Functional Diversity Metrics Research Articles

Short-term effects of experimental trampling on alpine grasslands in Shangri-la, China

Alpine grasslands provide essential ecosystem functions and services, yet they are increasingly subject to anthropogenic perturbations. Northwest Yunnan (NWY) is one of the most popular tourist destinations in China, and alpine grasslands of NWY are particularly susceptible to human recreational activities such as hiker trampling. However, studies that explicitly evaluate the effects of trampling disturbance on alpine communities of NWY are very limited, let alone research testing the responses of these communities to trampling from a functional trait perspective. The present research is performed in alpine grasslands within and outside of a core nature conservation area of Shangri-La, NWY of China, to study species- and community-level responses of alpine communities to simulated trampling through a functional trait-based approach. The results showed that although species-specific differences existed, alpine plants generally showed rapid morphological changes in response to trampling disturbance. At the community level, trampling disturbance caused strong shifts in taxonomy-based diversity metrics (e.g., species richness, Simpson’s index and Shannon’s index) and functional trait-based diversity metrics (e.g., functional richness, functional evenness, functional divergence, and community-weighted mean trait values). Specifically, increased trampling intensity led to a decrease in taxonomic diversity. Meanwhile, functional richness decreased, while functional evenness and functional divergence increased with an increase in trampling intensity. Also, characteristics of alpine community traits had changed towards those with shorter height, reduced leaf size and lower LDMC, and such strong shifts in taxonomic and functional diversity might further affect the functioning and value of alpine grasslands. Therefore, the protection of high-altitude natural grasslands with high sensitivity and vulnerability is urgent, especially as they are increasingly experiencing multiple environmental and climatic stressors nowadays.

Functional diversity in the intertidal macrobenthic community at sewage-affected shores from Southwestern Atlantic

Sewage pollution effect in a coastal area of the Southwestern Atlantic was tested, through the use of analysis of biological traits (BTA) and functional indices. Changes in the macrobenthic functional structure between the sewage outfall site and remote sites were observed. At the site in the discharge point, functional features related to organic enrichment were observed, such as deposit feeders, burrow dwellers and inhabitants of tubes, with low relative mobility and opportunistic species of the first and the second order. The functional indexes (Evenness, Dispersion, and Functional Specialization) showed the highest values in the sites far from the discharge point. The AMBI was positively correlated with FRic and negatively with FEve and FSpe. The opposite occurred with the M-AMBI. BTA and functional indices showed the changes that occurred due to sewage impacts in the benthic assemblages on rocky coasts in SW Atlantic.Sewage pollution effect in a coastal area of the Southwestern Atlantic was tested, through the use of functional diversity metrics (analysis of biological traits and functional indices). Biological samples were taken during spring and autumn (2015–2016), in four sampling sites distributed at different distances from the sewage outfall. Changes in the macrobenthic functional structure between the sewage outfall site and remote sites were observed. The functional indexes (Evenness, Dispersion, and Functional Specialization) showed the highest values in the sites far from the discharge point. Correlations between functional and environmental quality indices (AMBI and M-AMBI) were significant. The AMBI was positively correlated with Functional Richness and negatively with Functional Evenness and Functional Specialization. The opposite occurred with the M-AMBI. The analysis of biological traits and functional diversity indices represent informative and useful tools to describe the different aspects of sewage impacts in the benthic assemblages on rocky coasts in SW Atlantic. At the site in the discharge point, functional features related to organic enrichment were observed, such as deposit feeders, burrow dwellers and inhabitants of tubes, with low relative mobility and opportunistic species of the first and the second order.

A multimetric index for assessment of aquatic ecosystem health based on macroinvertebrates for the Zio river basin in Togo

The use of multimetric indices as tools for assessing aquatic ecosystem health in most of the developing countries such as Togo is still lacking. To fill this gap, we developed a macroinvertebrates-based multimetric index for the Zio river basin of Togo. Forty-two sites were assessed for the development and the validation of the Multimetric Index of Zio River Basin (MMIZB). Thirty-nine candidate metrics belonging to four categories (composition metrics, functional feeding metrics, diversity metrics and tolerance measure metrics) were evaluated. After comprehensive multiple selection procedure, six core metrics were retained to provide the final MMIZB. The results showed that the MMIZB responded to a set of organic pollution (chemical oxygen demand, ammonium, total suspended solid) and hydromorphological alterations, which corresponded to a set of gradients of human pressures affecting the ecological integrity of Zio river basin water bodies (r = 0.78, p < 0.001). The final macroinvertebrate index well distinguished the reference sites and impaired sites of a validation data set (p < 0.001) and showed a significant relationship between water and habitat quality based on Prati’s index (r = 0.73, p < 0.001) and Multimetric Macroinvertebrates Index of Vietnam (MMI_Vietnam) (r = 0.88, p < 0.001). This work underlines the relevance of the MMIZB as an effective tool for biological monitoring and decision making in water management of Zio river basin.

Environmental variation, functional diversity and identity predicting community biomass in an old-growth subtropical broad-leaved forest

The relationship between biodiversity and ecosystem functioning (BEF) has emerged as a central issue in ecosystem ecology. Two broad classes of hypotheses, the mass ratio and niche complementarity effects, are proposed to explain the positive relation between biodiversity and ecosystem functioning in multiple experimental and natural systems. Environmental variation is noted as a key regulator of forest community biomass in natural systems and the under-story tree layer is often overlooked, as the canopy tree species are more likely to contribute to total community biomass. We determined community biomass of over-story, mid-story and under-story tree layers and employed environmental factors, functional diversity metrics of leaf traits to explain the variation in community biomass in an old-growth forest. We found that topographic and edaphic factors were of vital importance in regulating the standing biomass of each tree layer. Although functional diversity displayed positive effects on standing biomass across all tree strata, the standing biomass was more affected by functional identity than diversity in over-story and mid-story tree layers. Across all strata, the most significant correlation between functional diversity and standing biomass in under-story tree layer may suggest strengthened interspecific complementary interactions. Our study confirms that environmental variation is a strong driver of forest community biomass, and the relative importance of the mass ratio and the niche complementarity hypothesis vary across tree strata in explaining diversity effects on standing biomass.

Functionally redundant communities do not show differences in the main environmental drivers of different diversity metrics

We investigated which environmental variables of floodplain lakes act as potential drivers of fish assemblages and how they explain the variation in taxonomic and functional diversity of the community. We evaluated the taxonomic richness, functional dispersion (the distribution of species abundances with different traits) and redundancy (how similar the species are) of fish communities from six floodplain lakes of the upper Parana River floodplain, evaluating whether they respond to the same set of predictor variables. We predict that the variation in taxonomic richness will be explained by limnological variables that express the characteristics of the water and the functional variation by variables that express the physical structure of the habitat. We sampled limnological and habitat structural variables and fish communities of each floodplain lake in a span of 14 years. Functional diversity was evaluated from six functional traits. The three diversity indices were used as response variables in Generalized Linear Mixed Models (GLMMs), while environmental variables were used as predictor variables. Taxonomic richness was best explained by total phosphorus, water transparency, depth and water level, while functional dispersion was explained by water level. Functional redundancy was explained by the water transparency variable. Our results show that taxonomic and functional diversity metrics may have environmental predictors in common, but the taxonomic richness is more predictable depending on the environmental gradient than the functional diversity. Besides, the floodplain lakes showed high functional redundancy. This may suggest that in functionally redundant communities, the main drivers of different diversity metrics do not differ.

Functional trait diversity is a stronger predictor of multifunctionality than dominance: Evidence from an Afromontane forest in South Africa

Studies on how biodiversity influences ecosystem multifunctionality (EMF) help elucidate ecological mechanisms (e.g. niche complementarity and selection) underlying provision of multiple ecosystem services. While it is acknowledged that biodiversity contributes to EMF, the relative importance of functional traits diversity (niche complementarity) and dominance (selection effects) for EMF needs further investigation. To address this gap, we analysed how tree species diversity influences EMF, using data on species functional traits (specific wood density, specific leaf area and maximum plant height) and four ecosystem functions (carbon storage, habitat quality, forage provision and rockfall protection) in an Afromontane forest in South Africa. We tested the hypotheses that (i) trait diversity rather than dominance would link species richness to EMF; and (ii) diversity rather than species richness effects would increase with the level of EMF. For all possible scenarios of EMF indices, functional trait diversity metrics, especially functional divergence and functional richness correlated positively with EMF. On the other hand, functional dominance also influenced EMF, but played limited role in mediating EMF response to species richness, when compared with functional diversity. Results further revealed that total diversity effects, not species richness effect, generally increased with the level of EMF. In summary, we show that species richness does not fully capture the functional contribution of different species. Compared to dominance, trait diversity had significant advantage in explaining biodiversity-EMF relationship, stressing a greater role of niche complementarity as mechanism underpinning delivery of multiple functions. We argue that functional dominance reflects more the competitive dominance of traits and species within a given community and therefore is more likely to have greater effects on single functions than on multifunctionality.

Effects of future agricultural change scenarios on beneficial insects

Insects provide vital ecosystem services to agricultural systems in the form of pollination and natural pest control. However, there are currently widespread declines in the beneficial insects which deliver these services (i.e. pollinators and ‘natural enemies’ such as predators and parasitoids). Two key drivers of these declines have been the expansion of agricultural land and intensification of agricultural production. With an increasing human population requiring additional sources of food, further changes in agricultural land use appear inevitable. Identifying likely trajectories of change and predicting their impacts on beneficial insects provides a scientific basis for making informed decisions on the policies and practices of sustainable agriculture.We created spatially explicit, exploratory scenarios of potential changes in the extent and intensity of agricultural land use across Great Britain (GB). Scenarios covered 52 possible combinations of change in agricultural land cover (i.e. agricultural expansion or grassland restoration) and intensity (i.e. crop type and diversity). We then used these scenarios to predict impacts on beneficial insect species richness and several metrics of functional diversity at a 10km (hectad) resolution. Predictions were based on species distribution models derived from biological records, comprising data on 116 bee species (pollinators) and 81 predatory beetle species (natural enemies).We identified a wide range of possible consequences for beneficial insect species richness and functional diversity as result of future changes in agricultural extent and intensity. Current policies aimed at restoring semi-natural grassland should result in increases in the richness and functional diversity of both pollinators and natural enemies, even if agricultural practices remain intensive on cropped land (i.e. land-sparing). In contrast, any expansion of arable land is likely to be accompanied by widespread declines in richness of beneficial insects, even if cropping practices become less intensive (i.e. land-sharing), although effects of functional diversity are more mixed.

Patch size and vegetation structure drive changes to mixed-species flock diversity and composition across a gradient of fragment sizes in the Western Andes of Colombia

Abstract Forest fragmentation is a leading driver of biodiversity loss, yet its effects on positive species interactions remain poorly known. We examined the effects of fragmentation on mixed-species bird flocks in the Western Andes of Colombia. Using 500-m transect surveys (n = 14 transects), we sampled flocks in 8 fragments (range: 10–173 ha) and an unfragmented reference site within the same altitudinal band (1,900–2,200 m.a.s.l.) and matrix type (cattle pasture). We evaluated the relative contributions of 9 predictor variables, including patch size, distance from edge, and selective aspects of vegetation structure on the composition, size, species richness, functional diversity, and phylogenetic diversity of flocks. We found effects of both patch size and vegetation structure on flock species richness, size, and functional diversity, but no support for edge effects. Generally, flock richness and size responded differently to fragmentation than did functional and phylogenetic diversity metrics. Both flock size and richness increased with patch size, but this variable had no effect on functional and phylogenetic diversity. Flock richness and size increased in high-canopy forests with greater foliage height diversity, whereas unlogged, old-growth primary forests with large-diameter trees had lower flock richness and size, but significantly greater functional diversity. Phylogenetic diversity was not affected by patch size, edge effects, or vegetation structure. We found differences in flock composition in response to fragmentation. Richness of Furnariidae in flocks increased with increasing distance from edge and foliage height diversity, whereas that of Thraupidae and boreal migrant species increased in early successional and forest edge flocks, respectively. All flock diversity metrics differed significantly seasonally, with smaller, less diverse flocks observed in January–March than in June–August. Flocking behavior persisted in 10-ha fragments, likely because Andean flocks are “open membership” in nature, but there was extensive species turnover as forest edge and generalist species replaced forest-interior species in smaller fragments.

Assembly mechanisms of dung beetles in temperate forests and grazing pastures

The role of deterministic and stochastic mechanisms in community assembly is a key question in ecology, but little is known about their relative contribution in dung beetle assemblages. Moreover, in human modified landscapes these mechanisms are crucial to understand how biodiversity can be maintained in productive agroecosystems. We explored the assembly mechanisms driving dung beetle assemblages in forests and grazed grassland patches, and assessed the role of dung availability, soil hardness and moisture, elevation and land use heterogeneity as environmental predictors of functional diversity. To determine the underlying assembly mechanisms, we estimated functional diversity metrics (functional richness, evenness and divergence) and their departure from the predicted values by null models. We also used GLMs to assess the influence of environmental variables on functional diversity. In most cases, stochastic processes prevailed in structuring dung beetle assemblages and, consequently, environmental variables were not good predictors of dung beetle functional diversity. However, limiting similarity was found as a secondary mechanism with an effect on dung beetle assemblages in grasslands. Our results highlight the importance of stochastic processes that may reflect a metacommunity dynamic. Therefore, restoring landscape connectivity might be more important than habitat quality for the conservation of these functionally diverse beetle assemblages.

Plant Diversity and Agroecosystem Function in Riparian Agroforests: Providing Ecosystem Services and Land-Use Transition

Achieving biologically diverse agricultural systems requires a commitment to changes in land use. While in-field agrobiodiversity is a critical route to such a transition, riparian systems remain an important, yet understudied, pathway to achieve key diversity and ecosystem services and targets. Notably, at the interface of agricultural landscapes and aquatic systems, the diversification of riparian buffers with trees reduces the non-point source pollution in waterways. However, in riparian agroforestry systems, little is known about herbaceous community patterns and, importantly, the herbaceous community’s role in governing carbon (C) and nitrogen (N) cycling. Our study investigated herbaceous community taxonomic and phylogenetic diversity patterns in riparian (i) grasslands (GRASSLAND), (ii) rehabilitated agroforests (AGROFOREST-REHAB), and (iii) remnant forests (AGROFOREST-NATURAL). We then determined the biodiversity-ecosystem function relationships between community functional diversity metrics, C and N cycling, and greenhouse gas fluxes. We observed significant differences in taxonomic and phylogenetic diversity among riparian buffer types. We found that herbaceous plant communities in riparian agroforestry systems expressed plant trait syndromes associated with fast-growing, resource acquiring strategies, while grassland buffer plants exhibited slow-growing, resource conserving strategies. Herbaceous communities with high functional diversity and resource acquiring trait syndromes, such as those in the agroforestry riparian systems, were significantly correlated with lower rates of soil CO2 efflux and N mineralization, both of which are key fluxes related to ecosystem service delivery. Our findings provide further evidence that functionally diverse, and not necessarily taxonomically diverse, plant communities are strongly correlated to positive ecosystem processes in riparian agroforestry systems, and that these communities contribute to the transition of agricultural lands toward biologically and functionally diverse landscapes.

Spatial distribution of functional traits of bryophytes along environmental gradients in an Atlantic Forest remnant in north-eastern Brazil

ABSTRACTBackground: Functional trait-based approaches have been used to identify patterns of plant species diversity and composition related to environmental variability/changes. Bryophytes are rapidly affected by perturbations and thus their traits and distribution are expected to show well-defined relationships with environmental variability.Aim: To quantify the impacts of fragmentation on the diversity and structure of epiphytic bryophytes to vertical and horizontal environmental gradients in an Atlantic Forest remnant.Methods: Six functional traits related to water relations and light tolerance were recorded and one of them, the leaf lobule area in liverworts, was selected for morphometric measurements along the gradients analysed. Functional diversity and composition metrics of bryophytes along gradients were compared.Results: Functional diversity changed little along the vertical and horizontal gradients. Conversely, the functional composition of traits changed markedly. Traits related to water storage, such as the presence and area of lobules, and to protection against excess light incidence, such as dark pigments, were more numerous in the canopy and at the fragment edge.Conclusions: Functional composition is more correlated with the vertical and horizontal gradients than functional diversity. The lobule of liverworts stood out as the most relevant trait to explain the adaptive strategies of bryophytes.

Examples of Understory Plant Communities Observed in Post‐Agricultural Recent Woodlands and Uninterrupted Ancient Forests

We investigated how passive rewilding, a conservation strategy increasingly seen as an emerging tool to counterbalance biodiversity and nature degradation, may spontaneously restore plant communities to a state comparable to ancient forests. Looking beyond species identities, we coupled several taxonomic, functional, and phylogenetic diversity metrics to compare recent and ancient forests. While ancient forests harbored single species compositions, recent woodlands showed a higher phylogenetic richness and distinctiveness and few changes in the functional structure. Our study provides evidence that passive rewilding also promotes the establishment of rich and original understory plant communities, which is important for the conservation of forest biodiversity. Photo credit: Loïs Morel. These photographs illustrate the article “Passive rewilding may (also) restore phylogenetically rich and functionally resilient forest plant communities” by Loïs Morel, Lou Barbe, Vincent Jung, Bernard Clément, Annik Schnitzler and Frédéric Ysnel published in Ecological Applications. https​://doi.org/10.1002/eap.2007

Species richness and functional-trait effects on fine root biomass along a subtropical tree diversity gradient

There is evidence that different facets of biodiversity such as species richness (SR), phylogenetic diversity (PD) and functional diversity (FD) can modulate ecosystem functioning via niche-complementarity or mass-ratio effects, but the support for these hypotheses on fine root biomass remains unclear. In a tree diversity gradient in subtropical forests (ranging from 2 to 10 tree species), we identified the species identity of fine roots (≤ 2 mm in diameter) using a molecular method. This allowed computation of PD as well as trait-based FD and community-weighted means (CWM) metrics, which were then tested as predictors of fine root biomass. Three metrics (SR, CWM of specific root length and PD) were positively related to root biomass. SR was the best predictor of fine root biomass and its predicting ability depended on stand density. The predicting power of CWM of specific root length varied with the soil nutrient status. Overall, the results supported both tested hypotheses (mass-ratio and niche-complementarity) that seem to be non-mutually exclusive. Furthermore, our findings emphasize that stand density and soil nutrient status are the important variables driving fine root biomass and trait-values.

Protected areas alone rarely predict mammalian biodiversity across spatial scales in an Albertan working landscape

Protected areas (PA) networks are promoted globally as an effective method of biodiversity conservation and are increasingly implemented to meet the Convention on Biological Diversity Aichi objectives. However, whether PA networks actually conserve biodiversity, and how surrounding landscape features impact their efficacy, is controversial. We used a landscape approach to test whether mammalian biodiversity is maintained locally in PA networks, and whether landscape disturbance in the surrounding matrix detrimentally impacts biodiversity. We measured mammalian biodiversity using camera traps and functional diversity metrics, an approach that could be broadly applied to PA networks in working landscapes globally. We used generalized linear models to relate mammalian biodiversity metrics to natural, anthropogenic, and protected habitats across a range of 20 spatial scales to encompass increasing amounts of matrix. Biodiversity metrics increased with proportion of natural habitats at small scales and decreased with anthropogenic disturbance at large scales surrounding PAs. We found the conservation value of PAs are largely determined by the natural habitat remaining undisturbed, and the degree and type of disturbance in the surrounding working landscape. Implementing protected areas in degraded ecosystems, without addressing that degradation, will likely not achieve mammalian biodiversity conservation goals. We suggest, to achieve Aichi objectives, PAs placed in areas of high natural habitat and mitigated development will provide the best value for mammalian biodiversity conservation.

Passive rewilding may (also) restore phylogenetically rich and functionally resilient forest plant communities.

Passive rewilding is increasingly seen as a promising tool to counterbalance biodiversity losses and recover native forest ecosystems. One key question, crucial to understanding assembly processes and conservation issues underlying land-use change, is the extent to which functional and phylogenetic diversity may recover in spontaneous recent woodlands. Here, we compared understorey plant communities of recent woodlands (which result from afforestation on agricultural lands during the 20th century) with those of ancient forests (uninterrupted for several centuries) in a hotspot of farmland abandonment in western Europe. We combined taxonomic, functional, and phylogenetic diversity metrics to detect potential differences in community composition, structure (richness, divergence), conservation importance (functional originality and specialization, evolutionary distinctiveness) and resilience (functional redundancy, response diversity). The recent and ancient forests harbored clearly distinct compositions, especially regarding the taxonomic and phylogenetic facets. Recent woodlands had higher taxonomic, functional and phylogenetic richness and a higher evolutionary distinctiveness, whereas functional divergence and phylogenetic divergence were higher in ancient forests. On another hand, we did not find any significant differences in functional specialization, originality, redundancy, or response diversity between recent and ancient forests. Our study constitutes one of the first empirical pieces of evidence that recent woodlands may spontaneously regain plant communities phylogenetically rich and functionally resilient, at least as much as those of ancient relict forests. As passive rewilding is the cheapest restoration method, we suggest that it should be a very useful tool to restore and conserve native forest biodiversity and functions, especially when forest areas are restricted and fragmented.

Impacts of an indigenous settlement on the taxonomic and functional structure of dung beetle communities in the Venezuelan Amazon

In the last 50 years, traditionally nomadic indigenous communities in Amazonia have increasingly adopted more sedentary lifestyles as a result of external influences. Permanent settlements lead to the concentration of disturbances (e.g., forest extraction and hunting) and threaten vulnerable species as well as those that provide important ecosystem services such as dung beetles. Here we evaluated the abundance, taxonomic, and functional structure (composition and diversity) of an ecological indicator group—dung beetles—along a disturbance gradient associated with a permanent settlement of the Joti people in the Amazonian region of Venezuela. We applied generalized linear model to assess the response of dung beetle abundance to settlement distance and latent variable model to assess the influence of settlement distance on taxonomic diversity and functional structure. We found the abundance of roller-species increased but small-bodied beetles decreased away from the settlement. We found that proximity to the Joti settlement did not affect metrics of taxonomic and functional diversity of the dung beetle assemblages in general, although functional evenness was lower away from the settlement. In contrast, we found impacts on the functional composition of dung beetles, with significant increase in the community-weighted means for roller species and large-bodied dung beetles away from Joti settlement. Our findings suggest that the transition from nomadism to a more sedentary lifestyle has not caused widespread collapse in the diversity of dung beetle assemblages surrounding the settlement, however significant trends were observed in species-specific responses to human impact, and these responses were mediated by functional traits.

Drivers of subtropical forest dynamics: The role of functional traits, forest structure and soil variables

AbstractQuestionHow do biotic forest conditions, in terms of plant functional traits and tree basal area, and soil variables influence old‐growth forest dynamics?LocationA subtropical old‐growth forest in Southern Brazil.MethodsForest inventories were conducted in 1999 and 2017, in 24 permanent plots of 500 m2. All trees with a circumference at breast height of ≥ 30 cm were measured, identified to the species level, and tagged. We fitted linear models to evaluate the effect of the biotic variables of initial forest communities (tree basal area, trait community‐weighted mean [CWM] and both species and functional diversity metrics) and of soil variables on forest dynamics. These models included biomass dynamics (annual rate of biomass increment and mortality) and demographic rates (recruitment and mortality rates). Furthermore, linear models were used to evaluate the effect of tree survival, recruitment and mortality and biomass increment on the net biomass change.ResultsWe observed a positive effect of species diversity and a negative effect of CWM leaf phosphorus content on the biomass increment. Biomass loss was positively related to basal area and negatively related to the CWM of leaf nitrogen content. Overall, net biomass change was negatively influenced by biomass loss due to mortality. Recruitment rates were negatively affected by soil potassium content and were positively affected by soil pH and functional evenness of the community. Mortality rates were positively predicted by soil clay content and negatively predicted by species diversity.ConclusionsCommunity functional traits, basal area and soil variables predicted growth, mortality and recruitment dynamics of this subtropical old‐growth forest. This work provides important information about the biomass and demographic dynamics of subtropical forests, showing that initial community characteristics influence the gain and loss of biomass and individuals over a period of almost two decades.

Effects of climate and land-use gradients on avian phylogenetic and functional diversity in a tropical dry forest

Climate and habitat influence the distribution and dynamics of biodiversity. Investigating their influence on spatial patterns of phylogenetic (PD) and functional diversity (FD) is essential to understanding the response of ecological assemblages to changes in these factors. Here, we investigate the patterns of PD and FD of birds from the Brazilian dry forest Caatinga, and their relationship to gradients in climate and vegetation heterogeneity. For over 500 species distributed at 123 assemblages, we investigated the effect of these factors on a standardized measure of phylogenetic diversity (sesPD) phylogenetic dispersion (PDis), the functional richness (FRic), functional dispersion (FDis), taxon restrictedness, and functional uniqueness. Climate was the best predictor of all metrics of functional and phylogenetic diversity, whereas forest cover was relevant for FRic only. The independent effects of climate and habitat highlight their different roles in determining ecological and evolutionary diversities of avian assemblages in this semiarid biome. Additionally, most species are geographically restricted, but functionally redundant, suggesting a spatial turnover between different species with similar functional traits. Complementary effects of climate and habitat change act in concert in reducing ecological redundancy in assemblages less disturbed, and functional uniqueness in assemblages at the extreme of the aridity gradient in the Caatinga.

Evaluating functional diversity conservation for freshwater fishes resulting from terrestrial protected areas

Abstract Protected areas are one of the hammers in conservation toolkits, yet few protected areas exist that were designed to protect freshwater ecosystems. This is problematic as freshwater ecosystems are among the most threatened systems on earth. Nonetheless, terrestrial protected areas (TPAs) may afford spill‐over benefits to freshwater ecosystems included within their boundaries, but evaluations of these potential benefits for the protection of freshwater fish diversity are lacking. Using fish community data from 175 lakes inside, outside, or bordering TPAs in Ontario, Canada, we sought to determine if TPAs preserve fish functional diversity. We focused on functional diversity because previous work indicated no taxonomic differences between these lakes, but a difference in normalised‐length size‐spectra slopes inside versus outside TPAs (indicator of unique predator–prey ratios and trophic energy transfer). We expected that communities inside TPAs would show greater functional diversity (i.e. functional dispersion and functional richness) and have more extreme trait combinations (i.e. functional divergence) than communities outside or bordering TPAs. We also tested for differences in the rarity of species‐specific functional traits between fish communities inside, outside, or bordering TPAs, between thermal guilds, and across average body size and overall prevalence of the species. Our results indicated no significant differences in functional diversity among lake fish communities inside, outside, or bordering TPAs. However, fish communities inside TPAs had more extreme trait combinations than outside TPAs because abundant species in lake communities outside TPAs had more ubiquitous trait combinations than abundant fishes inside TPAs. Small‐bodied species showed greater functional rarity than large‐bodied species, indicating that small‐bodied fishes fill functionally unique roles while the most prevalent, large‐bodied species possess a more generalist set of traits. Overall, the similarity of functional diversity metrics for lake fish communities inside, outside, or bordering TPAs in Ontario suggests that TPAs capture the functional diversity of Ontario's lake fish communities. However, we encourage similar evaluations in regions where environmental conditions and stressors are more distinct across TPA boundaries than they are in Ontario, as these types of evaluations will inform guidelines for the design of freshwater protected areas and monitoring of their effectiveness in the future.

Trait‐based ecology of fishes: A quantitative assessment of literature trends and knowledge gaps using topic modelling

AbstractSpecies traits are a new data currency to enhance our understanding of ecological patterns and processes. Trait‐based studies of fishes are numerous in comparison with other animal groups, reflecting the diversity of fish forms and functions they provide to aquatic ecosystems. We conduct a retrospective examination of literature to identify knowledge gaps and provide guidance for future research in trait‐based fish ecology. We apply an automated text mining and topic modelling to track the evolution of research topics within peer‐reviewed articles of functional traits in marine and freshwater fishes published over the past half century, explore the inter‐connections among those topics and identify emerging avenues for investigation. By mapping the topic landscape of the literature, 16 latent topics emerged that vary in their prevalence. Our results show a decline in the frequency of studies using reproductive traits to model and explore the way fish allocate energy for reproduction, and increase in studies reporting functional diversity metrics and utilizing the concept of multivariate functional space. Research focused on contributions of fish traits to ecosystem functioning also has increased in frequency. We revealed large gaps in information between growing and decreasing topics and that these gaps were derived from different types of traits being considered. We suggest that scientists break‐free from the traditions of their research field by targeting investigations that: (a) apply functional diversity metrics to a broader assortment of traits, (b) focus on traits influencing energy allocation to growth/reproduction and (c) integrate trophic‐web and behavioural studies with other topics.