Diversity partitioning, which decomposes gamma diversity into alpha and beta components, is commonly used to obtain measures that quantify spatial/temporal diversity and compositional similarity or ...dissimilarity among assemblages. We focus on the decomposition of diversity as measured by Hill numbers (parameterized by a diversity order q ≥ 0).
At least three diversity‐partitioning schemes based on Hill numbers have been proposed. These schemes differ in the way they formulate alpha diversity. We focus on comparing two classes of alpha diversities, developed, respectively, by Routledge (1979) and Chiu et al. (2014). Both are defined for all diversity orders q ≥ 0. Because these two approaches to quantifying alpha have not been compared in the literature; it has been unclear how to choose a proper alpha formulation for practical applications.
We review the two classes of alpha diversities and discuss the properties of their corresponding beta and (dis)similarity measures. Our research offers clear guidelines regarding the choice of an alpha formula: (a) If the goal is to assess compositional (dis)similarity among (unweighted) species relative abundance datasets, then the two alpha formulas are identical, leading to the same beta and (dis)similarity measures. (b) If the goal is to assess compositional (dis)similarity among (unweighted) species raw abundance datasets, then Chiu et al.’s approach should be used. Their beta can be monotonically transformed to various (dis)similarity measures in the range 0, 1. (c) If each assemblage is weighted by its absolute, total abundance (i.e. assemblage size), but the goal is to assess compositional (dis)similarity among species relative abundance datasets, then Routledge’s approach should be used. In this case, construction of legitimate (dis)similarity measures among species relative abundance datasets for unequal assemblage sizes/weights, for any order q ≥ 0, has not been addressed in the literature. Here we propose non‐monotonic transformations of Routledge’s beta to fill this gap.
The extension of our analysis to phylogenetic diversity partitioning is generally parallel. We apply various species/taxonomic and phylogenetic dissimilarity measures to Taiwan’s plant data; the results provide insights into the assessment of a reintroduction programme of Formosan sika deer into a forest area. Pertinent sampling and related issues are also discussed.
Background
MacArthur and Wilson's theory of island biogeography has been a foundation for obtaining testable predictions from models of community assembly and for developing models that integrate ...across scales and disciplines. Historically, however, these developments have focused on integration across ecological and macroevolutionary scales and on predicting patterns of species richness, abundance distributions, trait data and/or phylogenies. The distribution of genetic variation across species within a community is an emerging pattern that contains signatures of past population histories, which might provide an historical lens for the study of contemporary communities. As intraspecific genetic diversity data become increasingly available at the scale of entire communities, there is an opportunity to integrate microevolutionary processes into our models, moving towards development of a genetic theory of island biogeography.
Motivation/goal
We aim to promote the development of process‐based biodiversity models that predict community genetic diversity patterns together with other community‐scale patterns. To this end, we review models of ecological, microevolutionary and macroevolutionary processes that are best suited to the creation of unified models, and the patterns that these predict. We then discuss ongoing and potential future efforts to unify models operating at different organizational levels, with the goal of predicting multidimensional community‐scale data including a genetic component.
Main conclusions
Our review of the literature shows that despite recent efforts, further methodological developments are needed, not only to incorporate the genetic component into existing island biogeography models, but also to unify processes across scales of biological organization. To catalyse these developments, we outline two potential ways forward, adopting either a top‐down or a bottom‐up approach. Finally, we highlight key ecological and evolutionary questions that might be addressed by unified models including a genetic component and establish hypotheses about how processes across scales might impact patterns of community genetic diversity.
Epiphytic bryophytes are important components of forest ecosystems and play important roles in maintaining biodiversity and ecosystem function. However, the main factors driving epiphytic bryophyte ...diversity remain unclear. We collected the tree epiphytic bryophytes from a one-hectare plot within a temperate deciduous broadleaf forest (China). Canonical correspondence analyses and Mantel tests were used to establish linear regression models and thus dissect the effects of environmental variables (topography, light and bark physicochemical properties) on the species diversity, functional diversity, and phylogenetic diversity of epiphytic bryophytes. The relationship between environmental variables and epiphytic bryophyte diversity was analyzed using piecewise structural equation modeling. Results showed that the physicochemical properties of the bark directly influenced the species diversity and phylogenetic diversity of the epiphytic bryophytes. The physical and chemical properties of bark also indirectly affected the functional diversity of the epiphytic bryophytes. Elucidation of the factors driving epiphytic bryophyte diversity provides insights into their conservation.
Soil microbe diversity plays a key role in dryland ecosystem function under global climate change, yet little is known about how plant-soil microbe relationships respond to climate change. Altered ...precipitation patterns strongly shape plant community composition in deserts and steppes, but little research has demonstrated whether plant biodiversity attributes mediate the response of soil microbial diversity to long- and short-term precipitation changes. Here we used a comparative study to explore how altered precipitation along the natural and experimental gradients affected associations of soil bacterial and fungal diversity with plant biodiversity attributes (species, functional and phylogenetic diversity) and soil properties in desert-shrub and steppe-grass communities. We found that along both gradients, increasing precipitation increased soil bacterial and fungal richness in the desert and soil fungal richness in the steppe. Soil bacterial richness in the steppe was also increased by increasing precipitation in the experiment but was decreased along the natural gradient. Plant biodiversity and soil properties explained the variations in soil bacterial and fungal richness from 43 % to 96 % along the natural gradient and from 19 to 46 % in the experiment. Overall, precipitation effects on soil bacterial or fungal richness were mediated by plant biodiversity attributes (species richness and plant height) or soil properties (soil water content) along the natural gradient but were mediated by plant biodiversity attributes (functional or phylogenetic diversity) in the experiment. These results suggest that different mechanisms are responsible for the responses of soil bacterial and fungal diversity to long- and short-term precipitation changes. Long- and short-term precipitation changes may modify plant biodiversity attribute effects on soil microbial diversity in deserts and steppes, highlighting the importance of precipitation changes in shaping relationships between plant and soil microbial diversity in water-limited areas.
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•Precipitation changes strongly affect soil microbe diversity in deserts and steppes.•Precipitation effects on soil microbe diversity were mediated by vegetation or soil properties.•Precipitation changes can modify plant biodiversity attribute effects on soil microbial diversity.•The short-term response of soil fungal diversity to precipitation changes mirrors long-term shifts in space.
1. Grazing by large ungulates may affect plant species richness and diversity at multiple spatial and/or temporal scales, because grazing affects small-scale resource heterogeneity and plant ...interactions at the local scale, while effects at the landscape scale are related to grazing intensity and timing. 2. We used diversity partitioning to analyse long-and short-term effects of cattle grazing on plant species richness and diversity in an experimental spatial hierarchy in Mediterranean annual grassland. Short-term changes during secondary succession in grazed plots (2003-2005) at two grazing intensities (heavy and moderate) were analysed and compared with long-term protected vegetation. We applied Hill's q-diversity metrics at q = 0 (species richness) and q = 2 (reciprocal Simpson diversity) to examine the partitioning of species richness and diversity between their alpha (a) and beta (â) components in the different treatments at four spatial scales: quadrats, within exclosures, within plots, within treatments. 3. At q = 0, α-diversity was always significantly lower, and β-diversity significantly higher, than predicted by the randomised null model. Diversity partitioning at q = 2 showed a similar trend at the quadrat scale. At the exclosure scale, partitioning exhibited a similar trend during the first 2 years of secondary succession but did not deviate from the null model in the third year, as observed in protected vegetation in all years. 4. At q = 0, diversity decreased across all treatments in the short term. At q = 2, diversity was initially higher in grazed plots than in protected vegetation; α and β components both decreased during secondary succession, to the levels observed in the protected vegetation. 5. Synthesis and applications. Lower dominance in grazed vegetation indicates that grazing affects competitive exclusion at the local, small scale and accentuates natural heterogeneity (e.g. patchiness of soil resources, presence of rocks in the landscape) at a larger scale. The results of this study emphasise the importance of grazing as a management tool for maintaining plant diversity at multiple scales. This is a major concern worldwide, as the area covered by natural ecosystems continues to dwindle, necessitating management of grasslands for multiple functions such as animal production, resource protection and wildlife enhancement.
The year 2020 and the next few years are critical for the development of the global biodiversity policy agenda until the mid-21
st
century, with countries agreeing to a Post-2020 Global Biodiversity ...Framework under the Convention on Biological Diversity (CBD). Reducing the substantial and still rising impacts of invasive alien species (IAS) on biodiversity will be essential if we are to meet the 2050 Vision where biodiversity is valued, conserved, and restored. A tentative target has been developed by the IUCN Invasive Species Specialist Group (ISSG), and formally submitted to the CBD for consideration in the discussion on the Post-2020 targets. Here, we present properties of this proposal that we regard as essential for an effective Post-2020 Framework. The target should explicitly consider the three main components of biological invasions, i.e. (i) pathways, (ii) species, and (iii) sites; the target should also be (iv) quantitative, (v) supplemented by a set of indicators that can be applied to track progress, and (vi) evaluated at medium- (2030) and long-term (2050) time horizons. We also present a proposed set of indicators to track progress. These properties and indicators are based on the increasing scientific understanding of biological invasions and effectiveness of responses. Achieving an ambitious action-oriented target so that the 2050 Vision can be achieved will require substantial effort and resources, and the cooperation of a wide range of stakeholders.
Our modern legal system is based on the principle of equality. But is equality perhaps not also a concept that inadequately describes the complexity of normative orders? Highly differentiated ...societies with a multitude of collective identities and functional rationalities are in a permanent state of tension with this legal postulate. The contributions to this volume examine how this tension has developed in Europe and Latin America over the last 200 years
Iron Formations (IF) are among the most threatened environments due to the extensive mining activities. Mesovoid Shallow Substratum (MSS) in IF represents a poorly known subterranean environment and ...evaluating its fauna has the potential for expanding knowledge about the distribution of troglobiotic populations. We evaluated the spatiotemporal distribution of the subterranean fauna in the MSS of IF in Brazil. We sampled the MSS invertebrate fauna and described the community patterns of troglobiotic and non-troglobiotic species. A total of 22,821 individuals and 276 morphospecies belonging to two phyla were found: Annelida and Arthropoda. Acariformes, Diptera, Hymenoptera, Blattodea, and Collembola represented 92.2% of the individuals sampled. Nine troglobiotic morphospecies belonging to four groups were sampled: Araneae (1), Entomobryomorpha (6), Poduromorpha (1), and Pseudoscorpiones (1). We found a high compositional dissimilarity of troglobiotic and non-troglobiotic species in terms of spatial β-diversity (among MSS sites) and temporal β-diversity (among months). The observed spatial β-diversity of troglobiotic species sampled in the MSS is greater than that of non-troglobiotic species. The temporal variation is similar for both groups. The richness difference component contributed more to spatial and temporal β-diversity for troglobiotic species, while higher replacement values for non-troglobiotic species were observed. Average values of temporal β-diversity and the replacement component were greater for non-troglobiotic than for troglobiotic species, while the richness difference component had an opposite pattern. The spatiotemporal β-diversity patterns suggest a medium-to-low connectivity of invertebrate populations that colonize the MSS, favoring the adoption of strategies for conserving broader areas in the context of IF.
At the core of plant regeneration, temperature and water supply are critical drivers for seed dormancy (initiation, break) and germination. Hence, global climate change is altering these ...environmental cues and will preclude, delay, or enhance regeneration from seeds, as already documented in some cases. Along with compromised seedling emergence and vigour, shifts in germination phenology will influence population dynamics, and thus, species composition and diversity of communities. Altered seed maturation (including consequences for dispersal) and seed mass will have ramifications on life history traits of plants. Predicted changes in temperature and precipitation, and thus in soil moisture, will affect many components of seed persistence in soil, e.g. seed longevity, dormancy release and germination, and soil pathogen activity. More/less equitable climate will alter geographic distribution for species, but restricted migratory capacity in some will greatly limit their response. Seed traits for weedy species could evolve relatively quickly to keep pace with climate change enhancing their negative environmental and economic impact. Thus, increased research in understudied ecosystems, on key issues related to seed ecology, and on evolution of seed traits in nonweedy species is needed to more fully comprehend and plan for plant responses to global warming.
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