Shifts in Assembly Rules and Loss of Zooplankton Functional Diversity Across Hypereutrophic Fishponds

Understanding the structural concordance between taxonomic and functional diversity (FD) metrics is essential for improving the ecological interpretation of community patterns in biomonitoring programs. This study evaluated the concordance between taxonomic and FD metrics of benthic macroinvertebrates along a fluvial habitat quality gradient in the Paute River Basin, Ecuador. Macroinvertebrate communities were sampled over six years at twelve sampling points and assessed using four taxonomic metrics: Shannon diversity (H), the Margalef index (DMg), family richness (N), and the Andean Biotic Index (ABI). Functional diversity was evaluated using four metrics: weighted functional dendrogram-based diversity (wFDc), Rao's quadratic entropy (Rao), functional dispersion (FDis), and functional richness (FRic). The fluvial habitat index (FHI) was used as an environmental reference to evaluate diversity metric responses. K-means clustering was independently applied to each metric, and pairwise concordance was quantified using the Measure of Concordance (MoC) and overlap in sampling points groupings across replicates. Most metrics (except FRic and N) showed clear responsiveness to the FHI gradient, confirming their ecological relevance. Strong structural concordance was observed between H and DMg and the FD metrics Rao, FDis, and wFDc, showing that these metrics captured similar yet complementary aspects of community organization. In contrast, ABI showed marked sensitivity to the FHI gradient but low concordance with functional metrics, suggesting distinct dimensions of biological integrity not encompassed by trait-based metrics. These findings highlight the value of combining taxonomic and functional metrics to detect both broad and subtle ecological changes. Integrating metrics with differing structural properties and environmental sensitivities can enhance the robustness of freshwater biomonitoring frameworks, especially in systems undergoing ecological transition or habitat degradation.

Associations among taxonomic diversity, functional diversity and evolutionary distinctiveness vary among environments

Alaskan Arctic shelf communities are currently experiencing dramatic changes that will likely affect ecosystem functioning of Arctic marine benthic communities. Here, functional diversity based on biological traits was used to assess differences and similarities in ecosystem functioning between 2 shelf systems that are geographically close but vary in many environmental influences: the Arctic Beaufort and Chukchi Sea epibenthic communities. We hypothesized that (1) patterns of functional composition and diversity metrics reflect patterns in taxonomic composition and diversity metrics in these 2 shelf communities; and (2) patterns in functional diversity metrics are distinct between the 2 shelves. We evaluated 9 biological traits (body form, body size, feeding habit, fragility, larval development, living habit, movement, reproductive strategy, sociability) for 327 taxa in 2014 and 2015. For each trait, multiple modalities (specific expressions within a trait) were considered. Patterns in functional diversity metrics on both shelves reflected those in taxonomic diversity metrics. However, shelf communities were more similar in functional- than in taxonomic composition. Beaufort Sea communities had higher functional dissimilarity and functional evenness driven by differences in the modalities within body form, body size, larval development, and reproductive strategy. These traits primarily affect nutrient cycling, energy turnover, and recovery from disturbances, suggesting a stronger potential for future maintenance of ecosystem function, and indicating a more even use of resources in the Beaufort Sea. The combination of functional and taxonomic diversity metrics enabled a comprehensive understanding of how ecological niche space is used and how epibenthic communities function in Alaskan Arctic shelf systems.

Questions(1) Does grassland vegetation differ in its taxonomic, phylogenetic and functional alpha diversity between strictly grazed parcels (SGP) and mowed‐and‐grazed parcels (MGP)? (2) Do we observe differences in the responses of functional diversity (reflecting differences in the interspecific variation of a trait in the plant community) and community‐weighted mean trait values (CWMs, reflecting the characteristics of the dominant species)? (3) How do diversity and CWM patterns respond to disturbance and fertilization gradients measured by agronomic descriptors in both parcel types?LocationFrench Jura Mountains.MethodsWe compared taxonomic, phylogenetic and functional diversities (based on Rao quadratic entropy) and CWMs between the two management types (SGP and MGP). We then used agronomic variables, describing both defoliation regime and fertilization intensity over the past 10 yrs to explain diversity indices and CWMs in a partial redundancy analysis (pRDA).ResultsTaxonomic and phylogenetic diversities were higher in SGP than in MGP, as well as functional diversity computed for qualitative traits (clonal growth organs and leaf distribution along the stem). Contrary to expectations from literature, we found higher CWM for leaf dry matter content (LDMC) in intensively and regularly cut grasslands compared to only grazed grasslands, which can be explained by the higher dominance of grass species in hay meadows. In addition, constrained ordination revealed that taxonomic, phylogenetic and some functional diversity metrics were negatively affected by defoliation intensity (mowing frequency), while most CWMs were mainly influenced by fertilization intensity, either by the available N input or by the role of commercial inorganic fertilizers, depending on the trait considered.ConclusionsOur study revealed consistent patterns between the various facets of biodiversity in grasslands according to the main management regime. Taking agronomic gradients into account suggests the importance of considering both CWMs and functional diversity, which respond variously to agricultural practices. Conservation of high diversity in grasslands, whatever the facet considered, implies keeping some parcels exclusively grazed and limiting N inputs, especially those from inorganic commercial fertilizers.

While taxonomic metrics are common indicators for assessing impact of acid mine drainage (AMD) on macroinvertebrates, functional diversity metrics are scarcely used. We tested the hypothesis that functional diversity metrics could be used as indicators for assessing impact of AMD on macroinvertebrates. Differences in both taxonomic metrics and functional diversity metrics were examined among sites with varying levels of AMD impact. AMD led to loss of sensitive functional groups and resulted in low functional diversity in the impacted sites. Functional richness, functional Shannon's index and functional Brillouin's index were significantly correlated with all key AMD parameters. Compared to taxonomic metrics, functional diversity metrics had higher correlations with most key AMD parameters. Functional diversity metrics were more informative than taxonomic metrics for assessing impact of AMD on macroinvertebrates since they were more effective at indicating mild or moderate AMD pollution. Functional Shannon's index and functional Brillouin's index were the most precise metrics.

Mammal functional diversity and habitat heterogeneity: Implications for hominin habitat reconstruction

ABSTRACTAimDespite unprecedented environmental change due to anthropogenic pressure, recent work has found increasing dissimilarity due to turnover but no overall trend in species diversity through time at the local scale. Functional diversity provides a potentially powerful alternative approach for understanding community composition by linking shifts in species identity to the characteristics that underpin ecosystem processes. Here we present the first multitaxa, multisystem analysis of functional diversity and composition through time.LocationGlobal, with a North American focus.Time Period1923–2014.Major Taxa StudiedMammals, Birds.MethodsWe paired thousands of bird and mammal assemblage time series from the BioTIME database with existing trait data representative of species' functional roles to reconstruct time series of functional diversity and composition metrics. Our dataset included 2432 time series of yearly observations from 50 studies with a maximum spatial extent of 95 km2. Using generalised linear mixed models, we estimated general and study‐level trends for those metrics.ResultsWe found no overall temporal trends in functional diversity metrics. Study characteristics such as taxa, realm, biome, or protection status did not distinguish between types of change exhibited by communities. We found evidence of a temporal increase in fish consumption across all communities but no evidence to support multiple predictions for specific traits, including decreasing body size, dietary shifts or changes in bird foraging strata.Main ConclusionsGeneral temporal trends indicate that on the aggregate, studies do not exhibit consistent changes in functional diversity across many taxa, biomes and realms. At the study level, the majority of studies showed no temporal trends in species or functional diversity, with the remainder of the studies falling into broad categories of functional diversity change independent of species richness, functional redundancy loss (species richness declines with functional richness maintained) and increasing species richness sometimes accompanied by increasing functional richness.

Observing functional diversity continuously in time and space using satellite imagery forms the basis for studying impact, interactions, and feedback of environmental change mechanisms on ecosystems and biodiversity globally. Functional diversity of plant traits links ecosystem functioning and biodiversity. This work presents an approach to map and quantify functional diversity of physiological forest traits derived from 20 m Sentinel-2 data in a temperate forest ecosystem. We used two complementary data sources, namely high-resolution, as well as spatially resampled airborne imaging spectroscopy data and Sentinel-2 data, to ensure our methods support consistently mapping functional diversity from space. We retrieved three physiological traits related to forest health, stress, and potential productivity, namely chlorophyll, carotenoid, and water content, from airborne imaging spectroscopy and Sentinel-2 data using corresponding spectral indices as proxies. We analyzed changes in two functional diversity metrics, namely functional richness and divergence, at different spatial resolutions. Both functional diversity metrics depend on the size and number of pixels to derive functional diversity as a function of distance, leading to different interpretations. When mapping functional diversity using Sentinel-2 data, small-scale patterns <1.1 ha were no longer visible, implying a minimum calculation area with 60 m radius recommended for retrieval of functional diversity metrics. The spectrally convolved and spatially resampled airborne spectroscopy data and the native Sentinel-2 data were correlated with r = 0.747 for functional richness and r = 0.709 for divergence in a 3.1 ha neighborhood. Functional richness was more affected by the differences in trait maps between the acquisitions resulting from effects in illumination and topography compared with functional divergence. Further differences could be explained by varying illumination/observation effects and phenological status of the vegetation at acquisition. Our approach demonstrates the importance of spatial and spectral resolution when scaling diversity assessments from regional to continental scales.

Characterising changes in functional diversity at large spatial scales provides insight into the impact of human activity on ecosystem structure and function. However, the approach is often based on trait data sets that are incomplete and unrepresentative, with uncertain impacts on functional diversity estimates. To address this knowledge gap, we simulated random and biased removal of data from three empirical trait data sets: an avian data set (9579 species), a plant data set (2185 species) and a crocodilian data set (25 species). For these data sets, we assessed whether functional diversity metrics were robust to data incompleteness with and without using imputation to fill data gaps. We compared two metrics each calculated with two methods: functional richness (calculated with convex hulls and trait probabilities densities) and functional divergence (calculated with distance‐based Rao and trait probability densities). Without imputation, estimates of functional diversity (richness and divergence) for birds and plants were robust when 20%–70% of species had missing data for four out of 11 and two out of six continuous traits, respectively, depending on the severity of bias and method used. However, when missing traits were imputed, functional diversity metrics consistently remained representative of the true value when 70% of bird species were missing data for four out of 11 traits and when 50% of plant species were missing data for two out of six traits. Trait probability densities and distance‐based Rao were particularly robust to missingness and bias when combined with imputation. Convex hull‐based estimations of functional richness were less reliable. When applied to a smaller data set (crocodilians, 25 species), all functional diversity metrics were much more sensitive to missing data. Expanding global morphometric data sets to represent more taxa and traits, and to quantify intraspecific variation, remains a priority. In the meantime, our results show that widely used methods can successfully quantify large‐scale functional diversity even when data are missing for half of species, provided that missing traits are estimated using imputation. We recommend the use of trait probability densities or distance‐based Rao when working with large incomplete data sets and filling data gaps with imputation.

Biological indicators are frequently used to assess the effects of anthropogenic stressors on freshwater ecosystems. The structure of fish communities and their response to stressors have been commonly described by taxonomic richness, diversity and evenness. More recently, functional structure of communities has also been suggested to be a reliable indicator of disturbance. This article aimed at testing whether taxonomic and functional diversity metrics can provide comparable or complementary information on the response of fish communities to eutrophication and abundance of non‐native species in reservoirs. Comparison of the responses of taxonomic and functional diversities to biogeography, habitat and stressors was made in 112 French reservoirs. Widely observed effects of biogeographic and habitat variables on taxonomic and functional diversities were identified. Taxonomic and functional richness metrics notably increased with lake area and temperature respectively. Taxonomic diversity metrics did not respond to any stressor, while all functional diversity metrics were found to be impacted by non‐native species. Eutrophication was further found to decrease the impact of non‐native species on two functional diversity metrics: evenness and divergence. Our study therefore reveals that functional metrics are more sensitive than taxonomic metrics to anthropogenic stressors in the studied reservoirs. Still, the multiple linear regressions tested had overall low explanatory power. Further refinements will thus be needed to use this type of metrics in an impact assessment scheme.

Analysis of functional diversity, based on plant traits and community structure, provides a promising approach for exploration of the adaptive strategies of plants and the relationship between plant traits and ecosystem functioning. However, it is unclear how the number of plant traits included influences functional diversity, and whether or not there are quantitatively dependent traits. This information is fundamental to the correct use of functional diversity metrics. Here, we measured 34 traits of 366 plant species in nine forests from the tropical to boreal zones in China. These traits were used to calculate seven functional diversity metrics: functional richness (functional attribute diversity (FAD), modified FAD (MFAD), convex hull hypervolume (FRic)), functional evenness (FEve), and functional divergence (functional divergence (FDiv), functional dispersion (FDis), quadratic entropy (RaoQ)). Functional richness metrics increased with an increase in trait number, whereas the relationships between the trait divergence indexes (FDiv and FDis) and trait number were inconsistent. Four of the seven functional diversity indexes (FAD, MFAD, FRic, and RaoQ) were comparable with those in previous studies, showing predictable trends with a change in trait number. We verified our hypothesis that the number of traits strongly influences functional diversity. The relationships between these predictable functional diversity metrics and the number of traits facilitated the development of a standard protocol to enhance comparability across different studies. These findings can support integration of functional diversity index data from different studies at the site to the regional scale, and they focus attention on the influence of quantitative selection of traits on functional diversity analysis.

AimFunctional diversity encapsulates whole‐community responses to environmental gradients mediated by species traits. Under trait convergence, similar responses may cause distantly related taxa to exhibit spatially correlated functional diversity. We investigated whether similar responses of reef fish, coral and algal functional richness and disparity to the environment produce spatially correlated functional diversity patterns.LocationBrazilian marine biogeographical province.TaxonReef fish, corals, algae.MethodsWe analysed data from 40 coastal and oceanic sites distributed across 27 degrees of latitude in the Brazilian province. Using traits, we measured functional richness (FRic) and disparity (Rao's Q) and calculated Pearson's correlation () between pairs of metrics and taxa. We used Bayesian multivariate linear models to model taxa functional richness and disparity relative to sea surface temperature (SST), turbidity, salinity, species richness and region, and to estimate the residual correlation () between metrics after accounting for these variables.ResultsThe best fitted model contained SST, species richness and region, and explained about 56% of the variation in FRic and Rao's Q across taxa. Yet, FRic and Rao's Q of fish, algae and corals responded differently to environmental variables. Functional diversity metrics were less correlated between algae and corals than compared to fish. Observed correlations of FRic and Rao's Q were low to intermediate across taxa (average = 0.14), and residual correlations were even lower (average = 0.02).Main conclusionsSST, species richness and region had a widespread role in determining spatially congruent functional diversity offish, algae and corals across Brazilian reefs, despite their fundamentally different evolutionary histories. Low residual spatial correlations suggest that other mechanisms might also contribute to functional diversity patterns of reef taxa independently. Given the role of SST, species richness and region, the functional structure of these reefs might be compromised by climate change, pollution and overfishing.

Windstorm effects on herbaceous vegetation in temperate forest ecosystems: Changes in plant functional diversity and species trait values along a disturbance severity gradient

Background and aims - Recent methodological and theoretical advances in community ecology have allowed more robust exploration of complementary facets of biodiversity in plant communities. Focusing on semi-natural permanent grasslands of the French Jura Mountains, we assessed how taxonomic, phylogenetic and functional diversity metrics vary among three phytosociological vegetation units. Methods - We selected a sample of 135 relevés out of a phytosociological database, depicting three phytosociological orders (Brometalia erecti, Arrhenatheretalia elatioris and Trifolio repentis-Phleetalia pratensis) and including 381 vascular plant species. We built a phylogenetic tree based on sequences of two genes encoding chloroplast proteins, from which we computed phylogenetic diversity metrics that we compared to various taxonomic, single-trait and multi-trait functional metrics, including communityweighted means of functional traits (CWMs). Key results - Most diversity metrics and CWMs significantly differed among vegetation units. Within each facet of biodiversity, the different metrics showed complementary results. Moreover, even when considering diversity metrics comparable in mathematical terms, i.e. based on Rao quadratic entropy, the results were largely non-redundant among the facets of biodiversity. Phylogenetic diversity and multi-trait functional diversity show opposite responses to vegetation units, as well as a low phylogenetic signal. These two results suggest that phylogenetic diversity cannot be used as a simple proxy for functional diversity. Conclusion - This study highlights the importance of taking into consideration different facets for a better understanding of biodiversity. In particular, phylogenetic and functional facets appear highly informative, and could thus be used in addition to taxonomic diversity metrics as indicators of conservation value. © 2014 Botanic Garden Meise and Royal Botanical Society of Belgium.

Macrophyte communities have major role in the functioning of freshwater ecosystems. However, there is gap in knowledge about how natural and anthropogenic hydro-morphological disturbances affect their functional diversity and trait structure, particularly in the temperate large rivers. In this study we investigated the effect of hydro-morphology on functional diversity and trait structure of macrophyte communities in the middle section of the Danube course. We collected macrophyte and environmental data from 947 sampling units in the main river channel and connected side waterbodies. We extracted data on 18 traits with 65 trait states and calculated seven functional diversity metrics and cumulative weighted means of trait states (CWMs). We applied redundancy analysis (RDA) to investigate the response of functional diversity metrics to the environmental variables, and Variation Partitioning to determine whether natural, or anthropogenic subset of hydro-morphological factors is more important predictor of functional diversity. To relate CWMs and environmental variables, we performed RLQ and fourth-corner analysis, followed by false discovery rate procedure. Hydro-morphological variables explained 36.7% of the variability in the functional diversity metrics. Combined effect of two subsets of environmental variables explained largest part of the variability in functional diversity metrics. Six associations between traits and environmental variables were found. We found that functional diversity metrics indicate prevailing ecological processes, from environmental to biotic filtering, along the natural—anthropogenic hydro-morphological gradient. We concluded that functional diversity metrics are potentially useful tools in the identification of the causes of ecological degradation, and could be applied in river bioassessments and management.