Low SLA Research Articles

Interspecific trait differences drive plant community responses on serpentine soils

Abstract Serpentine ecosystems are characterised by multiple environmental stressors: high levels of trace metals such as nickel (Ni), low availability of macronutrients and low water retention. These harsh environmental conditions exert a strong selective force on the vegetation, but their effect on community assembly processes and the functional trait composition remains unknown. In 26 plots on four serpentine sites on Lesbos Island (Greece), we measured six leaf functional traits related to resource acquisition and stress resistance on the 20 most abundant plant species. We quantified the proportion of variance explained by inter‐ and intraspecific trait differences and tested if individual species showed changes in trait values explained by soil Ni content. We investigated the adaptive value and the community level changes for each trait along the natural soil Ni gradient using a mixed model approach and functional diversity analyses. We tested the role of the abundant serpentine endemic and Ni‐hyperaccumulating species Odontarrhena lesbiaca in driving these patterns. Intraspecific variation explained by soil Ni content is smaller than 4%, and most of the variance is explained by interspecific differences in trait values. Most species do not show significant changes in trait values in response to soil Ni. At the community level, low specific leaf areas, small and thick leaves are selected on high Ni soils. Functional diversity analyses suggest a shift towards a stress tolerance syndrome (thick and small leaves with low SLA values) and an increase in functional diversity on Ni‐rich soils. However, these patterns are driven by the increasing abundance of O. lesbiaca. The endemic Ni hyperaccumulator has a stress tolerance strategy with small thick leaves and low SLA, while the community of broadly distributed species show an increase in trait values related to dominance and fast growth. Synthesis. Intraspecific variation in leaf trait responds little to soil metal toxicity. Endemic species harbour unique trait values compared to species with broad distribution which should justify their conservation as a priority.

Non-structural carbohydrate concentrations in tree organs vary across biomes and leaf habits, but are independent of the fast-slow plant economic spectrum.

Carbohydrate reserves play a vital role in plant survival during periods of negative carbon balance. Under a carbon-limited scenario, we expect a trade-offs between carbon allocation to growth, reserves, and defense. A resulting hypothesis is that carbon allocation to reserves exhibits a coordinated variation with functional traits associated with the 'fast-slow' plant economics spectrum. We tested the relationship between non-structural carbohydrates (NSC) of tree organs and functional traits using 61 angiosperm tree species from temperate and tropical forests with phylogenetic hierarchical Bayesian models. Our results provide evidence that NSC concentrations in stems and branches are decoupled from plant functional traits. while those in roots are weakly coupled with plant functional traits. In contrast, we found that variation between NSC concentrations in leaves and the fast-slow trait spectrum was coordinated, as species with higher leaf NSC had trait values associated with resource conservative species, such as lower SLA, leaf N, and leaf P. We also detected a small effect of leaf habit on the variation of NSC concentrations in branches and roots. Efforts to predict the response of ecosystems to global change will need to integrate a suite of plant traits, such as NSC concentrations in woody organs, that are independent of the 'fast-slow' plant economics spectrum and that capture how species respond to a broad range of global change drivers.

Effects of plant leaf traits, abundance and phylogeny on differentiation of herbivorous insect assemblages in Mediterranean mixed forest

AbstractHerbivorous insect assemblages are functionally diverse, with each species exploiting plant tissues in different ways. Availability and palatability of plant tissues influence the diversity and composition of herbivorous insect assemblages. However, few studies have compared herbivorous insect assemblages and their ecological correlates across multiple plant species within the same plant community. Here, we sampled insect assemblages from the canopies of 1060 plants belonging to 36 woody species in two mixed Mediterranean forest stands. 401 insect species were classified as herbivores and grouped into sucker or chewer guilds. We explored differences in the diversity and composition of each insect guild across plant species, and tested their relationships with plant leaf traits, abundance or phylogeny, and explored whether the structures of plant-herbivorous insect networks depended on any of the studied plant traits. Plant identity accounted for the highest proportion of variation in the composition of each insect guild. Plant species abundance showed a positive effect on both insect guilds’ diversity. Suckers’ diversity was higher in plant species with deciduous leaves and low SLA, while the composition was more similar between phylogenetically closer plant species. Chewers diversity increased with the leaf area, while plants with similar LA, leaf nitrogen, SLA and distinct leaf habit showed more similar assemblages. Similarly, closely related angiosperms showed similar chewer assemblages. Plant–insect interaction networks present a modular structure, in which plants belonging to the same module tend to be related and share more sucker species. We add to the evidence supporting the role of plant species features as filters for structuring their associated herbivore insect assemblages.

Wear resistance and flexural properties of low force SLA- and DLP-printed splint materials in different printing orientations: An in vitro study

ObjectivesTo investigate the influence of material and printing orientation on wear resistance and flexural properties of one low force SLA- and two DLP-printed splint materials and to compare these 3D-printed splints to a subtractively manufactured splint material. MethodsTwo DLP-printed (V-Print splint, LuxaPrint Ortho Plus) and one low force SLA-printed (Dental LT Clear) material, where specimens were printed in three printing orientations (0°, 45°, 90°), were investigated. In addition, one milled splint material (Zirlux Splint Transparent) was examined. A total of 160 specimens were produced for both test series. The two-body wear test was performed in a chewing simulator (80′000 cycles at 50 N with 5–55 °C thermocycling). Steatite balls were used as antagonists. The wear pattern was analyzed with a 3D digital microscope in terms of maximum vertical intrusion depth (mm) and total volume loss (mm³). The flexural properties were investigated by three-point bending in accordance with ISO 20795-1: 2013 (denture base polymers). The flexural strength (MPa) and the flexural modulus (MPa) were measured. Two-way ANOVA was performed to investigate the effects of the two independent variables material and printing orientation for the three 3D-printed materials. The comparison of the printing orientations within one material was carried out with one-way ANOVA with post-hoc Tukey tests. ResultsTwo-way ANOVA revealed that wear and flexural properties are highly dependent on the 3D-printed material (p < 0.001). Across groups, a significant effect was observed for wear depth (p = 0.031) and wear volume (p = 0.044) with regard to printing orientation but this was not found for flexural strength (p = 0.080) and flexural modulus (p = 0.136). One-way ANOVA showed that both DLP-printed groups showed no significant differences within the printing orientations in terms of wear and flexural properties. Dental LT Clear showed that 90° oriented specimens had higher flexural strength than 0° oriented ones (p < 0.001) and 45° oriented specimens also showed higher values than 0° ones (p = 0.038). No significant differences were observed within the printing orientations for flexural modulus and wear behaviour within this group. T-tests showed that the milled splints exhibited statistically higher wear resistance and flexural properties compared to all three 3D-printed splint materials (p < 0.001) and that highly significant differences were found between the 3D-printed splint materials for both test series. ConclusionWithin the limitations of this in vitro study, it can be stated that wear behaviour and flexural properties are highly dependent on the 3D-printed material itself. Currently, milled splints exhibit higher wear resistance and flexural properties compared to 3D-printed splint materials. The printing orientation has a minor influence on the properties investigated. Nevertheless, two-way ANOVA also showed a significant influence of printing orientation in the wear test across groups and one-way ANOVA detected significant effects for SLA material in terms of flexural strength, with printing in 90° showing the highest flexural strength. Therefore, anisotropy was found in SLA material, but it can be limited with the employed printing parameters. Both DLP-printed materials showed no significant difference within the printing orientation.

Functional diversity along disturbance and environmental gradients in Ethiopian moist Afromontane forest

Considering multiple measures to fully capture functional diversity is important. However, the effects of disturbance gradients on diversity have been controversial, as species diversity alone may not fully capture these effects. This study aimed to evaluate trait-based diversity across disturbance gradients in the moist Afromontane forest of Ethiopia, Yayu Coffee Forest Biosphere Reserve (YCFBR). Vegetation data and relevant traits related to plant-life strategies, competition, and responses to disturbances were collected. A multiple regression model was used to test the response of functional diversity to disturbances and environmental gradients. The results revealed functional diversity in plant communities, including dendrogram-based functional diversity for plot-based (FDp), functional richness (FRic), functional evenness (FEve), functional divergence (FDiv), functional dispersions (FDis), and community-weighted mean of maximum tree height (CWM.Hmax), showed decreasing patterns with increasing disturbance intensity in the YCFBR. Additionally, the findings highlighted that FDis and Hmax are the most vulnerable functional traits to anthropogenic factors and are less tolerant in disturbed ecosystem environments. Therefore, reducing disturbances is crucial to maintaining higher levels of these functional diversities. For example, the results showed that the CWM.Hmax declined from 27.25 m to 15 m, indicating a shift towards shorter plant species. In contrast, the community-weighted mean of woody density (CWM.WD), the community-weighted mean of specific leaf area (CWM.SLA), and the community-weighted mean of seed mass (CWM.SM) increased significantly with an increase in disturbance intensity. For instance, CWM.SM and CWM.SLA changed from 5 to 14.25 (g) and 90 to 130 (cm2/g), respectively. These indices may serve as indicators of ecosystem resilience at disturbed forest ecosystem sites. Furthermore, the regression results indicated that FDp, FRic, FEve, FDiv, FDis, CWM.WD, and CWM.Hmax showed increasing patterns with increasing species richness, which suggests that protecting and promoting species diversity can contribute to maintaining high levels of functional diversity. The mixed effects model revealed that anthropogenic disturbance and elevational gradients had significant effects on functional diversity in the YCFBR. Therefore, when managing and conserving biodiversity in heterogeneous environments, both anthropogenic factors and environmental variables need to be considered. Species with low SLA and SM are recommended for the restoration of disturbed ecosystems. Overall, this study demonstrates that trait-based functional diversity is useful for predicting the adaptation potentials of species in heterogeneous environments and disturbance gradients.

Effects of urban, peri-urban and rural land covers on plant functional traits around Bogotá, Colombia

AbstractThe Global South has suffered an accelerated population and urban growth. This has created multiple impacts at the regional level such as erosion, soil degradation and biodiversity loss, as well as temperature increase in the cities causing urban heat islands. Bogotá, the capital of Colombia, is one of the largest cities in the Global South and in the last five decades has undergone a rapid urban transition, impacting surrounding ecosystems. However, little is known about how urbanization affects the local flora. To understand how plants are responding and adapting to urbanization processes in the city of Bogotá, we used a land cover gradient of urban, peri-urban and rural areas, and four plant functional traits (leaf area [LA], specific leaf area [SLA], leaf dry matter content [LDMC] and wood density [WD]). We analyzed 16 species shared in at least two land covers. Although urban and peri-urban areas had higher temperatures and higher LDMC and lower SLA values than rural areas, there were no significant differences in functional traits between land covers. Some species showed significant changes between land covers, indicating that there is a species-specific response to urbanization. Considering the need for urban areas to prioritize species that promote cooling and exhibit resistance to stress, as well as the capacity to adapt to climate change, it is essential to include plants possessing different combinations of functional traits.

Salinity exposure affects lower-canopy specific leaf area of upland trees in a coastal deciduous forest

Sea level rise and increasing storm surges are likely to affect the canopy physiology, ecology, and structure of coastal forests, even well in advance of tree mortality. Laboratory and greenhouse studies have documented that saltwater exposure can trigger changes in leaf-level physiology and morphology, but few in situ studies have examined how tree-specific leaf area (SLA), the ratio of leaf area to mass and a crucial trait and model parameter, is affected by saline soils. We conducted an observational study of SLA in a mid-Atlantic (USA) coastal deciduous forest, taking advantage of a natural gradient in salinity along a tidal creek. Measured SLA of the 239 trees and seven species sampled ranged from Carya glabra (N = 6 trees, mean SLA = 277.9 ± 36.3 cm2/g) to Fagus grandifolia (N = 60, 321.9 ± 62.9 cm2/g); as expected, trees species and canopy position (sun versus shade) significantly affected SLA. For trees (N = 100) directly exposed to the tidal creek, salinity was highly significant after accounting for species (P < 0.001), with trees in the lower reaches of the creek having lower SLA. Leaf area index (LAI), computed from SLA and litter traps, ranged from 4.8 to 15.8 and was inversely related to salinity exposure; the spatial variability in leaf litter production contributed much more to LAI uncertainty than did SLA variability. These in situ results are correlative but consistent with the hypothesis, based on previous greenhouse studies, that the stress of chronic salinity exposure changes species’ leaf morphology. Our findings are useful for understanding the growing effects of saltwater intrusion into upland forests, as well as parameterizing and testing ecosystem-scale models simulating forest stressors and disturbances at the terrestrial-aquatic interface.

Differential patterns of within- and between-population genetically based trait variation in Lupinus angustifolius.

Within-population genetic and phenotypic variation play a key role in the development of adaptive responses to environmental change. Between-population variation is also an essential element in assessing the evolutionary potential of species in response to changes in environmental conditions. In this context, common garden experiments are a useful tool to separate the genetic and environmental components of phenotypic variation. We aimed to assess within- and between-population phenotypic variation of Lupinus angustifolius L. in terms of its evolutionary potential to adapt to ongoing climate change. We evaluated populations' phenotypic variation of foliar, phenological and reproductive traits with a common garden experiment. Patterns of functional trait variation were assessed with (1) mixed model analyses and coefficients of variation (CVs) with confidence intervals, (2) principal component analyses (PCAs) and (3) correlations between pairs of traits. Analyses were performed at the population level (four populations) and at the latitude level (grouping pairs of populations located in two latitudinal ranges). Phenotypic variation had a significant genetic component associated with a latitudinal pattern. (1) Mixed models found lower specific leaf area, advanced flowering phenology and lower seed production of heavier seeds in southern populations, whereas CV analyses showed lower within-latitude variation especially in phenological and reproductive traits in southern populations. (2) PCAs showed a clearer differentiation of phenotypic variation between latitudes than between populations. (3) Correlation analyses showed a greater number of significant correlations between traits in southern populations (25 vs. 13). Between-population phenotypic variation was determined by contrasting temperature and drought at different latitude and elevation. Southern populations had differential trait values compatible with adaptations to high temperatures and drought. Moreover, they had lower within-population variation and a greater number of trait correlations probably as a result of these limiting conditions, making them more vulnerable to climate change.

Integrating defense and leaf economic spectrum traits in a tropical savanna plant.

Allocation to plant defense traits likely depends on resource supply, herbivory, and other plant functional traits such as the leaf economic spectrum (LES) traits. Yet, attempts to integrate defense and resource acquisitive traits remain elusive. We assessed intraspecific covariation between different defense and LES traits in a widely distributed tropical savanna herb, Solanum incanum, a unique model species for studying allocations to physical, chemical, and structural defenses to mammalian herbivory. We found that in a multivariate trait space, the structural defenses - lignin and cellulose - were positively related to the resource conservative traits - low SLA and low leaf N. Phenolic content, a chemical defense, was positively associated with resource acquisitive traits - high SLA and high leaf N - while also being associated with an independent third component axis. Both principal components 1 and 3 were not associated with resource supply and herbivory intensity. In contrast, spine density - a physical defense - was orthogonal to the LES axis and positively associated with soil P and herbivory intensity. These results suggest a hypothesized "pyramid" of trade-offs in allocation to defense along the LES and herbivory intensity axes. Therefore, future attempts to integrate defense traits with the broader plant functional trait framework, such as the LES, needs a multifaceted approach that accounts for unique influences of resource acquisitive traits and herbivory risk.

Variation in Leaf Functional and Plant Defense Traits of Introduced Eucalyptus Species across Environmental Gradients in Their New Range in Southern China

Due to the rapid development of China’s economy, the demand for wood is steadily increasing. Eucalyptus species have been introduced in large quantities because of their fast growth, strong adaptability, and wide utility. To understand the phenological changes in introduced Eucalyptus in its new range, we carried out a field investigation to examine leaf functional and chemical defense traits of three introduced species (E. saligna, E. grandis and E. robusta) over latitudinal and altitudinal gradients in southern China. We sampled multiple stands of each species, and measured the leaf physical characteristics (e.g., leaf width, leaf thickness, and specific leaf area [SLA]), leaf nitrogen (N) and phosphorus (P) content, and phenolic compounds. We found that many functional traits (e.g., leaf size and thickness) decreased at lower latitudes, especially in E. grandis, possibly to reduce heat and water loss under higher temperatures. In E. grandis, we found that leaf P was lower at higher latitudes and altitude, and phenolics increased with elevation, while in E. robusta, both leaf N and P decreased with altitude. These findings suggested that both species were more conservative in resource allocation, with E. grandis possessing enhanced chemical defenses in response to the conditions experienced at higher elevations. In addition, we found the tree populations at the northern range limit of E. robusta had lower SLA, suggesting a more conservative growth strategy, In contrast, small populations in the northern part of the ranges of E. grandis had higher SLA, indicating range expansion at the edge of the species’ geographic distribution. Overall, it is particularly important to consider intraspecific trait differences across wide geographic areas when studying the spread of invasive species in the new range.

Effects of Drought Stress and Ca Supply on the Biomass Allocation Strategies of Poplar and Mulberry

In order to investigate the effect of Ca on the biomass allocation strategies of tree species with different growth rates under drought conditions, we treated poplar (Populus canadensis cv) cuttings and mulberry (Morus alba) seedlings with two soil moisture levels (40 ± 5% and 80 ± 5% maximum water holding capacity) and two soil Ca levels (0 and 200 mg·kg−1 Ca2+) in a greenhouse experiment, and then measured the Ca uptake, growth, gas exchange parameters, biomass allocation, and leaf traits. Drought induced a reduction in biomass accumulation of poplar cuttings and mulberry seedlings, and the cuttings and seedlings exhibited different biomass allocation patterns in response to drought stress. Under Ca0 treatment, poplar cuttings allocated more biomass to leaves and less biomass to stems under drought conditions, leading to an increased leaf/stem (L/St) ratio and higher SLA than under moist conditions in order to maintain higher Pn, and had enhanced WUE to cope with drought stress. Under the same treatment, mulberry seedlings allocated more biomass to roots and less biomass to stems, leading to an increased root/shoot (R/S) ratio and lower SLA, to improve drought resistance. Ca200 treatment decreased the growth of poplar cuttings and mulberry seedlings, whereas it enhanced the WUE, root growth, and R/S ratio of poplar cuttings and the WUE of mulberry seedlings, and alleviated drought stress in both species.

Intraspecific trait variation and changing life-history strategies explain host community disease risk along a temperature gradient.

Predicting how climate change will affect disease risk is complicated by the fact that changing environmental conditions can affect disease through direct and indirect effects. Species with fast-paced life-history strategies often amplify disease, and changing climate can modify life-history composition of communities thereby altering disease risk. However, individuals within a species can also respond to changing conditions with intraspecific trait variation. To test the effect of temperature, as well as inter- and intraspecifc trait variation on community disease risk, we measured foliar disease and specific leaf area (SLA; a proxy for life-history strategy) on more than 2500 host (plant) individuals in 199 communities across a 1101 m elevational gradient in southeastern Switzerland. There was no direct effect of increasing temperature on disease. Instead, increasing temperature favoured species with higher SLA, fast-paced life-history strategies. This effect was balanced by intraspecific variation in SLA: on average, host individuals expressed lower SLA with increasing temperature, and this effect was stronger among species adapted to warmer temperatures and lower latitudes. These results demonstrate how impacts of changing temperature on disease may depend on how temperature combines and interacts with host community structure while indicating that evolutionary constraints can determine how these effects are manifested under global change. This article is part of the theme issue 'Infectious disease ecology and evolution in a changing world'.

Forecasting Cloud Application Workloads WithCloudInsightfor Predictive Resource Management

Predictive cloud resource management has been widely adopted to overcome the limitations of reactive cloud autoscaling. The predictive resource management is highly relying on workload predictors, which estimate short-/long-term fluctuations of cloud application workloads. These predictors tend to be pre-optimized for specific workload patterns. However, such predictors are still insufficient to handle real-world cloud workloads whose patterns may be unknown a priori, may dynamically change over time and may be irregular. As a result, these predictors often cause over-/under-provisioning of cloud resources. To address this problem, we have created CloudInsight, a novel cloud workload prediction framework, leveraging the combined power of multiple workload predictors. CloudInsight creates an ensemble model using multiple predictors to make accurate predictions for real workloads. The weights of the predictors in CloudInsight are determined at runtime with their accuracy for the current workload using multi-class regression. The ensemble model is periodically optimized to handle sudden changes in the workload. We evaluated CloudInsight with various real workload traces. The results show that CloudInsight has 13–27 percent higher accuracy than state-of-the-art predictors. Moreover, the results from trace-based simulations with a cloud resource manager show that CloudInsight has 15–20 percent less under-/over-provisioning periods, resulting in high cost-efficiency and low SLA violations.

Nurse-target functional match explains plant facilitation strength

Functional trait combinations underlie assembly rules of plant communities. In harsh environments, facilitation is widespread but its strength varies greatly between pairs of interacting nurse-target plants. Here, we investigated whether functional traits of potential nurse and target species can jointly predict the sign and strength of their interactions. In order to estimate the facilitation strength for 60 nurse-target species combinations, we conducted field experiments in a seasonally dry tropical forest. We estimated eight key functional traits (canopy diameter, leaf C:N, leaf ∂C13, specific leaf area, number of months without leaves, wood density, hydraulic diameter and root volume) for 20 potential mature nurse species established under field conditions. For three target species, four key functional traits were estimated for seedlings grown in greenhouse conditions (total dry biomass, plant water content, root:shoot ratio, and apical growth rate). Our results showed that facilitation strength can be explained by the interaction between nurse and target traits. Facilitation increased when low SLA nurses interacted with targets investing in apical growth, thus acquisitive targets are benefited by the greater availability of resources left by conservative nurses. Facilitation also increased when nurses with lower values of leaf ∂C13 interacted with high root:shoot ratio targets, so early release of light and soil resources due to nurse earlier leaf loss benefits drought resistant targets. Besides, root volume of the nurse promoted facilitation, probably due to improvements on soil conditions. Functional trait match can shed light on plant community assembly rules and help promote ecosystem restoration and management.

Relative importance of region, seasonality and weed management practice effects on the functional structure of weed communities in French vineyards

Winegrowers have diversified their weed management practices over the last two decades changing the structure and the composition of weed communities. Complementary to taxonomic studies, trait-based approaches are promising ways for a better understanding of weed community responses to environmental and agronomic filters. In the present study, the impacts of climate, soil characteristics, seasons and weed management practices (chemical weeding, tillage and mowing) were assessed on weed communities from 46 plots in three French wine-growing regions (Champagne, Languedoc and Rhône valley). These agro-environmental gradients structuring weed communities according to their combinations of traits were highlighted using multivariate analysis (RLQ). The impacts of these filters on Community Weighted Means (CWM) and Community Weighted Variance (CWV) of weed communities were analysed using mixed and null modelling. Our results showed that spatio-temporal and weed management practice variables explained from 13% to 48% of the total variance of CWM (specific leaf area, maximum height, seed mass, flowering onset and duration and lateral spread). Region, seasonality and management practices explained 53%, 28% and 19% of CWM marginal variance, respectively. Weed management impacted CWM and CWV through two main gradients: (i) a soil disturbance gradient with high mechanical disturbance of soil in tilled plots and low mechanical disturbance in chemically weeded plots and (ii) a vegetation cover gradient with high vegetation abundance in mowed plots compared to barer soils in tilled and chemically weeded plots. In Languedoc, chemical weeding filtered weed communities with ruderal strategy trait values (low seed mass, small-stature) while mowed communities were more competitive (higher seed mass, higher stature and lower SLA). In Languedoc and Champagne, tillage favoured communities with high seed mass that increases the viability of buried seeds and high lateral spread values associated to the ability to resprout after tillage. This study demonstrated that trait-based approaches can be successfully applied to perennial cropping systems such as vineyards, in order to understand community assembly to better guide weed management practices.

Genetic Variability and G×E Interactions in a Diverse Set of Groundnut Accessions

Background: Knowledge of the genetic diversity for various agronomic traits and their interaction with the environment and subsequent classification of genotypes will be beneficial for identification of divergent and stable sources of agronomic traits. Methods: A set of 96 groundnut germplasm accessions belonging to four botanical groups were evaluated for three years (2017 to 2019) for pod yield and component traits using AMMI analysis and subsequently accessions were classified based Euclidean cluster analysis. Result: Among different botanical groups, Virginia genotypes matured late and possessed high SPAD chlorophyll meter readings (SCMR) and pod yield compared to Spanish types. The component traits of pod maturity like days to flowering (first and 50%) showed low heritability and high genotype × environment interaction (GEI) and significant negatively affected sound mature kernel (SMK) and shelling per centage (SP). The cumulative contribution of environment and GEI component to the total variance was the highest in the expression of SP (67%) followed by days to maturity (54%) and days to 50% flowering (52%). Euclidean distance-based cluster analysis grouped the 96 accessions into five major clusters. Cluster I had accessions with higher pod yield, whereas cluster V contained accessions with low SLA, high SCMR and moderate pod yield. High yielding as well as stable accessions identified based on AMMI stability value (ASV) are NRCG 17332, 10076, 17268, 17197, 17108, 10106, 10089 and 17165. Trait specific as well as stable accessions identified in the present study can be useful donors for groundnut breeding programme.

Variación de los caracteres foliares en comunidades vegetales del centro de la Argentina bajo diferentes condiciones climáticas y de uso del suelo

Leaf functional traits in a plant community are the result of the effect of environmental conditions and have a direct impact on ecosystem properties and functioning. We analyzed the variations of five leaf functional traits in plant communities from central Argentina under different climatic conditions and anthropogenic use determining changes in physiognomy. Study sites were located in Córdoba province (Argentina) within four phytogeographic units categorized according to their climatic condition based on an aridity index; they were named as ‘climatic units’ 1, 2, 3 and 4, following a gradient from lower to higher temperature and aridity. In each climatic unit we selected six sites located in two physiognomies corresponding to different degrees of anthropogenic use: 3 sites in woodlands (less use), and 3 sites in grasslands/shrublands (more intense use). We measured five leaf traits (specific leaf area [SLA], leaf dry matter content [LDMC], leaf toughness, leaf thickness and decomposability), and we calculated the community weighted mean for each trait for each site. The variations in functional leaf traits were mainly determine by climatic conditions. The physiognomic change, because of anthropogenic use, also affected these variations, but this effect was conditioned by climate. Under colder and wetter climatic conditions, the removal of tree species result in communities dominate mainly by grasses with conservative foliar trait values (e.g., lower SLA, higher leaf toughness and lower decomposability). However, in warmer and drier climatic conditions, the removal of tree species did not imply a change in the functional strategy of the community as it resulted in an increase dominance of grasses and dicotyledonous shrub species with relatively lower foliar toughness and high decomposability. Our results show the interactive effect of climate and anthropogenic use on the variations in leaf functional traits and the complexity to predict the effects of such variations on ecosystem processes.

Major histocompatibility complex class II genetic diversity and the genetic influence on gut microbiota in Guizhou minipigs.

Major histocompatibility complex (MHC) is an important complex that presents antigen to T cells. The second exon of swine MHC (SLA) class II genes has antigen binding sites that bind with extracellular antigen. Populations with high MHC gene diversity result in low gut microbiota, and individuals with MHC gene heterozygote have lower gut microbiota diversity than that of homozygote. The pig is an animal with organs physiologically and anatomically similar to humans than any other mammal, and the pig is also suitably developed as a laboratory animal to establish the animal models of human disease. However, the relationship between SLA genetic diversity and the gut microbes of the pig is ambiguous. We studied the characterization of SLA class II genes and calculated the genetic diversity, and then we selected experimental animal groups divided by different SLA genotypes to investigate the gut microbiota composition by sequencing V3 to V4 hypervariable regions of bacterial 16s rRNA from fecal samples. Our results showed that Guizhou minipigs had a low SLA genetic diversity, which may be due to the small founder population. The Guizhou minipig population deviated from neutral selection and balancing selection, which shows that Guizhou minipigs experience a strong artificial selection in recent years. We observed that the sex differences influenced gut microbiota much more deeply than that of genetics. Our results also showed that the individual with heterozygote of genes at the SLA class II region had much higher abundant gut microbiota than that of the homozygote.

Traits as determinants of species abundance in a grassland community

AbstractQuestionsThe patterns in abundances of plant species and the processes which determine these patterns have been intensively studied. While recent investigations have recognized plant functional traits as important determinants of species abundances, intraspecific trait variability as a driver of species abundance patterns has largely been ignored. The objective of this study was to quantify the effect of intraspecific trait variability and trait dissimilarity from mean community characteristics (community‐weighted mean [CWM]) on the abundance of six widely distributed grassland species, while controlling for the possible influence of environmental conditions for three commonly used plant functional traits (Plant height — PH; specific leaf area — SLA; and leaf dry matter content — LDMC).LocationSpecies‐rich alvar grasslands in western Estonia.MethodsWe quantified the discrete effects of environmental conditions, intraspecific trait variability, and trait difference from CWM on species abundance and assessed individual contributions of both traits and environmental characteristics on species abundance patterns.ResultsWe found a strong and consistent relationship between species’ abundance and their intraspecific trait variability, where the biggest proportion of variation was explained by PH and SLA respectively. Local populations with larger PH and LDMC, and lower SLA were more abundant compared to populations having different values of these traits. Significant unimodal dependence of species abundance on CWM was detected for two species for which the optimum values of SLA and LDMC were close to the CWM values. For other species, the relationship between optimum trait values and CWM values was monotonous. The effect of measured environmental conditions (e.g., soil depth, above‐ground biomass, and soil fertility) and trait difference from CWM on species abundance patterns was minor when compared to the effect of intraspecific trait variability.ConclusionsOur study demonstrated a strong relationship between intraspecific trait variability and local performance of species within communities.

Plant functional traits reflect different dimensions of species invasiveness.

Trait-based invasiveness studies typically categorize exotic species as invasive or noninvasive, implicitly assuming species form two homogenous groups. However, species can become invasive in different ways (e.g., high abundance, fast spread), likely relying on different functional traits to do so. As such, binary classification may obscure traits associated with invasiveness. We tested whether (1) the way in which invasiveness is quantified influences its correlation with functional traits and (2) different demography-based metrics are related to different sets of traits. Using a case study of 251 herbs exotic to Victoria, Australia, we quantified species' invasiveness using 10 metrics: four continuous, demography-based dimensions of invasiveness (spread rate, local abundance, geographic and environmental range sizes) and six binary classifications of invasiveness (based on alternative sources and invasion criteria). We examined the correlation between species' invasiveness and a set of four traits known to relate to plant demography and invasion. Then, we examined whether different demographic dimensions of invasiveness were better explained by different sets of traits. We found that the way invasiveness was quantified was important: different traits were linked with different invasiveness metrics, and some traits showed opposite effects across metrics. Species with fast spread were either tall with small seeds (i.e., good colonizers), or had heavy, animal-dispersed seeds. Plants with a large environmental range had greater plasticity for some traits. Locally abundant plants had low SLA and heavy seeds (i.e., strong competitors). Animal dispersal was also key to reach a large geographic range. No traits were consistently related to the six binary classifications. Our results indicate that exotic plants are invasive in different ways and rely on different combinations of traits to be so. Some traits (e.g., seed mass) had complex relationships with invasion: they apparently promote, hampered, or had no influence on different dimensions of invasiveness. Our findings are consistent with the notion that plant species use strategies that may be near optimal under some, but not all, ecological conditions. Compared to binary classifications of invasiveness, the use of invasiveness dimensions advances clearer hypothesis testing in invasion science.