Emergent neutrality in consumer-resource dynamics.

Rafael D’Andrea,James P. O’Dwyer,Theo Gibbs,Jacopo Grilli

doi:10.1371/journal.pcbi.1008102

Rafael D’Andrea, James P. O’Dwyer + Show 2 more

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https://doi.org/10.1371/journal.pcbi.1008102

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Abstract

Neutral theory assumes all species and individuals in a community are ecologically equivalent. This controversial hypothesis has been tested across many taxonomic groups and environmental contexts, and successfully predicts species abundance distributions across multiple high-diversity communities. However, it has been critiqued for its failure to predict a broader range of community properties, particularly regarding community dynamics from generational to geological timescales. Moreover, it is unclear whether neutrality can ever be a true description of a community given the ubiquity of interspecific differences, which presumably lead to ecological inequivalences. Here we derive analytical predictions for when and why non-neutral communities of consumers and resources may present neutral-like outcomes, which we verify using numerical simulations. Our results, which span both static and dynamical community properties, demonstrate the limitations of summarizing distributions to detect non-neutrality, and provide a potential explanation for the successes of neutral theory as a description of macroecological pattern.

Highlights

One of the central questions in community ecology is how species interactions affect community structure and ecological dynamics, and whether summarized representations of the latter can be used to make inferences about the former
Given the natural history observation of ubiquitous phenotypic differences between species, it is surprising that neutral theory has successfully predicted a broad range of biodiversity patterns, and simultaneously unsurprising that these results have not convinced ecologists that the natural world is neutral
Prominent among these successes is the prediction of a broad range of species abundances, matching the functional form for the species abundance distribution observed in multiple high-diversity communities [12, 16,17,18]

Summary

Introduction

One of the central questions in community ecology is how species interactions affect community structure and ecological dynamics, and whether summarized representations of the latter can be used to make inferences about the former Macroecological patterns such as species abundance distributions in particular have been extensively studied, and often used in inference approaches [1,2,3]. Neutral theory assumes that all species and individuals in a community are ecologically equivalent, and community assembly is a purely stochastic process, with differences in species abundances resulting from demographic noise [11, 12] This hypothesis has been heavily tested across many taxonomic groups and environmental contexts [13,14,15,16], and despite its radical assumptions, has had some success in describing macroecological patterns. It has been argued that the patterns that neutral theory successfully fits do not uniquely reflect the underlying ecological properties of the species involved; in particular, it is possible that summarized indices of community structure and dynamics may look neutral even when species are not ecologically equivalent [2, 27,28,29,30,31]

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