Explore the vast range of titles available.

The regulation of body temperature (thermoregulation) and of water balance (defined here as hydroregulation) are key processes underlying ecological and evolutionary responses to climate fluctuations in wild animal populations. In terrestrial (or semiterrestrial) ectotherms, thermoregulation and hydroregulation closely interact and combined temperature and water constraints should directly influence individual performances. Although comparative physiologists traditionally investigate jointly water and temperature regulation, the ecological and evolutionary implications of these coupled processes have so far mostly been studied independently. Here, we revisit the concept of thermo‐hydroregulation to address the functional integration of body temperature and water balance regulation in terrestrial ectotherms. We demonstrate how thermo‐hydroregulation provides a framework to investigate functional adaptations to joint environmental variation in temperature and water availability, and potential physiological and/or behavioral conflicts between thermoregulation and hydroregulation. We extend the classical cost–benefit model of thermoregulation in ectotherms to highlight the adaptive evolution of optimal thermo‐hydroregulation strategies. Critical gaps in the parameterization of this conceptual optimality model and guidelines for future empirical research are discussed. We show that studies of thermo‐hydroregulation refine our mechanistic understanding of physiological and behavioral plasticity, and of the fundamental niche of the species. This is illustrated with relevant and recent examples of space use and dispersal, resource‐based trade‐offs, and life‐history tactics in insects, amphibians, and nonavian reptiles.

(Lamb.) Hook is a high-quality, fast-growing plantation-tree species widely distributed in southern China, and a commercial timber species unique to China that plays a vital role in meeting wood demand and maintaining ecological security. Although the morphological and physiological adaptations of seedlings to light stress have been extensively documented separately, their interplay remains a critical gap in our knowledge and understanding of plant ecophysiology. Particularly, the synergistic mechanisms between phenotypic adaptations and metabolic regulation remain unclear. This study employed 1-year-old, clonal, seedlings as test materials to investigate the coordinated effects of different light intensity gradients (100%, 68%, 27%, 12%, and 5% of full sunlight) on the morphological and physiological responses. (1) Under decreasing light intensity, seedling height to diameter ratio and specific leaf area were 30.10% and 64.38% greater than of those recorded under 100% light intensity. The observed changes in growth maximized light capture capacity. Further, root growth, root to shoot ratio, and seedling quality index decreased with decreasing light intensity. (2) Leaf non-structural carbohydrate contents decreased significantly, along with key carbohydrate-metabolizing enzyme activities, and leaf carbon∶nitrogen and carbon∶phosphorus ratios. (3) High light intensities increased cytokinin and abscisic acid contents, whereas the lowest (5%) light intensity tested enhanced the accumulation of gibberellin, but had no significant effect on indoleacetic acid content. These results indicate that seedlings used a dual adaptation strategy that combined \"photoprotection under high light intensity\" with \"efficient resource utilization under low light intensity\" through coordinated morphological and physiological adjustments. Our study provides a scientific basis for managing nursery light conditions and plantation light environment during early development of seedlings. Specifically, we recommend a 68% light intensity for optimal seedling production.

Groundwater lowering can produce dramatic changes in the physiological performance and survival of plant species. The impact of decreasing water availability due to climate change and anthropogenic groundwater extraction on coastal dune ecosystems has become of increasing concern, with uncertainties about how vegetation will respond in both the short and long terms. We aimed to evaluate the water‐use responses of different plant functional types to increasing groundwater table depth and how this would affect their physiology in Mediterranean coastal dune systems differing in aridity. We modelled water‐table depth, quantified the contribution of different soil layers to plant water through Bayesian isotope mixing models and used a combination of spectral and isotope data to characterize plant ecophysiology. We found that increasing depth to groundwater triggered water uptake adjustments towards deeper soil layers only in the dry season. These adjustments in water source use were made by conifer trees (Pinus pinea, P. pinaster) and hygrophytic shrubs (Erica scoparia, Salix repens) but not by the xerophytic shrub Corema album. Moreover, we observed a greater use of groundwater under semi‐arid conditions. Accompanying the greater use of water from deep soil layers as a response to increasing groundwater depth, the semi‐arid dimorphic‐rooted conifer tree P. pinea and hygrophytic shrub E. scoparia declined their water content (WI), without implications on photosynthetic parameters, such as chlorophyll content (CHL), photochemical index (PRI) and δ13C. Unexpectedly, under semi‐arid conditions, the shallow‐rooted xerophytic shrub C. album, associated with an absence of water source use adjustments, showed a decline in WI, CHL and PRI with groundwater table lowering. We provide insight into how different species, belonging to different functional types, are acclimating to groundwater changes in a region experiencing climatic drought and a scarcity in groundwater due to anthropogenic exploitation. Greater depth to groundwater combined with limited precipitation can have a significant effect on plants’ water source use and ecophysiology in semi‐arid coastal dune ecosystems. A plain language summary is available for this article. Plain Language Summary

Climate change combined with human activities has altered the spatial and temporal patterns of summer extreme heat in the Mu Us Desert. To determine how those rodents living in the desert respond to increased extreme heat in summer, in July 2022, during the hottest month, we examined the rodent species, vegetation coverage, and small-scale heterogeneity in ambient temperature in the southeastern Mu Us Desert. The results showed that Meriones meridianus, Meriones unguiculatus, and Cricetulus longicaudatus were found in the study area, where the vegetation coverage is 33.5–40.8%. Moreover, the maximum temperature of the desert surface was 61.8 °C. The maximum air temperature at 5 cm above the desert surface was 41.3 °C. The maximum temperature in the burrow at a depth of 15 cm was 31 °C. M. unguiculatus might experience 4–9.3 h of heat stress in a day when exposed outside the burrow, whereas M. meridianus would experience 8.5–10.8 h of heat stress. Yet, inside the burrow, both species were barely exposed to heat stress. In conclusion, adjustments in behavioral patterns can be the main way that rodents in the Mu Us Desert adapt to the extreme heat in the summer.

Abstract Technologies that can mitigate the stressful effect of water deficit and assist in seedling recovery are necessary. This study aimed to evaluate the effect of hydrogel doses on mitigating water deficit stress and the recovery of Inga edulis Mart. seedlings in the post-stress period. The seedlings were grown under the following water management regimes: control - daily irrigation; water restriction (WR) - seedling irrigation suppression + 50 mL of Hydrogel (H); WR + 100 mL of H, and WR + 150 mL of H. The seedlings were evaluated in two periods: P0 - when the photosynthetic rate (A) of the seedlings of at least one of the treatments subjected to irrigation suppression with or without hydrogel reached values close to zero; REC (recovery) - after P0 in the seedlings of each treatment, irrigation was resumed until the seedlings previously subjected to WR of each treatment reached values of A ≥ 50% to that of the control seedlings. Adding 100 mL of hydrogel delayed the stressful effect of water deficit on the photosynthetic rate. Furthermore, it assisted in a more rapid post-stress recovery while keeping the Rubisco carboxylation efficiency high upon recovery. Resumo Tecnologias que possam contribuir na mitigação do efeito estressante do déficit hídrico e auxiliar na recuperação de mudas são necessárias. Objetivou-se nessa pesquisa avaliar o efeito de doses de hidrogel na mitigação do estresse por déficit hídrico e na recuperação de mudas de Inga edulis Mart. no pós-estresse. As mudas foram cultivadas sob os seguintes manejos hídricos: controle -irrigação realizada diariamente; restrição hídrica (RH) - suspensão da irrigação das mudas + 50 mL de Hidrogel (H); RH + 100 mL de H e RH + 150 mL de H. As mudas foram avaliadas em dois períodos: F0 – quando a taxa fotossintética (A) das mudas, de pelo menos um dos tratamentos, submetidos à suspensão da irrigação alcançou valores próximos a zero; REC (recuperação) – após a F0 nas mudas de cada tratamento, realizou-se a retomada da irrigação até que as mudas previamente submetidas a RH de cada tratamento atingissem valores de A ≥ 50% ao das mudas controle. A adição de 100 mL de hidrogel retardou o efeito estressante do déficit hídrico sobre A e auxiliou na recuperação de maneira mais rápida no pós-estresse, mantendo elevada a eficiência de carboxilação da Rubisco na recuperação.

Abstract Depending on the intensity and ecological successional classification of plants, light availability can become an unfavorable condition for producing high-quality seedlings. We hypothesized that applying silicon sources might contribute to inducing tolerance to different shading levels for Peltophorum dubium (Spreng.) Taub. seedlings. Two independent experiments were developed: I) the application of five doses of silicon oxide (SiO2: 0.0; 1.0; 2.0; 4.0; and 6.0 g L-1); and II) the application of five doses of potassium silicate (K2SiO3: 0.0; 5.0; 10.0; 15.0; and 20.0 mL L-1 of water). Both were associated with three shading levels: 0% (direct sunlight), 30%, and 50%. In experiment I, we observed that seedlings were more responsive to shading levels and had little influence from foliar application of SiO2, with higher growth, biomass, and quality values when grown under direct sunlight (0% shading). In experiment II, the foliar application of 20.0 mL L-1 of K2SiO3 contributed to greater heights under 0% and 30% shading. Meanwhile, under 50% shading, the dose of 5.0 K2SiO3 favored the species' growth. The application of K2SiO3 favored the increase in the dry mass of the aerial part (DMAP). The highest biomass production and seedling quality occurred under 0% and 30% shading. The 50% shaded environment was most unfavorable to the growth and quality of P. dubium seedlings. Even though the seedlings were not very responsive to silicon sources, K2SiO3 provided a greater response than SiO2. High-quality seedling production is favored when the seedlings are grown under direct sunlight (0% shading). Resumo A disponibilidade luminosade dependendo da intensidade e a classificação ecológica sucessional das plantas pode se tornar uma condição desfavorável a produção de mudas de alta qualidade. Hipotetizamos que a aplicação de fontes de silício pode contribuir na indução da tolerância a diferentes níveis de sombreamento para mudas de Peltophorum dubium (Spreng.) Taub. Foram desenvolvimentos dois experimentos independentes: I) aplicação de cinco doses de óxido de silício (SiO2): 0,0; 1,0; 2,0; 4,0 e 6,0 g L-1) e II) aplicação de cinco doses de silicato de potássio (K2SiO3): 0,0; 5,0; 10,0; 15,0 e 20,0 mL L-1 de água, ambos associados a três níveis de sombreamento: 0% (pleno sol), 30% e 50%. No experimento I, observamos que as mudas foram mais responsivas aos níveis de sombreamento e pouco influenciadas pela aplicação foliar de SiO2, com maiores valores de crescimento, biomassa e qualidade quando produzidas sob pleno sol (0% sombreamento). No experimento II, a aplicação foliar de 20,0 mL L-1 de K2SiO3 contribuiu em maiores alturas sob 0% e 30%, enquanto que sob 50% de sombreamento a dose de 5,0 K2SiO3 favoreceu o crescimento da espécie. A aplicação de K2SiO3 favoreceu no incremento de massa seca da parte aérea. As maiores produções de biomassa e qualidade das mudas foram sob 0% e 30% de sombreamento. O ambiente com 50% de sombreamento foi mais desfavorável ao crescimento e qualidade das mudas de P. dubium. Embora as mudas sejam pouco responsivas as fontes de silício, o K2SiO3 contrubuiu mais do que o SiO2. A produção de mudas de alta qualidade é favorecida quando cultivadas sob pleno sol (0% de sombreamento).

Through phenotypic plasticity, bones can change in structure and morphology, in response to physiological and biomechanical influences over the course of individual life. Changes in bones also occur in evolution as functional adaptations to the environment. In this study, we report on the evolution of bone mass increase (BMI) that occurred in the postcranium and skull of extinct aquatic sloths. Although non-pathological BMI in postcranial skeleton has been known in aquatic mammals, we here document general BMI in the skull for the first time. We present evidence of thickening of the nasal turbinates, nasal septum and cribriform plate, further thickening of the frontals, and infilling of sinus spaces by compact bone in the late and more aquatic species of the extinct sloth Thalassocnus. Systemic bone mass increase occurred among the successively more aquatic species of Thalassocnus, as an evolutionary adaptation to the lineage's changing environment. The newly documented pachyostotic turbinates appear to have conferred little or no functional advantage and are here hypothesized as a correlation with or consequence of the systemic BMI among Thalassocnus species. This could, in turn, be consistent with a genetic accommodation of a physiological adjustment to a change of environment.

The predicted effects of global change (GC) will be exacerbated in the more densely populated cities of the future, especially in the Mediterranean basin where some environmental cues, such as drought and tropospheric ozone (O 3 ) pollution, already mine seriously plant survival. Physiological and biochemical responses of a Mediterranean, evergreen, isohydric plant species ( Quercus ilex ) were compared to those of a sympatric, deciduous, anisohydric species ( Q. pubescens ) under severe drought (20% of the effective daily evapotranspiration) and/or chronic O 3 exposure (80 ppb for 5 h day −1 for 28 consecutive days) to test which one was more successful in those highly limiting conditions. Results show that (i) the lower reduction of total leaf biomass of Q. ilex as compared to Q. pubescens when subjected to drought and drought × O 3 (on average −59 vs −70%, respectively); (ii) the steeper decline of photosynthesis found in Q. pubescens under drought (−87 vs −81%) and drought × O 3 (−69 vs −59%, respectively); (iii) the increments of malondialdehyde (MDA) by-products found only in drought-stressed Q. pubescens ; (iv) the impact of O 3 , found only in Q. pubescens leaves and MDA, can be considered the best probes of the superiority of Q. ilex to counteract the effect of mild-severe drought and O 3 stress. Also, an antagonistic effect was found when drought and O 3 were applied simultaneously, as usually happens during typical Mediterranean summers. Our dataset suggests that on future, the urban greening should be wisely pondered on the ability of trees to cope the most impacting factors of GC, and in particular their simultaneity.

Background Understanding the mechanisms underlying plant water use in response to drought is critical to predicting the trend of ecosystem development under a changing environment, while the responses of water use in clonal plants with interconnected ramets to drought are far less clear than trees. Method In this study, we conducted manipulated drought by excluding 50% annual throughfall at a stand level in a Moso bamboo ( Phyllostachys heterocycla ) forest, to determine how water use of the Moso bamboo responds to drought stress, and whether bamboo culms of different developmental stages show synchronized responses given the existence of physiological integration. Three developmental stages of bamboo culms (i.e., young, mature and old) were investigated and measurements were made on sap flow density ( J s ), leaf water potential at predawn ( ψ pre ) and midday ( ψ mid ), leaf water potential at turgor loss ( ψ TLP ), leaf stomatal density and size, and the maximum stomatal conductance ( g w(max) ) was calculated. Results Under the manipulative drought conditions, the values of J s significantly decreased in the mature culms but not in the young and old culms. g w(max) remained unchanged in mature culms, and increased in the young and old culms. Drought significantly reduced ψ mid of the young culms, resulting in more negative ψ TLP in the young culms compared with the old ones. Conclusions The results imply that the young culms adopted the drought tolerance strategy, while the old culms tended to adopt the drought avoidance strategy. Both the young and old culms are capable of maintaining relatively stable J s under drought by structural and physiological adjustments. Our findings demonstrate the variable responses of water use in bamboo culms of different developmental stages to drought, suggesting an unsynchronized responses of water use to water stress among culms in clonal plants.

Soil microbial communities (SMC) play a central role in the structure and function of desert ecosystems. However, the high variability of annual precipitation could results in the alteration of SMC and related biological processes depending on soil water potential. The nature of the physiological adjustments made by SMC in order to obtain energy and nutrients remains unclear under different soil resource availabilities in desert ecosystems. In order to examine this dynamic, the present study examined the effects of variation in annual precipitation on physiological adjustments by the SMC across two vegetation-soil systems of different soil organic matter input in an oligotrophic desert ecosystem. We collected soil samples in the Cuatro Ciénegas Basin (Mexico) under two vegetation covers: rosetophylous scrub (RS) and grassland (G), that differ in terms of quantity and quality of organic matter. Collections were conducted during the years 2011, 2012, 2013 and 2014, over which a noticeable variation in the annual precipitation occurred. The ecoenzymatic activity involved in the decomposition of organic matter, and the concentration of dissolved, available and microbial biomass nutrients, were determined and compared between sites and years. In 2011, we observed differences in bacterial taxonomic composition between the two vegetation covers. The lowest values of dissolved, available and microbial nutrients in both cover types were found in 2012. The G soil showed higher values of dissolved and available nutrients in the wet years. Significant positive correlations were detected between precipitation and the ratios Cmic:Nmic and Cmic:Pmic in the RS soil and Cmic:Pmic and Nmic:Pmic in the G soil. The slopes of the regression with Cmic and Nmic were higher in the G soil and lower in the RS soil. Moreover, the SMC under each vegetation cover were co-limited by different nutrients and responded to the sum of water stress and nutrient limitation. Soil community within both sites (RS and G) may be vulnerable to drought. However, the community of the site with lower resources (RS) is well adapted to acquire P resources by ecoenzyme upregulation during years with adequate precipitation, suggesting that this community is resilient after drought occurs. Under the Global Climate Change scenarios for desert ecosystems that predict reduced annual precipitation and an increased intensity and frequency of torrential rains and drought events, the soil microbial communities of both sites could be vulnerable to drought through C and P co-limitation and reallocation of resources to physiological acclimatization strategies in order to survive.