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Abstract Foundational concepts of trait spaces, including phenotypic plasticity and function of traits, should be expanded and better integrated with ecological theory. This article addresses two areas where plasticity theory can become further integrated with ecological, evolutionary, and developmental thinking. First is the idea that not only trait means within environments and plasticity of trait means across environments is optimized by selection, but that the entire shape of phenotype distributions such as variance or skew should be optimized within and across environments. In order for trait distribution shape to evolve into adaptations, there must be a genetic basis for and selection upon variation in distribution shapes and their plasticities. I present published and new data demonstrating genetic control and selection for higher moments of phenotype distributions; though, plasticity in these values has not yet been tested. Genetic control of phenotype distribution moments is shown for Neurospora crassa ascospore size and shape. Selection on trait distribution moments is shown for Eurosta solidaginis gall size. Second, there is a tradition in modeling plasticity as an adaptive strategy that pits it as an alternative to ecological specialization or generalization. However, these strategies need not be considered alternatives. Rather, with environmental fluctuation within generations plasticity may produce additive or non-additive intermediate (generalist) phenotypes, or something new altogether. I present published and new data on the snail Physa virgata and fish Gambusia affinis that show plasticity produces partly intermediate (generalist) and partly unique phenotypic elements in mixed and fluctuating environments. Plasticity can thus be viewed in the context of a broader trait space and as having broader ecological roles than currently is conceived.

With urbanization identified as being one of the key drivers of change in global land use, and the rapid expansion of urban areas world‐wide, it is relevant to evaluate how novel ecological conditions in cities shape species functional traits, which are essential for how species interact with their environments and with each other. Despite the many comparative studies on organisms living in urban and non‐urban areas, our knowledge on species responses to urban environments remains limited. For one, much of the ecological research has assumed that the environment changes in a linear fashion from the city core to the city edges, whereas in reality the environments within the cities are highly heterogeneous. Furthermore, studies on species responses to these highly variable ecosystems are often based on interspecific mean trait values, which ignore the potential for high levels of intraspecific variation among individuals in key functional traits. The current study investigated intraspecific functional trait differences for four functional traits associated with body size, mobility and resource selection among rural and urban populations of two common bumblebee species, Bombus pascuorum and Bombus lapidarius, in urban centres and adjacent rural areas in Switzerland. We document shifts in functional traits towards smaller individuals and higher multidimensional trait variation in urban populations compared to rural conspecifics of both species. This shows that urban individuals for both species are on average smaller sized but populations are distinctively different from rural population by increasing their trait richness and diversifying their trait combinations. In addition, we found bimodality in tongue length within urban B. pascuorum populations. Our results suggest that urban and rural populations possibly experience differential selection pressures resulting in trait differences across and among populations. We argue that variations in the respective foraging landscapes in cities leads to smaller sized but phenotypically more diverse populations, and drive functional trait divergence. The main quality, originalty and value of this work is that it provides evidence of trait shifts in urban bumblebees. The results show, that urban bumblebees are on average smaller sized but populations are phenotypically more diverse and distinctively different from rural conspecifics.

1. The environmental filtering hypothesis predicts that the abiotic environment selects species withsimilar trait values within communities. Testing this hypothesis along multiple – and interacting –gradients of climate and soil variables constitutes a great opportunity to better understand and predictthe responses of plant communities to ongoing environmental changes.2. Based on two key plant traits, maximum plant height and specific leaf area (SLA), we assessedthe filtering effects of climate (mean annual temperature and precipitation, precipitation seasonality),soil characteristics (soil pH, sand content and total phosphorus) and all potential interactions on thefunctional structure and diversity of 124 dryland communities spread over the globe. The functionalstructure and diversity of dryland communities were quantified using the mean, variance, skewnessand kurtosis of plant trait distributions.3. The models accurately explained the observed variations in functional trait diversity across the124 communities studied. All models included interactions among factors, i.e. climate–climate (9%of explanatory power), climate–soil (24% of explanatory power) and soil–soil interactions (5% ofexplanatory power). Precipitation seasonality was the main driver of maximum plant height, andinteracted with mean annual temperature and precipitation. Soil pH mediated the filtering effects ofclimate and sand content on SLA. Our results also revealed that communities characterized by a lowvariance can also exhibit low kurtosis values, indicating that functionally contrasting species canco-occur even in communities with narrow ranges of trait values.4. Synthesis. We identified the particular set of conditions under which the environmental filteringhypothesis operates in drylands world-wide. Our findings also indicate that species with functionallycontrasting strategies can still co-occur locally, even under prevailing environmental filtering. Interactionsbetween sources of environmental stress should be therefore included in global trait-basedstudies, as this will help to further anticipate where the effects of environmental filtering will impactplant trait diversity under climate change.

Average responses of forest foliar traits to elevation are well understood, but far less is known about trait distributional responses to elevation at multiple ecological scales. This limits our understanding of the ecological scales at which trait variation occurs in response to environmental drivers and change. We analyzed and compared multiple canopy foliar trait distributions using field sampling and airborne imaging spectroscopy along an Andes-to-Amazon elevation gradient. Field-estimated traits were generated from three community-weighting methods, and remotely sensed estimates of traits were made at three scales defined by sampling grain size and ecological extent. Field and remote sensing approaches revealed increases in average leaf mass per unit area (LMA), water, nonstructural carbohydrates (NSCs) and polyphenols with increasing elevation. Foliar nutrients and photosynthetic pigments displayed little to no elevation trend. Sample weighting approaches had little impact on field-estimated trait responses to elevation. Plot representativeness of trait distributions at landscape scales decreased with increasing elevation. Remote sensing indicated elevation-dependent increases in trait variance and distributional skew. Multiscale invariance of LMA, leaf water and NSC mark these traits as candidates for tracking forest responses to changing climate. Trait-based ecological studies can be greatly enhanced with multiscale studies made possible by imaging spectroscopy.

The functional traits of organisms within multispecies assemblages regulate biodiversity effects on ecosystem functioning. Yet how traits should assemble to boost multiple ecosystem functions simultaneously (multifunctionality) remains poorly explored. In a multibiome litter experiment covering most of the global variation in leaf trait spectra, we showed that three dimensions of functional diversity (dispersion, rarity, and evenness) explained up to 66% of variations in multifunctionality, although the dominant species and their traits remained an important predictor. While high dispersion impeded multifunctionality, increasing the evenness among functionally dissimilar species was a key dimension to promote higher multifunctionality and to reduce the abundance of plant pathogens. Because too-dissimilar species could have negative effects on ecosystems, our results highlight the need for not only diverse but also functionally even assemblages to promote multifunctionality. The effect of functionally rare species strongly shifted from positive to negative depending on their trait differences with the dominant species. Simultaneously managing the dispersion, evenness, and rarity in multispecies assemblages could be used to design assemblages aimed at maximizing multifunctionality independently of the biome, the identity of dominant species, or the range of trait values considered. Functional evenness and rarity offer promise to improve the management of terrestrial ecosystems and to limit plant disease risks.

The measurement efficiency of a grid multidimensional computerized classification test (grid MCCT), which makes a classification decision per dimension, can be improved by taking the correlations between the dimensions into account in the termination criterion. The higher the correlations, the better the improvement in measurement efficiency. However, a termination criterion utilizing inter-dimensional information (i.e., SPRT-C; Liu et al., 2022 ) was found to yield lower levels of correct classification rates than not utilizing it (i.e., SPRT-SF; Seitz & Frey, 2013 ) under the between-item grid MCCT when the cutoff was set at the mean of the latent trait distribution. This study proposes a pre-rule to determine whether the SPRT-SF or SPRT-C should be used during the process of classification test administration. Through a series of simulation studies, the results showed that our proposed method (called P-SPRT) can substantially improve upon the SPRT-C in terms of correct classification rates, while maintaining its high measurement efficiency in terms of test length. This paper concludes with a discussion of the findings and further applications.

Aim: Despite several recent efforts to map plant traits and to identify their climatic drivers, there are still major gaps. Global trait patterns for major functional groups, in particular, the differences between woody and herbaceous plants, have yet to be identified. Here, we take advantage of big data efforts to compile plant species occurrence and trait data to analyse the spatial patterns of assemblage means and variances of key plant traits. We tested whether these patterns and their climatic drivers are similar for woody and herbaceous plants. Location: New World (North and South America). Methods: Using the largest currently available database of plant occurrences, we provide maps of 200 × 200 km grid-cell trait means and variances for both woody and herbaceous species and identify environmental drivers related to these patterns. We focus on six plant traits: maximum plant height, specific leaf area, seed mass, wood density, leaf nitrogen concentration and leaf phosphorus concentration. Results: For woody assemblages, we found a strong climate signal for both means and variances of most of the studied traits, consistent with strong environmental filtering. In contrast, for herbaceous assemblages, spatial patterns of trait means and variances were more variable, the climate signal on trait means was often different and weaker. Main conclusion: Trait variations for woody versus herbaceous assemblages appear to reflect alternative strategies and differing environmental constraints. Given that most large-scale trait studies are based on woody species, the strikingly different biogeographic patterns of herbaceous traits suggest that a more synthetic framework is needed that addresses how suites of traits within and across broad functional groups respond to climate.

Plants adapt seed traits in response to different environmental triggers, supporting the survival of the next generation. To elucidate the mechanistic understanding of such adaptations it is important to characterize the distributions of seed traits by phenotyping seeds on an individual scale and to correlate these traits with corresponding plant properties. Here we introduce a seed-to-plant-tracking pipeline which enables automated handling and high precision phenotyping of Arabidopsis seeds as well as germination detection and early growth quantification of emerging plants. It includes previously published measurement platforms ( pheno Seeder, Growscreen), which were improved for very small seeds. We demonstrate the performance of the pipeline by comparing seeds from two consecutive generations of elevated temperature during flowering with control seeds. Relative standard deviation of repeated seed mass measurements was reduced to 0.2%. We identified an increase in seed mass, volume, length, width, height, and germination time as well as a darkening of the seeds under the treatment. A correlation analysis revealed relationships between seed and plant traits, e.g., a highly significant negative correlation between seed brightness and germination time, and a positive correlation between seed mass and early growth rate, but no correlation between time of emergence and morphometric seed traits (e.g., mass, volume). Thus, the seed-to-plant tracking provides the basis for investigating the mechanism of seed and plant trait variation and transgenerational inheritance.

Benthic biodiversity is of global significance for the provision of ecosystem services and the mediation of global biogeochemical cycles. The lack of detailed spatial distributions of the functions and vulnerabilities of the benthos critically prevents us from protecting benthic biodiversity and its functioning in the context of increasing human perturbations and climate change. Here, we propose a multidisciplinary approach to bridging in situ benthic data to the maps of macrobenthic functions and vulnerabilities at the scale of the northwestern shelf of the Black Sea. Our findings show that oxygen availability is a key driver of the functional trait composition of macrozoobenthic communities. Shallower well-oxygenated areas support high biomixing and bioirrigation on muddier-sandier substrata and high biodeposition on coarser substrata associated with mussel reef communities. In contrast, at depleted oxygen areas at the edge of the shelf, macrobenthic communities are functionally impoverished with only a combination of a few typical opportunistic traits, and those communities have a negligible impact on ecosystem functions. Mapping of vulnerabilities and functions of benthic communities can support marine management strategies aligned with the United Nations Sustainable Development Goal 14: Life Below Water.

In forest succession, the ecological strategies of the dominant species that are based on functional traits are important in the determination of both the mechanisms and the potential directions of succession. Thirty-one plots were established in the Loess Plateau region of northern Shaanxi in China. Fifteen leaf traits were measured for the 31 dominant species that represented the six stages of succession, and the traits included four that were related to morphology, seven to stoichiometry and four to physiological ecology. The species from the different successional stages had different patterns of distribution of the traits, and different key traits predicted the turnover of the species during succession. The ash and the cellulose contents were key regulatory factors of species turnover in the early successional communities, and the trait niche forces in sugar and leaf dry mass content might become more important with the progression of succession. When only the three herb stages were considered, a progressive replacement of the ruderal by the competitive–ruderal species occurred in the intermediate stages of succession, which was followed by the stress-tolerant–competitive or the competitive-stress tolerant-ruderal strategists late in the succession. Thus, the different species that occurred in the different stages of succession shared different trait-based ecological strategies. Additionally, these differences occurred concomitantly with a shift toward competitive-stress tolerant-ruderal strategies.