Divergent trends in functional and phylogenetic structure in reptile communities across Africa

Till Ramm,Juan L Cantalapiedra,Mark-Oliver Rödel,Johannes Müller,Philipp Wagner,Johannes Penner

doi:10.1038/s41467-018-07107-y

Abstract

Despite extensive research on ecological community compositions, general patterns across large-scale environmental gradients have remained unclear. A widely used explanatory model is the stress dominance hypothesis (SDH), predicting that the relative influence of environmental filtering is greater in stressful habitats while competition is more important in benign environments. Here, we test the SDH using African squamates as a model system to facilitate general predictions on community structures amidst changing global environments. For the first time we investigate changes in functional, phylogenetic and species diversity across continental, environmental gradients within a multidimensional, phylogenetically informed approach. Results suggest that phylogenetic patterns of African squamates were likely shaped by clade-specific biogeographic histories, whereas functional structure reflects SDH predictions. We further detected significant structuring at both local and regional spatial scales, emphasizing the impact of regional-historical processes on local assemblages, and the need for broad conceptual frameworks to detect general patterns of community composition.

Highlights

Despite extensive research on ecological community compositions, general patterns across large-scale environmental gradients have remained unclear
Our results show that the functional community structure of African squamate reptiles largely follows the predictions of the stress dominance hypothesis (SDH)
We will focus on the net relatedness index3 (NRI) results, while differences to nearest taxon index3 (NTI) will be discussed when appropriate

Summary

Introduction

Despite extensive research on ecological community compositions, general patterns across large-scale environmental gradients have remained unclear. Trait-based functional diversity measures are probably more sensitive to reflect local ecological processes, while phylogenetic patterns in combination with species richness can provide information on processes acting at higher spatiotemporal levels, such as a clades biogeographic history[2,22]. In support of this view, several studies showed that phylogenetic diversity is probably a poor proxy for functional diversity and vice versa[23,24,25,26,27] even when the traits under consideration show a phylogenetic signal[16,28,29]. By examining different spatial scales (i.e. local communities and biomes), we test if different assembly processes shape local and regional species pools (see e.g. Pavoine & Bonsall[2]; Cantalapiedra et al.21), and discuss our findings by incorporating phylogenetic diversity, species richness and the biogeographic history of African squamates

Methods

Results

Conclusion