Niche conservatism in Gynandropaa frogs on the southeastern Qinghai-Tibetan Plateau.

Junhua Hu,Olivier Broennimann,Jianping Jiang,Yan Huang,Antoine Guisan,Bin Wang

doi:10.1038/srep32624

Abstract

The role of ecological niche in lineage diversification has been the subject of long-standing interest of ecologists and evolutionary biologists. Gynandropaa frogs diversified into three independent clades endemic to the southeastern Qinghai-Tibetan Plateau. Here, we address the question whether these clades kept the same niche after separation, and what it tells us about possible diversification processes. We applied predictions in geographical (G)-space and tests of niche conservatism in environmental (E)-space. Niche models in G-space indicate separate regions with high suitability for the different clades, with some potential areas of sympatry. While the pair of central and eastern clades displayed the largest niche overlap for most variables, and strict niche equivalency was rejected for all clade-pairs, we found no strong evidence for niche divergence, but rather the signature of niche conservatism compared to null models in E-space. These results suggest a common ancestral ecological niche, and as such give good support to divergence through allopatric speciation, but alternative explanations are also possible. Our findings illustrate how testing for niche conservatism in lineage diversification can provide insights into underlying speciation processes, and how this information may guide further research and conservation practices, as illustrated here for amphibians on the Qinghai-Tibetan Plateau.

Highlights

Whether ecological factors promote lineage diversification and speciation has been an outstanding question in ecology and evolutionary biology during the last decade[1,2,3,4,5]
The Qinghai-Tibetan Plateau (QTP) and its adjacent areas is an interesting region for evaluating the use of niche tests to uncover lineage diversification processes
We tested niche conservatism and the relation to lineage diversification based on up-to-date phylogeographic knowledge[25,27,38]

Summary

Introduction

Whether ecological factors promote lineage diversification and speciation has been an outstanding question in ecology and evolutionary biology during the last decade[1,2,3,4,5]. Underlying most ENMs, the environmental data (e.g. temperature) are often spatially correlated, potentially confounding meaningful niche divergence with geographic distance[20] This problem of spatial autocorrelation is unavoidable but can be addressed by using null models when testing niche conservatism versus divergence[9,20]. The Qinghai-Tibetan Plateau (QTP) and its adjacent areas is an interesting region for evaluating the use of niche tests to uncover lineage diversification processes It spans three biodiversity hotspots: Himalaya, Indo-Burma and the mountains of southwestern China[24]. The southeastern QTP is characterized by a landscape of river gorges and steep mountain ridges with a series of parallel alpine ridges and rivers running north to south Such topographical complexity within a rather small geographical region led to dramatic ecological stratification and environment heterogeneity[30]. Thereby, the southeastern QTP is a well suited region for inquiring into the inertial tendency of organisms to maintain their current ecological niche (conservatism) and the effects of natural selection on populations, which differ in habitat across ecological landscapes

Methods

Results

Conclusion