Ecotone formation through ecological niche construction: the role of biodiversity and species interactions.

Kevin Liautaud,Michel Loreau,Matthieu Barbier

doi:10.1111/ecog.04902

Abstract

Rapid changes in species composition, also known as ecotones, can result from various causes including rapid changes in environmental conditions, or physiological thresholds. The possibility that ecotones arise from ecological niche construction by ecosystem engineers has received little attention. In this study, we investigate how the diversity of ecosystem engineers, and their interactions, can give rise to ecotones. We build a spatially explicit dynamical model that couples a multispecies community and its abiotic environment. We use numerical simulations and analytical techniques to determine the biotic and abiotic conditions under which ecotone emergence is expected to occur, and the role of biodiversity therein. We show that the diversity of ecosystem engineers can lead to indirect interactions through the modification of their shared environment. These interactions, which can be either competitive or mutualistic, can lead to the emergence of discrete communities in space, separated by sharp ecotones where a high species turnover is observed. Considering biodiversity is thus critical when studying the influence of species–environment interactions on the emergence of ecotones. This is especially true for the wide range of species that have small to moderate effects on their environment. Our work highlights new mechanisms by which biodiversity loss could cause significant changes in spatial community patterns in changing environments.

Highlights

IntroductionWhether species composition changes gradually, or forms discrete zones along environmental gradients has been the subject of a long-standing debate in ecology
We investigate the effect of these differences on emergent competition or facilitation between ecosystem engineers, and how this could play a role in ecotone emergence
We investigated the role of biodiversity and species interactions in the emergence of ecotones through ecological niche construction

Summary

Introduction

Whether species composition changes gradually, or forms discrete zones along environmental gradients has been the subject of a long-standing debate in ecology The above function is characterized by the species’ fundamental niche centre Ci, i.e. the value of the environmental factor for which its carrying capacity reaches its maximum value max i This unimodal, continuous distribution ensures a gradual response of each species to changes in the environment. The presence of direct competition between species can have an influence on species distributions in space (Liautaud et al 2019), we describe this case in Supplementary material Appendix 3 In this simplified model, the only role played by growth rates is to determine how fast species reach their carrying capacities, and which equilibrium is reached from given initial conditions when there are multiple equilibria.

Results

Discussion

Data availability statement