Disentangling the role of environment in cross-taxon congruence of species richness along elevational gradients

Carolina S Ramos,Martina E Pocco,Julieta Filloy,Pablo Picca

doi:10.1038/s41598-021-83763-3

Abstract

Spatial patterns of species richness have been found to be positively associated, a phenom called cross-taxon congruence. This may be explained by a common response to environment or by ecological interactions between taxa. Spatial changes in species richness are related to energy and environmental heterogeneity but their roles in cross-taxon congruence remain poorly explored. Elevational gradients provide a great opportunity to shed light on the underlying drivers of species richness patterns. We study the joint influence of environment and biotic interactions in shaping the cross-taxon congruence of plants and orthopterans species richness, along three elevational gradients in Sierras Grandes, central Argentina. Elevational patterns of species richness of orthopterans and plants were congruent, being temperature the best single predictor of both patterns supporting the energy-related hypotheses. Using a structural equation model, we found that temperature explained plant richness directly and orthopteran richness indirectly via orthopteran abundance. Cross-taxon congruence is likely due to a common response of both taxa to temperature although via different theoretical mechanisms, possibly, range limitations for plants and foraging activity for orthopterans. We disentangled the role of temperature in determining the cross-taxon congruence of plants and orthopterans by showing that a common response to the environment may mask different mechanisms driving the diversity of different taxonomic groups.

Highlights

Spatial patterns of species richness have been found to be positively associated, a phenom called cross-taxon congruence
The soil nutrient component remained relatively constant throughout the elevational gradients
Richness patterns of plants and orthopterans were congruent along elevational gradients, showing both taxa a response to temperature over a potential interaction between them

Summary

Introduction

Spatial patterns of species richness have been found to be positively associated, a phenom called cross-taxon congruence This may be explained by a common response to environment or by ecological interactions between taxa. Energy-related hypotheses have the strongest support to explain spatial diversity patterns but the mechanisms underlying those patterns are still e lusive[18] These hypotheses propose that energy limits species richness through at least three different mechanisms. In mountain systems, a great slope is related to a major micro-environmental gradient and major microhabitat complexity[22] If this hypothesis prevailed, a positive relationship between species richness and habitat heterogeneity measures would be expected, irrespective of the altitudinal level where maximum values of those measures occur in each elevational gradient

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Conclusion