Plasticity In Traits Research Articles

Effects of food level and fecal material on the plasticity of metamorphic traits in Asiatic toad, Bufo gargarizans, in Central China

Abstract According to Richards’ hypothesis, the presence of a nonpigmented unicellular alga in the intestinal tract of tadpoles is believed to be the inhibitory factor that affects their growth. It is proposed that thecanimals eat their fecal material containing these algal cells, which are then reintroduced into their systems when the alga is shed with the feces and dropped to the bottom. In this study, we aimed to investigate the plasticity of metamorphic traits in the Asiatic toad (Bufo gargarizans) under different combinations of fecal material and food levels. Our findings revealed that B. gargarizans tadpoles reared at high food levels exhibited accelerated larval periods but had smaller metamorphic sizes compared to those reared at low food levels. This suggests that the tadpoles prioritize rapid development at the expense of body mass during metamorphosis. Furthermore, our study discovered evidence supporting the positive effect of fecal material on tadpole growth, as indicated by the investigation of growth rate. Importantly, the presence of feces did not result in smaller body mass on average for Asiatic toad tadpoles compared to those raised in the absence of fecal material. The difference in body mass between fecal material treatments tended to be smaller at low food levels, implying that feces does not inhibit growth in B. gargarizans tadpoles. Therefore, our results contradict Richards’ hypothesis and provide support for a novel mechanism that is selected for in areas where coprophagy is likely to be advantageous, particularly in times of food scarcity.

Intraspecific Variability of Xylem Hydraulic Traits of Calligonum mongolicum Growing in the Desert of Northern Xinjiang, China

Plant hydraulic traits are essential for understanding and predicting plant drought resistance. Investigations into the mechanisms of the xylem anatomical traits of desert shrubs in response to climate can help us to understand plant survival strategies in extreme environments. This study examined the xylem anatomical traits and related functional traits of the branches of seven Calligonum mongolicum populations along a precipitation gradient, to explore their adaptive responses to climatic factors. We found that (1) the vessel diameter (D), vessel diameter contributing to 95% of hydraulic conductivity (D95), hydraulic weighted vessel diameter (Dh), vessel density (VD), percentage of conductive area (CA), thickness-to-span ratio of vessels ((t/b)2), and theoretical hydraulic conductivity (Kth) varied significantly across sites, while the vessel group index (Vg), wood density (WD), and vulnerability index (VI) showed no significant differences. (2) Principal component analysis revealed that efficiency-related traits (Kth, Dh, D95) and safety-related traits (VI, VD, inter-wall thickness of the vessel (t)) were the primary factors driving trait variation. (3) Precipitation during the wettest month (PWM) had the strongest influence, positively correlating with (t/b)2 and negatively with D, D95, Dh, CA, and Kth. (4) Structural equation modeling confirmed PWM as the main driver of Kth, with indirect effects through CA. These findings indicate that C. mongolicum displays high plasticity in xylem traits, enabling adaptation to changing environments, and providing insight into the hydraulic strategies of desert shrubs under climate change.

Contrasting responses of an invasive plant to herbivory of native and introduced insects

BackgroundInteractions between alien plants and insect herbivores in introduced ranges may determine their invasion success. However, few studies have investigated whether alien plants respond differently to native and introduced herbivores in their introduced ranges and whether genotypes of alien plants matter. We conducted a greenhouse experiment to examine the effects of herbivory by a native insect (Spodoptera litura), by an introduced insect (S. frugiperda), and simultaneously by both insect species on growth, morphology, and biomass allocation of 17 genotypes of an invasive alien clonal plant Hydrocotyle verticillata, and used selection gradient analysis to test which herbivory conditions favor selection of a specific leaf or root trait value.ResultsDifferent genotypes of H. verticillata showed significant variation in growth, morphology, and biomass allocation, but their responses to herbivory were relatively consistent. All three herbivory treatments significantly decreased total mass and stolon mass, but herbivory of S. frugiperda increased specific leaf area. Herbivory of S. litura and simultaneous herbivory of both insect species also decreased leaf mass, petiole mass, root mass, and ramet mass. Selection gradient analysis showed that leaf and root traits varied under different herbivory treatments. To achieve greater fitness, as measured by total mass and/or number of ramets, H. verticillata favored larger leaf area under herbivory by S. frugiperda, larger leaf area and lower specific leaf area under herbivory by S. litura, and larger leaf area, lower specific leaf area, and lower root-to-shoot ratio under simultaneous herbivory.ConclusionsH. verticillata demonstrated contrasting responses to herbivory by native and introduced insects, showing a remarkable ability to coordinate leaf trait plasticity and optimize biomass allocation. This strategy allows H. verticillata to achieve greater fitness under various herbivory conditions, potentially contributing to its invasion success. These findings highlight the importance of plant–herbivore interactions in shaping invasion dynamics and underscore the complex adaptive mechanism that enables invasive plants to establish and spread in introduced ranges.

A new dimension of leaf economic spectrum: temporal instability of relationships among genotypes.

Leaf economic spectrum (LES) relationships have been studied across many different plant lineages and at different organizational scales. However, the temporal stability of the LES relationships is largely unknown. We used the wild blueberry system with high genotypic diversity to test whether trait-trait relationships across genotypes demonstrate the same LES relationships found in the global database (GLOPNET) and whether they are stable across years. We studied leaf structure, photosynthesis, and leaf nutrients for 16 genotypes of two wild blueberry species semi-naturally grown in a common farm in Maine, USA, across 4 yr. We found substantial variation in leaf structure, physiology, and nutrient traits within and among genotypes, as well as across years in wild blueberries. The LES trait-trait relationships (covariance structure) across genotypes were not always found in all years. The trait syndrome of wild blueberries was shifted by changing environmental conditions over the years. Additionally, traits in 1 yr cannot be used to predict those of another year. Our findings show that LES generally holds among genotypes but is temporally unstable, stressing the significant influence of trait plasticity in response to fluctuating environmental conditions across years, and the importance of temporal dimensions in shaping functional traits and species coexistence.

The Effects of Different Grazing Periods on the Functional Traits of Leymus chinensis (Trin.) Tzvelev in a Typical Inner Mongolia Steppe

Plant functional traits are effective indicators and predictors of environmental change, revealing plants’ ecological countermeasures and adaptability through phenotypic plasticity. We conducted a 6-year grazing experiment on typical temperate grassland to assess the impact of different grazing periods on the plasticity and variability of the functional traits of Leymus chinensis and the relationship between traits and individual plant biomass. Our study included four treatments: CK (enclosure), T1 (grazing in May and July), T2 (grazing in June and August), and T3 (grazing in July and September). The results for 13 functional traits indicated that the T3 treatment showed the smallest reduction in individual plant biomass, plant height, leaf area, stem length, and leaf length, making it the most effective type of grassland management and optimal for the maintenance and restoration of L. chinensis traits. Under T1, T2, and T3, the plasticity of stem weight, total leaf weight, total leaf area, and stem length was higher and crucial for regulating individual plant biomass. The results underscore that the changes and plasticity of dominant species under grazing treatments are key to understanding the relationship between ecosystem function and grassland management. This study provides a theoretical basis and data support for the adaptive utilization and restoration management of typical grassland resources.

Divergent Flowering Time Responses to Increasing Temperatures Are Associated With Transcriptome Plasticity and Epigenetic Modification Differences at FLC Promoter Region of Arabidopsis thaliana.

Understanding the genetic, and transcriptomic changes that drive the phenotypic plasticity of fitness traits is a central question in evolutionary biology. In this study, we utilised 152 natural Swedish Arabidopsis thaliana accessions with re-sequenced genomes, transcriptomes and methylomes and measured flowering times (FTs) under two temperature conditions (10°C and 16°C) to address this question. We revealed that the northern accessions exhibited advanced flowering in response to decreased temperature, whereas the southern accessions delayed their flowering, indicating a divergent flowering response. This contrast in flowering responses was associated with the isothermality of their native ranges, which potentially enables the northern accessions to complete their life cycle more rapidly in years with shorter growth seasons. At the transcriptome level, we observed extensive rewiring of gene co-expression networks, with the expression of 25 core genes being associated with the mean FT and its plastic variation. Notably, variations in FLC expression sensitivity between northern and southern accessions were found to be associated with the divergence FT response. Further analysis suggests that FLC expression sensitivity is associated with differences in CG, CHG and CHH methylation at the promoter region. Overall, our study revealed the association between transcriptome plasticity and flowering time plasticity among different accessions, providing evidence for its relevance in ecological adaptation. These findings offer deeper insights into the genetics of rapid responses to environmental changes and ecological adaptation.

Associations Between Developmental Stability, Canalization, and Phenotypic Plasticity in Response to Heterogeneous Experience.

The processes of developmental stability, canalization, and phenotypic plasticity have ecological and evolutionary significance, and been studied extensively, but mostly separately and thus the relationships between them are not straightforward. Our objective was to better integrate these processes in the context of temporally heterogeneous environments. We did this by investigating the effects of early experience with temporal heterogeneity in water availability on associations between developmental stability, canalization, and phenotypic plasticity. We subjected eight plant species to a first round of alternating inundation and drought vs. constantly moderate water treatments (heterogeneous experience) and a second round of water conditions (to test plasticity). We measured fluctuating asymmetry (FA) in leaf size, intra- and inter-individual variation (CVintra and CVinter), and plasticity (PI) in traits and analyzed correlations between these variables across all species. Results showed little correlations between FA, CVintra and PI, several positive correlations between FA and CVinter in more stressful conditions, especially in as well as positive correlations between CVinter and PI initially and negative correlations between them later. These suggested the complexity of these relationships, which can depend on whether plasticity occurs. Greater inter-individual variation will more likely cooperate with plasticity before or during plastic response, whereas higher canalization may reflect phenotypic convergence. Both higher FA and CVintra can reflect faster growth, while CVintra may also reflect plant growth stage, and the two mechanisms should cooperate in response to environmental challenges. The complexity of these relationships suggests plants deal with environmental variation in elaborate and integrative ways which can be affected by many factors.

Natural selection on floral volatiles and other traits can change with snowmelt timing and summer precipitation.

Climate change is disrupting floral traits that mediate mutualistic and antagonistic species interactions. Plastic responses of these traits to multiple shifting conditions may be adaptive, depending on natural selection in new environments. We manipulated snowmelt date over three seasons (3-11 d earlier) in factorial combination with growing-season precipitation (normal, halved, or doubled) to measure plastic responses of volatile emissions and other floral traits in Ipomopsis aggregata. We quantified how precipitation and early snowmelt affected selection on traits by seed predators and pollinators. Within years, floral emissions did not respond to precipitation treatments but shifted with snowmelt treatment depending on the year. Across 3 yr, emissions correlated with both precipitation and snowmelt date. These effects were driven by changes in soil moisture. Selection on several traits changed with earlier snowmelt or reduced precipitation, in some cases driven by predispersal seed predation. Floral trait plasticity was not generally adaptive. Floral volatile emissions shifted in the face of two effects of climate change, and the new environments modulated selection imposed by interacting species. The complexity of the responses underscores the need for more studies of how climate change will affect floral volatiles and other floral traits.

Plasticity response of desert shrubs to intense drought events at different phenophases under the context of climate change

Global climate change has led to the frequent occurrence of intense drought events in mid-latitude desert ecosystems, coupled with uneven rainfall distribution across phenophases within the year. However, the impact of intense drought events at different phenophases on plant growth and drought resistance strategies still lacks clear conclusions. We selected the typical desert semi-shrubs Artemisia ordosica as our research object, and constructed a rain shelter to simulate intense drought events (without rainfall for 30 consecutive days) during the sprouting, vegetative growth, flowering and fruiting stages. Based on this, we analyzed the differential impacts of intense drought events at different phenophases on the phenotypic characteristics (e.g. shrub height, cover, volume, specific leaf area) and functional traits (ANPP accumulation and allocation) of A. ordosica. The experiment employed a randomized complete block design with three replicates for each treatment. The results indicate that: (1) Under intense drought events at different phenophases, all phenotypic characteristic indicators of A. ordosica significantly decreased. (2) Contrary to the significant negative correlation between twig number and twig size in response to rainfall variations, under intense drought conditions, there is a significant positive correlation between the two, indicating a synergistic effect. (3) The impact of intense drought events at different phenophases on the ANPP (aboveground net primary production) accumulation of A. ordosica varied significantly. The degree of impact is as follows: the flowering and fruiting stage > the sprouting stage > the vegetative growth stage. (4) A. ordosica adapted to intense drought by increasing the proportion of reproductive growth and decreasing the proportion of vegetative growth. Our results reveal the phenotypic and functional trait plasticity response mechanisms of A. ordosica to intense droughts at different phenophases, laying a foundation for predicting the impacts of climate change on desert ecosystems.

Context-specific variation in life history traits and behavior of Aedes aegypti mosquitoes.

Aedes aegypti, the vector for dengue, chikungunya, yellow fever, and Zika, poses a growing global epidemiological risk. Despite extensive research on Ae. aegypti's life history traits and behavior, critical knowledge gaps persist, particularly in integrating these findings across varied experimental contexts. The plasticity of Ae. aegypti's traits throughout its life cycle allows dynamic responses to environmental changes, yet understanding these variations within heterogeneous study designs remains challenging. A critical aspect often overlooked is the impact of using lab-adapted lines of Ae. aegypti, which may have evolved under laboratory conditions, potentially altering their life history traits and behavioral responses compared to wild populations. Therefore, incorporating field-derived populations in experimental designs is essential to capture the natural variability and adaptability of Ae. aegypti. The relationship between larval growing conditions and adult traits and behavior is significantly influenced by the specific context in which mosquitoes are studied. Laboratory conditions may not replicate the ecological complexities faced by wild populations, leading to discrepancies in observed traits and behavior. These discrepancies highlight the need for ecologically relevant experimental conditions, allowing mosquito traits and behavior to reflect field distributions. One effective approach is semi-field studies involving field-collected mosquitoes housed for fewer generations in the lab under ecologically relevant conditions. This growing trend provides researchers with the desired control over experimental conditions while maintaining the genetic diversity of field populations. By focusing on variations in life history traits and behavioral plasticity within these varied contexts, this review highlights the intricate relationship between larval growing conditions and adult traits and behavior. It underscores the significance of transstadial effects and the necessity of adopting study designs and reporting practices that acknowledge plasticity in adult traits and behavior, considering variations due to larval rearing conditions. Embracing such approaches paves the way for a comprehensive understanding of contextual variations in mosquito life history traits and behavior. This integrated perspective enables the synthesis of research findings across laboratory, semi-field, and field-based investigations, which is crucial for devising targeted intervention strategies tailored to specific ecological contexts to combat the health threat posed by this formidable disease vector effectively.

Gene expression plasticity in response to rapid and extreme elevation changes in Perdix hodgsoniae (Tibetan Partridge)

Abstract Phenotypic plasticity is a vital biological process facilitating the persistence of organisms amid rapid environmental changes. Investigating the genetic basis of plastic traits necessitates transplantation experiments, but much of the existing research has focused on laboratory model systems. Transplant experiments in the wild may provide better understanding of how plasticity operates in the context of real-world challenges. However, performing transplantation experiments in non-model systems, such as birds, could be challenging. In this study, we aim to develop Perdix hodgsoniae (Tibetan Partridge) inhabiting the highlands of the Tibetan Plateau as a suitable system to study genetic basis underlying short-term plastic response to rapid changes in elevation. We did a first attempt of field-based transplantation experiment by exposing P. hodgsoniae individuals to extreme change in elevation from their native elevation (3,623 m) to a low elevation outside their natural distribution range (500 m). We compared changes in gene expression in these birds at different time points, pre-transplant (Day 0), and post-transplant (Day 3 and Day 22). The birds successfully survived transplantation and exhibited well-being after 22 days. We identified a total of 715 differentially expressed genes (DEGs) across these 3 time points. Our analysis revealed a genome-wide decrease in expression following the transplantation, indicating that the birds possibly exhibited stress-induced transcriptional attenuation (SITA) because of the extreme change in elevation, suggesting a broader response at the transcriptional level, possibly as a mechanism to cope with extreme changes in the environment. Our analysis further suggested that heat stress posed an immediate challenge for the birds following the transplant, as we identified changes in expression in many genes associated with heat stress response. Our findings affirm the viability of conducting transplant experiments in the P. hodgsoniae and provides initial insights into gene expression changes associated with the plastic response to rapid changes in elevation in these birds.

Seasonal acclimation of photosynthetic thermal tolerances in six woody tropical species along a thermal gradient

Abstract Extreme heat events are becoming increasingly common, and the short‐term acclimation of photosynthesis will have a large impact on plant performance. Trees in lowland tropical forests, which are hypothesized to have limited abilities to tolerate rising temperatures, may need to rely on short‐term acclimation of their more plastic traits, like photosynthetic thermal tolerance, to persist in the face of increasingly variable climates. Here, we investigated seasonal acclimation of thermal tolerances in plant species of the moist Amazon. Specifically, we measured the photosynthetic thermal tolerances of six common woody Amazonian species at the beginning and at the end of the dry season to determine the species' abilities to acclimate to intra‐annual changes to climate. In addition, we used the natural thermal gradient present at our research site to test the acclimation of individual plants to maximum air temperatures not currently observed elsewhere in the moist lowland Amazon (up to ~43°C). Between seasons, there were significant overall increases in the thermal tolerances of three species (i.e. higher thermal tolerances in the hotter dry season), suggesting that leaf megathermy is prominent in these species. Also, three species acclimated their thermal tolerances to microsite‐level differences in seasonal temperature maxima, suggesting closer fidelity between leaf and air temperatures (i.e. limited homeothermy) for these species. Our results show that some woody species from the moist Amazon can acclimate their thermal tolerances over short time‐scales, although acclimation is likely insufficient to overcome thermal stress during extreme temperature events. Some species may therefore be more sensitive to heatwaves than others, which could impact survival and composition of tropical lowland forests into the future. Read the free Plain Language Summary for this article on the Journal blog.

Early life food intake modulates effects of diet restriction on lifespan and fecundity in later life in a predatory mite (Acari: Phytoseiidae)

Abstract The nutritional status of an individual can significantly influence its life history traits, including development, growth, reproduction, and survival. In the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae), the plasticity of life history traits, such as developmental time and size at maturity, is influenced by the quality and quantity of food. This study aimed to investigate the effects of dietary restriction at different life stages (i.e., juvenile, early adulthood, and later adulthood) on the lifespan and fecundity of P. persimilis. We found that reduced dietary intake during early adulthood resulted in a shorter lifespan for both male and female P. persimilis. Furthermore, this study demonstrated a sex-specific response to dietary restriction: it extended the lifespan of males but reduced that of females during later adulthood. Diet restriction during the postovipositional period of females showed the most variable life history trait response. Our results showed that the impact of diet restriction at different life stages can have combined influences on the postovipositional duration of P. persimilis, where the individuals receiving diet restriction during immature development and early adulthood had a greater reduction in ovipositional duration as those experiencing diet restriction during late adulthood. In addition, we observed a positive correlation between the lifespan and fecundity of females, with higher prey availability increasing both. The insights obtained from our research contribute to a better understanding of the aging process and dietary requirements of P. persimilis, which can facilitate the development of more effective biological control strategies using this predator for spider mites in agriculture.

An appreciation of apex-to-base variation in xylem traits will lead to more precise understanding of xylem phenotypic plasticity.

Xylem air embolism is the primary cause of drought-related tree mortality. Phenotypic plasticity of xylem traits is key for species acclimation to environmental variability and evolution. It is widely believed that plants increase xylem embolism resistance in response to drought. However, I argue that this hypothesis, based on extensive literature, relies on sampling methods that overlook predictable anatomical patterns, potentially biasing our understanding of acclimation and adaptation strategies.

Phenotypic plasticity of water-related traits reveals boundaries to the adaptive capacity of a dominant European grass species under increased drought

The intensification of droughts due to climate change is a global concern, and many plant species face increasing water deficits. Understanding the role of phenotypic plasticity in plant adaptation to these changing conditions is crucial. This research focuses on Bromopsis erecta, a dominant perennial grass in European and Mediterranean grasslands, to predict its potential adaptation to climate change. We assessed plants from shallow and deep soils (i.e., with contrasting water reserves) of a Mediterranean rangeland in southern France, and tested the effect of six years of experimentally increased summer drought compared to the ambient conditions on plant traits, survival and abundance. In both field and common garden experiments, we measured water-related traits, including static traits under non-limiting water conditions, and dynamic traits, such as rates of trait variation during drought. Trait plasticity was determined as a reaction norm to increasing soil water stress and was tested against changes in B. erecta abundance over the past decade, including the study period. Trait plasticity was detected only for leaf dry matter content (LDMC), revealing that the resource strategy of B. erecta became more conservative over less than a decade with higher LDMC and leaf thickness according to the plant economic spectrum. No plasticity was found for osmotic potential or specific leaf area. The variability of other traits was ascribed to the possible lagging effect of previous water stress and was associated more with soil depth than with previous summer drought intensity. The abundance decline of B. erecta, which dropped from 20 % to around 5 % in shallow soils, was not associated with the plasticity of LDMC but was positively correlated with variations in leaf base membrane damage, meaning unexpectedly, that plants exposed to the most severe summer drought also had the most sensitive leaf base membranes, a possible sign of maladaptive trait plasticity in the population. This key trait response reveals boundaries to the adaptive capacity of this perennial grass to survive pluri-annual drought.

No evidence for an up-regulation of female immune function in response to elevated risk of sexual conflict.

Sexual conflict is widespread among sexually reproducing organisms. Phenotypic plasticity in female resistance traits has the potential to moderate the harm imposed by males during mating, yet female plasticity has rarely been explored. In this experiment, we investigated whether female seed beetles invest more in immunocompetence, measured as phenoloxidase (PO) capacity, when exposed to cues signalling a greater risk of sexual conflict. Risk perception was manipulated by housing focal individuals alone or with a companion as developing larvae, followed by exposure to a mating-free male- or female-biased social environment when adults. We predicted that females exposed to cues of increased sexual conflict would have increased PO capacity. However, PO capacity did not differ between either larval or adult social treatments. Our results suggest that females may not perceive a risk to their fitness on the basis of increased male presence or are unable to adjust this aspect of their phenotype in response to that risk.

Epigenetic responses of trees to environmental stress in the context of climate change.

In long-lived tree populations, when environmental change outpaces rates of evolutionary adaptation, plasticity in traits related to stress tolerance, dormancy, and dispersal may be vital for preventing extinction. While a population's genetic background partly determines its ability to adapt to a changing environment, so too do the many types of epigenetic modifications that occur within and among populations, which vary on timescales orders of magnitude faster than the emergence of new beneficial alleles. Consequently, phenotypic plasticity driven by epigenetic modification may be especially critical for sessile, long-lived organisms such as trees that must rely on this plasticity to keep pace with rapid anthropogenic environmental change. While studies have reported large effects of DNA methylation, histone modification, and non-coding RNAs on the expression of stress-tolerance genes and resulting phenotypic responses, little is known about the role of these effects in non-model plants and particularly in trees. Here, we review new findings in plant epigenetics with particular relevance to the ability of trees to adapt to or escape stressors associated with rapid climate change. Such findings include specific epigenetic influences over drought, heat, and salinity tolerance, as well as dormancy and dispersal traits. We also highlight promising findings concerning transgenerational inheritance of an epigenetic 'stress memory' in plants. As epigenetic information is becoming increasingly easy to obtain, we close by outlining ways in which ecologists can use epigenetic information better to inform population management and forecasting efforts. Understanding the molecular mechanisms behind phenotypic plasticity and stress memory in tree species offers a promising path towards a mechanistic understanding of trees' responses to climate change.

Experience shapes wild boar spatial response to drive hunts

Human-induced disturbances of the environment are rapid and often unpredictable in space and time, exposing wildlife to strong selection pressure favouring plasticity in specific traits. Measuring wildlife behavioural plasticity in response to human-induced disturbances such as hunting pressures is crucial in understanding population expansion in the highly plastic wild boar species. We collected GPS-based movement data from 55 wild boars during drive hunts over three hunting seasons (2019–2022) in the Czech Republic and Sweden to identify behavioural plasticity in space use and movement strategies over a range of experienced hunting disturbances. Daily distance, daily range, and daily range overlap with hunting area were not affected by hunting intensity but were clearly related to wild boar hunting experience. On average, the post-hunt flight distance was 1.80 km, and the flight duration lasted 25.8 h until they returned to their previous ranging area. We detected no relationship in flight behaviour to hunting intensity or wild boar experience. Wild boar monitored in our study showed two behavioural responses to drive hunts, “remain” or “leave”. Wild boars tended to “leave” more often with increasing hunting experience. Overall, this study highlights the behavioural plasticity of wild boar in response to drive hunts.

Variation in vessel traits of northern red oak (Quercus rubra L.) provenances revealed high phenotypic plasticity to prevailing environmental conditions

Key messageRed oak provenances responded with high plasticity and intra-annual variability in vessel traits to studied climatic conditions, indicating weak signals of local adaptation and providing opportunities for forest management.The climate change-induced increase in frequency and severity of extreme events has revealed a high vulnerability of various major tree species in Europe, stressing the need for selecting climate-resilient species for forest management. In this context, adaptive strategies of northern red oak (Quercus rubra L.) were examined, using wood anatomical data derived from a provenance trial. We investigated the interannual variation in vessel traits of red oak provenances planted at three sites along a precipitation gradient in Germany. We compared the climate sensitivity of German provenances with those from North America to analyze plasticity and to identify signals of local adaptation in vessel traits. The results revealed variations in vessel traits between all sites, pointing to site-specific responses to prevailing environmental conditions. Differences between provenances were prevalent for vessel size-related traits, with site-specific higher values for German provenances at wet sites. Climate signals, which varied between traits, were strongest for vessel density and the relative conductive area. Vessel traits were found to depend both on previous-year conditions as and on spring climate conditions during the onset of vessel formation. The site-specific response in extreme years deviate significantly between drought and frost events. A trade-off between resistance to extremes and vessel diameter could not be demonstrated, and provenances with larger vessel diameters showed higher frost resistance. The observed high plasticity in vessel traits and the site-specific variation to climate influences point to an adjustment in vessel formation to the prevailing environmental conditions.

Differential phenotypic plasticity of subalpine trees predicts trait integration under climate warming.

Understanding limiting factors of phenotypic plasticity is essential given its critical role in shaping biological adaptation and evolution in changing environments. It has been proposed that the pattern of phenotypic correlation could constrain trait plasticity. However, the interplay between phenotypic plasticity and integration has remained contentious. We experimentally simulated climate warming in juveniles of three subalpine tree species by exposing them to three-year in situ open-top chambers (OTCs), and then measured functional plasticity of 72 eco-physiological traits to evaluate whether phenotypic integration constituted an intrinsic constraint to plasticity. We also tested the relationship between the differences in plasticity and maintenance in trait integration. Phenotypic plasticity was positively associated with integration in deciduous tree species under warming. The difference in the plasticity of two paired traits could predict their integration in different environments, where traits displaying more similar plasticity were more likely to be correlated. Our study showed no indication that phenotypic integration constrained plasticity. More importantly, we demonstrated that differential plasticity between traits might result in a notable reorganization of the trait associations, and that warming commonly induced a tighter phenotype. Our study provides new insights into the interplay between phenotypic plasticity and integration in subalpine trees under climate warming.