Predicted impacts of climatic change on ant functional diversity and distributions in eastern North American forests

Israel Del Toro,Rogério R Silva,Aaron M Ellison,Alan Andersen

doi:10.1111/ddi.12331

Abstract

AbstractAimsClimatic change is expected to rearrange species assemblages and ultimately affect organism‐mediated ecosystem processes. We focus on identifying patterns and relationships between common ant species (representing 99% of total ant records) richness and functional diversity; modelling how these patterns may change at local and regional scales in future climatic conditions; and interpreting how these changes might influence ant‐mediated ecosystem processes.LocationForested ecosystems of eastern North America.MethodsWe used a previously published dataset to evaluate functional diversity at 67 sites in the eastern U.S. and quantified 14 taxonomic, morphometric and natural history traits for 70 common ant species in the region. We used functional diversity metrics, functional groups and species distribution modelling methods to address our aims. We used stacked species distribution models and stacked functional group models to predict species assemblages and functional richness at the 67 sites and at a regional scale for current and future climatic conditions.ResultsSpecies richness and functional diversity are positively correlated throughout the region. Under future climate scenarios, species richness and functional group richness were predicted to decrease in southern ecoregions and increase in northern ecoregions. This may be due to increased thermal stress for species in the southern extent of their ranges and increased habitat suitability in the northern ecoregions. Decomposers, arthropod community regulators and seed dispersers are forecast to be the most threatened ant functional groups.Main ConclusionsClimate change will likely lead to major changes in ant species richness and functional group richness in the forests of the north‐eastern United States, and this may substantially alter ant‐mediated ecosystem processes and services.

Highlights

The best-fit regression line better approximated the 1:1 ratio line suggesting that S-functional group models (FGMs) might be useful in predicting functional diversity patterns at large geographic scales (Fig. 2B)
The majority of sites we studied in eastern North America (80%) have six or more functional groups at each site and functional evenness (FEve) was not correlated with richness or latitude, suggesting that functional roles of ants as soil movers, decomposers, seed dispersers and community regulators are important and widespread throughout eastern North America
Functional diversity tends to increase, as do the number of functional groups, a pattern that is common in nature and contributes to the understanding of how communities assemble by highlighting patterns of niche filtering (Mouchet et al, 2010)

Summary

Introduction

We focus on identifying patterns and relationships between common ant species (representing 99% of total ant records) richness and functional diversity; model how these patterns may change at local and regional scales in future climatic conditions; and interpret how these changes might influence ant-mediated ecosystem processes. We used stacked species distribution models and stacked functional group models to predict species assemblages and functional richness at the 67 sites and at a regional scale for current and future climatic conditions.

Results

Conclusion