Trait-based Studies Research Articles

Trait-based study predicts glycerol/diol dehydratases as a key function of the gut microbiota of hindgut-fermenting carnivores

BackgroundMicrobial pdu and cob-cbi-hem gene clusters encode the key enzyme glycerol/diol dehydratase (PduCDE), which mediates the transformation of dietary nutrients glycerol and 1,2-propanediol (1,2-PD) to a variety of metabolites, and enzymes for cobalamin synthesis, a co-factor and shared good of microbial communities. It was the aim of this study to relate pdu as a multipurpose functional trait to environmental conditions and microbial community composition. We collected fecal samples from wild animal species living in captivity with different gut physiology and diet (n = 55, in total 104 samples), determined occurrence and diversity of pdu and cob-cbi-hem using a novel approach combining metagenomics with quantification of metabolic and genetic biomarkers, and conducted in vitro fermentations to test for trait-based activity.ResultsFecal levels of the glycerol transformation product 1,3-propanediol (1,3-PD) were higher in hindgut than foregut fermenters. Gene-based analyses indicated that pduC harboring taxa are common feature of captive wild animal fecal microbiota that occur more frequently and at higher abundance in hindgut fermenters. Phylogenetic analysis of genomes reconstructed from metagenomic sequences identified captive wild animal fecal microbiota as taxonomically rich with a total of 4150 species and > 1800 novel species but pointed at only 56 species that at least partially harbored pdu and cbi-cob-hem. While taxonomic diversity was highest in fecal samples of foregut-fermenting herbivores, higher pduC abundance and higher diversity of pdu/cbi-cob-hem related to higher potential for glycerol and 1,2-PD utilization of the less diverse microbiota of hindgut-fermenting carnivores in vitro.ConclusionOur approach combining metabolite and gene biomarker analysis with metagenomics and phenotypic characterization identified Pdu as a common function of fecal microbiota of captive wild animals shared by few taxa and stratified the potential of fecal microbiota for glycerol/1,2-PD utilization and cobalamin synthesis depending on diet and physiology of the host. This trait-based study suggests that the ability to utilize glycerol/1,2-PD is a key function of hindgut-fermenting carnivores, which does not relate to overall community diversity but links to the potential for cobalamin formation.5QUW1NVLR3PN1Ur7W1hKTuVideo

Variation in Copepod Morphological and Life History Traits along a Vertical Gradient of Freshwater Habitats

Understanding trait selection factors is vital for decoding the processes shaping species’ assemblages. However, trait-based studies in freshwater crustacean copepod assemblages are scarce, especially in groundwater environments. We explored how environmental filtering influences functional traits in copepod assemblages across four freshwater habitats (an alluvial aquifer, a hyporheic zone, a stream benthic zone and a lake littoral) along a depth gradient. Each habitat had distinct environmental templates based on light, temperature and dissolved oxygen. We analysed 4898 individuals from 43 copepod species and examined 12 morphological and life history traits. The results revealed significant differences in copepod traits among habitats, notably in ovigerous female biomass, egg biomass and ovigerous female percentages. Furthermore, despite some statistical uncertainty, notable differences were also observed in the number of juveniles, male-to-female abundance ratios and overall biomass. No significant differences were observed in juvenile biomass, egg characteristics, body size dimorphism or juvenile-to-adult ratios among habitats. The trait variations offer insights into copepod-mediated ecosystem services, particularly carbon recycling. To gain a deeper understanding of copepod adaptations to environmental features and anthropogenic changes, future research should consider additional functional traits, such as locomotion and feeding habits.

Scaling effects of temperature on parasitism from individuals to populations.

Parasitism is expected to change in a warmer future, but whether warming leads to substantial increases in parasitism remains unclear. Understanding how warming effects on parasitism in individual hosts (e.g. parasite load) translate to effects on population-level parasitism (e.g. prevalence, R0 ) remains a major knowledge gap. We conducted a literature review and identified 24 host-parasite systems that had information on the temperature dependence of parasitism at both individual host and host population levels: 13 vector-borne systems and 11 environmentally transmitted systems. We found a strong positive correlation between the thermal optima of individual- and population-level parasitism, although several of the environmentally transmitted systems exhibited thermal optima >5°C apart between individual and population levels. Parasitism thermal optima were close to vector performance thermal optima in vector-borne systems but not hosts in environmentally transmitted systems, suggesting these thermal mismatches may be more common in certain types of host-parasite systems. We also adapted and simulated simple models for both types of transmission modes and found the same pattern across the two modes: thermal optima were more strongly correlated across scales when there were more traits linking individual- to population-level processes. Generally, our results suggest that information on the temperature dependence, and specifically the thermal optimum, at either the individual or population level should provide a useful-although not quantitatively exact-baseline for predicting temperature dependence at the other level, especially in vector-borne parasite systems. Environmentally transmitted parasitism may operate by a different set of rules, in which temperature dependence is decoupled in some systems, requiring the need for trait-based studies of temperature dependence at individual and population levels.

Intra- and inter-specific leaf trait responses of understorey species to changes in forest maturity

Coppice forest management impacts understorey vegetation. This is particularly true for habitat specialists (priority elements in conservation) who prefer closed canopy conditions associated with mature forests. Most trait-based studies of forest understorey focus on interspecific differences, which neglect the role of intraspecific variability. Here, we tackled this issue by examining how leaf traits respond (intra- and inter-specifically) to different stages of stand maturity for habitat specialist and generalist species. We measured the leaf area (LA), leaf dry matter content (LDMC) and specific leaf area (SLA) for 1,932 individuals belonging to 71 understorey species in 18 beech coppice forests grouped in three stages of stand maturity (i.e., post-logging, n = 5; recovering, n = 5; old stands, n = 8). We assessed leaf trait variation across stages of forest maturity for the entire community, and for specialists and generalists separately using monotonic trend tests. Then, we disentangled the proportion of variation attributable to intraspecific variability and interspecific differences of specialists and generalists using variance decomposition. We found significant positive trends in community-level SLA and negative ones in LDMC with increasing stand maturity. Beech forest understorey specialists (but not generalists) explained these patterns. The contribution of intra- and inter-specific components was dependent upon the trait under consideration and habitat specialization. For specialists, intraspecific variability was significant for all leaf traits and could explain 15.2% of model variance for SLA, 4.2% for LA and 3.1% for LDMC along the stand maturity gradient. Interspecific differences were significant for LDMC (29.8% of variance explained) and SLA (7.6%). For generalists, intraspecific variability was not significant; interspecific differences were significant for LA and explained 26.2 % of variability along the stand maturity gradient. We revealed that the maturity of coppice stands have different effects on generalist and specialist species. Habitat specialists are responsive to subtle changes in forest stand age both intra- and interspecifically, with their prevalence being function- and trait-dependent. Interspecific differences explained most of the LDMC (resource conservation) variance, while intraspecific variability accounted most of the SLA (light capture) variance. Generalists contribute to community-level trait variation, yet these species were less responsive to changes in forest stand age. To assess the impact of forest management on understories and refine the effectiveness of monitoring plans, we recommend focusing on habitat specialists, ideally including both trait variability within- and among-species.

Linear extension, skeletal density, and calcification rates of the blue coral Heliopora coerulea

The brooding reef-building octocoral Heliopora is widespread on Indo-West Pacific reefs and appears to be relatively resistant to thermal stress, which may enable it to persist locally while scleractinians diminish under Anthropocene conditions. However, basic physiological measurements of “blue corals” are lacking and prevent their inclusion in trait-based studies. We address this by quantifying rates (mean ± SE) of linear extension (0.86 ± 0.05 cm yr−1) and skeletal density (2.01 ± 0.06 g cm−3) to estimate calcification rates (0.87 ± 0.08 g cm−2 yr−1) for the small branching/columnar morphology of Heliopora coerulea. We postulate that H. coerulea may become an increasingly important reef-builder under ocean warming due to its relative resistance to thermal stress and high skeletal density that make colonies less vulnerable to storm damage under ocean acidification. Moreover, Heliopora corals are likely dispersal limited suggesting they may be an underappreciated genus for restoration of stress-tolerant reef-building capacity on degraded reefs.

Exploring Macroinvertebrates Ecological Preferences and Trait-Based Indicators of Suspended Fine Sediment Effects in the Tsitsa River and Its Tributaries, Eastern Cape, South Africa

The taxonomy-based response pattern of macroinvertebrates to sediment stress is well established, with tolerant taxa increasing in impacted conditions, while sensitive taxa decrease along a deteriorating water quality gradient. However, the distribution patterns of traits in response to environmental stress gradient, including suspended sediments, remain unclear, particularly in Africa, where trait-based studies are under-explored. We examined the distribution patterns of macroinvertebrate traits along a suspended sediment stress gradient and identified tolerant and sensitive traits for suspended sediment stress. We sampled macroinvertebrates and environmental variables seasonally in winter, spring, summer and autumn of 2016 to 2018 in eight selected sites in the Tsitsa River and its tributaries. We selected 12 traits and ecological preferences, resolved them into 47 trait attributes, and analysed them using the RLQ and fourth-corner analyses. Our results revealed that macroinvertebrate traits and ecological preferences were differentially influenced by fine suspended sediments in the Tsitsa River and its tributaries. Traits such as a preference for CPOM, collector-filtering, and a high sensitivity to oxygen depletion, were deemed sensitive to suspended sediments stress, exhibiting positive associations with the control sites, and negatively associated with any of the environmental parameters (sediment grain sizes, turbidity, TSS and EC). Tolerant indicator traits included a high tolerance of oxygen depletion, skating and a preference for FPOM. The fourth-corner analysis results indicated that suspended fine sediment grain sizes, (including coarse sand, fine silt and clay) were the most important variables influencing macroinvertebrate trait distribution patterns during the dry season, while gravel, mud and medium sand were more important during the wet season. Overall, our study provided critical insights towards trait-based responses of macroinvertebrates communities to suspended sediment stress, key information that could stimulate the development of macroinvertebrate trait-based biomonitoring tools for the assessment of suspended sediment stress in the Afrotropical region.

Opportunities and challenges in assessing climate change vulnerability through genomics

By investigating how past selection has affected allele frequencies across space, genomic tools are providing new insights into adaptive evolutionary processes. Now researchers are considering how this genomic information can be used to predict the future vulnerability of species under climate change. Genomic vulnerability assessments show promise, but challenges remain.

Leaf and root traits, but not relationships among traits, vary with ontogeny in seedlings

Although leaf and root traits may change considerably throughout plant development, ontogenetic variation is rarely considered in trait-based ecology. Studies focused on how morphological root traits change throughout ontogeny are especially rare. Our objectives were to determine how ontogeny influences seedling traits to inform trait selection for future studies and to advance understanding of how traits at early developmental stages influence seedling growth. We measured traits from eleven herbaceous species at several developmental stages. We used Bayesian random effects models to assess the effects and variation resulting from species identity and ontogeny for each trait. We used principal component analysis and multiple regression to identify which dominant axes of variation were correlated with future growth rates. Variation in traits resulting from ontogeny was greatest for growth rates and root elongation rates. Relationships among traits were similar at all ontogenetic stages, but which principal component axes were correlated with future growth depended on stage; at the earliest harvest, the axis related to tissue construction was linked to future growth rate, whereas, at the last harvest, three independent axes were related to future growth rate. In our study, traits including leaf dry matter content, root tissue density, and root diameter varied little throughout seedling development and thus may be promising candidates for future trait-based studies. Linking suites of traits to growth strategies may be particularly fruitful for understanding plant strategies throughout early development, as multivariate relationships among traits appear to be more ontogenetically stable than individual traits.

Intraspecific variability of leaf traits and functional strategy of Himantoglossum adriaticum H. Baumann

Trait-based studies have become extremely common in plant ecology. In this work we analysed intraspecific trait variation of Himantoglossum adriaticum, a European endemic orchid species of Community interest, to investigate whether different populations growing on managed and abandoned semi-natural dry grasslands show differences in the CSR strategy. In seven populations occurring in Veneto Region (NE Italy), we measured H. adriaticum maximum vegetative height, leaf traits (LA, LDMC, SLA) and calculated the CSR strategy. Through CCA we investigated the relationship between plant traits and both plant community attributes (cover and height of herbs and shrubs), and geomorphologic features (aspects and slope). PERMANOVA test was used to investigate if the CSR strategy of H. adriaticum varied according to the management regime. Results showed that individuals of H. adriaticum develop different strategies when growing in different habitats. Specifically, individuals growing in managed fully sunny dry grasslands reached higher vegetative height (MH), had lower values of SLA and a higher relative contribution of the C parameter than individuals growing in abandoned dry grasslands, which, on the contrary, were shorter, had higher values of SLA (and correspondingly lower values of LDMC) and a higher relative contribution of the R parameter. Further data on reproductive traits (e.g. fruit and seed-set) may corroborate our results. Although the number of individuals addressed in this study is rather low, and our conclusions may not be considered of general validity for the species, our study demonstrated the applicability of the CSR strategy scheme in detecting functional strategies at intraspecific level.

A new comprehensive trait database of European and Maghreb butterflies, Papilionoidea

Trait-based analyses explaining the different responses of species and communities to environmental changes are increasing in frequency. European butterflies are an indicator group that responds rapidly to environmental changes with extensive citizen science contributions to documenting changes of abundance and distribution. Species traits have been used to explain long- and short-term responses to climate, land-use and vegetation changes. Studies are often characterised by limited trait sets being used, with risks that the relative roles of different traits are not fully explored. Butterfly trait information is dispersed amongst various sources and descriptions sometimes differ between sources. We have therefore drawn together multiple information sets to provide a comprehensive trait database covering 542 taxa and 25 traits described by 217 variables and sub-states of the butterflies of Europe and Maghreb (northwest Africa) which should serve for improved trait-based ecological, conservation-related, phylogeographic and evolutionary studies of this group of insects. We provide this data in two forms; the basic data and as processed continuous and multinomial data, to enhance its potential usage.

Relative contribution of plant traits and soil properties to the functioning of a temperate forest ecosystem in the Indian Himalayas

Plant-soil interactions are a major determinant of changes in forest ecosystem processes and functioning. We conducted a trait-based study to quantify the contribution of plant traits and soil properties to above- and below-ground ecosystem properties in temperate forest in the Indian Himalayas. Nine plant traits (leaf area, specific leaf area, leaf water content, leaf dry matter content, leaf carbon (C), nitrogen (N), phosphorus (P), leaf C/N, and leaf N/P) and eight soil properties (pH, moisture, available N, P, potassium (K), total C, N, P) were selected for determination of their contribution to major ecosystem processes (above-ground biomass C, soil organic C, soil microbial C, soil microbial N, soil microbial P, and soil respiration) in temperate forest. Among the plant traits leaf C, N, P, and leaf N/P ratio proved to be the main contributors to above-ground biomass, explaining 20–27% of variation. Leaf N, P, and leaf N/P were the main contributors to below-ground soil organic C, soil microbial C, soil microbial N, soil microbial P, and soil respiration (explaining 33% of variation). Together, the soil properties, pH, available P, total N and C explained 60% of variation in above-ground biomass, while pH and total C explained 56% of variation in soil organic C. Other soil properties (available P, total C and N) also explained much of the variation in soil microbial C (52%) and soil microbial N (67%), while soil pH explained some of variation in soil microbial N (14%). Available P, total N, and pH explained soil microbial P (81%), while soil respiration was only explained by soil total C (70%). Thus, leaf traits and soil characteristics significantly explaining variations in above- and below-ground ecosystem processes and functioning in temperate forest in the Indian Himalayas. Consequently, tree species for afforestation, restoration, and commercial forestry should be carefully selected, as they can influence the climate change mitigation potential of forest in terms of C stocks in biomass and soils.

Functional Divergence Drives Invasibility of Plant Communities at the Edges of a Resource Availability Gradient

Invasive Alien Species (IAS) are a serious threat to biodiversity, severely affecting natural habitats and species assemblages. However, no consistent empirical evidence emerged on which functional traits or trait combination may foster community invasibility. Novel insights on the functional features promoting community invasibility may arise from the use of mechanistic traits, like those associated with drought resistance, which have been seldom included in trait-based studies. Here, we tested for the functional strategies of native and invasive assemblage (i.e., environmental filtering hypothesis vs. niche divergence), and we assessed how the functional space determined by native species could influence community invasibility at the edges of a resource availability gradient. Our results showed that invasive species pools need to have a certain degree of differentiation in order to persist in highly invaded communities, suggesting that functional niche divergence may foster community invasibility. In addition, resident native communities more susceptible to invasion are those which, on average, have higher resource acquisition capacity, and lower drought resistance coupled with an apparently reduced water-use efficiency. We advocate the use of a mechanistic perspective in future research to comprehensively understand invasion dynamics, providing also new insights on the factors underlying community invasibility in different ecosystems.

Trait integration and functional differentiation among co-existing plant species.

Determining which traits characterize strategies of coexisting species is important to developing trait-based models of plant communities. First, global dimensions may not exist locally. Second, the degree to which traits and trait spectra constitute independent dimensions of functional variation at various scales continues to be refined. Finally, traits may be associated with existing categorical groupings. We assessed trait integration and differentiation across 57 forest understory plant species in Douglas-fir forests of western Oregon, United States. We combined measurements for a range of traits with literature-based estimates of seed mass and species groupings. We used network analysis and nonmetric multidimensional scaling ordination (NMS) to determine the degree of integration. We observed a strong leaf economics spectrum (LES) integrated with stem but not root traits. However, stem traits and intrinsic water-use efficiency integrated LES and root traits. Network analyses indicated a modest grouping of a priori trait dimensions. NMS indicated that multivariate differences among species were related primarily to (1) rooting depth and plant height vs. specific root length, (2) the LES, and (3) leaf size vs. seed mass. These differences were related to species groupings associated with growth and life form, leaf lifespan and seed dispersal mechanisms. The strategies of coexisting understory plant species could not be reduced to a single dimension. Yet, species can be characterized efficiently and effectively for trait-based studies of plant communities by measuring four common traits: plant height, specific leaf area, leaf size, and seed mass.

Species interactions and environmental context affect intraspecific behavioural trait variation and ecosystem function.

Functional trait-based approaches are increasingly adopted to understand and project ecological responses to environmental change; however, most assume trait expression is constant between conspecifics irrespective of context. Using two species of benthic invertebrate (brittlestars Amphiura filiformis and Amphiura chiajei), we demonstrate that trait expression at individual and community levels differs with biotic and abiotic context. We use PERMANOVA to test the effect of species identity, density and local environmental history on individual (righting and burrowing) and community (particle reworking and burrow ventilation) trait expression, as well as associated effects on ecosystem functioning (sediment nutrient release). Trait expression differs with context, with repercussions for the faunal mediation of ecosystem processes; we find increased rates of righting and burial behaviour and greater particle reworking with increasing density that are reflected in nutrient generation. However, the magnitude of effects differed within and between species, arising from site-specific environmental and morphological differences. Our results indicate that traits and processes influencing change in ecosystem functioning are products of both prevailing and historic conditions that cannot be constrained within typologies. Trait-based study must incorporate context-dependent variation, including intraspecific differences from individual to ecosystem scales, to avoid jeopardizing projections of ecosystem functioning and service delivery.

A global database for metacommunity ecology, integrating species, traits, environment and space

The use of functional information in the form of species traits plays an important role in explaining biodiversity patterns and responses to environmental changes. Although relationships between species composition, their traits, and the environment have been extensively studied on a case-by-case basis, results are variable, and it remains unclear how generalizable these relationships are across ecosystems, taxa and spatial scales. To address this gap, we collated 80 datasets from trait-based studies into a global database for metaCommunity Ecology: Species, Traits, Environment and Space; “CESTES”. Each dataset includes four matrices: species community abundances or presences/absences across multiple sites, species trait information, environmental variables and spatial coordinates of the sampling sites. The CESTES database is a live database: it will be maintained and expanded in the future as new datasets become available. By its harmonized structure, and the diversity of ecosystem types, taxonomic groups, and spatial scales it covers, the CESTES database provides an important opportunity for synthetic trait-based research in community ecology.

Limitations of trait-based approaches for stressor assessment: The case of freshwater invertebrates and climate drivers.

The appeal of trait-based approaches for assessing environmental vulnerabilities arises from the potential insight they provide into the mechanisms underlying the changes in populations and community structure. Traits can provide ecologically based explanations for observed responses to environmental changes, along with predictive power gained by developing relationships between traits and environmental variables. Despite these potential benefits, questions remain regarding the utility and limitations of these approaches, which we explore focusing on the following questions: (a) How reliable are predictions of biotic responses to changing conditions based on single trait-environment relationships? (b) What factors constrain detection of single trait-environment relationships, and how can they be addressed? (c) Can we use information on meta-community processes to reveal conditions when assumptions underlying trait-based studies are not met? We address these questions by reviewing published literature on aquatic invertebrate communities from stream ecosystems. Our findings help to define factors that influence the successful application of trait-based approaches in addressing the complex, multifaceted effects of changing climate conditions on hydrologic and thermal regimes in stream ecosystems. Key conclusions are that observed relationships between traits and environmental stressors are often inconsistent with predefined hypotheses derived from current trait-based thinking, particularly related to single trait-environment relationships. Factors that can influence findings of trait-based assessments include intercorrelations of among traits and among environmental variables, spatial scale, strength of biotic interactions, intensity of habitat disturbance, degree of abiotic stress, and methods of trait characterization. Several recommendations are made for practice and further study to address these concerns, including using phylogenetic relatedness to address intercorrelation. With proper consideration of these issues, trait-based assessment of organismal vulnerability to environmental changes can become a useful tool to conserve threatened populations into the future.

Latitude-associated evolution and drivers of thermal response curves in body stoichiometry.

Trait-based studies are needed to understand the plastic and genetic responses of organisms to warming. A neglected organismal trait is elemental composition, despite its potential to cascade into effects on the ecosystem level. Warming is predicted to shape elemental composition through shifts in storage molecules associated with responses in growth, body size and metabolic rate. Our goals were to quantify thermal response patterns in body composition and to obtain insights into their underlying drivers and their evolution across latitudes. We reconstructed the thermal response curves (TRCs) for body elemental composition [C (carbon), N (nitrogen) and the C:N ratio] of damselfly larvae from high- and low-latitude populations. Additionally, we quantified the TRCs for survival, growth and development rates and body size to assess local thermal adaptation, as well as the TRCs for metabolic rate and key macromolecules (proteins, fat, sugars and cuticular melanin and chitin) as these may underlie the elemental TRCs. All larvae died at 36°C. Up to 32°C, low-latitude larvae increased growth and development rates and did not suffer increased mortality. Instead, growth and development rates of high-latitude larvae were lower and levelled off at 24°C, and mortality increased at 32°C. This latitude-associated thermal adaptation pattern matched the 'hotter-is-better' hypothesis. With increasing temperatures, low-latitude larvae decreased C:N, while high-latitude larvae increased C:N. These patterns were driven by associated changes in N contents, while C contents did not respond to temperature. Consistent with the temperature-size rule and the thermal melanism hypothesis, body size and melanin levels decreased with warming. While all traits and associated macromolecules (except for metabolic rate that showed thermal compensation) assumed to underlie thermal responses in elemental composition showed thermal plasticity, these were largely independent and none could explain the stoichiometric TRCs. Our results highlight that thermal responses in elemental composition cannot be explained by traditionally assumed drivers, asking for a broader perspective including the thermal dependence of elemental fluxes. Another key implication is that thermal evolution can reverse the plastic stoichiometric thermal responses and hence reverse how warming may shape food web dynamics through changes in body composition at different latitudes.

Does trait variation within broadly distributed species mirror patterns across species? A case study in Puerto Rico.

Although populations are phenotypically diverse, the majority of trait-based studies have focused on examining differences among species. The justification for this broadly applied approach is based on the assumption that differences among species are always greater than within species. This is likely true for local communities, but species are often broadly distributed across a wide range of environments and patterns of intraspecific variation might surpass differences among species. Therefore, an appropriate interpretation of the functional diversity requires an assessment of patterns of trait variation across different ecological scales. In this study, we examine and characterize patterns of leaf trait variation for species that are broadly distributed along an elevational gradient. We focus on seven leaf traits that represent a main axis of functional differentiation in plants reflecting the balance between photosynthetic efficiency, display, and stomatal conductance. We evaluated patterns of trait variance across ecological scales (elevation, species, populations, and individuals) and examined trait covariance at both within species and across species levels, along the elevation gradient. Our results show three key patterns: (1) intraspecific leaf trait variation for broadly distributed species is comparable to the interspecific trait variation, (2) the trait variance structure is highly variable across species, and (3) trait coordination between pairs of leaf traits is evident across species along the gradient, but not always within species. Combined, our results show that trait coordination and covariance are highly idiosyncratic across broadly distributed and co-occurring species, indicating that species may achieve similar functional roles even when exhibiting different phenotypes. This result challenges the traditional paradigm of functional ecology that assumes single trait values as optimal solutions for environments. In conclusion, patterns of trait variation both across and within species should be considered in future studies that assess trade-offs among traits over environmental gradients.

Unveiling cryptic ecological functions: prospects in plant invasions

Invasion ecology has much advanced since its inception. Nevertheless, explanation, prediction, and management of biological invasions remain difficult. Management of alien species is often hindered by crypticity in biological invasions. The present study attempts to address the crypticity in ecological functions using insights from selected plant species, namely Lantana camara L. (sensu lato), an established invader and Ricinus communis L., a naturalized species in India. The study species have a broad habitat suitability range and continue to expand in India. We hypothetically placed the study species on the unified framework for biological invasions to assess the performance strategies (manifestations of changing or novel ecological functions) which facilitate a species to breach/overcome the environmental barrier (light availability) and expand in time and space. Results affirmed hypothetical placement of the two species on the unified framework. In view of the results, Lantana camara is expanding its range in shaded habitats and Ricinus communis, as of now, exhibits boom and bust cycles, but may pose a significant invasion risk in the near future through breach of an environmental barrier. The study enabled us to understand how plant performance-related traits and species’ trait modulation potential assist the species in breaching/overcoming barriers to colonize, invade and/or expand. The study generates an impetus for trait-based studies focusing on understudied cryptic functional changes of species.

On the development of a predictive functional trait approach for studying terrestrial arthropods.

The characterization of ecological communities with functional traits allows to consider simultaneously the ability of a species to survive and reproduce in an environment, its interactions with other species and its effects on the ecosystem. Functional traits have been studied mainly by plant ecologists, but are increasingly common in the study of other taxa including arthropods. Arthropods represent a group for which a functional trait approach could be highly profitable because of their high diversity, abundance, ubiquity and role in many important ecological processes. This review synthesizes two decades of functional trait research on terrestrial arthropods. We show that while the approach has gained popularity, particularly in the last decade, the absence of clearly postulated hypotheses is a recurrent problem limiting generalization. Furthermore, studied traits are often poorly related to studied functions. To address these problems, we propose a step-by-step protocol to postulate clear hypotheses prior to trait selection and emphasize the need for a common set of more generalizable traits in future studies. Extending the functional trait approach to arthropods opens the door to improving our understanding of interspecific interactions and potential links between response and effect traits. We present the concept of trait-matching with several examples of arthropod traits known to be effective predictors of consumer-resource interactions. The development of a successful functional trait approach for terrestrial arthropods will necessitate an understanding of relevant traits, standardized measurement protocols and open access databases to share this information. Such progress will provide ecologists with a new set of tools to answer broad questions in several fields including the study of community assembly, ecological networks and multitrophic functionality.