Quantifying the overall effect of biotic interactions on species distributions along environmental gradients

TL;DR

This paper introduces ELGRIN, a novel statistical model that integrates ecological network knowledge, environmental data, and species occurrences to disentangle the effects of biotic interactions and environment on species distributions.

Contribution

ELGRIN is a new model that combines interspecific interactions, environmental factors, and species data to better understand their combined influence on distributions.

Findings

ELGRIN effectively separates biotic and abiotic effects on species distributions.

The model performs well with simulated and real data across various interaction types.

Application to European Alps vertebrates reveals the impact of biotic interactions.

Abstract

Separating environmental effects from those of interspecific interactions on species distributions has always been a central objective of community ecology. Despite years of effort in analysing patterns of species co-occurrences and the developments of sophisticated tools, we are still unable to address this major objective. A key reason is that the wealth of ecological knowledge is not sufficiently harnessed in current statistical models, notably the knowledge on interspecific interactions. Here, we develop ELGRIN, a statistical model that simultaneously combines knowledge on interspecific interactions (i.e., the metanetwork), environmental data and species occurrences to tease apart their relative effects on species distributions. Instead of focusing on single effects of pairwise species interactions, which have little sense in complex communities, ELGRIN contrasts the overall effect of species interactions to that of the environment. Using various simulated and empirical data, we demonstrate the suitability of ELGRIN to address the objectives for various types of interspecific interactions like mutualism, competition and trophic interactions. We then apply the model on vertebrate trophic networks in the European Alps to map the effect of biotic interactions on species distributions.Data on ecological networks are everyday increasing and we believe the time is ripe to mobilize these data to better understand biodiversity patterns. ELGRIN provides this opportunity to unravel how interspecific interactions actually influence species distributions.