DOI: 10.5061/dryad.hdr7sqvgs
title: Data from: Elevation is a stronger predictor of morphological trait divergence than competition in a radiation of tropical lizards

description: 1. Adaptations for efficient performance are expected to shape animal
 morphology based on selection for microhabitat use and ecological forces.
 The presence of competitor species is predicted to cause niches to
 contract and enhance trait divergence. Therefore, increased species
 richness is expected to lead to greater trait divergence, and to result in
 reduced overlap and similarity between morphologies of sympatric species.
 2. We examined patterns of morphospace occupancy and partitioning in the
 skink fauna of New Guinea, the world’s largest tropical island. Because
 skink species richness is largely decoupled from elevation in New Guinea,
 we could examine the effects of both factors (as proxies for competition
 and abiotic conditions), on morphospace occupancy and partitioning. 3. We
 measured 1860 specimens from 79 species of skinks throughout Papua New
 Guinea, and examined their morphospace occupancy in a spatial context. We
 calculated for each assemblage within equal-area cells, the volume of
 morphospace occupied by all skinks, the mean volume occupied per species,
 and the mean distance and overlap between all species pairs. We then
 examined if these metrics are related to species richness and elevation.
 4. Elevation is a stronger predictor of morphospace occupancy than species
 richness. As elevation increases intraspecific variation decreases and
 morphologies become more similar to each other, such that overall
 morphospace occupancy decreases. Highland skinks are, on average, smaller,
 thinner, and shorter limbed than lowland species. 5. We hypothesize that
 harsh climates in the New Guinea highland habitats impose strong selection
 on skinks to occupy specific areas of morphospace that facilitate
 efficient thermoregulation in sub-optimal thermal conditions. We conclude
 that the effect of competition on trait divergence on a community and
 assemblage scale is eclipsed by abiotic selection pressures in these harsh
 environments.
description: The dataset is saved as an R project, which includes all the
 associated data and code necessary to run the analyses. The
 "data" folder in the project contains two .csv files:
 1. data_pca.csv contains all morphometric measurements used in
 the analyses. 2. all_skinks.csv contains
 species-specific information used for sensitivity analyses.
 Furthermore, the folder contains shapefiles for all species used
 in the study (PNG_Scincidae), species for sensitivity analyses
 (PNG_skinks_notMeasured), a quarter-degree grid of PNG (PNG_25), and a
 raster file with a digitat elevation model of PNG (PNG_DEM).
 Descriptions of how the data were collected are written in full
 in the Methods section of the manuscript.
description: The R project is fully standalone, and all analyses can be run by
 running the .rmd file. The code will export results as .csv files into the
 "Results" folder, and plots as .pdf files into the
 "Plots" folder. The code was designed to
 function on R v4, and may not run well on earlier versions of R. The code
 may take several days to fully run, depending on your machine.