A functional perspective for breeding and wintering waterbird communities: temporal trends in species and trait diversity

Waterbird communities are prone to strong temporal changes both seasonally and annually, but little is known about how this affects their functional diversity and community assembly. Detecting temporal trends in taxonomic and functional diversity within (alpha diversity) and between (beta diversity) communities in breeding and wintering seasons could give insight into the ecological processes driving those trends. In this study, we investigated trends in wintering and breeding waterbirds within and between eleven wetlands in Mediterranean Spain, using a 28‐year time‐series up to 2017. We assessed the temporal trends in taxonomic and functional diversity measures, and compared observed functional diversity values with null expectations, in order to explore the mechanisms driving community assembly. We found increases over time in species richness and in the occupied functional space for both wintering and breeding communities, indicating that species with distinct functional roles were added in both seasons. However, the distribution of the abundances in the functional space was different for breeding and wintering communities. Dissimilarity of species and functional traits decreased among wetlands, suggesting that some of the same functional traits were added to the different wetlands, increasing regional homogenization through time. This is reflected in increases over time in mean body mass, diet plasticity and in the importance of fish in waterbird diets, plus declines in the dietary importance of invertebrates and in plasticity of feeding strata. Furthermore, species composition between wintering and breeding communities, but not trait composition, has become more similar through time. Our results highlight that annual changes, and especially seasonal changes, in the composition of waterbird communities have different effects on their functional diversity, and are influenced by opposing community assembly mechanisms.     

Shrub and precipitation interactions shape functional diversity of nematode communities on the Qinghai–Tibet Plateau

Land use and climate change alter biodiversity patterns and ecosystem functioning worldwide. Land abandonment with consequent shrub encroachment and changes in precipitation gradients are known factors in global change. Yet, the consequences of interactions between these factors on the functional diversity of belowground communities remain insufficiently explored. Here, we investigated the dominant shrub effects on the functional diversity of soil nematode communities along a precipitation gradient on the Qinghai–Tibet Plateau. We collected three functional traits (life-history C–P value, body mass, and diet) and calculated the functional alpha and beta diversity of nematode communities using kernel density n-dimensional hypervolumes. We found that shrubs did not significantly alter the functional richness and dispersion, but significantly decreased the functional beta diversity of nematode communities in a pattern of functional homogenization. Shrubs benefited nematodes with longer life-history, larger body mass, and higher trophic levels. Moreover, the shrub effects on the functional diversity of nematodes depended strongly on precipitation. Increasing precipitation reversed the effects shrubs have on the functional richness and dispersion from negative to positive but amplified the negative effects shrubs have on functional beta diversity of nematodes. Benefactor shrubs had stronger effects on the functional alpha and beta diversity of nematodes than allelopathic shrubs along a precipitation gradient. A piecewise structural equation model showed that shrubs and its interactions with precipitation indirectly increased the functional richness and dispersion through plant biomass and soil total nitrogen, whereas it directly decreased the functional beta diversity. Our study reveals the expected changes in soil nematode functional diversity following shrub encroachment and precipitation, advancing our understanding of global climate change on nematode communities on the Qinghai–Tibet Plateau.     

Contrasting effects of space and environment on functional and phylogenetic dissimilarity in a tropical forest

Aims The evolutionary history and functional traits of species can illuminate ecological processes supporting coexistence in diverse forest communities. However, little has been done in decoupling the relative importance of these mechanisms on the turnover of phylogenetic and functional characteristics across life stages and spatial scales. Therefore, this study aims to estimate the contribution of environment and dispersal on the turnover of phylogenetic and functional diversity across life stages and spatial scales, in order to build a coherent picture of the processes responsible for species coexistence.     

Multifaceted biodiversity modelling at macroecological scales using Gaussian processes

Aim

Modelling the response of β‐diversity (i.e., the turnover in species composition among sites) to environmental variation has wide‐ranging applications, including informing conservation planning, understanding community assembly and forecasting the impacts of climate change. However, modelling β‐diversity is challenging, especially for multiple diversity facets (i.e., taxonomic, functional and phylogenetic diversity), and current methods have important limitations. Here, we present a new approach for predicting the response of multifaceted β‐diversity to the environment, called Multifaceted Biodiversity Modelling (MBM). We illustrate the approach using both a plant diversity dataset from the French Alps and a set of simulated data. We also provide an implementation via an R package.

Location

French Alps.

Methods

For both the French Alps and the simulated communities, we compute β‐diversity indices (e.g., Sørensen dissimilarity, mean functional/phylogenetic pairwise distance) among site pairs. We then apply Gaussian process regression, a flexible nonlinear modelling technique, to predict β‐diversity in response to environmental distance among site pairs. For comparison, we also perform similar analyses using Generalized Dissimilarity Modelling (GDM), a well‐established method for modelling β‐diversity in response to environmental distance.

Results

In the Alps, we observed a general increase in taxonomic (TD) and functional (FD) β‐diversity (i.e., site pairs were more different from each other) as the climatic distance between site pairs increased. GDM performed better for TD and FD when fitting to calibration data, whereas MBM performed better for both when predicting to a validation dataset. For phylogenetic β‐diversity, MBM outperformed GDM in predicting the observed decrease in phylogenetic β‐diversity with increasing climatic distance.

Main conclusions

Multifaceted Biodiversity Modelling provides a flexible new approach that expands our capacity to model multiple facets of β‐diversity. Advantages of MBM over existing methods include simpler assumptions, more flexible modelling, potential to consider multiple facets of diversity across a range of diversity indices, and robust uncertainty estimation.

     

Environmental drivers of species composition and functional diversity of dung beetles along the Atlantic Forest–Pampa transition zone

Human activities are causing a rapid loss of biodiversity, which impairs ecosystem functions and services. Therefore, understanding which processes shape how biodiversity is distributed along spatial and environmental gradients is a first step to guide conservation and management efforts. We aimed to determine the relative explanatory importance of biogeographic, environmental, landscape and spatial variables on assemblage dissimilarities and functional diversity of dung beetles along the Atlantic Forest–Pampa (i.e. forest–grassland) transition zone located in Southeast South America. We described each site according to their biogeographic position, environmental conditions, landscape features and spatial patterns. The compositional dissimilarity was partitioned into turnover and nestedness components of β‐diversity. Mantel tests and generalised dissimilarity models were used to relate β‐diversity and its components to biogeographic, environmental, landscape and spatial variables. Variation partitioning analysis was used to estimate the pure and shared variation in species composition and functional diversity explained by the four categories of predictors. Biome domain was the main factor causing dung beetle compositional dissimilarity, with a high species replacement between Atlantic Forest and Pampa. Biogeographic, environmental, landscape and spatial distances also affected the patterns of dung beetle dissimilarity and β‐diversity components. The shared effects of the four sets of predictors explained most of the variation in dung beetle composition. A similar response pattern was found for dung beetle functional diversity, which excluded biogeographic effects. Only the pure effects of environmental and spatial predictors were significant for species composition and functional diversity. Our results indicate that dung beetle species composition and functional diversity are jointly driven by environmental, landscape and spatial predictors with higher pure environmental and spatial effects. The forest–grassland transition zone promotes a strong species and trait replacement highly influenced both by environmental filtering and dispersal limitation.     

Insights on the functional composition of specialist and generalist birds throughout continuous and fragmented forests

A decline in species number often occurs after forest fragmentation and habitat loss, which usually results in the loss of ecological functions and a reduction in functional diversity in the forest fragments. However, it is uncertain whether these lost ecological functions are consistently maintained throughout continuous forests, and so the importance of these functions in continuous forests remains unknown. Point counts were used to assess both the taxonomic and functional diversity of specialist and generalist birds from sampling in a continuous primary forest compared with forest fragments in order to investigate the responses of these groups to forest fragmentation. We also measured alpha and beta diversity. The responses of specialists and generalists were similar when we assessed all bird species but were different when only passerines were considered. When examining passerines we found lower total taxonomic beta diversity for specialists than for generalists in the continuous forest, while taxonomic beta diversity was higher in the fragmented forest and similar between bird groups. However, total functional beta‐diversity values indicated clearly higher trait regularity in continuous forest for specialists and higher trait regularity in fragments for generalists. Specialists showed significantly higher functional alpha diversity in comparison with generalists in the continuous forest, while both groups showed similar values in fragments. In passerines, species richness and alpha functional diversity of both specialist and generalist were explained by forest connectivity; but, only fragment size explained those parameters for specialist passerines. We suggest that considering subsets of the community with high similarity among species, as passerines, provides a better tool for understanding responses to forest fragmentation. Due to the regularity of specialists in continuous forest, their lost could highly affect functionality in forest fragments.     

Interdecadal changes in ichthyofauna in a tropical bay with high anthropogenic influences: functional stability despite turnover predominance

Functional characteristics of species are of great importance for understanding their roles in ecosystems and can be used to detect long-term chances in the environment. We evaluated temporal changes (1983–1985 and 2017–2019) in taxonomic and functional indices of the fish fauna in shallow areas of a tropical bay heavily impacted by anthropogenic activities in recent decades. The hypothesis that functional indices change over time as a result of environmental degradation was tested. Our results showed a significant decrease in species richness and abundance over time, and in functional richness, while others functional diversity indices (divergency, evenness, and originality) remained stable. Thirteen functional groups were detected, some of which contained only one species, raising concerns about the loss of ecosystem functions due to ongoing changes. We also observed an increase in beta diversity over time, which may be the result of a decrease in local richness without leading to regional extinctions. Turnover was the most important process in structuring the fish fauna at the evaluated time scale. The relative stability of the functional structure and the higher levels of turnover seem to be related to the dominance of functional groups, within which species replace each other according to their responses to environmental filters that select for specific functional traits. Incorporating functional diversity indices and beta diversity variations in the fish community helped to enhance the existing information about this coastal system by offering improved estimates of biological diversity through diverse approaches. The predominance of turnover identified in the preset study suggests a dynamic and fluctuating species composition within the habitat. In this sense, habitat preservation should prioritize the protection of diverse habitats to accommodate a broad spectrum of species.     

Macroecological scale effects of biodiversity on ecosystem functions under environmental change

Conserving different spatial and temporal dimensions of biological diversity is considered necessary for maintaining ecosystem functions under predicted global change scenarios. Recent work has shifted the focus from spatially local (α‐diversity) to macroecological scales (β‐ and γ‐diversity), emphasizing links between macroecological biodiversity and ecosystem functions (MB–EF relationships). However, before the outcomes of MB–EF analyses can be useful to real‐world decisions, empirical modeling needs to be developed for natural ecosystems, incorporating a broader range of data inputs, environmental change scenarios, underlying mechanisms, and predictions. We outline the key conceptual and technical challenges currently faced in developing such models and in testing and calibrating the relationships assumed in these models using data from real ecosystems. These challenges are explored in relation to two potential MB–EF mechanisms: “macroecological complementarity” and “spatiotemporal compensation.” Several regions have been sufficiently well studied over space and time to robustly test these mechanisms by combining cutting‐edge spatiotemporal methods with remotely sensed data, including plant community data sets in Australia, Europe, and North America. Assessing empirical MB–EF relationships at broad spatiotemporal scales will be crucial in ensuring these macroecological processes can be adequately considered in the management of biodiversity and ecosystem functions under global change.     

Contrasting patterns of phylogenetic diversity across climatic zones of Western Ghats: A biodiversity hotspot in peninsular India

This study attempts to understand the biogeographic history of the Western Ghats forests by investigating decoupling between phylogenetic and taxonomic diversity. We specifically test whether the deciduous forests have been recently established, whether the southern region was a refuge, and whether the deciduous and evergreen forest species have disparate evolutionary histories. We used species composition data from 23 forest types along the Western Ghats for all woody angiosperms above 10‐cm diameter at breast height. Forests were broadly grouped as either evergreen or deciduous. Mean phylogenetic distances corrected for species richness and mean phylogenetic beta diversity corrected for shared species were assessed using z‐scores from null distributions. Null distributions were generated by randomizing the species relationships on the phylogeny. We found that all evergreen forests showed a greater phylogenetic diversity as compared with null expectations. Deciduous forests showed the inverse pattern. Within the evergreen belt, there was a decreasing phylogenetic diversity from south to north, as predicted by the southern refuge hypothesis. The phylogenetic beta diversity across evergreen–deciduous forests was lesser than the null expectation, whereas it was much higher across forests within the evergreen belt. This study provides the first phylogenetic evidence for the antiquity of evergreen forests as well as the southern refuge hypothesis in the Western Ghats. The deciduous forests species have shared evolutionary histories with the evergreen forest species, suggesting multiple shifts between evergreen and deciduous states through the lineages. Conversely, the evergreen species exhibited a disparate evolutionary history across these forests, possibly owing to sharper ecological or climatic gradients.     

汾河中上游湿地植被β多样性

探讨和揭示群落构建机制(生态位理论和中性理论)是生态学和生物地理学研究的热点和难点之一。研究β多样性格局及其与空间距离和环境异质性的关系为解释群落构建机制提供了一定的理论依据,以往群落β多样性的研究主要集中于物种组成的差异性,对种间在进化关系和功能属性方面的差异则关注较少。在野外调查的基础上,分析了汾河中上游湿地植被Tβ(taxonβ-diversity)、Pβ(phylogeneticβ-diversity)和Fβ(functionalβ-diversity)多样性格局及其与空间距离和生境异质性的关系。结果表明:(1)随着样地间距离的增加,Tβ、Pβ和Fβ整体上表现出逐渐增加的趋势,即表现出群落的距离衰减效应。(2)土壤因子中,TP是影响样地间Tβ、Pβ和Fβ的主要因子(P0.05);p H、TOC和TN对Tβ、Pβ和Fβ的影响均未达到显著水平(P0.05)。(3)由于受到空间扩散限制和生境异质性的影响,样地间β多样性表现出较大的差异,Tβ(0.66—1)、Pβ(0.42—0.85)和Fβ(0.51—0.94)。(4)尽管Tβ、Pβ和Fβ反映了多样性的不同方面,但三者之相关性极显著(P0.01);(5)对Tβ、Pβ和Fβ多样性格局及其与空间距离和生境异质性的关系进行研究,表明环境因子和扩散限制共同决定着β多样性的格局,即群落的构建机制由生态位理论和中性理论共同主导。     

高原鼠兔干扰对高寒草甸植物物种和功能性状beta多样性的影响

采用野外空间多点同步取样,分析了高原鼠兔干扰对高寒草甸植物物种beta多样性和植物功能性状beta多样性的影响,确定了高原鼠兔干扰下高寒草甸植物物种和功能性状beta多样性的变化途径,分别提出了高原鼠兔干扰区域内,基于植物物种多样性和功能性状多样性的高寒草甸植物多样性维持策略。结果表明,高原鼠兔干扰使高寒草甸植物物种相似性显著降低了28.1%,植物功能相似性降低了28.7%。尽管高原鼠兔干扰没有改变高寒草甸植物物种和功能性状beta多样性的变化途径,且对植物物种和功能性状的嵌套组分不存在显著影响,但高原鼠兔干扰显著降低了植物物种和功能性状周转组分所占的比例,降幅分别为36.6%和34.3%。高原鼠兔干扰区域内,高寒草甸植物物种beta多样性的变化以周转为主导(周转占比81.4%;嵌套占比:18.6%),植物功能性状beta多样性的变化以嵌套为主导(嵌套占比64.9%;周转占比35.1%)。因此,针对划定的高原鼠兔干扰区,需要同时保护区域内所有高原鼠兔栖息地(多位点保护),以达到维持植物物种多样性的目的,而可以仅通过保护该区域内植物功能性状丰富的位点,即可维持较高的植物功能多样性。