Towards a Periodic Table of Niches, or Exploring the Lizard Niche Hypervolume

Pianka, Eric R.

Department of Integrative Biology

University of Texas

Austin, Texas 78712

erp@austin.utexas.edu

Vitt, Laurie J.

Sam Noble Museum and Department of Biology University of Oklahoma

Norman, Oklahoma 73072

Pelegrin, Nicolás

Laboratorio de Ecología y Conservación de la Herpetofauna

Instituto de Diversidad y Ecología Animal (Consejo Nacional de Investigaciones Científicas y Técnicas–Universidad Nacional de Córdoba [UNC]) and Centro de Zoología Aplicada (UNC) Rondeau 798 X5000AVP

Córdoba, Argentina

Fitzgerald, Daniel B.

Program in Ecology and Evolutionary Biology and Department of Wildlife and Fisheries Sciences

Texas A&M University

College Station, Texas 77843

Winemiller, Kirk O.

Program in Ecology and Evolutionary Biology and Department of Wildlife and Fisheries Sciences

Texas A&M University

College Station, Texas 77843

Unrelated species have evolved to fill similar niches in different regions, suggesting a periodic table of niches could be constructed and applied to all organisms. We compiled ecological data for lizards to examine patterns of global and regional niche diversification, and employed a multivariate statistical approach to develop the beginnings for a periodic table of niches. Datasets for five major niche dimensions (50+ variables in all) were assembled for 134 species of lizards representing 24 of the 38 extant families. Niche dimensions include habitat, diet, life history, metabolism, and defense. Principal Coordinates Analyses (PCoA) were performed on these five datasets and scores for the first 3 dimensions were used as input for a Principal Components Analysis (PCA). The resulting PCA captured 61.7% of the variance in the first three axes. 3D models facilitate exploration of the first three axes of major gradients within the 50+ dimensional hypervolume. The first gradient includes body size, foraging mode, and clutch size. The second corresponds to metabolism, and terrestrial versus arboreal microhabitat. The third includes activity time, life history, and diet. Natural dichotomies are activity time, foraging mode, parity mode, and habitat. Regression tree analysis identified 103 niche conservatisms within clades and 100 convergences among clades. Extending this approach to other taxa should ultimately lead to a wider understanding of niche evolution among vertebrates. Throughout, the paper features a back-and-forth interplay among outright natural history, niche theory, state-of-the-art multivariate statistical analyses, and downloadable rotatable 3-D plots.