Jenkins, DG. 2011. Ranked species occupancy curves reveal common patterns among diverse metacommunities. Global Ecology & Biogeography 20:486-497. (original) (raw)
Oikos, 2015
Metacommunity theory, which has gained a central position in ecology, accounts for the role of migration in patterns of diversity among communities at diff erent scales. Community isolation has a main role in this theory, but is diffi cult to estimate empirically, partly due to the taxon-dependent nature of dispersal. Landscapes could be perceived as either fragmented or connected for organisms with contrasting dispersal abilities. Indeed, the dispersal ability of a taxon, and the spatial scale at which eco-evolutionary processes shape local diversity, determine a taxon-dependent metacommunity network. In this paper, we introduce a methodology using graph theory to defi ne this taxon-dependent metacommunity network and then to estimate the isolation of local communities. We analyzed the relative importance of local conditions versus community isolation as determinants of community richness for 25 taxa inhabiting 18 temporary ponds. Although local factors have been the foci of most previous empirical and theoretical considerations, we demonstrate that the metacommunity network is an equally important contributor to local diversity. We also found that the relative eff ect of local conditions and the metacommunity network depend on body size and taxon abundance. Local diversity of larger species was more aff ected by patch isolation, while taxon abundances were associated with positive or negative eff ects of isolation. Our results provide empirical support for the proposed role of metacommunity networks as determinants of community diversity and show the taxon-dependent nature of these networks.
Alternative models of community assembly emphasize regional, stochastic, dispersal-based processes or local, deterministic, niche-based processes. Community ecology's historical focus on local processes implicitly assumes that local processes surpass regional processes over time or across space to derive nonrandom metacommunity structure (i.e., a quorum effect). Quorum effects are expected late in succession among nearby sites, whereas quorum effects are not expected early in succession among distant sites. I conducted a metaanalysis of zooplankton data sets encompassing time scales of one to thousands of years and spatial scales of ,1 m to thousands of kilometers. Species co-occurrence analyses statistically evaluated presence/absence patterns relative to random patterns obtained with Monte Carlo null models. A series of weighted analyses was conducted and alternative randomization algorithms and null models were evaluated.
A global database for metacommunity ecology, integrating species, traits, environment and space
Scientific Data
The use of functional information in the form of species traits plays an important role in explaining biodiversity patterns and responses to environmental changes. Although relationships between species composition, their traits, and the environment have been extensively studied on a case-by-case basis, results are variable, and it remains unclear how generalizable these relationships are across ecosystems, taxa and spatial scales. To address this gap, we collated 80 datasets from trait-based studies into a global database for metaCommunity Ecology: Species, Traits, Environment and Space; “CESTES”. Each dataset includes four matrices: species community abundances or presences/absences across multiple sites, species trait information, environmental variables and spatial coordinates of the sampling sites. The CESTES database is a live database: it will be maintained and expanded in the future as new datasets become available. By its harmonized structure, and the diversity of ecosystem...
METACOMMUNITY MODELS PREDICT THE LOCAL–REGIONAL SPECIES RICHNESS RELATIONSHIP IN A NATURAL SYSTEM
Ecology, 2007
Many natural communities exhibit positive relationships between local and regional species richness (LSR-RSR relationships), which can be either linear or curvilinear. Previous models have shown that the form of this relationship depends on the relative rates of colonization and extinction and the sensitivity of these rates to competition. We use simple models to show that the LSR-RSR relationship also depends on the type of metacommunity structure (Levins-like or mainland-island), and our models generate a wider range of realistic forms than do most previous models. We parameterize and test our models with two independent data sets for Daphnia in rock pools on islands in Finland and Sweden. We find that the Levins-like model with competition correctly predicts the observed LSR-RSR relationship and provides the best fit to the average local species richness per island. Simulations show that our models are robust to relaxing our assumption of identical species properties. Our study is one of the first to make and successfully test quantitative predictions for how a widely studied community pattern, the LSR-RSR relationship, arises from metacommunity dynamics.
The American Naturalist, 2003
Species diversity may be additively partitioned within and among samples (a and b diversity) from hierarchically scaled studies to assess the proportion of the total diversity (g) found in different habitats, landscapes, or regions. We developed a statistical approach for testing null hypotheses that observed partitions of species richness or diversity indices differed from those expected by chance, and we illustrate these tests using data from a hierarchical study of forest-canopy beetles. Two null hypotheses were implemented using individual-and sample-based randomization tests to generate null distributions for a and b components of diversity at multiple sampling scales. The two tests differed in their null distributions and power to detect statistically significant diversity components. Individual-based randomization was more powerful at all hierarchical levels and was sensitive to departures between observed and null partitions due to intraspecific aggregation of individuals. Sample-based randomization had less power but still may be useful for determining whether different habitats show a higher degree of differentiation in species diversity compared with random samples from the landscape. Null hypothesis tests provide a basis for inferences on partitions of species richness or diversity indices at multiple sampling levels, thereby increasing our understanding of how a and b diversity change across spatial scales.
Species diversity in neutral metacommunities: a network approach
Ecology Letters, 2007
Biologists seek an understanding of the processes underlying spatial biodiversity patterns. Neutral theory links those patterns to dispersal, speciation and community drift. Here, we advance the spatially explicit neutral model by representing the metacommunity as a network of smaller communities. Analytic theory is presented for a set of equilibrium diversity patterns in networks of communities, facilitating the exploration of parameter space not accessible by simulation. We use this theory to evaluate how the basic properties of a metacommunity -connectivity, size, and speciation rate -determine overall metacommunity c-diversity, and how that is partitioned into aand b-components. We find spatial structure can increase c-diversity relative to a well-mixed model, even when h is held constant. The magnitude of deviations from the well-mixed model and the partitioning into aand b-diversity is related to the ratio of migration and speciation rates. c-diversity scales linearly with metacommunity size even as aand b-diversity scale nonlinearly with size.
Fragmentation alters beta-diversity patterns of habitat specialists within forest metacommunities
Ecography, 2012
e relative importance of local, regional and historical factors in controlling the spatial patterns of plant species distribution is still poorly known and challenging for conservation ecology. We conducted an empirical study to link the spatial variation of species and environments among forest patches embedded in contrasted agricultural matrices. We compared how forest herb communities responded to spatial environmental gradients and past forest cover. We found low values of -diversity in both unfragmented and highly fragmented systems, independently from local and regional diversities. As fragmentation increased, the spatial structure of local plant communities was more complex and spatial effects explained an increasing proportion of -diversity, suggesting that the importance of dispersal limitations increased and played out at broad spatial scales. However, where spatio-temporal isolation of forest patches was the highest, local species assemblages could not be explained, suggesting that the metacommunity functioning was disrupted. Where the historical continuity was high, local environmental characteristics explained a significant amount of species assemblages within metacommunities, suggesting habitat-selection processes. Beta-diversity and variations in presence-absence of species were also influenced by the intensity of landscape management, via the permeability of both forest edges and the matrix. is spatially-explicit analysis of metacommunities revealed that forest fragmentation impacts beta-diversity by altering not only the relative importance of deterministic and stochastic processes, but also the spatial scales at which they act. ese results provide empirical support for the conservation of ancient forests and the maintenance of a high connectedness between fragments within agricultural landscapes.
Ecological Indicators, 2015
We introduce a measure of Environmental Consistency (ECo), which assesses the probability of reducing homogeneity in the environmental factors within a species' distribution by randomly displacing its occurrences. ECo is computed by applying null model analysis to a species incidence matrix where each locality is associated with a set of environmental values. Environmental homogeneity is measured, for each species, as the average multiparametric distance between any pair of localities where the species occurs. ECo can account for the effect of species interactions and resource availability by using different null models that permit or forbid occurrence displacements altering species local abundance or species prevalence. ECo provides researchers with a flexible statistical framework to address a wide range of ecological and biogeographical issues. We investigated in depth the properties and the potentialities of ECo, showing how it integrates the concepts of Eltonian and Grinnelian niches. We demonstrate that a close relationship exists between niche breadth at species level and environmental consistency of species assemblages. In addition, we provide evidence that ecological consistency is closely related to species range. A software to compute ECo is freely available at http://forest.jrc.ec.europa.eu/download/software/eco. When environmental variables can be measured at sites of a species' occurrence, Ecological Niche Modelling (ENM) can be used to estimate dimensions of the species' fundamental ecological niche. Then, these estimates can be used to reconstruct species distribution by area suitability . The two approaches, i.e. the examination of species per site matrices and ENM are somehow complementary. Yet, the conceptual integration of species/locality analyses and ENM is not straightforward.
Ecology, 2011
Dispersal among ecological communities is usually assumed to be random in direction, or to vary in distance or frequency among species. However, a variety of natural systems and types of organisms may experience dispersal that is biased by directional currents or by gravity on hillslopes. We developed a general model for competing species in metacommunities to evaluate the role of directionally biased dispersal on species diversity, abundance, and traits. In parallel, we tested the role of directionally biased dispersal on communities in a microcosm experiment with protists and rotifers. Both the model and experiment independently demonstrated that diversity in local communities was reduced by directionally biased dispersal, especially dispersal that was biased away from disturbed patches. Abundance of species (and composition) in local communities was a product of disturbance intensity but not dispersal directionality. High disturbance selected for species with high intrinsic growth rates and low competitive abilities. Overall, our conclusions about the key role of dispersal directionality in (meta)communities seem robust and general, since they were supported both by the model, which was set in a general framework and not parameterized to fit to a specific system, and by a specific experimental test with microcosms.