Variation In Functional Diversity Research Articles

Functional diversity performs a key role in the isolation of nitrogen-fixing and phosphate-solubilizing bacteria from soil.

Functional diversity covers diverse functional traits of microorganisms in an ecosystem. Thus, we hypothesized that it could play an important role in the isolation of nitrogen-fixing and phosphate-solubilizing bacteria. These bacteria have been considered as biofertilizer for sustainable agriculture development. Soils were collected from different sites of agricultural field and performed several microbiological tests in which we observed considerable differences in heterotrophic microbial abundance and microbial activities among the microcosms. Functional diversity depends on both microbial richness and evenness. Based on the results of metabolic fingerprinting of the carbon sources of BiOLOG-ECO plates, richness and evenness was measured by determining Shannon diversity index and Gini coefficient, respectively. The results showed significant differences in both microbial richness and evenness, suggesting considerable variation of functional diversity among the microcosms. Thereafter, nitrogen-fixing and phosphate-solubilizing bacteria were isolated on Burk's and Pikovskaya media, respectively. The results revealed considerable variation of both types of bacterial abundance among the microcosms. Microcosm (T2) showing the highest functional diversity houses the maximum numbers of nitrogen-fixing and phosphate-solubilizing bacteria. Similarly, the microcosm (T5) exhibiting the lowest functional diversity houses the minimum numbers of nitrogen-fixing and phosphate-solubilizing bacteria. Thus, a strong positive correlation was observed between functional diversity and both types of bacterial abundance among the soil samples. Higher richness and evenness lead to the development of increased functional diversity that facilitates to accommodate substantial numbers of nitrogen-fixing and phosphate-solubilizing bacteria in soil. Taken together, the results demonstrated that functional diversity plays an important role in the isolation of nitrogen-fixing and phosphate-solubilizing bacteria from soil.

Multispecies plant invasion increases function but reduces variability across an understorey metacommunity

Several plant traits have been linked to invasion success in studies involving single alien species or invaded versus non-invaded communities. Less consideration has been given to how invasion by multiple alien species changes community-wide traits and functional structure at landscape scales. Changes to community functional structure by multispecies invasion may have consequences for ecosystem function. Therefore, it is important to identify which traits of naturalized aliens are responsible for optimizing patterns of trait convergence and divergence. Here, we examine if invasion by multiple alien species is related to changes in community-wide functional traits, and patterns of trait convergence and divergence, across an invasion gradient. We collected field data in Victoria, Australia, on traits previously associated with invasion success from 15 × 500 m2 plots. These plots encompassed a range of relative alien cover (~ 3–61%) and represented a multispecies invasion gradient. We tested relationships of each trait to the invasion gradient. We also determined trait convergence and divergence patterns across the gradient, using a trait divergence analysis. Specific leaf area and proportion of annual species significantly increased with the level of invasion. Annual life history and flowering duration maximised trait-convergence, but the two traits had different relationships to the invasion gradient. Specific leaf area, annual life history, leaf dry mass and seed mass maximised trait divergence. Evidence of trait-divergence along the gradient is represented by an increase in functional diversity with invasion level. However, variation in functional diversity was higher in little-invaded communities and stabilised at intermediate and high levels of invasion. Traits (specific leaf area and annual life history) associated with invasion success at a landscape scale are traits promoting rapid life cycle completion, and increases in multispecies invasion leads to an increase in functional diversity but a decline in its variation.

Different responses of predator and prey functional diversity to fragmentation.

The study of functional diversity, or the range of species' ecological roles in a community, is a rapidly expanding area in ecology. Given the extent that ecosystems are being altered, effort should shift toward assessing variation in functional diversity across landscapes with the goal of improving land use management decisions. We construct a workflow that creates three-dimensional surfaces and maps of functional diversity to examine changes in beetle functional diversity across an Indiana, USA landscape. We sampled 105 prey wood-borer and predator beetle species along a gradient of forest fragmentation across Indiana and used a number of functional traits from literature sources to capture their functional roles. We developed newly measured functional traits to estimate several traits relevant to beetles' ecological function that was unknown and not easily measured. Functional diversity indices (FRic, FDis, FDiv, and FEve) were calculated from species abundance and functional traits and used to assess changes in functional diversity along the fragmentation gradient. We predicted that habitat fragmentation would have a greater negative impact on predator beetle functional diversity than prey wood-borer functional diversity. Landscape metrics most important to the functional diversity of both wood-borer and predator beetle communities were landscape division index (LDI, an assessment of landscape subdivision) and mean shape index (MSI, a measure of patch shape complexity). Overall, three-dimensional surfaces of functional diversity and functional diversity maps across the Indiana landscape revealed that beetle functional diversity was greatest with minimal landscape subdivision. Opposite to what we predicted, we found that the prey wood-borer functional diversity was more negatively impacted by LDI than the predator beetle functional diversity. Furthermore, predator beetle functional diversity was greater with increasing MSI. The map predicted predator FRic to be highest in forested areas with intact habitat and also less sensitive to habitat fragmentation adjacent to more continuous forest. We propose that land management may be guided by revealing landscapes that are most appropriate for maximizing functional diversity of multiple communities or shifting the relative abundance within prey and beneficial predator beetle functional groups with the use of three-dimensional plots or maps.

Partitioning the functional variation of tree seedlings during secondary succession in a tropical lowland rainforest

AbstractThe seedling stage is a key phase in the regeneration dynamics of forest communities. The functional diversity of tree seedlings is closely related to the structuring and functioning of forest ecosystems. Here, we examined and partitioned variations of tree seedlings in functional diversity over a chronosequence (younger secondary forest, 18–30 yr; older secondary forest, 60 yr; and old growth forest) after shifting cultivation in a tropical lowland rainforest area on Hainan Island, China. Results showed that the variations of seedling functional diversities revealed a unimodal pattern during the secondary succession. The functional diversities of seedlings were overall lower in the secondary than in old growth forests. The relative role of edaphic factors and tree community factors changed with the successional process. The variations in functional diversity explained by edaphic factors were higher than those by tree community factors in the younger secondary forest. However, with the procession of secondary succession, variations in functional diversities of seedlings explained by tree community factors were increasing. The determinants for functional diversities of seedlings varied with successional stages. Seedling functional diversities were affected by edaphic factors in the younger secondary growth forest. Meanwhile, in the older secondary forest, seedling functional diversities were affected mostly by soil nutrients and tree community factors. In the old growth forest, seedling functional diversities were affected by available nitrogen and tree community factors. Our results suggest that edaphic factors play an important role in the younger secondary forest, while tree community factors in the older secondary forest and unexplained factors in the old growth forest.

Floristic composition, site conditions and diversity of poet’s daffodil (Narcissus radiiflorus Salisb.) hay meadows in the Venetian Pre-Alps and outer Dolomites (N-Italy): implications for conservation and restoration

Hay meadows are an important component of the alpine landscape, which evolved over millennia of human activities. When traditionally managed, hay meadows support a rich flora and are recognized for high species diversity. However, both intensification and abandonment can lead to a loss of biodiversity in this vegetation. In this paper, the focus was on the hay meadows where Narcissus radiiflorus Salisb. forms white mosaic carpets during the blooming period. This vegetation was studied through 26 phytosociological relevés, taken in the Venetian Pre-Alps and outer Dolomites (Northern Italy). Relevés were numerically classified and analysed in their relationships with site conditions. Moreover, diversity metrics were calculated for detecting the conservation status of hay meadows subjected to different types of disturbance. The results showed that poet’s daffodils’ dominance brings together hay meadows showing a substantial range of floristic and ecologic variation and that part of the stands dominated by Narcissus radiiflorus could be referred to a habitat type regarded as prioritary for nature conservation. Moreover, management-related variations in functional diversity suggested that the best practice recommended for conservation and restoration of this habitat is the continuation of traditional late mowing. This practice will allow preserving both biodiversity and ecosystem functions and services.

Temporal changes in bird functional diversity across the United States.

Global changes are modifying the structure of species assemblages, but the generality of resulting diversity patterns and of their drivers is poorly understood. Any such changes can be detected and explained by comparing temporal trends in taxonomic and functional diversity over broad spatial extents. In this study, we addressed three complementary questions: How did bird taxonomic and functional diversity change over the past 40years in the conterminous United States? Are these trends non-linear? Can temporal variations in functional diversity be explained by broad-scale changes in climate and vegetation productivity? We quantified changes in taxonomic and functional diversity for 807 bird assemblages over the past four decades (1970-2011) considering a suite of 16 ecological traits for 435 species. We found increases in local bird species richness and taxonomic equitability that plateaued in the early 2000's while total abundance declined over the whole period. Functional richness, the total range of traits in an assemblage, increased due to the rising prevalence of species with atypical life-history strategies and under-represented habitat or trophic preferences. However, these species did not trigger major changes in the functional composition of bird assemblages. Inter-annual variations in climate and primary productivity explained the richness of bird life-history traits in local assemblages, suggesting that these traits are influenced by broad-scale environmental factors, while others respond more to more local drivers. Our results highlight that a comparative analysis of the multiple facets of functional diversity can raise novel insights on processes underlying temporal trends in biodiversity.

Assessing the spatial variation of functional diversity estimates based on dendrograms in phytoplankton communities

ABSTRACT Variation in phytoplankton functional diversity is partioned and mapped using several indices and linkage methods based on dendrograms. The relationships between diversity metrics and major environmental predictors, including zooplankton density, were assessed in 29 phytoplankton communities of floodplain lakes distributed along the Middle Araguaia River in central Brazil. The dendrogram-based functional diversity indices were Functional Group Richness, Functional Diversity, Mean Pairwise Distance and Mean Nearest Taxon Distance, whereas seven different hierarchical agglomerative linkage methods we used. The performance of indices were compared using ANOVA and their spatial variation in response to major environmental predictors evaluated. The results indicate that variation in functional diversity values is primarily a product of the type of index chosen. This variation was statistically significant in 90 % of the floodplain lakes studied; however, a spatial pattern of variation in index values along the river was not detected. Furthermore, environmental constraints, including zooplankton density, were weak predictors of functional diversity indices. Therefore, the mathematical characteristics of indices are of primary importance in explaining variation among functional diversity values.

Riparian plant guilds become simpler and most likely fewer following flow regulation

Abstract River regulation affects riparian systems world‐wide and conservation and restoration efforts are essential to retain biodiversity, and the functioning and services of riverine ecosystems. Effects of regulation on plant species richness have been widely addressed, but the filtering effect of regulation on guilds has received less attention. We used a functional trait approach to identify adaptive plant strategies through regulation‐tolerant traits and predict shifts of riparian vegetation communities in response to regulation. We analysed variation in functional diversity across gradients of hydrological alteration in northern Sweden in relation to modified timing and infrequent major floods, along with frequent short‐term inundation. Functional richness was similar in all study sites, but species richness declined with increasing intensity of regulation, and the species lost were largely functionally redundant (i.e. co‐existing species that have similar contribution to an ecosystem function). Guilds of species intolerant to waterlogging were particularly unsuccessful in most regulated sites as they were affected by hydropower dams which replace major fluvial disturbances with frequent short inundation events. We predict that this guild will disappear, with likely consequences for the entire riverine ecosystem. Synthesis and applications. We conclude that functional traits tolerant to waterlogging or submergence and lack of major fluvial disturbances were key to understanding our results. We suggest that the functional trait approach can be integrated with knowledge of other ecosystem components to provide an understanding of ecosystem function that can be used to guide fluvial ecosystem management.

Wading bird functional diversity in a floodplain: Influence of habitat type and hydrological cycle

AbstractWaterbirds play important roles in maintaining ecosystem functioning in wetlands. However, the lack of essential information about the levels of interaction between waterbirds and wetland characteristics is a major impediment for service valuation. In this study, we examined the influence of the flood pulse across different freshwater habitats on the functional diversity and possible assembly structuring mechanisms of herons and storks in a neotropical floodplain. We investigated functional richness, evenness and divergence as descriptors of the functional diversity in rivers, channels and both connected and isolated lagoons across different phases of the hydrological cycle. We also compared observed values of functional diversity with expected null models to untangle the main mechanisms driving assemblages. We found spatiotemporal variation in functional diversity in wader assemblages of the high Paraná River floodplain. The functional diversity of Pelecaniformes and Ciconiiformes varied mainly in rivers, channels and connected lagoons opposed to isolated lagoons in a floodplain, and mostly during flood events, right after floods or after a long period of drought. This suggests that the variation in the water level plays different roles in maintaining wading birds' functional diversity in connected and isolated habitats. Also, wading bird assemblages in this floodplain may be structured by neutral mechanisms, independent of habitat type or hydrological period, which may support the idea that species traits are not important in explaining their coexistence patterns. Our study contributes to the understanding of how environmental variations may affect functional diversity, a first step towards understanding how changes in waterbird communities affect the magnitude and stability of services provided by them.

Inferring community assembly processes from trait diversity across environmental gradients

Abstract:Environmental filtering and competitive interactions are important ecological processes in community assembly. The contribution of the two processes to community assembly can be evaluated by shifts in functional diversity patterns. We examined the correlations between functional diversity of six traits (leaf chlorophyll concentration, dry matter content, size, specific leaf area, thickness and wood density) and environmental gradients (topography and soil) for 92 species in the 20-ha Dinghushan forest plot in China. A partial Mantel test showed that most of the community-weighted mean trait values changed with terrain convexity and soil fertility, which implied that environmental filtering was occurring. Functional diversity of many traits significantly increased with increasing terrain convexity and soil fertility, which was associated with increased light and below-ground resources respectively. These results suggest that co-occurring species are functionally convergent in regions of strong abiotic stress under the environmental filtering, but functionally divergent in more benign environments due to resource partitioning and competitive interactions. Single-trait diversity and multivariate functional diversity had different relationships with environmental factors, indicating that traits were related to different niche axes, and associated with different ecological processes, which demonstrated the importance of focusing niche axes in traits selection. Between 9% and 41% of variation in functional diversity of different traits was explained by environmental factors in stepwise multiple regression models. Terrain convexity and soil fertility were the best predictors of functional diversity, which contributed 30.5% and 29.0% of total R2to the model. These provided essential evidence that different environmental factors had distinguishing impacts on regulating diversity of traits.

高寒草甸种间性状差异和物种均匀度对物种多样性与功能多样性关系的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 高寒草甸种间性状差异和物种均匀度对物种多样性与功能多样性关系的影响 DOI: 10.5846/stxb201405070903 作者: 作者单位: 陕西师范大学生命科学学院,陕西师范大学生命科学学院,中国科学院西北高原生物研究所,陕西师范大学生命科学学院,陕西师范大学生命科学学院,陕西师范大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31070382) Effects of interspecific trait dissimilarity and species evenness on the relationship between species diversity and functional diversity in an alpine meadow Author: Affiliation: College of life Sciences,Shaanxi Normal university,Xi’an,College of life Sciences,Shaanxi Normal university,Xi’an,Northwest Institute of Plateau Biology,Chinese Academy of Sciences,College of life Sciences,Shaanxi Normal university,Xi’an,College of life Sciences,Shaanxi Normal university,Xi’an,College of life Sciences,Shaanxi Normal university,Xi’an Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:物种多样性(SD)与功能多样性(FD)之间存在多种关系,但由于生态系统功能主要由物种的功能属性决定,因而功能多样性对生态系统功能的影响大于物种多样性的影响。但在种间性状差异和物种均匀度这两个构成功能多样性的基本成分中,何者对功能多样性影响更大,并进而决定SD-FD关系尚不明确。通过在高寒矮嵩草(Kobresia humilis)草甸为期6a的刈割(留茬1 cm、3 cm及不刈割)和施肥(尿素7.5 g m-2 a-1＋磷酸二胺1.8 g m-2 a-1、不施肥)控制实验,研究了种间性状差异(33个物种13个性状)和物种均匀度(所有物种)对物种多样性(所有物种)与功能多样性(33个物种13个性状)之间关系的影响。研究结果显示:(1)物种多样性与功能多样性正相关,它们与多性状种间差异负相关,而与物种均匀度正相关。物种均匀度是导致功能多样性变化的主要因素,也是导致SD-FD正相关的原因,这是因为随着物种多样性增加,物种均匀度的增加程度大于多性状种间差异的减少程度,因而功能多样性增加,SD-FD正相关;(2)功能多样性指数(FDRao和FDis)随物种多样性指数(H')减速递增,表明群落存在一定的功能冗余,且功能冗余随物种多样性的增大而增大,但尚未达到产生SD-FD无相关性的极限H'值;(3)功能多样性对高寒草甸生态系统地上净初级生产力(ANPP)的影响大于物种多样性的影响,二元线性回归显示在同时考虑二者对ANPP的影响时,可排除物种多样性的作用。但由于物种多样性下降或物种丧失引起的物种功能性状丢失或性状空间维度减小将导致功能多样性降低,表明它们之间存在一定互补性,在研究生物多样性与生态系统功能关系时,同时考虑物种多样性和功能多样性的影响仍十分必要。 Abstract:Species diversity (SD) and functional diversity (FD) have previously been reported to be associated in a variety of ways, and identifying the relationship between these two parameters is important for our understanding the relationship between biodiversity and ecosystem functioning. Since ecosystem functioning is mainly influenced by plant functional attributes, it is widely held that functional diversity exerts a greater influence upon ecosystem functioning than does species diversity. However, it remains unclear which basic component of functional diversity (i.e., species evenness or trait dissimilarity among species) contributes more to functional diversity and thus determines or alters the SD-FD relationship. In this study, a field manipulation experiment was conducted in an alpine Kobresia humilis meadow at the Haibei Research Station of the Chinese Academy of Sciences from 2007 to 2012. The experiment employed a split-plot design, in which vegetation was clipped to one of two lengths (above ground stubble =1 cm or 3 cm) or left unclipped. Subplots were treated with fertilizer (urea 7.5 g m-2 a-1 + ammonium phosphate 1.8 g m-2 a-1) or remained unfertilized. Data analysis methods, e.g. general linear model univariate ANOVA, multivariate analysis, binary linear regression and curve fitting, were employed to analyze the effects of these treatments on trait dissimilarity among species (dij, 13 traits of 33 species), community species evenness (Pielou evenness index, J) and community species diversity (Shannon-Wiener index,H'), and functional diversity (Rao index, FDRao; Functional dispersion, FDis) (13 traits of 33 species), as well as potential relationships among these measures. 1) SD (H') was significantly positively correlated with FD (FDRao, FDis), and J was positively correlated with SD (H') and FD (FDRao, FDis), whereas dij (dissimilarity of 13 traits among 33 species) was negatively correlated with SD (H') and FD (FDRao, FDis). J was more strongly correlated with SD (H') than dij, and was also correlated with FD (FDRao, FDis). Thus, it can be concluded that species evenness is a major driving factor of both variation in FD and the positive correlation between SD and FD. 2) Curve fitting revealed that the increase in FD (FDRao, FDis) leveled off as SD (H') increased, indicating that a certain degree of functional redundancy occurred in the community and that this increased with species diversity. As a result, species diversity (H') failed to reach the limit that would result in a non-significant correlation between species diversity and functional diversity. 3) The effect of FD (FDRao, FDis) on aboveground net primary productivity (ANPP) of the alpine meadow ecosystem was greater than that of SD (H'). Binary linear regression showed that the effect of SD (H') on ANPP was negligible compared with that of FD (FDRao,FDis).It should be noted that the loss of functional traits or a reduction in the number of trait space dimensions, such as results from the decline or loss of species diversity, would inevitably reduce the functional diversity of community, indicating a complementary relationship between species diversity and functional diversity. Thus, future studies on the relationship between biodiversity and ecosystem functioning should focus simultaneously on the effects of both species diversity and functional diversity on ecosystem functioning. 参考文献 相似文献 引证文献

Scale and scope matter when explaining varying patterns of community diversity in riverine metacommunities

Large-scale species and genetic metacommunity patterns are influenced by variation in environmental factors and distance between communities, according to previous studies. However, these studies often used different measures to assess patterns of metacommunity diversity, distances between communities and grain sizes at which environmental variables are measured. This hinders interpretations and generalizations of the underlying process that drive metacommunity diversity. We applied a synthetic and multi-analytical approach to identify general factors structuring the diversity of a large riverine metacommunity. Using complementing approaches we analyzed how distance, measured as Euclidean or topological distance, and environmental factors, assessed at different grain sizes, influenced different measures of metacommunity diversity (species richness, functional richness and phylogenetic diversity) of mayfly, stonefly and caddisfly species in a large river network (river Rhine, Switzerland). We found the amount of explained variation in species diversity was generally unaffected by grain size, but improved with the use of topological distance, compared to Euclidean distance. Variation in functional diversity was best explained by environmental factors at small grain sizes and topological distance. Variation in phylogenetic diversity was best explained when environmental variables were assessed at larger grain sizes and Euclidean distance was used. Overall, our results indicate that processes structuring metacommunity diversity may differ at the species, functional or phylogenetic level of the community, as recently postulated in the metacommunity–phylogenetics approach. While such differences may hinder comparisons across studies using different methodologies, it offers opportunities to disentangle the structuring factors within metacommunities by applying multiple analytical approaches to the same dataset.

To what extent could functional diversity be a useful tool in inferring ecosystem responses to past climate changes?

Functional diversity (the amount of inter-specific variation in functional traits in an ecological community) has been receiving increased attention in ecological studies because it does not treat all species identically, as taxonomical diversity does, but rather according to the role they have within a community. Therefore, functional diversity (FD) can provide information capable of revealing the processes that structured past faunal complexes (FCs) (seen as “spatio-temporal” meta-communities) and promoted their dynamic changes. Each FC gathers faunal assemblages from different territories. Thus, species composition of local faunas may differ from site to site, though the ecological structure may be substantially the same. In such cases, it is appropriate to classify species into functional groups and study the changes in their relative abundance over time. This allows to quantify the functional aspect of biodiversity and to establish its relationships with ecosystem functioning and environmental constraints through changes in the amount of resource partitioning among species. The research focused on the variation of the relative abundance of mammalian ecological groups in SW European FCs, examined in the light of Early to Middle Pleistocene profound climate changes known as Mid-Pleistocene Revolution. The population density (that is marginally affected by climatic and geographical factors) is here proposed as the best proxy for the abundance of individuals of a species in a FC. This approach has the advantage of avoiding the effects of time averaging on fossil data and other sampling issues that paleontologists routinely face (e.g. taphonomic biases). Results obtained indicate that the comparison of FD variation across a region and the analysis of its changes over time can provide interesting hints for scrutinizing in detail the dynamic effect of climatic shifts in restructuring past mammalian communities.

Variations in functional diversity in snowbed plant communities determining snowbed continuity

Snowbed habitats are home to plant species that have adapted to particular environmental conditions (i.e. long-lasting snow cover and short growing seasons). The presence of most of these species is dependent on a long period of snow cover and so their conservation may well depend in the future on their ability to adapt to the effects of climate change. The aim of this study was to assess the persistence of snowbed communities using functional trait and functional diversity indices. We used data for plant species abundances from 32 snowbeds in Andorra (Pyrenees) classified according to certain environmental variables (elevation, exposure, soil type and temperature) and snow cover duration. Nine functional traits were used to evaluate the functional diversity, which was characterised as consisting of functional richness, functional evenness, functional dispersion, functional divergence and the community-weighted mean trait values. In two snowbeds, plant traits were also recorded and variation analysed along a snowmelt gradient. We found that snowbed specialist species had functional traits that were well adapted to the particular abiotic conditions of snowbed habitats but that there was a predominance of the functional traits of grass species in species originating in neighbouring communities. We found less functional richness, fewer strategies and lower competitive ability in the adapted species as the severity of the abiotic conditions increased. Snowbed specialist species appear to be less sensitive to the length of the growing season than species from neighbouring communities. Our results suggest that non-specialist species will tend to appear more frequently in those snowbed habitats affected by the reduction in snow cover duration.

Global patterns of functional diversity and assemblage structure of island parasitoid faunas

AbstractAimThe processes leading to the assembly of ecological communities can determine their functional structure. We assess the influence of biogeographical correlates associated with species diversity gradients on the global patterns of functional diversity of island parasitoid assemblages (Hymenoptera,Braconidae). We also evaluate whether island assemblages present a non‐random functional structure.LocationFifty‐three archipelagos distributed world‐wide.MethodsSix traits related to morphology, attack strategy and development were used to measure functional diversity and determine the level of departure from randomness on trait diversity between islands and their corresponding species pool, through null models. We used generalized and partial regressions to determine the influence of different predictors (climate, regional and local island characteristics) on the functional diversity of island assemblages, comparing results with those obtained for species richness. We also evaluated whether any of the predictors or particular species traits were related to the patterns obtained when comparing island assemblages with null models.ResultsMost of the geographical variation in functional diversity was not explained by the predictors evaluated, while for species richness these explained over 70% of spatial variation. The abiotic characteristics of islands with functionally clustered parasitoid biotas (c. 40% of all islands) did not differ from those of other islands. Comparisons between functionally clustered assemblages and those expected randomly from the species pool indicated a higher percentage of that the former included proportionally fewer ectoparasitoid and idiobiont species, which attack fewer host orders and prefer the egg and larval stages of their hosts.Main conclusionsThe predictors correlated with functional diversity differ from those driving species richness patterns. We argue that biotic filters associated with the structure of the host communities may be important determinants of the assembly of many island parasitoid faunas, leading to assemblages dominated by species presenting particular ranges of trait values that differ from those in their pool of potential colonists.

Nesting strategies affect altitudinal distribution and habitat use in Alpine dung beetle communities

1. Dung beetles are key contributors to a suite of ecosystem services. Understanding the factors that dictate their distributions is a necessary step towards preventing negative impacts of biodiversity loss.2. Alpine dung beetle communities were analysed along altitudinal gradients to assess how different components of the community, defined in terms of nesting strategy [dung‐ovipositing Aphodiidae (DOAs), soil‐ovipositing Aphodiidae (SOAs) and two paracoprid (PAR) groups, Geotrupidae and Scarabaeidae] and parameters relevant to dung removal rates (species richness, total biomass and functional diversity), are distributed, and to identify to which environmental factors they respond.3. Species richness declined with altitude. There was no significant variation in functional diversity or total biomass in relation to altitude. There were significant variations when considered by nesting group:DOAspecies richness and biomass decreased,SOAbiomass increased, and Geotrupidae biomass showed a non‐linear trend, as altitude increased.4. Functional diversity and total species richness were positively related to vegetation cover.DOAspecies richness was highest in forest and scrub;SOAspecies richness was highest in grassland andPARspecies richness was lowest in rocky areas.5. Dung beetle species show different trends in species richness and biomass depending on nesting strategy. Management to promote the dung beetle community should include maintenance of a mosaic of habitat types. Given the likely importance of species richness and biomass to ecosystem functioning, and the complimentary effect of different dung beetle groups, such a strategy may protect and enhance the ecosystem services that Alpine dung beetles provide.

Ontogenetic trait variation influences tree community assembly across environmental gradients

Intraspecific trait variation is hypothesized to influence the relative importance of community assembly mechanisms. However, few studies have explicitly considered how intraspecific trait variation among ontogenetic stages influences community assembly across environmental gradients. Because the relative importance of abiotic and biotic assembly mechanisms can differ among ontogenetic stages within and across environments, ontogenetic trait variation may have an important influence on patterns of functional diversity and inferred assembly mechanisms. We tested the hypothesis that variation in functional diversity across a topo‐edaphic gradient differs among ontogenetic stages and that these patterns reflect a shift in the relative importance of different assembly mechanisms. In a temperate forest in the Missouri Ozarks, USA, we compared functional diversity of leaf size and specific leaf area (SLA) of 34 woody plant species at two ontogenetic stages (adults and saplings) to test predictions about how the relative importance of abiotic and biotic filtering changes among adult and sapling communities. Local communities of adults had lower mean SLA and lower functional dispersion of SLA than expected by chance, particularly at the resource‐limited end of the topo‐edaphic gradient, suggesting an important role for abiotic filtering among co‐occurring adults. In contrast, local communities of saplings often had higher functional dispersion of leaf size and SLA than expected by chance regardless of their location along the topo‐edaphic gradient, suggesting an important role for biotic filtering among co‐occurring saplings. Moreover, the overall strength of trait‐environment relationships varied between saplings and adults for both leaf traits, generally resulting in stronger environmental shifts in mean trait values and trait dispersion for adults relative to saplings. Our results illustrate how community assembly mechanisms may shift in their relative importance during ontogeny, leading to variable patterns of functional diversity across environmental gradients. Moreover, our results highlight the importance of integrating ontogeny, an important axis of intraspecific trait variability, into approaches that use plant functional traits to understand community assembly and species coexistence.

Between‐ and within‐species trait variability and the assembly of sapling communities in forest patches

AbstractQuestionsWhat is the magnitude of between‐species trait variability (BSV) and within‐species trait variability (WSV) of specific leaf area (SLA) in a sapling meta‐community? To what extent do species turnover and WSV influence community‐level mean trait responses to an environmental gradient and trait spread patterns across this gradient? What is the role of WSV for mean plant responses to environmental variation and niche partitioning in structuring sapling communities?LocationForest patches within a native grassland matrix in southern Brazil.MethodsWe recorded saplings in community plots across a canopy openness gradient in forest patches and described each of the 1129 individuals using SLA. First, we partitioned trait variation into BSV and WSV irrespective of co‐occurrence in plots. Then, using the community data, we partitioned the total variation of community‐weighted trait means (CWM) and Rao's functional diversity (FD) into components explained by canopy openness, species turnover and WSV. We also partitioned the effects of WSV between and within plots on FD. Finally, we explored the responses of CWM and FD to the gradient using the whole trait variability, only BSV or only WSV.ResultsSpecific leaf area presented a substantial proportion of variation within species (37%), although it varied more between species (63%). Species turnover and WSV explained 48% and 19% of the variation in CWM across the gradient, respectively. Species turnover and WSV explained 51% and 45% of the variation in FD across the gradient, respectively. SLA varied within species more along the gradient than within communities. Within‐species variability enhanced shifts in CWM and FD across the gradient. Canopy openness significantly predicted CWM at all levels, and FD at all but the within‐species level.ConclusionsPlastic responses of species mirrored the average response of communities to the environmental gradient. Within‐species trait variability enhanced the mean plant responses to environmental variation as well as niche partitioning, and was especially important in enabling species to establish in a wider portion of the environmental gradient. Our study provides new evidence that population‐level phenomena matter for community assembly.

Functional diversity decreases with temperature in high elevation ant fauna

Severe environmental conditions filter community species compositions, forming clines of functional diversity along environmental gradients. Here, the changes in functional diversity in ant assemblages with severe environmental conditions in the Swiss Alps were investigated. Eight sites were sampled along an elevation gradient (1800–2550 m). The variation in functional diversity was analysed along an elevation gradient considering four traits: social structure (monogynous vs. polygynous), worker size, pupal development, and nest structure. Ant species richness and functional diversity decreased with decreasing temperature. Species found in colder habitats tended to live in subterranean nests rather than in mounds and exhibit a polymorphism in queen number, either within or across populations. The phylogenetic diversity did not decrease at colder temperature: Formicinae and Myrmicinae occupied the full range of elevations investigated. An insulation experiment indicated that mounds are more thermally insulated against the cold compared with soil. The absence of a mound‐building ant from high elevations probably results from a reduction in the amount of vegetal materials provided by coniferous trees. More severe abiotic conditions at higher elevations act as a filter on ant assemblages, directly through physiological tolerances to the abiotic conditions and indirectly as the vegetation necessary for nest building shifts with elevation.

Responses of Aquatic Insect Functional Diversity to Landscape Changes in Atlantic Forest

AbstractThe Atlantic Forest domain, one of the 25 world's hotspots for biodiversity, has experienced dramatic changes in its landscape. While the loss of species diversity is well documented, functional diversity has not received the same amount of attention. In this study, we evaluated functional diversity of insects in streams utilizing three indices: functional diversity (FD), functional dispersion (FDis), and functional divergence (FDiv), seeking to understand the roles of three predictor sets in explaining functional patterns: (1) bioclimatic and landscape variables; (2) spatial variables; and (3) local environmental variables. We determined the amount of variation in different measures of functional diversity that was explained by each predictor set and their interplays using variation partitioning. Our study showed that variation in functional diversity is better explained by a set of variables linked to different scales dependent on spatial structures, indicating the importance of landscape and mainly environmental variables in the functional organization of aquatic insect communities, and that the relative importance of predictor sets depends on the indices considered. Variation in FD was better explained by the interplay among the three predictor sets and by local environmental variables, whereas variation in FDis was better explained by spatial variables and by the interplay between environmental and spatial variables. Variation in FDiv was not significantly explained by any predictors. Our study adds more evidence on the harmful effects caused by landscape changes on biodiversity in the Atlantic Forest, suggesting that these effects also influence the functional organization of stream insect communities.