Niche and neutral models predict asymptotically equivalent species abundance distributions in high-diversity ecological communities

AbstractEcological models of community dynamics fall into two main categories. The neutral theory of biodiversity correctly predicts various large-scale ecosystem characteristics such as the species abundance distributions. On a smaller scale, the niche theory of species competition explains population dynamics and interactions between two to a dozen species. Despite the successes of the two theories, they rely on two contradictory assumptions. In the neutral theory each species is competitively equivalent while in the niche theory every species is specialized to exploit a specific part of its environment. Here we propose a resolution to this contradiction using a game theory model of competition with an attractor hyperplane as its equilibrium solution. When the population dynamics shifts within the hyperplane, it is selectively neutral. However, any movement perpendicular to the hyperplane is subject to restoring forces similar to what is predicted by the niche theory. We show that this model correctly reproduces empirical species abundance distributions and is also compatible with species removal experiments.

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The Dynamic Hypercube as a Niche Community Model

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.686403 ◽

2021 ◽

Vol 9 ◽

Author(s):

John M. Halley ◽

Stuart L. Pimm

Keyword(s):

Community Dynamics ◽

Neutral Theory ◽

Species Abundance ◽

Ecological Communities ◽

Evolutionary Time ◽

Community Model ◽

Theory Of Island Biogeography ◽

Species Abundance Distributions ◽

Hypercube Model ◽

Zero Sum

Different models of community dynamics, such as the MacArthur–Wilson theory of island biogeography and Hubbell’s neutral theory, have given us useful insights into the workings of ecological communities. Here, we develop the niche-hypervolume concept of the community into a powerful model of community dynamics. We describe the community’s size through the volume of the hypercube and the dynamics of the populations in it through the fluctuations of the axes of the niche hypercube on different timescales. While the community’s size remains constant, the relative volumes of the niches within it change continuously, thus allowing the populations of different species to rise and fall in a zero-sum fashion. This dynamic hypercube model reproduces several key patterns in communities: lognormal species abundance distributions, 1/f-noise population abundance, multiscale patterns of extinction debt and logarithmic species-time curves. It also provides a powerful framework to explore significant ideas in ecology, such as the drift of ecological communities into evolutionary time.

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The prevalence and impact of transient species in ecological communities

10.1101/163816 ◽

2017 ◽

Author(s):

Sara Snell ◽

Brian S. Evans ◽

Ethan P. White ◽

Allen H. Hurlbert

Keyword(s):

Spatial Scales ◽

Species Abundance ◽

Careful Consideration ◽

Ecological Communities ◽

Transient Species ◽

Ecological Patterns ◽

Species Abundance Distributions ◽

Species Area ◽

Using Data ◽

Taxonomic Groups

AbstractTransient species occur infrequently in a community over time and do not maintain viable local populations. Because transient species interact differently than non-transients with their biotic and abiotic environment, it is important to characterize the prevalence of these species and how they impact our understanding of ecological systems. We quantified the prevalence and impact of transient species in communities using data on over 17,000 community time series spanning an array of ecosystems, taxonomic groups, and spatial scales. We found that transient species are a general feature of communities regardless of taxa or ecosystem. The proportion of these species decreases with spatial scale leading to a need to control for scale in comparative work. Removing transient species from analyses influences the form of a suite of commonly studied ecological patterns including species-abundance distributions, species-energy relationships, species-area relationships, and temporal turnover. Careful consideration should be given to whether transient species are included in analyses depending on the theoretical and practical relevance of these species for the question being studied.

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On the variability of Species Abundance Distributions with trophic guild and community structure

10.1101/289348 ◽

2018 ◽

Author(s):

David García-Callejas

Keyword(s):

Trophic Level ◽

Trophic Interactions ◽

Species Abundance ◽

Trophic Levels ◽

Individual Species ◽

Trophic Guilds ◽

Ecological Communities ◽

Trophic Guild ◽

Marine Habitats ◽

Species Abundance Distributions

AbstractSpecies Abundance Distributions (SADs) are one of the most studied properties of ecological communities, and their variability has been studied mostly in the context of horizontal communities, i.e. sets of species from a particular trophic guild. However, virtually all ecological communities encompass several trophic guilds, and the trophic interactions between them are key for explaining the persistence and abundance of individual species. Here I ask whether trophic interactions are also important in shaping Species Abundance Distributions of the different guilds of a community. I analyze the variation in SAD shape across trophic guilds in model and empirical communities. For that, I use a theoretical model that allows tracking the variations in abundances across trophic levels. The relationship between SAD shape and (1) trophic level, and (2) degree of predator specialization is analyzed using mixed-effect models. I combine this approach with an analysis of 4676 empirical datasets spanning terrestrial, marine and freshwater habitats, for which the variation in SAD shape is related to (1) trophic guild, and (2) habitat type. The evenness of model SADs is positively correlated to the trophic level of the guild considered, and also to the number of prey species per predator. These findings are confirmed by the empirical data: there is a significant relationship between SAD evenness and trophic guild, whereby primary producers display the most uneven SADs and pure carnivores the most even ones. Furthermore, regardless of trophic guild, SADs from marine habitats are the most even ones, with terrestrial SADs being the most uneven.

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Fuzzy Quantification of Common and Rare Species in Ecological Communities (FuzzyQ)

10.1101/2020.08.12.247502 ◽

2020 ◽

Author(s):

Juan A. Balbuena ◽

Clara Montlleó ◽

Cristina Llopis-Belenguer ◽

Isabel Blasco-Costa ◽

Volodimir L. Sarabeev ◽

...

Keyword(s):

Rare Species ◽

Clustering Algorithm ◽

Species Abundance ◽

R Package ◽

Ecological Communities ◽

Wide Range ◽

Species Abundance Distributions ◽

The Common ◽

Spatio Temporal ◽

The Impact

Abstract1. Most species in ecological communities are rare whereas only a few are common. This distributional paradox has intrigued ecologists for decades but the interpretation of species abundance distributions remains elusive.2. We present Fuzzy Quantification of Common and Rare Species in Ecological Communities (FuzzyQ) as an R package. FuzzyQ shifts the focus from the prevailing species-categorization approach to develop a quantitative framework that seeks to place each species along a rare-commonness gradient. Given a community surveyed over a number of sites, quadrats, or any other convenient sampling unit, FuzzyQ uses a fuzzy clustering algorithm that estimates a probability for each species to be common or rare based on abundance-occupancy information. Such as probability can be interpreted as a commonness index ranging from 0 to 1. FuzzyQ also provides community-level metrics about the coherence of the allocation of species into the common and rare clusters that are informative of the nature of the community under study.3. The functionality of FuzzyQ is shown with two real datasets. We demonstrate how FuzzyQ can effectively be used to monitor and model spatio-temporal changes in species commonness, and assess the impact of species introductions on ecological communities. We also show that the approach works satisfactorily with a wide range of communities varying in species richness, dispersion and abundance currencies.4. FuzzyQ produces ecological indicators easy to measure and interpret that can give both clear, actionable insights into the nature of ecological communities and provides a powerful way to monitor environmental change on ecosystems. Comparison among communities is greatly facilitated by the fact that the method is relatively independent of the number of sites or sampling units considered. Thus, we consider FuzzyQ as a potentially valuable analytical tool in community ecology and conservation biology.

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How selection structures species abundance distributions

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2012.1379 ◽

2012 ◽

Vol 279 (1743) ◽

pp. 3722-3726 ◽

Cited By ~ 17

Author(s):

Anne E. Magurran ◽

Peter A. Henderson

Keyword(s):

Habitat Structure ◽

Fish Community ◽

Rank Order ◽

Species Abundance ◽

Estuarine Fish ◽

Ecological Communities ◽

Abundance Distribution ◽

Species Abundance Distributions ◽

Characteristic Species ◽

Safety In Numbers

How do species divide resources to produce the characteristic species abundance distributions seen in nature? One way to resolve this problem is to examine how the biomass (or capacity) of the spatial guilds that combine to produce an abundance distribution is allocated among species. Here we argue that selection on body size varies across guilds occupying spatially distinct habitats. Using an exceptionally well-characterized estuarine fish community, we show that biomass is concentrated in large bodied species in guilds where habitat structure provides protection from predators, but not in those guilds associated with open habitats and where safety in numbers is a mechanism for reducing predation risk. We further demonstrate that while there is temporal turnover in the abundances and identities of species that comprise these guilds, guild rank order is conserved across our 30-year time series. These results demonstrate that ecological communities are not randomly assembled but can be decomposed into guilds where capacity is predictably allocated among species.

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