Testing biodiversity theory using species richness of reef-building corals across a depth gradient

T. Edward Roberts*, Sally A. Keith, Carsten Rahbek, Tom C.L. Bridge, M. Julian Caley, Andrew H. Baird

*Corresponding author for this work

Research output: Contribution to journalLetterResearchpeer-review

8 Citations (Scopus)

Abstract

Natural environmental gradients encompass systematic variation in abiotic factors that can be exploited to test competing explanations of biodiversity patterns. The species–energy (SE) hypothesis attempts to explain species richness gradients as a function of energy availability. However, limited empirical support for SE is often attributed to idiosyncratic, local-scale processes distorting the underlying SE relationship. Meanwhile, studies are also often confounded by factors such as sampling biases, dispersal boundaries and unclear definitions of energy availability. Here, we used spatially structured observations of 8460 colonies of photo-symbiotic reef-building corals and a null-model to test whether energy can explain observed coral species richness over depth. Species richness was left-skewed, hump-shaped and unrelated to energy availability. While local-scale processes were evident, their influence on species richness was insufficient to reconcile observations with model predictions. Therefore, energy availability, either in isolation or in combination with local deterministic processes, was unable to explain coral species richness across depth. Our results demonstrate that local-scale processes do not necessarily explain deviations in species richness from theoretical models, and that the use of idiosyncratic small-scale factors to explain large-scale ecological patterns requires the utmost caution.

Original languageEnglish
Article number20190493
JournalBiology Letters
Volume15
Issue number10
Number of pages5
ISSN1744-9561
DOIs
Publication statusPublished - 1 Oct 2019

Keywords

  • Biodiversity
  • Community assembly processes
  • Corals
  • Depth
  • Species richness gradients
  • Species–energy hypothesis

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