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Summary Studies have explored how traits separate plants ecologically and the trade‐offs that underpin this separation. However, uncertainty remains as to the taxonomic scale at which traits can predictably separate species. We studied how physiological traits separated three Pinus (Pinus banksiana, Pinus resinosa, and Pinus strobus) species across three sites. We collected traits from four common leaf and branch measurements (light–response curves, CO2–response curves, pressure–volume curves, and hydraulic vulnerability curves) across each species and site. While common, these measurements are not typically measured together due to logistical constraints. Few traits varied across species and sites as expected given the ecological preferences of the species and environmental site characteristics. Some trait trade‐offs present at broad taxonomic scales were observed across the three species, but most were absent within species. Certain trade‐offs contrasted expectations observed at broader scales but followed expectations given the species' ecological preferences. We emphasize the need to both clarify why certain traits are being studied, as variation in unexpected but ecologically meaningful ways often occurs and certain traits might not vary substantially within a given lineage (e.g. hydraulic vulnerability in Pinus), highlighting the role a trait selection in trait ecology. [ABSTRACT FROM AUTHOR]

The genetic architecture of trait variance has long been of interest in genetics and evolution. One of the earliest attempts to understand this architecture was presented in Lerner's Genetic Homeostasis (1954). Lerner proposed that heterozygotes should be better able to tolerate environmental perturbations because of functional differences between the alleles at a given locus , with each allele optimal for slightly different environments. This greater robustness to environmental variance, he argued, would result in smaller trait variance for heterozygotes. The evidence for Lerner's hypothesis has been inconclusive. To address this question using modern genomic methods, we mapped loci associated with differences in trait variance (vQTL) on 1,101 individuals from the F34 of an advanced intercross between LG/J and SM/J mice. We also mapped epistatic interactions for these vQTL in order to understand the influence of epistasis for the architecture of trait variance. We did not find evidence supporting Lerner's hypothesis, that heterozygotes tend to have smaller trait variances than homozygotes. We further show that the effects of most mapped loci on trait variance are produced by epistasis affecting trait means and that those epistatic effects account for about a half of the differences in genotypic-specific trait variances. Finally, we propose a model where the different interactions between the additive and dominance effects of the vQTL and their epistatic partners can explain Lerner's original observations but can also be extended to include other conditions where heterozygotes are not the least variable genotype. [ABSTRACT FROM AUTHOR]

Measuring the variability in persons' behaviors and experiences using ecological momentary assessment is time-consuming and costly. We investigate whether interval responses provided through a dual-range slider (DRS) response format can be used as a simple and efficient alternative: Respondents indicate variability in their behavior in a retrospective rating by choosing a lower and an upper bound on a continuous, bounded scale. We investigate the psychometric properties of this response format as a prerequisite for further validation. First, we assess the test–retest reliability of factor-score estimates for the width of DRS intervals. Second, we test whether factor-score estimates of the visual analog scale (VAS) and the location of DRS intervals show convergent validity. Third, we investigate whether factor-score estimates for the DRS are uncorrelated between different personality scales. We present a longitudinal multitrait-multimethod study using two personality scales (Extraversion, Conscientiousness) and two response formats (VAS, DRS) at two measurement occasions (6–8 weeks apart) for which we estimate factor-score correlations in a joint item response theory model. The test–retest reliability of the width of DRS intervals was high ( ρ ^ ≥. 73 ). Also, convergent validity between location scores of VAS and DRS was high ( ρ ^ ≥. 88 ). Conversely, discriminant validity of the width of DRS intervals between Extraversion and Conscientiousness was poor ( ρ ^ ≥. 94 ). In conclusion, the DRS seems to be a reliable response format that could be used to measure the central tendency of a trait equivalently to the VAS. However, it might not be well suited for measuring intra-individual variability in personality traits. [ABSTRACT FROM AUTHOR]

Leaf traits are good indicators of ecosystem functioning and plant adaptations to environmental conditions. We examined whether leaf trait variability at species and community levels in Mediterranean woody vegetation is explained by growth form, regeneration mode, and vegetation type. We studied several plant communities across five vegetation types – semi‐closed forest, open forest, closed shrubland, open shrubland, and scrubland – in southwestern Anatolia, Türkiye. Using linear mixed models, community‐weighted trait means, and principal component analysis, we tested how much variability in three leaf traits (specific leaf area, leaf thickness, and leaf area) is accounted for species, growth form, regeneration mode, and vegetation type. Despite a large amount of leaf trait variability both within‐ and among‐species existed, functional groups still accounted for a significant part of this variability. Resprouters had higher SLA and leaf area and lower leaf thickness than non‐resprouters. However, further functional separation in regeneration mode, by considering the propagule‐persistence trait and the seed bank locality, explained leaf trait variability better than only resprouting ability. Although no consistent pattern was observed in three leaf traits in the growth form, we found evidence for the difference in SLA and leaf thickness between shrubs and large shrubs, and subshrubs had smaller leaves than other growth forms. Vegetation type also accounted for a substantial amount of leaf trait variability. Specifically, plant communities in closed habitats had larger leaf area than open ones, and those in scrublands had higher SLA, lower leaf thickness, and lower leaf area than other vegetation types. Climate and phylogeny had limited contribution to the results obtained, with the exception of a significant phylogenetic effect in explaining the differences in SLA between resprouters and non‐resprouters. Our results suggest that multiple drivers are responsible for shaping plant trait variability in Mediterranean plant communities, including growth form, regeneration mode, and vegetation type. [ABSTRACT FROM AUTHOR]

The hydraulic architecture of woody plants may show intra‐ and interspecific variations along aridity gradients as a result of wood trait trade‐offs, which depend on species‐specific abilities to withstand or evade drought. Plant hydraulic architecture can be defined as the set of different cell types involved in water transport through the soil–plant‐atmosphere continuum. At the present time, there are two models designed to understand trade‐offs among xylem wood functional traits, developed by Baas and Pratt, respectively. The first model presents a triangular trade‐off space where three main plant xylem functions are linked to each other to provide resistance to embolism in evolutionary time. The second model depicts xylem cell types associated with their main functions, namely vessel‐transport, parenchyma‐storage and fibre‐support. We propose here a new model considering the same relative xylem cell trait abundance for three desert species with different drought tolerance strategies along an aridity gradient of more than 300 mm. Hence, our model may account for both intra‐ and interspecific variations in wood traits for species from different localities along an aridity gradient. The tree Neltuma flexuosa showed little intraspecific variation in the medium drought resistance portion of the trade‐off space, suggesting this species is independent from rainfall. Larrea divaricata showed a similar low intraspecific variation, but the spatial location in the trade‐off space suggests it has a high tolerance to drought. The third species, Bulnesia retama, showed a higher intraspecific variation within the trade‐off space, changing its hydraulic architecture in more fibre area with increasing aridity. Our model seems to be a generalized tool to assess both intra‐ and interspecific variations in trade‐offs for hydraulic architecture among woody plants as a response to drought. [ABSTRACT FROM AUTHOR]

Summary: Functional traits offer a promising avenue to improve predictions of species range shifts under climate change, which will entail warmer and often drier conditions. Although the conceptual foundation linking traits with plant performance and range shifts appears solid, the predictive ability of individual traits remains generally low. In this review, we address this apparent paradox, emphasizing examples of woody plants and traits associated with drought responses at the species' rear edge. Low predictive ability reflects the fact not only that range dynamics tend to be complex and multifactorial, as well as uncertainty in the identification of relevant traits and limited data availability, but also that trait effects are scale‐ and context‐dependent. The latter results from the complex interactions among traits (e.g. compensatory effects) and between them and the environment (e.g. exposure), which ultimately determine persistence and colonization capacity. To confront this complexity, a more balanced coverage of the main functional dimensions involved (stress tolerance, resource use, regeneration and dispersal) is needed, and modelling approaches must be developed that explicitly account for: trait coordination in a hierarchical context; trait variability in space and time and its relationship with exposure; and the effect of biotic interactions in an ecological community context. [ABSTRACT FROM AUTHOR]

Background: The rat estrous cycle first characterized by Long and Evans in 1922 profoundly affected the course of endocrine research. Investigators took advantage of sex steroid hormone fluctuations associated with the cycle to assess hormonal influences on anxiety, depression, food intake, stress, brain structure and other traits. Similarities of the rat estrous and human menstrual cycles facilitated understanding of human reproductive physiology. I assessed the impact of awareness of the estrous cycle on the emergence of a sex bias that excluded female rats from biomedical research. Methods: Beginning with the 1918 volume of the American Journal of Physiology and ending in 1976 when the journal subdivided into several separate disciplinary journals, all studies conducted on rats were downloaded; the use of females, males, both sexes and sex left unspecified was tabulated for 485 articles. A second analysis tracked the number of rat estrous cycle studies across all disciplines listed in PubMed from 1950 to 2021. Results: The description and awareness of variability associated with the rat estrous cycle was correlated with a precipitous decline in investigations that incorporated both sexes, a marked increase in male-only studies and a striking sex bias that excluded female rats. The number of rat estrous cycles studies increased markedly from earlier decades to a peak in 2021. Conclusions: The initial description the rat estrous cycle was correlated with a substantial decline in investigations that incorporated both sexes; one result was a marked increase in male-only studies and a striking sex bias that excluded female rats from biomedical research. Recognition of the advantages of studies that incorporate the rat estrous cycle has resulted in recent years in an increase of such investigations. Female rats and females of several other species are not more variable than their male counterparts across traits, arguing for female inclusion without requiring cycle monitoring. There, remain, however, many advantages of incorporating the estrous cycle in contemporary research. Highlights: The neglect of females in biomedical research has been well documented in the past decade. The initial description of the rat estrous cycle in 1922 was correlated with a subsequent decrease in studies that utilized female rats, a marked increase in male-only studies, and a sex bias against females based on the erroneous belief that they are more variable than males. Recently there has been a substantial increase in studies that incorporate the rat estrous cycle. [ABSTRACT FROM AUTHOR]

Intraspecific trait variation has tremendous importance for species interactions and community composition. A major source of intraspecific trait variation is an organism's developmental stage; however, timing is rarely considered in studies of the ecological effects of intraspecific variation. Here, we examine the role of time in the ecology of intraspecific trait variation, focusing on plants and their interactions with other organisms. Trait variation due to differences in developmental timing has unique features and dynamics, distinguishing it from variation due to genes or the environment. When time is considered in studies of intraspecific trait ecology, the degree of variability in timing within a population becomes a key factor structuring trait-mediated ecological interactions and community processes. Trait variation within species is important for shaping ecological interactions and communities. Traits vary greatly through individual ontogenetic and phenological development, and individuals within populations vary in their developmental timing. Timing therefore must be important for understanding intraspecific trait variation and its effects on ecology. However, this is rarely considered in the field. A temporally explicit approach to the study of intraspecific trait variation in ecology is needed to fully understand population and community dynamics. [ABSTRACT FROM AUTHOR]

In the current context of climate changes, which causes strong habitat variation, an understanding of the mechanisms underlying plant community dynamics is crucial to predict species fates. The taking of inter- and intraspecific trait variability into account would aid the identification of these mechanisms. Recently, a method involving the calculation of hypervolumes (n -dimensional spaces of trait values) was developed for the study of plant responses to their environments. Through hypervolume comparison, we examined the effects of interannual variations in abiotic conditions on aquatic plant communities in ponds of the sub-Antarctic Iles Kerguelen. This model system is particularly relevant for the examination of the consequences of climate changes–related habitat variation, as aquatic plant communities are adapted to cold and overall stable habitat conditions and the sub-Antarctic climate is changing rapidly. We conducted field sampling over four years at three sites. For all aquatic species, we measured five foliar, shoot, and clonal traits characterizing individual growth strategies that are likely to respond to variations in abiotic conditions on 1565 ramets over the four years. We measured 10 abiotic variables to characterize the plants' habitats every three months during the survey period. Hypervolumes were calculated for each site and year to assess variation in aquatic plant strategies at the community level. We demonstrated (i) the importance of spatiotemporal gradients of trophic status, temperature, and pH and dissolved oxygen concentration for the functional structure of aquatic plant communities; (ii) that the shape of the mean response was trait dependent, with traits related to plant metabolism (specific leaf area and specific internode mass) and three-dimensional space exploration (height and internode length) responding to the three spatiotemporal abiotic gradients; (iii) that selection pressures were especially high on aerial traits relative to clonal traits; and (iv) that given the community response to interannual variations of abiotic conditions, environmental changes should impact macrophyte community productivity. Synthesis. We conclude that the examination of interannual abiotic variation over four years is sufficient to detect rapid responses of macrophyte communities, with likely reliance on phenotypic plasticity. Our findings may inform the characterization of future functional changes in aquatic plant communities of the sub-Antarctic region, where similar species are found. • Habitat variations related to climate changes affect aquatic plant communities. • We studied the aquatic plant communities in the sub-Antarctic Iles Kerguelen. • Their functional structure over 4 years at 3 sites was approached by hypervolumes. • Rapid responses of the communities to interannual abiotic variations are detected. • Environmental changes should impact aquatic plant community productivity. [ABSTRACT FROM AUTHOR]

The dry and wet seasons in the Neotropics have strong effects on soil water and nutrient availability, as well as on forest dynamics. Despite these major effects on forest ecology, little is known on how leaf traits vary throughout the seasons in tropical rainforest trees.Here, we investigated the influence of seasonal variations in climate and soil characteristics on leaf trait variation in two tropical tree species. We measured two leaf traits, thickness and water mass per area, in 401 individuals of two species of Symphonia (Clusiaceae) in the Paracou research station in French Guiana tropical lowland rainforest.We found a significant effect of seasonal variation on these two leaf traits. Soil relative extractable water was a strong environmental predictor of leaf trait variation in response to seasonal variation. Reduced soil water availability during the dry season was associated with increased leaf thickness and water mass per area, possibly as a result of stomatal closure.Our findings advocate the need to account for environmental seasonality when studying leaf traits in seasonal ecosystems such as tropical forests. [ABSTRACT FROM AUTHOR]

Some species intrinsically have a high invasiveness capacity, shown by high phenotypic plasticity and rapid growth, enabling a wide distribution across their native habitats and successful invasion in the introduced range. For such species, information from native habitats is critically important. An example is Glechoma hederacea, native to Eurasia but introduced and widespread in the USA. Our main objective was to investigate variation in traits of native G. hederacea populations across contrasting habitats: open, forest edge and understory. Vegetation was sampled and the ecophysiological and morphological traits were measured with accompanying environmental parameters. Results showed that in native habitats environmental conditions cover wide gradients of light and soil moisture. Plants had the highest cover in nutrient-rich, shaded habitats, representing the optimal habitat, indicating shade tolerance of G. hederacea. Plants from forest understory exhibited strong similarities in investigated traits to plants from the forest edge, even though this was a drier, sunnier habitat. Plants from open, sunny habitats experienced stress as indicated by the quantum efficiency of PSII and significantly higher sexual reproduction. Results show that G. hederacea is moderately tolerant simultaneously to shade and drought, a characteristic that has been reported for numerous invasive species, while at the same time it shares some characteristics with weedy plants. [ABSTRACT FROM AUTHOR]

Invasive plants can spread over climatically diverse areas. We explore the effects of drought on gas exchange and water relations on the invasive dune species Oenothera drummondii , using plants from four populations with different rainfall and temperatures regimes. Plant material was obtained germinating plants from one native and three non-native populations in a greenhouse. Drought stress was induced by withholding water. Responses to drought stressed plants were then compared to well-watered controls. Measurements of gas exchange, chlorophyll fluorescence and leaf traits were taken initially and every 10 days after water was withheld, until day 36 when plants were re-watered and recover capacity was measured. The effect of water stress was more evident in F v /F m and gas exchange variables. The results suggest that this species possess a mechanism of thermal dissipation of energy. Leaf relative water content was significant lower in drought stressed than control plants. At the end of withholding water period, stressed plants are separated from control plants along the axis I of the ordination analysis evidencing differences in functional traits. All plants recovered well after re-watering. Our results provide evidence for permanent differences in morphological traits and functional responses to drought stress among native and invasive populations of O. drummondii. Although we have only studied four populations, these results may provide evidence for the role of plasticity in contributing to the invasion success of this species. Image 1 • The 4 populations of Oenothera drummondii show different sensitivity to water stress. • The effect of water stress was more evident in gas exchange variables. • Stomatal closure lead NPQ to increase, a mechanism of thermal dissipation of energy. • The response to water stress is not the same in both Mediterranean populations. • All populations recover well after re-watering. [ABSTRACT FROM AUTHOR]

Research on the ecological and evolutionary roles of phytochemicals has recently progressed from studying single compounds to examining chemical diversity itself. A key conceptual advance enabling this progression is the use of species diversity metrics for quantifying phytochemical diversity. In this perspective, we extend the theory developed for species diversity to further our understanding of what exactly phytochemical diversity is and how its many dimensions impact ecological and evolutionary processes. First, we discuss the major dimensions of phytochemical diversity – richness, evenness, functional diversity, and alpha, gamma and beta diversity. We describe their potential independent roles in biotic interactions and the practical challenges associated with their analysis. Second, we re‐analyse the published and unpublished datasets to reveal that the phytochemical diversity experienced by an organism (or observed by a researcher) depends strongly on the scale of the interaction and the total amount of phytochemicals involved. We argue that we must account for these frames of reference to meaningfully understand diversity. Moving from a general notion of phytochemical diversity as a single measure to a precise definition of its multidimensional and multiscale nature yields overlooked testable predictions that will facilitate novel insights about the evolutionary ecology of plant biotic interactions. [ABSTRACT FROM AUTHOR]

Predicting future changes in habitat-associated species traits is an important step in understanding the ecological and evolutionary consequences of environmental change. However, models projecting phenotypic responses to future climate change typically assume populations will respond similarly across the range of a species, while local adaptation and spatial variation in environmental changes are rarely considered. In this study, among-population phenotypic variability was coupled with geographic variation in anticipated hydrologic changes to examine patterns of population-level phenotypic changes expected under future climatic change. To estimate phenotypic responses to watershed hydrology, phenotype-environment associations between body shape and contemporary streamflow were quantified among populations of six species of fishes (Cyprinidae). Future streamflow estimates (2070–2099) were then used to project body shapes within populations, assuming the same phenotype-environment relationships. All species exhibited significant associations between body shape and contemporary streamflow discharge and variability. However, these relationships were not consistent, even among species occupying similar vertical positions in the water column. When these phenotype-environment relationships were projected into future streamflow conditions, populations are not expected to respond uniformly across the species' ranges, and all but one species exhibited projected morphologies outside of the current range of morphological variation. These findings suggest local adaptation and spatial heterogeneity in environmental changes interact to influence variation in the degree of expected phenotypic responses to climate change at both the species and population level. Unlabelled Image • Stream discharge and variability drive intraspecific differences in fish morphology. • Future morphology (2070–2099) was projected from morphology-hydrology associations. • Future climate-induced hydrologic changes result in variable projected phenotypes. • Changes in environmental suitability will vary at the population and species levels. [ABSTRACT FROM AUTHOR]

Understanding the causes of variability in functional traits is an important question in earthworm ecology. While interspecific variation in anatomical dimensions for the same trait is well accepted, the role of environmental filters, soil degradation, and environmental stress in affecting the variability of functional traits is not well understood. In this study, we sought to determine the relative importance of environmental factors and earthworm species taxonomy on the variability in functional traits within species (intraspecific variability). We focused on eight functional traits including body mass, body length, body diameter, gizzard, gizzard thickness, septum thickness, typhlosole, and gut organic matter. We sampled earthworms of 11 different species in various regions of the eastern Amazon to determine the general responses of different species' characteristics when exposed to various ecosystem and soil conditions. Our results suggest that the functional traits of earthworms are influenced in different ways by environmental conditions. One set of traits, including body mass, body length, and body diameter, was more constant and independent of environmental variability, while another set, including gizzard diameter and length, gizzard muscle thickness, septum thickness, typhlosole, and intestinal organic matter, was more sensitive. The most affected by different environmental variables was septum thickness. We also examined which environmental factors are most important for trait variability. Our study highlights the importance of considering both environmental factors and taxonomic classification when studying the variability of functional traits within earthworm species. Overall, our results suggest that taxonomic classification alone is a good guide for estimating the major functional traits of earthworms in the Brazilian Amazon, but local conditions can their variability is which is essential for informing conservation efforts and maintaining ecosystem function. • Earthworm traits variability are better explained by accounting for soil conditions. • Body mass, length and diameter are less sensitive to variability of soil conditions. • Septa thickness variability is the most affected by environmental variables. • Taxonomic classification is a good guide to estimate functional traits. • Morphometric features should be used for gizzard development and body thickness. [ABSTRACT FROM AUTHOR]

• We present a novel trait-based vegetation model to represent the diversity of plant life strategies. • Plant life strategies are created in a hypervolume through trait value combinations. • Including plant trait variability improves representation of plant carbon storage and NPP. • Diversity allows communities' functional reorganization under environmental change. • Low precipitation leads to increase in roots investment at the expense of leaves and wood. The impacts of reduced precipitation on plant functional diversity and how its components (richness, evenness, divergence and composition) modulate the Amazon carbon balance remain elusive. We present a novel trait-based approach, the CArbon and Ecosystem functional-Trait Evaluation (CAETÊ) model to investigate the role of plant trait diversity in representing vegetation carbon (C) storage and net primary productivity (NPP) in current climatic conditions. We assess impacts of plant functional diversity on vegetation C storage under low precipitation in the Amazon basin, by employing two approaches (low and high plant trait diversity, respectively): (i) a plant functional type (PFT) approach comprising three PFTs, and (ii) a trait-based approach representing 3000 plant life strategies (PLSs). The PFTs/PLSs are defined by combinations of six traits: C allocation and residence time in leaves, wood, and fine roots. We found that including trait variability improved the model's performance in representing NPP and vegetation C storage in the Amazon. When considering the whole basin, simulated reductions in precipitation caused vegetation C storage loss by ∼60% for both model approaches, while the PFT approach simulated a more widespread C loss and abrupt changes in neighboring grid cells. We found that owing to high trait variability in the trait-based approach, the plant community was able to functionally reorganize itself via changes in the relative abundance of different plant life strategies, which therefore resulted in the emergence of previously rare trait combinations in the model simulation. The trait-based approach yielded strategies that invest more heavily in fine roots to deal with limited water availability, which allowed the occupation of grid cells where none of the PFTs were able to establish. The prioritization of root investment at the expense of other tissues in response to drought has been observed in other studies. However, the higher investment in roots also had consequences: it resulted, for the trait-based approach, in a higher root:shoot ratio (a mean increase of 74.74%) leading to a lower vegetation C storage in some grid cells. Our findings highlight that accounting for plant functional diversity is crucial when evaluating the sensitivity of the Amazon forest to climate change, and therefore allow for a more mechanistic understanding of the role of biodiversity for tropical forest ecosystem functioning. [ABSTRACT FROM AUTHOR]

Recently, a game-theoretic analysis highlighted the attractiveness of motivation asymmetry and anti-coordination as a strategy for groups to achieve multiple simultaneous goals. To test the prevalence of motivation asymmetry, a survey was performed that asked participants to divide resources among four different societal goals pertaining to economic growth, poverty reduction, health and environmental protection. It is shown, that the survey responses can be modelled by a Dirichlet distribution. It is argued, that the observed high diversity in priority combinations − while at first sight a problem − can be viewed as evidence for an “individual purpose game”, where there is a one-to-one mapping between group participants and the goals they are highly motivated to achieve. Based on these results, two strategies (the majority strategy and the heroic effort strategy) for achieving multiple simultaneous goals in a group are discussed. It is argued, that motivation asymmetry can − if understood in the light of game theory of voluntary efforts − lead to highly effective groups. Also, important implications for the field of ecology are dissussed. [ABSTRACT FROM AUTHOR]

There is unequivocal evidence that altered biodiversity, through changes in the expression and distribution of functional traits, can have large impacts on ecosystem properties. However, trait-based summaries of how organisms affect ecosystem properties often assume that traits show constancy within and between populations and that species contributions to ecosystem functioning are not overly affected by the presence of other species or variations in abiotic conditions. Here, we evaluate the validity of these assumptions using an experiment in which three geographically distinct populations of intertidal sediment-dwelling invertebrates are reciprocally substituted. We find that the mediation of macronutrient generation by these species can vary between different populations and show that changes in biotic and/or abiotic conditions can further modify functionally important aspects of the behaviour of individuals within a population. Our results demonstrate the importance of knowing how, when, and why traits are expressed and suggest that these dimensions of species functionality are not sufficiently well-constrained to facilitate the accurate projection of the functional consequences of change. Information regarding the ecological role of key species and assumptions about the form of species-environment interactions needs urgent refinement. [ABSTRACT FROM AUTHOR]

In mammals, trait variation is often reported to be greater among males than females. However, to date, mainly only morphological traits have been studied. Energy expenditure represents the metabolic costs of multiple physical, physiological, and behavioral traits. Energy expenditure could exhibit particularly high greater male variation through a cumulative effect if those traits mostly exhibit greater male variation, or a lack of greater male variation if many of them do not. Sex differences in energy expenditure variation have been little explored. We analyzed a large database on energy expenditure in adult humans (1494 males and 3108 females) to investigate whether humans have evolved sex differences in the degree of interindividual variation in energy expenditure. We found that, even when statistically comparing males and females of the same age, height, and body composition, there is much more variation in total, activity, and basal energy expenditure among males. However, with aging, variation in total energy expenditure decreases, and because this happens more rapidly in males, the magnitude of greater male variation, though still large, is attenuated in older age groups. Considerably greater male variation in both total and activity energy expenditure could be explained by greater male variation in levels of daily activity. The considerably greater male variation in basal energy expenditure is remarkable and may be explained, at least in part, by greater male variation in the size of energy-demanding organs. If energy expenditure is a trait that is of indirect interest to females when choosing a sexual partner, this would suggest that energy expenditure is under sexual selection. However, we present a novel energetics model demonstrating that it is also possible that females have been under stabilizing selection pressure for an intermediate basal energy expenditure to maximize energy available for reproduction. [ABSTRACT FROM AUTHOR]

Functional diversity is critical for ecosystem dynamics, stability and productivity. However, dynamic global vegetation models ( DGVMs) which are increasingly used to simulate ecosystem functions under global change, condense functional diversity to plant functional types ( PFTs) with constant parameters. Here, we develop an individual- and trait-based version of the DGVM LPJmL (Lund-Potsdam-Jena managed Land) called LPJmL- flexible individual traits ( LPJmL- FIT) with flexible individual traits) which we apply to generate plant trait maps for the Amazon basin. LPJmL- FIT incorporates empirical ranges of five traits of tropical trees extracted from the TRY global plant trait database, namely specific leaf area ( SLA), leaf longevity ( LL), leaf nitrogen content ( Narea), the maximum carboxylation rate of Rubisco per leaf area ( [ABSTRACT FROM AUTHOR]

Objective: The purpose of the present analysis was to quantify the magnitude of intersubject and intrasubject variation of sleep spindle characteristics in a sample of healthy young males. Materials and methods: A total of 32 volunteers (age range 20-30 years) participated in a crossover study aimed at investigating possible effects of Terrestrial Trunked Radio (TETRA) signals on cognitive performance and human brain activity during sleep and waking. Sleep was polysomnographically assessed on nine identically organized study nights per individual. The inter- and intraindividual variability of automatically detected stage 2 non-rapid eye movement (NREM) sleep spindle (11-16 Hz) characteristics (number, density, duration, frequency, amplitude) derived from C3-A2 was determined. Stability of individual differences and the underlying variations were quantified using intraclass correlation (ICC) and coefficients of variation (CV), respectively. Note that there was no significant exposure effect on the considered sleep spindle characteristics. Results: All sleep spindle variables showed an ICC coefficient higher than 0.8, indicating almost perfect stability of interindividual differences. Interindividual variability differed strongly between the considered spindle parameters (CV range: 2-53 %). Intraindividual variability was for all parameters less pronounced (mean CV range: 1-24 %), but their ratios underline the high degree of individuality of each of the investigated parameters. Conclusion: The present analysis confirms the strong individual night-to-night stability of sleep spindle characteristics reported by previous studies. The results provide further evidence for treating sleep spindles as a possible trait, an issue which should be considered in studies relying on a parallel-group design. These data can also be used as reference values. [ABSTRACT FROM AUTHOR]

Abstract: Both aboveground and belowground processes play important roles in tree-grass interactions in savannas. Little consideration has been given to within-site heterogeneity in the strengths of co-occurring canopy and root effects of trees on grasses in savanna communities. Here, we attempted to correlate the spatial pattern of grass morphological traits with the strengths of canopy and root effects. The results from a spatial analysis suggested that the grass traits had lower variability within the operating domain of the root effect than within that of the canopy effect in sub-canopy areas; in contrast, the operating domain of the root effect presented higher variability of grass traits than that of the canopy effect in inter-canopy areas. Combined with root investigations on vertical distribution patterns, these results suggested that the root effect appeared to outweigh the canopy effect in the sub-canopy areas, where apparent vertical root separation between trees and grasses was shown; while the canopy effect could outweigh the root effect in the inter-canopy areas, where root separation was not observed. This study could provide correlative information on the relative importance of canopy and root effects, and has some useful implications on within-site heterogeneity in terms of aboveground and belowground components in savannas. [Copyright &y& Elsevier]

Abstract: This study used daily diary data to model trait and state Positive Affect (PA) and Negative Affect (NA) using the Positive and Negative Affect Schedule (PANAS; ). Data were collected from 364 college students over five days. Intraclass correlation coefficients suggested approximately equal amounts of variability at the trait and state levels. Multilevel factor analysis revealed that the model specifying two correlated factors (PA, NA) and correlated uniqueness terms among redundant items provided the best fit. Trait and state PA and NA were generally associated with stress, anxiety, depression, and three types of self-esteem (performance, academic, social). The coefficients describing these relationships differed somewhat, suggesting that trait and state measurement may have different predictive utility. [Copyright &y& Elsevier]

Despite decades of sleep research by means of polysomnography (PSG), systematic interindividual differences in PSG-assessed sleep parameters have been scarcely investigated. The present study is the first to quantify interindividual variability in standard PSG-assessed variables of sleep structure in terms of stability and robustness as well as magnitude. Twenty-one carefully screened healthy young adults were studied continuously in a strictly controlled laboratory environment, where their PSGs were recorded for eight nights interspersed with three separate 36 h sleep deprivation periods. All PSG records were scored blind to subject and condition, using conventional criteria, and delta power in the non-REM sleep EEG was computed for four electrode derivations. Interindividual differences in sleep variables were examined for stability and robustness, respectively, by comparing results across equivalent nights (e.g. baseline nights) and across experimentally differentiated nights (baseline nights versus recovery nights following sleep deprivation). Among 18 sleep variables analyzed, all except slow-wave sleep (SWS) latency were found to exhibit significantly stable and robust – i.e. trait-like – interindividual differences. This was quantified by means of intraclass correlation coefficients (ICCs), which ranged from 36% to 89% across physiologic variables, and were highest for SWS (73%) and delta power in the non-REM sleep EEG (78–89%). The magnitude of the trait interindividual differences was considerable, consistently exceeding the magnitude of the group-average effect on sleep structure of 36 h total sleep deprivation. Notably, for non-REM delta power – a putative marker of sleep homeostasis – the interindividual differences were from 9.9 to 12.8 times greater than the group-average increase following sleep deprivation relative to baseline. Physiologic sleep variables did not vary among subjects in a completely independent manner – 61.1% of their combined variance clustered in three trait dimensions, which appeared to represent sleep duration, sleep intensity, and sleep discontinuity. Any independent functional significance of these sleep physiologic phenotypes remains to be determined. [ABSTRACT FROM AUTHOR]

• The effects of plant roots on rill erosion were studied under contrasting textured soils. • Sand content significantly affected root biomass traits. • Erosion-reducing effects of root traits were less efficient in heavy-textured soils. • Plant with dense fibrous roots could be the optimal species mixtures to stable sandy slopes. The effects of plant roots on water erosion are likely to vary according to the range of root traits and soil textures. However, little is known about the erosion-reducing potential of roots under different soil textures due to the lack of sufficient texture variations which come from a comparable system. In this study, we systematically investigate how root functional traits respond to soil sand contents and their combined effects on rill erosion. Seeding of Cynodon dactylon (L.) Pers. were grown in a greenhouse under varied proportions of sand mass (ranging from 14% to 83%) by mixing silty clay soil (Ultisols derived from quaternary red clay) and engineering sand. After six months growing, the root-soil composites were subjected to concentrated flow in a hydraulic flume to obtain soil detachment capacity (D c), then roots were separated to measure their morphology and architecture traits. The results showed that sand content significantly affected root morphology traits (e.g., RD and RLD) (p < 0.01). In contrast, root architecture traits (e.g., root fractal dimension, topological index and radius frequency distribution function) showed no significant changes with soil texture (p > 0.05). Generally, root strongly promoted soil cohesion and they mitigated rill erodibility in a coordinated way. Rill erodibility was mostly determined by soil texture even in soils with dense roots, and the erosion-reducing effects of roots were less efficient in heavy-textured soils. Moreover, no significant correlations were found between critical flow shear stress (τ c) and root traits, and soil with a loam texture displayed the lowest τ c. Those relationships are likely to exist elsewhere, but its strength and direction could be changed according to the root trait variability and the varied root-soil feedbacks. The results of this study would be quite relevant for soil erosion modeling and imply the bare sandy soils are more urgent to be recovered during engineering constructions. Moreover, the inclusion of plant with dense fibrous roots could be the optimal species mixtures to stable sandy slopes. [ABSTRACT FROM AUTHOR]

Ex situ collections of wild plants of conservation value are supposed to preserve the phenotypic variability of their wild source populations as well as their plastic responses to environmental stress. However, genetic erosion and adaptive evolutionary changes during cultivation are likely to impose strong constraints to those aims. To date, is it not known whether cultivation affects plant trait variability and stress response of species in botanic garden collections. We studied the effects of cultivation on the trait expression, genetic trait variability, and drought stress response in 12 plant species cultivated in Meise Botanic Garden, Belgium. We found that cultivation increased germination rate and leaf length across all species, while it decreased flowering and delayed the beginning of the flowering period in six drought-tolerant species. We furthermore found indications that plant response to drought was reduced by cultivation in some performance variables, while mortality due to drought slightly increased with cultivation. In three out of 10 traits measured, genetic variability decreased with increasing cultivation time in the botanic garden indicating a loss of evolutionary potential. Our results suggest that the preservation of the phenotypic status and evolutionary potential in ex situ collections is a challenging task and that the application of up-to-date protocols is decisive to achieve meaningful conservation collections. • Ex situ cultivation may reduce trait variability and stress response. • Drought-tolerant and drought-intolerant species respond differently to cultivation. • Implementation of up-to-date cultivation protocols is mandatory. [ABSTRACT FROM AUTHOR]

Changes in community structure concurrent with environmental forcing often form a precursor to changes in species diversity, and can have substantive consequences for ecosystem functioning. Here, we assess the effects of altered levels of evenness that are representative of different levels of eutrophication and changes in salinity associated with altered precipitation patterns, on the mediation of nutrient release by sediment-dwelling invertebrate communities. We find that an adjustment towards a more even distribution of species corresponds with an increase in sediment particle reworking that, in general, translates to increased levels of nutrient release. This response, however, is dependent on the functional role of each species in the community and is influenced by concomitant changes in salinity, especially when salinity extends beyond the range typically experienced by the community. Overall, our findings highlight the dynamic nature of species contributions to functioning and reinforce the importance of understanding when, and how, the mechanistic basis of species-environment interactions are modified as the influence of abiotic and biotic factors flex under periods of directional forcing. • The effect of benthic communities' altered evenness and salinity change was evaluated. • Higher evenness generally led to an increase in bioturbation and nutrient release. • Results were highly dependent on each species functional role in the community. • Salinity levels beyond those typical encountered alter evenness-function relations. • The magnitude and direction of changes in functioning is context dependent. [ABSTRACT FROM AUTHOR]