The dimensionality of individual niche variation.

Travis Ingram,Raul Costa‐Pereira,Márcio S Araújo

doi:10.1002/ecy.2129

Travis Ingram, Raul Costa‐Pereira + Show 1 more

Open Access

https://doi.org/10.1002/ecy.2129

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Abstract

The inherently multidimensional nature of the niche has not yet been integrated into the investigation of individual niche specialization within populations. We propose a framework for modeling the between- and within-individual components of the population niche as a set of variance-covariance matrices, which can be visualized with ellipses or ellipsoids. These niche components can be inferred using multiple response mixed models, and can incorporate diverse types of data, including diet composition, stable isotopes, spatial location, and other continuous measures of niche dimensions. We outline how considering both individual and population niches in multiple dimensions may enhance our understanding of key concepts in ecology and evolution. Considering multiple dimensions as well as the within-individual component of variation can lead to more meaningful measures of niche overlap between species. The impact of a population on its food web or ecosystem can depend on the degree of individual variation (via Jensen's inequality), and we suggest how the dimensionality of individual specialization could amplify this effect. Finally, we draw from concepts in quantitative genetics and the study of animal personalities to propose new hypotheses about the ecological and evolutionary basis of niche shifts in multiple dimensions. We illustrate key ideas using empirical data from sea otters, wetland frogs, and threespine stickleback, and discuss outstanding questions about the consequences of multidimensional niche variation. Setting variation among individuals in an explicitly multivariate framework has the potential to transform our understanding of a range of ecological and evolutionary processes.

Highlights

The ecological niche of an organism defines how it interacts with all aspects of its environment, and is an inherently multidimensional construct (Hutchinson 1957)
We show how this framework can alter predictions about key outcomes including the extent of niche overlap between species, the effect of individual variation on population mean processes and interactions, and the expected trajectory of niche shifts under ecological change
Potentially covarying dimensions of resources use, we propose extending the analysis of the continuous niche components total niche width (TNW), within-individual component (WIC) and between-individual component (BIC) into multiple ecological dimensions

Summary

INTRODUCTION

The ecological niche of an organism defines how it interacts with all aspects of its environment, and is an inherently multidimensional construct (Hutchinson 1957). We develop two related arguments: that robust measures of individual niche variation should consider multiple niche axes and their covariances rather than each axis in isolation, and that studies of multidimensional resource use should integrate both the between- and within-individual components of niche variation. We show how this framework can alter predictions about key outcomes including the extent of niche overlap between species ( in stable isotope studies), the effect of individual variation on population mean processes and interactions (e.g., via Jensen’s inequality), and the expected trajectory of niche shifts under ecological change. We illustrate these ideas using analyses of empirical and simulated niche data, and propose several novel and testable hypotheses about the consequences of multidimensional individual specialization

A FRAMEWORK FOR INVESTIGATING MULTIDIMENSIONAL INDIVIDUAL SPECIALIZATION

CONCLUSIONS AND FUTURE DIRECTIONS