therefore, urgently needed. As date palm (Phoenix dactylifera) evolved adaptation mechanisms to a xeric environment and can tolerate large diurnal and seasonal temperature fluctuations, we studied the protein expression changes in leaves, volatile organic compound emissions, and photosynthesis in response to variable growth temperatures and soil water deprivation. Plants were grown under controlled environmental conditions of simulated Saudi Arabian summer and winter climates challenged with drought stress. We show that date palm is able to counteract the harsh conditions of the Arabian Peninsula by adjusting the abundances of proteins related to the photosynthetic machinery, abiotic stress and secondary metabolism. Under summer climate and water deprivation, these adjustments included efficient protein expression response mediated by heat shock proteins and the antioxidant system to counteract reactive oxygen species formation. Proteins related to secondary metabolism were downregulated, except for the P. dactylifera isoprene synthase (PdIspS), which was strongly upregulated in response to summer climate and drought. This study reports, for the first time, the identification and functional characterization of the gene encoding for PdIspS, allowing future analysis of isoprene functions in date palm under extreme environments. Overall, the current study shows that reprogramming of the leaf protein profiles confers the date palm heat- and drought tolerance. We conclude that the protein plasticity of date palm is an important mechanism of molecular adaptation to environmental fluctuations.

Simulating the thermal impact of substrate temperature on ecological restoration in shallow urban rivers

Managing river temperature in highly urbanized stream systems is critical for maintaining aquatic ecosystems and associated beneficial uses. In this work, we updated and utilized a mechanistic river temperature model, i-Tree Cool River, to evaluate the cooling impacts of two ecological restoration scenarios: (1) an alternative streambed material limecrete and (2) shading effects of tree planting in riparian areas. The i-Tree Cool River model was modified to account for diurnal fluctuations of streambed temperature, which is relevant in shallow urban streams where lack of natural shading combined with low heat capacity of the water column can make diurnal fluctuations relatively extreme. The model was calibrated and validated on a 4.2 km reach of Compton Creek in the Los Angeles River watershed, California. Two native fish, arroyo chub (Gila orcuttii) and unarmored threespine stickleback (Gasterosteus aculeatus williamsoni), were considered the target species for assessing thermal habitat suitability. Key findings include: (1) model performance was improved when accounting for diurnal fluctuations in bed temperature (R2 increased from 0.43 to 0.68); and (2) substrate rehabilitation and tree planting can potentially reduce summertime temperatures to within the documented spawning temperature thresholds for the focal fish species. Using limecrete as an alternative material for the concrete bottom decreased the median river temperature metrics: maximum weekly maximum, maximum weekly average, and minimum weekly minimum temperatures by an average of 3 °C (13%) to 20.4 °C, 19.7 °C, and 17.8 °C, respectively. Tree planting in the riparian corridor decreased the average river temperature metrics by an average of 0.9 °C (4%) to 22.7 °C, 22 °C, and 19 °C, respectively. Combining the two scenarios decreased the river temperature metrics by an average of 4 °C (18%) to 18.2 °C. Therefore, water temperature would not be a limiting factor in potential reintroduction of the focal fish species to Compton Creek if restoration were implemented. Implications of this work could be used by urban forest and water managers for restoring thermally polluted rivers in other urban areas.

Modelling dry-weather temperature profiles in urban stormwater management ponds

One of the unintended consequences of urban stormwater quality management wet ponds is the thermal enrichment of the shallow pond water during the summer months. The outflow from thermally enriched ponds can degrade the cold and cool water aquatic habitat in urban streams. An accurate model of the pond temperature profile is needed to assess the pond effluent thermal load. However, most models developed for this purpose are process-based and not simple to use, requiring a lengthy monitoring dataset to calibrate. This paper introduces a new design/assessment tool to predict the hourly water temperatures in these ponds at different depths during the summer season dry-weather warming periods and the diurnal cycles. We compiled monitoring data from five ponds in the Greater Toronto Area from 2013 − 2016 to evaluate the ponds' thermal impact on the receiving cold water streams. Using these datasets, we developed a new equation that allows for separating the active upper portion and stable lower portion of the pond. This ensures the focus is on the active upper part, where the majority of the heat transfer within the pond occurs and exhibits diurnal temperature fluctuations. We also used machine-learning tools to develop accurate equations for the bottom temperature and surface temperature, as well as, key equation parameters that characterize the thermal profiles. The developed thermal profile equation allows for the simple determination of other key thermal metrics such as average temperature, energy stored, thermocline location, which may be used as inputs to model wet weather flow conditions and pond outflow temperature. The results show that the proposed machine-learning model is acceptably accurate and capable, according to the low mean absolute percentage error (MAPE) and coefficient of determination (R2) values of 5% and 0.965, respectively, for temperature prediction for all depths. This work provides a building block for the overall objective to develop a new, easy to use, wet weather explicit equation for predicting the outlet temperature from stormwater management wet ponds since it establishes the initial thermal condition before the storm hits.

Dung beetles show metabolic plasticity as pupae and smaller adult body size in response to increased temperature mean and variance

Though organisms may use thermal plasticity to cope with novel temperature regimes, our understanding of plastic responses is limited. Research on thermal plasticity has traditionally focused on the response of organisms to shifts in mean temperatures. However, increased temperature variation can have a greater impact on organismal performance than mean temperature alone. In addition, thermal plasticity studies are often designed to investigate plasticity in response to more extreme temperatures despite the fact that organisms make physiological adjustments to diurnal temperature fluctuations that they experience. Using pupae of the dung beetle Onthophagus taurus, we investigated the potential for plasticity in response to increasing temperature mean and variance using thermal regimes that were well within the species critical thermal limits. We reared 40 beetles from egg to pupae (n = 20) or adults (n = 20) at one of nine incubation treatments, including all combinations of three mean temperatures (22, 24, 26 °C) and three amplitudes of fluctuation (±2, ±4, ±8 °C). To measure thermal plasticity of pupae, we quantified CO2 production across a range of temperatures (i.e., 15, 20, 25, and 30 °C) for 20 beetles per treatment. The relationship between CO2 production and temperature provides an estimate of energetic costs at a given temperature (i.e., using the intercept) and thermal sensitivity (i.e., using the slope). We reared the remaining O. taurus in each treatment (n = 20) to adulthood and then recorded mass (g) to determine body size, a proxy for fitness. Pupae exhibited thermal plasticity in response to the additive and interactive effects of temperature mean and variance. Pupae reared in the warmest and most variable treatment (26 ± 8 °C) showed the greatest decrease in overall metabolism compared to all other treatments, and adult beetles from this treatment (26 ± 8 °C) were also significantly smaller than adult beetles from any other treatment. We found that both temperature mean and variance contributed to thermal plasticity of pupae and had consequences for adult body size, a trait related to dung beetle fitness. Importantly, the temperatures we used in our treatments are not extreme and are likely well below the critical thermal maxima of the species, demonstrating that organisms can make adjustments to temperatures they experience across diurnal or seasonal timescales.

A drought-driven model for the evolution of obligate apomixis in ferns: evidence from pellaeids (Pteridaceae).

Xeric environments impose major constraints on the fern life cycle, yet many lineages overcome these limitations by evolving apomixis. Here, we synthesize studies of apomixis in ferns and present an evidence-based model for the evolution and establishment of this reproductive strategy, focusing on genetic and environmental factors associated with its two defining traits: the production of "unreduced" spores (n = 2n) and the initiation of sporophytes from gametophyte tissue (i.e., diplospory and apogamy, respectively). We evaluated existing literature in light of the hypothesis that abiotic characteristics of desert environments (e.g., extreme diurnal temperature fluctuations, high light intensity, and water limitation) drive the evolution of obligate apomixis. Pellaeid ferns (Cheilanthoideae: Pteridaceae) were examined in detail, as an illustrative example. We reconstructed a plastid (rbcL, trnG-trnR, atpA) phylogeny for the clade and mapped reproductive mode (sexual versus apomictic) and ploidy across the resulting tree. Our six-stage model for the evolution of obligate apomixis in ferns emphasizes the role played by drought and associated abiotic conditions in the establishment of this reproductive approach. Furthermore, our updated phylogeny of pellaeid ferns reveals repeated origins of obligate apomixis and shows an increase in the frequency of apomixis, and rarity of sexual reproduction, among taxa inhabiting increasingly dry North American deserts. Our findings reinforce aspects of other evolutionary, physiological, developmental, and omics-based studies, indicating a strong association between abiotic factors and the establishment of obligate apomixis in ferns. Water limitation, in particular, appears critical to establishment of this reproductive mode.

Baseline Water Temperature: Estimation of the Annual Cycle of Surface Water Temperature in Lakes in North-Central Poland over the 1951–1968 Period

Water temperature is an important ecological variable that affects the functioning of lakes. Unfortunately, for many lakes there are no long-term observations enabling the assessment of changes in water temperatures. This makes it difficult to include this aspect in research into the biology, ecology and chemistry of such lakes. This paper presents a literature review related to changes of surface water temperatures in lakes and in particular describing the response of water temperatures and stratification to changing climate in Polish lakes. On this basis, a model based on the available data on water temperature in 931 Polish lakes in the years 1951–1968 was proposed, which allows to estimate the baseline water temperature on any day of the year. This model is calculated using the complementary error peak function on the 0–3 m water temperature dataset, which provides the best reduction of diurnal temperature fluctuations. It can be an alternative to the average temperature of surface waters, which are calculated on the basis of systematically collected data. Based on the average water temperature data obtained from 56 thermal profiles in 10 lakes in 2010–2019, the equation was analogically calculated. The average monthly water temperatures in June, July, August and September and the change in water temperature (0.24–0.30 °C decade−1) in the period 1951–1968/2010–2019 were estimated then. Similar regional or single lake trends have been found in studies by other authors covering a similar or longer period of time. The proposed method, which is suitable for simulating temperatures, especially in summer, enables the determination of the value of changes in surface water temperature in Polish lakes when only thermal profiles data from different dates are available, which can be especially helpful when analyzing hydrobiological results.

Concrete moisture diffusivity determination using electrical resistivity measurements

The movement of water in concrete structures and buildings is a fundamental subject and therefore it is necessary to understand the mechanisms and processes involved. This paper presents a method to estimate the moisture diffusivity of concrete using gravimetric measurements, together with discretised electrical resistivity measurements. To improve the repeatability of the method, various concrete mixes with and without supplementary cementitious materials were tested. The samples were conditioned under two regimes representing poor and good curing; the samples were then exposed to a simulated hot environment with a diurnal temperature fluctuation of 20–40°C and 60% ambient relative humidity. The basis of the method was to measure the amount of water absorbed by the concrete sample at different depths as a function of time and then Boltzmann's transformation was used to analyse the experimental results obtained. Once a master curve using the Boltzmann transformation is formed, the moisture diffusivity can be obtained. The results showed that the relationship between moisture diffusivity and moisture content can be described by an exponential function.

ESTIMATING THE INFLUENCE OF SOLAR RADIATION AT DIFFERENT SEASONS ON THE MODE OF DEFORMATION OF A SPAN STRUCTURE WITH AN ORTROTROPIC PLATE

&amp;lt;p&amp;gt;The article studies the effect of solar radiation at different seasons on the mode of deformation (MD) of a span structure with an orthotropic plate. The temperature fields of the elements of the structure were measured during daylight hours at different times of year at various air temperatures and sun positions. Cases were identified in which it is necessary to clarify the temperature values of the asphalt concrete road surfacing and the main beams obtained using a non-contact pyrometer, and by measuring the temperature with a contact thermometer.&amp;lt;/p&amp;gt; &amp;lt;p&amp;gt;During the year the elements of the span are in a wide temperature range. Using the developed finite element model of the span, taking into account the layers of road surfacing, the MD calculations were performed for each case of exposure to solar radiation according to the corrected results of field measurements. An analysis of the results of numerical studies allows us to conclude that diurnal and seasonal temperature fluctuations create significant additional stresses in the span, which should be taken into account when calculating the MD of spans of road bridges.&amp;lt;/p&amp;gt;

Growth, stress, and acclimation responses to fluctuating temperatures in field and domesticated populations of Manduca sexta.

Diurnal fluctuations in temperature are ubiquitous in terrestrial environments, and insects and other ectotherms have evolved to tolerate or acclimate to such fluctuations. Few studies have examined whether ectotherms acclimate to diurnal temperature fluctuations, or how natural and domesticated populations differ in their responses to diurnal fluctuations. We examine how diurnally fluctuating temperatures during development affect growth, acclimation, and stress responses for two populations of Manduca sexta: a field population that typically experiences wide variation in mean and fluctuations in temperature, and a laboratory population that has been domesticated in nearly constant temperatures for more than 300 generations. Laboratory experiments showed that diurnal fluctuations throughout larval development reduced pupal mass for the laboratory but not the field population. The differing effects of diurnal fluctuations were greatest at higher mean temperature (30°C): Here diurnal fluctuations reduced pupal mass and increased pupal development time for the laboratory population, but had little effect for the field population. We also evaluated how mean and fluctuations in temperature during early larval development affected growth rate during the final larval instar as a function of test temperature. At an intermediate (25°C) mean temperature, both the laboratory and field population showed a positive acclimation response to diurnal fluctuations, in which subsequent growth rate was significantly higher at most test temperatures. In contrast at higher mean temperature (30°C), diurnal fluctuations significantly reduced subsequent growth rate at most test temperatures for the laboratory population, but not for the field population. These results suggest that during domestication in constant temperatures, the laboratory population has lost the capacity to tolerate or acclimate to high and fluctuating temperatures. Population differences in acclimation capacity in response to temperature fluctuations have not been previously demonstrated, but they may be important for understanding the evolution of reaction norms and performance curves.

Parallel gene expression evolution in natural and laboratory evolved populations.

Ecological adaptation is frequently inferred by the comparison of natural populations from different environments. Nevertheless, inference of the selective forces suffers the challenge that many environmental factors covary. With well‐controlled environmental conditions, experimental evolution provides a powerful approach to complement the analysis of natural populations. On the other hand, it is apparent that laboratory conditions differ in many ways from natural environments, which raises the question as to what extent selection responses in experimental evolution studies can inform us about adaptation processes in the wild. In this study, we compared the expression profiles of replicated Drosophila melanogaster populations which have been exposed to two distinct temperature regimes (18/28 and 10/20°C) in the laboratory for more than 80 generations. Using gene‐wise differential expression analysis and co‐expression network analysis, we identified 541 genes and three coregulated gene modules that evolved in the same direction in both temperature regimes, and most of these changes probably reflect an adaptation to the space constraint or diurnal temperature fluctuation that is common in both selection regimes. In total, 203 genes and seven modules evolved temperature‐specific expression changes. Remarkably, we detected a significant overlap of these temperature‐adaptive genes/modules from experimental evolution with temperature‐adaptive genes inferred from natural Drosophila populations covering two different temperature clines. We conclude that well‐designed experimental evolution studies are a powerful tool to dissect evolutionary responses.

Population responses and fatty acid profiles of Brachionus calyciflorus (Rotifera) in relation to different thermal regimes.

Diurnal temperature fluctuations affect ectothermic species more than endothermic taxa. We tested the effect of three fixed temperatures (20, 25 and 30°C) and a 24h variable (20-30°C) on the population growth and fatty acid profiles of the common rotifer Brachionus calyciflorus. Depending on the temperature treatment, the peak population abundances of B. calyciflorus varied from 65 to 80 ind./ml, the lowest being on variable temperature range. The rate of population increase varied from 0.31 to 0.52 per day, highest being at 30°C. There was a curvilinear relationship between the population density and the egg ratio (number of eggs/female) in all the tested temperature regimes. The egg ratio was higher (>0.6) for treatments involving fixed temperatures, but for variable temperature regime, the egg ratios were lower (<0.5). Temperature also induced changes in the fatty acid content of B. calyciflorus. While the total saturated fatty acids increased, both mono-unsaturated and poly-unsaturated fatty acids decreased with increasing temperature regime. These results have been interpreted in relation to the role of temperature (both intensity and mode of exposure) on the population growth characteristics of rotifers.

Peak indoor air temperature reduction for buildings in hot-humid climate using phase change materials

A hot-humid climate, which is characterized by uniform diurnal temperature throughout the year, can provide a year-round opportunity to benefit from phase change materials (PCMs) for buildings' application. However, the small diurnal temperature fluctuation might restrict the PCMs' performance and efficiency. This paper investigates the capability of PCMs to decrease the peak indoor air temperature (Tᵢ) of naturally conditioned buildings in a hot-humid climate region by storing night coolness. To this end, field measurement has been conducted in existing buildings to identify the appropriate transition temperatures' range for PCM. Then, a macro-encapsulated PCM with different transition temperatures and quantities has been numerically examined. The results showed a considerable reduction in peak Tᵢ, particularly when using PCMs with lower transition temperatures and higher quantities. Although uncompleted PCM freezing was observed when lower transition temperatures were used, it was tackled by combining night ventilation. Moreover, the PCMs showed effective year-round performance and achieved a reduction in the peak Tᵢ reached up to 4.87 °C. The optimal performance was achieved when using a combination of NV and PCMs with the lowest transition temperature that ensured complete PCMs freezing. Therefore, the PCMs’ freezing temperature should be considered when selecting PCMs for such conditions.

Carpogenic Germinability of Diverse Sclerotinia sclerotiorum Populations Within the Southwestern Australian Grain Belt.

Sclerotinia stem rot, caused by the necrotrophic plant pathogen Sclerotinia sclerotiorum (Lib.) de Bary, is a major disease of canola and pulses in Australia. Current disease management relies greatly on cultural and chemical means of control. Timing of fungicide applications remains a challenge, because efficacy is dependent on accurate prediction of ascospore release and presence on the plant. The aims of this study were to determine the optimal temperature for carpogenic germination of S. sclerotiorum populations sampled from canola and lupin fields in southwestern Australia and characterize diversity using mycelial compatibility groupings (MCGs). Sclerotia were collected from four diseased canola and one diseased lupin field from across southwestern Australia. Forty sclerotia from each population were incubated at four alternating temperatures of 30/15, 20/15, 20/4, and 15/4°C (12-h/12-h light/dark cycle) and assessed every 2 to 3 days for a 180-day period. MCG groupings for populations were characterized using 12 reference isolates. Results indicated the time to initial carpogenic germination decreased as diurnal temperature fluctuations decreased, with a fluctuation of 5°C (20/15°C) having the most rapid initial germination followed by 11°C (15/4°C) followed by 16°C (20/4°C). Optimal germination temperature for all five populations was 20/15°C; however, population responses to other diurnal temperature regimes varied considerably. No germination was observed at 30/15°C. MCG results indicate extensive diversity within and between populations, with at least 40% of sclerotia within each population unable to be characterized. We suggest that this diversity has enabled S. sclerotiorum populations to adapt to varying environmental conditions within southwestern Australia.