DOI: 10.5061/dryad.gqnk98sxg
title: Investigating the biotic and abiotic drivers of body size disparity in communities of non-volant terrestrial mammals

description: AimThe species that compose local communities possess unique sets of
 functional and ecological traits that can be used as indicators of biotic
 and abiotic variation across space and time. Body size is a particularly
 relevant trait because species with different body sizes typically have
 different life history strategies and occupy distinct niches. Here we used
 the body sizes of non-volant (i.e., non-flying) terrestrial mammals to
 quantify and compare the body size disparity of mammal communities across
 the globe. LocationGlobal Time periodPresent Major taxa studiedNon-volant
 terrestrial mammals MethodsWe used IUCN range maps of 3,982 terrestrial
 mammals to identify 1,876 communities. We then combined diet data with
 data on climate, elevation, and anthropogenic pressures to evaluate these
 variables’ relative importance on the observed body size dispersion of
 these communities and its deviation from a null model. ResultsDispersion
 is significantly greater than expected in 54% of communities and
 significantly less than expected in 30% of communities. The number of very
 large species, continent, range sizes, diet disparity, and annual
 temperature collectively explain &gt;50% of the variation in observed
 dispersion, whereas continent, the number of very large species, and
 precipitation collectively explain &gt;30% of the deviation from the
 null model. Main conclusionsClimate and elevation have minimal predictive
 power, suggesting that biotic factors may be more important for explaining
 community body size distributions. Continent is consistently a strong
 predictor of dispersion, likely due to it capturing the effects of
 climate, human-induced extinctions, and more. Overall, our results are
 consistent with several plausible explanations, including, but not limited
 to, competitive exclusion, unequal distribution of resources,
 within-community environmental heterogeneity, habitat filtering, and
 ecosystem engineering. Further work focusing on other confounding
 variables, at finer spatial scales, and/or within more causal frameworks
 is required to better understand the driver(s) of these patterns.
description: # Investigating the biotic and abiotic drivers of body size disparity in
 communities of non-volant terrestrial mammals This repository contains the
 R code and (some) data files required to produce all of the analyses and
 plots in: ‘Investigating the biotic and abiotic drivers of body size
 disparity in communities of non-volant terrestrial mammals’ William
 Gearty, Lawrence H. Uricchio, and S. Kathleen Lyons ## Before running the
 code Before running this R script, we suggest that you download this
 folder and set it as your R working directory. Most data must be
 downloaded from external repositories and unzipped to specific folders
 before the analyses can be performed ([see specifics below](#data)).
 Required data files should then load when called in each script, and plot
 files will save within the same folder. ## Running the code Run
 `mammal_variance.R` to perform all analyses and produce all plots from the
 manuscript. Note that the analyses can take a few days to run completely.
 ## Required R packages Unless otherwise stated, the following packages can
 all be installed from CRAN: deeptime dggridR ggforce ggtern grid maptools
 (was retired in 2023; still available on R-Forge) moments MuMIn parallel
 patchwork quantreg relaimpo rgbif sf spData spDep stringr terra tidyverse
 viridis These scripts have been tested using R version 4.3.3 Copyright (C)
 2024 The R Foundation for Statistical Computing. ## Included Data The
 EltonTraits database ("EltonTraits.txt") contains species-level
 foraging attributes for mammals (and birds). The publication describing
 this database is available here:
 [https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/13-1917.1](https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/13-1917.1). The database is available on figshare here: [https://doi.org/10.6084/m9.figshare.c.3306933.v1](https://doi.org/10.6084/m9.figshare.c.3306933.v1). Thanks to the CC0 license, a copy of the database is also included here in the zipped folder "EltonTraits.zip". This folder should be unzipped and the "EltonTraits.txt" file should be moved to the root directory of the project. Metadata for this file is included in the "metadata.htm" file within this zipped folder. The original sources for the mammal functional trait data are documented in the "MamFuncDatSources.txt" file within the zipped folder. The elevation data ("gmted2010.zip") are coped from the USGS Global multi-resolution terrain elevation data 2010 (GMTED2010): [https://www.usgs.gov/coastal-changes-and-impacts/gmted2010](https://www.usgs.gov/coastal-changes-and-impacts/gmted2010). The data (mean statistic, 30 second resolution) can also be downloaded as a zip folder here: [https://topotools.cr.usgs.gov/gmted_viewer/gmted2010_global_grids.php](https://topotools.cr.usgs.gov/gmted_viewer/gmted2010_global_grids.php). These files should be unzipped and placed into a folder named "gmted2020". Metadata are available within the "gmted2010_fgdc_metadata.html" file and are also available here: [https://topotools.cr.usgs.gov/gmted_viewer/gmted2010_fgdc_metadata.html](https://topotools.cr.usgs.gov/gmted_viewer/gmted2010_fgdc_metadata.html). All GMTED2010 data products are publicly available; there are no restrictions or access constraints. ## External Data Needed for Analyses The IUCN range maps for terrestrial mammals ("MAMMALS_TERRESTRIAL_ONLY.zip") should be downloaded from the IUCN here: [https://www.iucnredlist.org/resources/spatial-data-download](https://www.iucnredlist.org/resources/spatial-data-download). The files should be unzipped and placed into a into a folder named "MAMMALS_TERRESTRIAL_ONLY". All forms of reposting, and any sub-licensing, reselling, or other forms of redistribution of IUCN Red List Data in their original format, either whole or in part, alone or combined with other data, including within Derivative Works, are strictly prohibited without the prior written permission of IUCN. Taxonomy ("taxonomy.csv") and synonym ("synonyms.csv") files for IUCN terrestrial mammals should be downloaded from the IUCN website here: [https://www.iucnredlist.org/search?dl=true&permalink=6da36cdc-5f19-46e7-b980-aeb06b2b6208](https://www.iucnredlist.org/search?dl=true&permalink=6da36cdc-5f19-46e7-b980-aeb06b2b6208). To download the files, click the "Download" dropdown, select "Search Summary", then submit a request for the data. All forms of reposting, and any sub-licensing, reselling, or other forms of redistribution of IUCN Red List Data in their original format, either whole or in part, alone or combined with other data, including within Derivative Works, are strictly prohibited without the prior written permission of IUCN. The Human Footprint Index data are available from the NASA Socioeconomic Data and Applications Center. The dataset from 1993 is available here: [https://sedac.ciesin.columbia.edu/data/set/wildareas-v3-1993-human-footprint](https://sedac.ciesin.columbia.edu/data/set/wildareas-v3-1993-human-footprint). The dataset from 2009 is available here: [https://sedac.ciesin.columbia.edu/data/set/wildareas-v3-2009-human-footprint](https://sedac.ciesin.columbia.edu/data/set/wildareas-v3-2009-human-footprint). Metadata is available at both of those locations under the "Metadata" tabs. The datasets are available as individual .tif files under the "Data Download" tabs. These two files should be moved to the root directory of the project. The Millenium Assessment's deforestation hotspot data are available from the NASA Socioeconomic Data and Applications Center here: [https://sedac.ciesin.columbia.edu/data/set/ma-rapid-land-cover-change](https://sedac.ciesin.columbia.edu/data/set/ma-rapid-land-cover-change). Metadata is available at this location under the "Metadata" tab. The dataset can be be downloaded as a zip folder under the "Data Download" tab. These files should be unzipped and placed into a folder named "def_hot_for". The bioclimatic variable data are available at WorldClim. The 30 second resolution dataset (v. 2.1) can be downloaded from the WorldClim website here: [https://www.worldclim.org/data/worldclim21.html](https://www.worldclim.org/data/worldclim21.html). Metadata is available at that location, and license information is available here: [https://www.worldclim.org/about.html](https://www.worldclim.org/about.html). The data can be downloaded as a large zip folder containing several .tif files. Once downloaded, the files should be unzipped and placed into a folder named "WorldClim".