Prevalence of multimodal species abundance distributions is linked to spatial and taxonomic breadth

Antao, Laura H., Connolly, Sean R., Magurran, Anne E., Soares, Amadeu, and Dornelas, Maria (2017) Prevalence of multimodal species abundance distributions is linked to spatial and taxonomic breadth. Global Ecology and Biogeography, 26 (2). pp. 203-215.

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Abstract

Aim: Species abundance distributions (SADs) are a synthetic measure of biodiversity and community structure. Although typically described by unimodal logseries or lognormal distributions, empirical SADs can also exhibit multiple modes. However, we do not know how prevalent multimodality is, nor do we have an understanding of the factors leading to this pattern. Here we quantify the prevalence of multimodality in SADs across a wide range of taxa, habitats and spatial extents.

Location: Global.

Methods: We used the second-order Akaike information criterion for small sample sizes (AIC(c)) and likelihood ratio tests (LRTs) to test whether models with more than one mode accurately describe the empirical abundance frequency distributions of the underlying communities. We analysed 117 empirical datasets from intensely sampled communities, including taxa ranging from birds, plants, fish and invertebrates, from terrestrial, marine and freshwater habitats.

Results: We find evidence for multimodality in 14.5% of the SADs when using AIC(c) and LRT. This is a conservative estimate, as AIC(c) alone estimates a prevalence of multimodality of 22%. We additionally show that the pattern is more common in data encompassing broader spatial scales and greater taxonomic breadth, suggesting that multimodality increases with ecological heterogeneity.

Main conclusions: We suggest that higher levels of ecological heterogeneity, underpinned by larger spatial extent and higher taxonomic breadth, can yield multimodal SADs. Our analysis shows that multimodality occurs with a prevalence that warrants its systematic consideration when assessing SAD shape and emphasizes the need for macroecological theories to include multimodality in the range of SADs they predict.

Item ID: 50297
Item Type: Article (Research - C1)
ISSN: 1466-8238
Keywords: community structure, diversity patterns, lognormal, logseries, Poisson lognormal mixture, spatial scale, taxonomic breadth
Funders: Wellcome Trust (WT), Fundação para a Ciência e a Tecnologia, Portugal (FCT), Marine Alliance for Science and Technology, Scotland (MATS)
Projects and Grants: WT ISSF grant 105621/Z/14/Z, FCT POPH/FSE SFRH/BD/90469/2012, MATS HR09011
Date Deposited: 20 Sep 2017 07:44
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060299 Ecology not elsewhere classified @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960899 Flora, Fauna and Biodiversity of Environments not elsewhere classified @ 100%
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