Jack-of-all-trades: phenotypic plasticity facilitates the invasion of an alien slug species

Invasive alien species might benefit from phenotypic plasticity by being able to (i) maintain fitness in stressful environments (‘robust’), (ii) increase fitness in favourable environments (‘opportunistic’), or (iii) combine both abilities (‘robust and opportunistic’). Here, we applied this framework, for the first time, to an animal, the invasive slug, Arion lusitanicus, and tested (i) whether it has a more adaptive phenotypic plasticity compared with a congeneric native slug, Arion fuscus, and (ii) whether it is robust, opportunistic or both. During one year, we exposed specimens of both species to a range of temperatures along an altitudinal gradient (700–2400 m a.s.l.) and to high and low food levels, and we compared the responsiveness of two fitness traits: survival and egg production. During summer, the invasive species had a more adaptive phenotypic plasticity, and at high temperatures and low food levels, it survived better and produced more eggs than A. fuscus, representing the robust phenotype. During winter, A. lusitanicus displayed a less adaptive phenotype than A. fuscus. We show that the framework developed for plants is also very useful for a better mechanistic understanding of animal invasions. Warmer summers and milder winters might lead to an expansion of this invasive species to higher altitudes and enhance its spread in the lowlands, supporting the concern that global climate change will increase biological invasions.     

Transgenerational plasticity mitigates the impact of global warming to offspring sex ratios

Global warming poses a threat to organisms with temperature‐dependent sex determination because it can affect operational sex ratios. Using a multigenerational experiment with a marine fish, we provide the first evidence that parents developing from early life at elevated temperatures can adjust their offspring gender through nongenetic and nonbehavioural means. However, this adjustment was not possible when parents reproduced, but did not develop, at elevated temperatures. Complete restoration of the offspring sex ratio occurred when parents developed at 1.5 °C above the present‐day average temperature for one generation. However, only partial improvement in the sex ratio occurred at 3.0 °C above average conditions, even after two generations, suggesting a limitation to transgenerational plasticity when developmental temperature is substantially increased. This study highlights the potential for transgenerational plasticity to ameliorate some impacts of climate change and that development from early life may be essential for expression of transgenerational plasticity in some traits.     

Seasonal phenotypic plasticity of wing melanisation in the cabbage white butterfly, Pieris rapae L. (Lepidoptera: Pieridae)

Abstract.  1. Effective thermoregulation is crucial for the fitness of small flying insects. Phenotypic plasticity of the ventral hindwing of pierid butterflies is widely recognised as adaptive for effective thermoregulation. Butterflies eclosing in cooler environments have more heavily melanised wings that absorb solar radiation, thus allowing flight under these cool conditions.
2. Many pierids also exhibit phenotypic plasticity of dorsal forewing melanisation but in this case, cooler environments reduce melanisation. It has been hypothesised that this plasticity is also adaptive because it increases solar reflection from the wing surfaces onto the body in certain basking postures.
3. The degree of seasonal variation in ventral hindwing and dorsal forewing melanisation of wild-caught Pieris rapae was quantified to determine if it shows patterns of plasticity similar to that documented for other Pieris species.
4. Male wing melanisation on both wing surfaces shows the characteristic seasonal, adaptive plasticity. However, only some dorsal forewing pattern elements of females conformed to the predictions of the hypothesis of adaptive dorsal forewing melanisation. Sexual dimorphism of wing pattern plasticity may result from, and/or affect, sexual dimorphism of behaviour and physiology of these butterflies.     

Climate warming and the evolution of morphotypes in a reptile

Climate warming is known to have effects on population dynamics through variations in survival, fecundity and density. However, the impacts of climate change on population composition are still poorly documented. Morphotypes are powerful markers to track changes in population composition. In the common lizard, Lacerta vivipara , individuals display two types of dorsal patterns: reticulated (R individuals) and linear (L individuals). We examined how local warming affected intrapopulation frequencies of these morphotypes across 11 years. We observed changes in morph frequency of dorsal patterns across years, paralleling the rise of spring temperatures. The proportion of R individuals increased with June temperatures in juveniles, yearlings, and adult males and females. Three mechanisms could explain these changes: phenotypic plasticity, microevolution and/or dispersal between populations. We investigated the ontogenetic determinism, fitness and recruitment rates associated with dorsal morphotypes. Dorsal pattern ontogeny showed temperature dependence but this relationship was not associated with the warming trend during this study. We found variation by morphotype in survival and clutch size, but these factors did not explain R frequency increases. Among all the parameters considered in this study, only a decrease of immigration, which was more pronounced in the L morphotype, could explain the change in population composition. To our knowledge, this provides the first evidence of the impact of climate warming on population composition due to its effects on immigration.     

Thermal sensitivity of a Neotropical amphibian (Engystomops pustulosus) and its vulnerability to climate change

A species’ thermal sensitivity and its exposure to climate variation are key components in the prediction of its vulnerability to climate change. We tested the thermal sensitivity of a tropical amphibian that lives in a mild constant climate in which the thermal tolerance range is expected to closely match the experienced environmental temperature. The air temperature that this species is exposed to varies between 21.9 and 31.6°C with an annual mean of 27.2°C. We estimated the microhabitat water temperature variation under vegetation shade, which buffers the temperature by 1.8°C in relation to that of the air, and with open canopy, where the water was 1.9°C warmer than the air temperature. With broods of tadpoles split into five treatments (15°C, 21°C, 28°C, 31°C, and 33°C), we estimated the critical thermal maximum (CTMax) and critical thermal minimum (CTMin) after at least 7 days of acclimation. Both CTMax (42.3°C) and CTMin (11.8°C) were more extreme than the temperature range estimated for the field. We estimated the optimum temperature (T_o = 28.8°C) and the thermal performance breadth (range: 23.3–34.1°C) based on growth rate (g/day). The animals were able to acclimate more extensively to cold than to warm temperatures. These performance curve traits closely matched the air temperature. The estimated vulnerability varied according to the microhabitat prediction model used. The combination of tadpole data on thermal sensitivity and macro‐ and microhabitat variation provides a necessary framework to understand the effects of climate change on tropical amphibians.     

Landscape effects on the thermotolerance of carabid beetles and the role of behavioral thermoregulation

Physiological thermotolerance and behavioral thermoregulation are central to seasonal cold adaptation in ectothermic organisms. For species with enhanced mobility, behavioral responses may be of greater importance in the cold stress response. Employing the carabid beetles as a study organism, the current study compared physiological thermotolerance and behavioral thermoregulation in carabid species inhabiting cereal fields in different landscape contexts, from fine grain heterogeneous “complex” landscapes to homogenous “simple” landscapes. Physiological thermotolerance was determined via measurement of the CT_min and chill coma temperature. Behavioral responses to cold temperature exposure were determined employing a purpose built arena, and thoracic temperature measured to estimate the efficacy of the behavior as a form of behavioral thermoregulation. Results revealed an influence of landscape composition on the cold tolerance of carabid beetles, although species differed in their sensitivity to landscape intensification. A reduced effect of landscape on the thermotolerance of larger carabid beetles was observed, thought to be the consequence of greater mobility preventing local acclimation to microclimatic variation along the landscape intensification gradient. Investigation into behavioral thermoregulation of the 3 largest species revealed burrowing behavior to be the main behavioral response to cold stress, acting to significantly raise carabid body temperature. This finding highlights the importance of behavioral thermoregulation as a strategy to evade cold stress. The use of behavioral thermoregulation may negate the need to invest in physiological thermotolerance, further offering explanation for the lack of landscape effect on the physiological thermotolerance of larger carabids.     

Integrating patterns of thermal tolerance and phenotypic plasticity with population genetics to improve understanding of vulnerability to warming in a widespread copepod

Differences in population vulnerability to warming are defined by spatial patterns in thermal adaptation. These patterns may be driven by natural selection over spatial environmental gradients, but can also be shaped by gene flow, especially in marine taxa with high dispersal potential. Understanding and predicting organismal responses to warming requires disentangling the opposing effects of selection and gene flow. We begin by documenting genetic divergence of thermal tolerance and developmental phenotypic plasticity. Ten populations of the widespread copepod Acartia tonsa were collected from sites across a large thermal gradient, ranging from the Florida Keys to Northern New Brunswick, Canada (spanning over 20° latitude). Thermal performance curves (TPCs) from common garden experiments revealed local adaptation at the sampling range extremes, with thermal tolerance increasing at low latitudes and decreasing at high latitudes. The opposite pattern was observed in phenotypic plasticity, which was strongest at high latitudes. No relationship was observed between phenotypic plasticity and environmental variables. Instead, the results are consistent with the hypothesis of a trade‐off between thermal tolerance and the strength of phenotypic plasticity. Over a large portion of the sampled range, however, we observed a remarkable lack of differentiation of TPCs. To examine whether this lack of divergence is the result of selection for a generalist performance curve or constraint by gene flow, we analyzed cytochrome oxidase I mtDNA sequences, which revealed four distinct genetic clades, abundant genetic diversity, and widely distributed haplotypes. Strong divergence in thermal performance within genetic clades, however, suggests that the pace of thermal adaptation can be relatively rapid. The combined insight from the laboratory physiological experiments and genetic data indicate that gene flow constrains differentiation of TPCs. This balance between gene flow and selection has implications for patterns of vulnerability to warming. Taking both genetic differentiation and phenotypic plasticity into account, our results suggest that local adaptation does not increase vulnerability to warming, and that low‐latitude populations in general may be more vulnerable to predicted temperature change over the next century.     

Assessing the sensitivity of bivalve populations to global warming using an individual‐based modelling approach

Climate change exposes benthic species populations in coastal ecosystems to a combination of different stressors (e.g., warming, acidification and eutrophication), threatening the sustainability of the ecological functions they provide. Thermal stress appears to be one of the strongest drivers impacting marine ecosystems, acting across a wide range of scales, from individual metabolic performances to geographic distribution of populations. Accounting for and integrating the response of species functional traits to thermal stress is therefore a necessary step in predicting how populations will respond to the warming expected in coming decades. Here, we developed an individual‐based population model using a mechanistic formulation of metabolic processes within the framework of the dynamic energy budget theory. Through a large number of simulations, we assessed the sensitivity of population growth potential to thermal stress and food conditions based on a climate projection scenario (Representative Concentration Pathway; RCP8.5: no reduction of greenhouse gas emissions). We focused on three bivalve species with contrasting thermal tolerance ranges and distinct distribution ranges along 5,000 km of coastline in the NE Atlantic: the Pacific oyster (Magallana gigas), and two mussel species: Mytilus edulis and Mytilus galloprovincialis. Our results suggest substantial and contrasting changes within species depending on local temperature and food concentration. Reproductive phenology appeared to be a core process driving the responses of the populations, and these patterns were closely related to species thermal tolerances. The nonlinear relationship we found between individual life‐history traits and response at the population level emphasizes the need to consider the interactions resulting from upscaling across different levels of biological organisation. These results underline the importance of a process‐based understanding of benthic population response to seawater warming, which will be necessary for forward planning of resource management and strategies for conservation and adaptation to environmental changes.     

Amazon Basin climate under global warming: the role of the sea surface temperature

The Hadley Centre coupled climate-carbon cycle model (HadCM3LC) predicts loss of the Amazon rainforest in response to future anthropogenic greenhouse gas emissions. In this study, the atmospheric component of HadCM3LC is used to assess the role of simulated changes in mid-twenty-first century sea surface temperature (SST) in Amazon Basin climate change. When the full HadCM3LC SST anomalies (SSTAs) are used, the atmosphere model reproduces the Amazon Basin climate change exhibited by HadCM3LC, including much of the reduction in Amazon Basin rainfall. This rainfall change is shown to be the combined effect of SSTAs in both the tropical Atlantic and the Pacific, with roughly equal contributions from each basin. The greatest rainfall reduction occurs from May to October, outside of the mature South American monsoon (SAM) season. This dry season response is the combined effect of a more rapid warming of the tropical North Atlantic relative to the south, and warm SSTAs in the tropical east Pacific. Conversely, a weak enhancement of mature SAM season rainfall in response to Atlantic SST change is suppressed by the atmospheric response to Pacific SST. This net wet season response is sufficient to prevent dry season soil moisture deficits from being recharged through the SAM season, leading to a perennial soil moisture reduction and an associated 30% reduction in annual Amazon Basin net primary productivity (NPP). A further 23% NPP reduction occurs in response to a 3.5 degrees C warmer air temperature associated with a global mean SST warming.     

全球变暖背景下土壤微生物呼吸的热适应性:证据、机理和争议

土壤微生物呼吸的热适应性被认为是决定陆地生态系统对全球变暖反馈作用的潜在重要机制,可能显著改变未来的气候变化趋势,然而学术界对于这一机制是否真实存在尚有分歧。阐述了土壤微生物呼吸的热适应性概念,从证据、机理和争议3方面对已有研究进展进行了综述和分析。土壤微生物呼吸的热适应性是微生物在群落尺度上对温度变化的适应性,具有坚实的生物学与生态学理论基础,研究者们运用各类指标已在许多实验中证实土壤微生物物种及群落的呼吸过程能够在高温环境产生适应性变化。土壤微生物呼吸的热适应性机理涉及生物膜结构变化、酶活性变化、微生物碳分配比例变化和微生物群落结构变化等方面。关于土壤微生物呼吸热适应性的争议可能是由研究方法、微生物物种及环境条件的差异引起的。根据对已有研究的分析,认为土壤微生物呼吸的热适应性是真实存在的,未来的研究可进一步探索土壤微生物呼吸的热适应性机理,深入研究环境和全球变化对土壤微生物呼吸的热适应性影响,定量评估土壤微生物呼吸的热适应性对陆地生态系统反馈过程的影响。     

Evolution of phenotypic plasticity: patterns of plasticity and the emergence of ecotypes

Phenotypic plasticity itself evolves, as does any other quantitative trait. A very different question is whether phenotypic plasticity causes evolution or is a major evolutionary mechanism. Existing models of the evolution of phenotypic plasticity cover many of the proposals in the literature about the role of phenotypic plasticity in evolution. I will extend existing models to cover adaptation to a novel environment, the appearance of ecotypes and possible covariation between phenotypic plasticity and mean trait value of ecotypes. Genetic assimilation does not sufficiently explain details of observed patterns. Phenotypic plasticity as a major mechanism for evolution--such as, invading new niches, speciation or macroevolution--has, at present, neither empirical nor model support.     

Ecological genetics of an induced plant defense against herbivores: additive genetic variance and costs of phenotypic plasticity

Abstract.— Adaptive phenotypic plasticity in chemical defense is thought to play a major role in plant-herbivore interactions. We investigated genetic variation for inducibility of defensive traits in wild radish plants and asked if the evolution of induction is constrained by costs of phenotypic plasticity. In a greenhouse experiment using paternal half-sibling families, we show additive genetic variation for plasticity in glucosinolate concentration. Genetic variation for glucosinolates was not detected in undamaged plants, but was significant following herbivory by a specialist herbivore, Pieris rapae . On average, damaged plants had 55% higher concentrations of glucosinolates compared to controls. In addition, we found significant narrow-sense heritabilities for leaf size, trichome number, flowering phenology, and lifetime fruit production. In a second experiment, we found evidence of genetic variation in induced plant resistance to P. rapae . Although overall there was little evidence for genetic correlations between the defensive and life-history traits we measured, we show that more plastic families had lower fitness than less plastic families in the absence of herbivory (i.e., evidence for genetic costs of plasticity). Thus, there is genetic variation for induction of defense in wild radish, and the evolution of inducibility may be constrained by costs of plasticity.     

Theory and performance of an infrared heater for ecosystem warming

In order to study the likely effects of global warming on future ecosystems, a method for applying a heating treatment to open-field plant canopies (i.e. a temperature free-air controlled enhancement (T-FACE) system) is needed which will warm vegetation as expected by the future climate. One method which shows promise is infrared heating, but a theory of operation is needed for predicting the performance of infrared heaters. Therefore, a theoretical equation was derived to predict the thermal radiation power required to warm a plant canopy per degree rise in temperature per unit of heated land area. Another equation was derived to predict the thermal radiation efficiency of an incoloy rod infrared heater as a function of wind speed. An actual infrared heater system was also assembled which utilized two infrared thermometers to measure the temperature of a heated plot and that of an adjacent reference plot and which used proportional–integrative–derivative control of the heater to maintain a constant temperature difference between the two plots. Provided that it was not operated too high above the canopy, the heater system was able to maintain a constant set-point difference very well. Furthermore, there was good agreement between the measured and theoretical unit thermal radiation power requirements when tested on a Sudan grass (Sorghum vulgare) canopy. One problem that has been identified for infrared heating of experimental plots is that the vapor pressure gradients (VPGs) from inside the leaves to the air outside would not be the same as would be expected if the warming were performed by heating the air everywhere (i.e. by global warming). Therefore, a theoretical equation was derived to compute how much water an infrared-warmed plant would lose in normal air compared with what it would have lost in air which had been warmed at constant relative humidity, as is predicted with global warming. On an hourly or daily basis, it proposed that this amount of water could be added back to plants using a drip irrigation system as a first-order correction to this VPG problem.     

Thermal plasticity of photosynthesis: the role of acclimation in forest responses to a warming climate

The increasing air temperatures central to climate change predictions have the potential to alter forest ecosystem function and structure by exceeding temperatures optimal for carbon gain. Such changes are projected to threaten survival of sensitive species, leading to local extinctions, range migrations, and altered forest composition. This study investigated photosynthetic sensitivity to temperature and the potential for acclimation in relation to the climatic provenance of five species of deciduous trees, Liquidambar styraciflua, Quercus rubra, Quercus falcata, Betula alleghaniensis, and Populus grandidentata. Open‐top chambers supplied three levels of warming (+0, +2, and +4 °C above ambient) over 3 years, tracking natural temperature variability. Optimal temperature for CO₂ assimilation was strongly correlated with daytime temperature in all treatments, but assimilation rates at those optima were comparable. Adjustment of thermal optima was confirmed in all species, whether temperatures varied with season or treatment, and regardless of climate in the species' range or provenance of the plant material. Temperature optima from 17° to 34° were observed. Across species, acclimation potentials varied from 0.55 °C to 1.07 °C per degree change in daytime temperature. Responses to the temperature manipulation were not different from the seasonal acclimation observed in mature indigenous trees, suggesting that photosynthetic responses should not be modeled using static temperature functions, but should incorporate an adjustment to account for acclimation. The high degree of homeostasis observed indicates that direct impacts of climatic warming on forest productivity, species survival, and range limits may be less than predicted by existing models.     

Behavioral adjustments and support use of François' langur in limestone habitat in Fusui,China: Implications for behavioral thermoregulation

Climatic factors such as temperature and humidity vary seasonally in primate habitats; thus, behavioral adjustments and microhabitat selection by primate species have been interpreted as behavioral adaptations. François' langur (Trachypithecus francoisi), a native species to southwest China and northern Vietnam, inhabits a limestone habitat with extreme climatic conditions. To understand the potential effects of climatic seasonality on this species, we collected data on the individual behavioral budgets in a T. francoisi group between January and December 2010 in Fusui County, China. Monthly, we performed 5–11 days of observation during this period, using focal animal sampling and continuous recording methods. We also recorded ambient temperature (T_a) and relative humidity (H_r) data at our study site. Results indicated that T_a and H_r were significantly correlated with each other and fluctuated dramatically on a daily, monthly, and seasonal basis. The amount of time spent resting, grooming, basking, and huddling also varied on a daily, monthly, and seasonal basis. The proportion of resting time and total sedentary activity time significantly increased at high and low T_as, respectively. The total sedentary time, resting time, and plant branch use all showed positive significant correlations with T_a. Our results suggest that behavioral adjustment and support use of T. francoisi, at least partly, were related to thermoregulation. T. francoisi minimized thermal stress through behavioral adjustments and support use. It is an adaptive behavior associated with the climatic extremes of limestone habitat. This study can potentially advise conservation management strategies in this specific habitat. Conservation efforts should focus on vegetation restoration in langurs' habitat, including those in the foothills.     

Advances in understanding the impacts of global warming on marine fishes farmed offshore: Sparus aurata as a case study

Monitoring variations in proteins involved in metabolic processes, oxidative stress responses, cell signalling and protein homeostasis is a powerful tool for developing hypotheses of how environmental variations affect marine organisms' physiology and biology. According to the oxygen- and capacity-limited thermal tolerance hypothesis, thermal acclimation mechanisms such as adjusting the activities of enzymes of intermediary metabolism and of antioxidant defence mechanisms, inducing heat shock proteins (Hsps) or activating mitogen-activated protein kinases may all shift tolerance windows. Few studies have, however, investigated the molecular, biochemical and organismal responses by fishes to seasonal temperature variations in the field to link these to laboratory findings. Investigation of the impacts of global warming on fishes farmed offsore, in the open sea, can provide a stepping stone towards understanding effects on wild populations because they experience similar environmental fluctuations. Over the last 30 years, farming of the gilthead sea bream Sparus aurata (Linnaeus 1758) has become widespread along the Mediterranean coastline, rendering this species a useful case study. Based on available information, the prevailing seasonal temperature variations expose the species to the upper and lower limits of its thermal range. Evidence for this includes oxygen restriction, reduced feeding, reduced responsiveness to environmental stimuli, plus a range of molecular and biochemical indicators that change across the thermal range. Additionally, close relationships between biochemical pathways and seasonal patterns of metabolism indicate a connection between energy demand and metabolic processes on the one hand, and cellular stress responses such as oxidative stress, inflammation and autophagy on the other. Understanding physiological responses to temperature fluctuations in fishes farmed offshore can provide crucial background information for the conservation and successful management of aquaculture resources in the face of global change.     

Impact of global warming on the tree species composition of boreal forests in Finland and effects on emissions of isoprenoids

This study aims to identify how climate change may influence total emissions of monoterpene and isoprene from boreal forest canopies. The whole of Finland is assumed to experience an annual mean temperature (T) increase of 4 °C and a precipitation increase of 10% by the year 2100. This will increase forest resources throughout the country. At the same time, the proportions of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) in southern Finland (60°≤ latitude < 65°N) will be reduced from the current 40–50% to less than 10–20%, with increased dominance of birches (Betula pendula and Betula pubescens). In northern Finland (65°≤ latitude < 70°N), the proportions of Norway spruce and Scots pine will be balanced at a level of about 40% as the result of an increase in Norway spruce from the current 21% to 37% and a concurrent reduction in Scots pine from 63% to 40%. The proportion of birches is predicted to increase from the current 17% to 23%, but these will become the dominant species only on the most fertile sites. Total mean emissions of monoterpene by Scots pine will be reduced by 80% in southern Finland, but will increase by 62% in the north. Emissions from Norway spruce canopies will increase by 4% in the south but by 428% in the north, while those from birch canopies will increase by about 300% and 113%, respectively. Overall emissions of monoterpene over the whole country amount to about 950 kg km^?2 y^?1 under current temperature conditions and will increase by 17% to 1100 kg km^?2 y^?1 with elevated temperature and precipitation, mainly because of an increase at northern latitudes. Under current conditions, emissions of isoprene follow the spatial distribution of spruce canopies (the only isoprene‐emitting tree species that forms forests in Finland) with four times higher emissions in the south than in the north. The elevated temperature and the changes in the areal distribution of Norway spruce will result in increases in isoprene emissions of about 37% in southern Finland and 435% in northern Finland. Annual mean isoprene emissions from Norway spruce canopies over the whole country will increase by about 60% up to the year 2100.     

Design and performance of combined infrared canopy and belowground warming in the B4WarmED (Boreal Forest Warming at an Ecotone in Danger) experiment

Conducting manipulative climate change experiments in complex vegetation is challenging, given considerable temporal and spatial heterogeneity. One specific challenge involves warming of both plants and soils to depth. We describe the design and performance of an open‐air warming experiment called Boreal Forest Warming at an Ecotone in Danger (B4WarmED) that addresses the potential for projected climate warming to alter tree function, species composition, and ecosystem processes at the boreal‐temperate ecotone. The experiment includes two forested sites in northern Minnesota, USA, with plots in both open (recently clear‐cut) and closed canopy habitats, where seedlings of 11 tree species were planted into native ground vegetation. Treatments include three target levels of plant canopy and soil warming (ambient, +1.7 °C, +3.4 °C). Warming was achieved by independent feedback control of voltage input to aboveground infrared heaters and belowground buried resistance heating cables in each of 72‐7.0 m² plots. The treatments emulated patterns of observed diurnal, seasonal, and annual temperatures but with superimposed warming. For the 2009 to 2011 field seasons, we achieved temperature elevations near our targets with growing season overall mean differences (?T_below) of +1.84 °C and +3.66 °C at 10 cm soil depth and (?T^above) of +1.82 °C and +3.45 °C for the plant canopies. We also achieved measured soil warming to at least 1 m depth. Aboveground treatment stability and control were better during nighttime than daytime and in closed vs. open canopy sites in part due to calmer conditions. Heating efficacy in open canopy areas was reduced with increasing canopy complexity and size. Results of this study suggest the warming approach is scalable: it should work well in small‐statured vegetation such as grasslands, desert, agricultural crops, and tree saplings (<5 m tall).     

Phenological shifts in North American red squirrels: disentangling the roles of phenotypic plasticity and microevolution

Phenological shifts are the most widely reported ecological responses to climate change, but the requirements to distinguish their causes (i.e. phenotypic plasticity vs. microevolution) are rarely met. To do so, we analysed almost two decades of parturition data from a wild population of North American red squirrels (Tamiasciurus hudsonicus). Although an observed advance in parturition date during the first decade provided putative support for climate change‐driven microevolution, a closer look revealed a more complex pattern. Parturition date was heritable [h² = 0.14 (0.07–0.21 (HPD interval)] and under phenotypic selection [β = ?0.14 ± 0.06 (SE)] across the full study duration. However, the early advance reversed in the second decade. Further, selection did not act on the genetic contribution to variation in parturition date, and observed changes in predicted breeding values did not exceed those expected due to genetic drift. Instead, individuals responded plastically to environmental variation, and high food [white spruce (Picea glauca) seed] production in the first decade appears to have produced a plastic advance. In addition, there was little evidence of climate change affecting the advance, as there was neither a significant influence of spring temperature on parturition date or evidence of a change in spring temperatures across the study duration. Heritable traits not responding to selection in accordance with quantitative genetic predictions have long presented a puzzle to evolutionary ecologists. Our results on red squirrels provide empirical support for one potential solution: phenotypic selection arising from an environmental, as opposed to genetic, covariance between the phenotypic trait and annual fitness.     

The effects of MIF-I, beta-endorphin and alpha-MSH on d-amphetamine induced paradoxical behavioral thermoregulation: possible involvement of the dopaminergic system

The neuropharmacological basis for d-amphetamine induced paradoxical behavioral thermoregulation remains unclear. This study examined thermoregulatory behavior of rats in a runway device that housed a heat source at one end and in which locomotion along the length of the runway could be observed. Sprague Dawley rats were pretreated with IP injections of saline, beta-endorphin, MIF-1, or alpha-MSH, with a repeat injection after 30 min. In a second experiment, d-amphetamine was administered as the repeat drug for all Ss. The results showed clear differences for heat-source-on vs. heat-source off. All peptides induced hypermotility, although no differentiated effects for the peptides on d-amphetamine induced paradoxical behavioral thermoregulation were found. These findings are discussed in light of the theoretical possibilities that: (a) a ceiling effect exists; (b) there are separate control systems for maintaining body temperature and another for behavioral thermoregulatory responses, and (c) other neurotransmitters may be involved in such induced paradoxical behavioral thermoregulation.