DOI: 10.5061/dryad.rv15dv4fs
title: Environmental context shapes the relationship between grass consumption and body size in African herbivore communities

description: Though herbivore grass dependence has been shown to increase with body
 size across herbivore species, it is unclear whether this relationship
 holds at the community level. Here we evaluate whether grass consumption
 scales positively with body size within African large mammalian herbivore
 communities and how this relationship varies with environmental context.
 We used stable carbon isotope and community occurrence data to investigate
 how grass dependence scales with body size within 23 savanna herbivore
 communities throughout eastern and central Africa. We found that dietary
 grass fraction increased with body size for the majority of herbivore
 communities considered, especially when complete community data were
 available. However, the slope of this relationship varied, and rainfall
 seasonality and elephant presence were key drivers of the variation—grass
 dependence increased less strongly with body size where rainfall was more
 seasonal and where elephants were present. We found also that the
 dependence of the herbivore community as a whole on grass peaked at
 intermediate woody cover. Intraspecific diet variation contributed to
 these community-level patterns: common hippopotamus (Hippopotamus
 amphibius) and giraffe (Giraffa camelopardalis) ate less grass where
 rainfall was more seasonal, whereas Cape buffalo (Syncerus caffer) and
 savanna elephant (Loxodonta africana) grass consumption were parabolically
 related to woody cover. Our results indicate that general rules appear to
 govern herbivore community assembly, though some aspects of herbivore
 foraging behavior depend upon local environmental context.
description: We quantified local grass dependence from a dataset of stable
 isotope data collected from across eastern and central Africa, Cerling
 <em>et al.</em> (2015). We identified which species were
 missing local data using a dataset of herbivore community composition,
 Rowan <em>et al.</em> (2020). We then computed regional
 species-level averages for those community members missing local diet
 data, also from the aforementioned stable isotope dataset. 
 We extracted species-level body mass estimates from EltonTraits
 (Wilman <em>et al.</em> 2014). We
 downloaded shapefiles for each community from the World Database on
 Protected Areas (WDPA). Using these shapefiles, we extracted environmental
 covariates for each herbivore community: we calculated mean annual
 rainfall, mean rainfall seasonality, mean annual temperature, and mean
 temperature seasonality for each community from climatic data layers
 downloaded from WorldClim 2.0 (Fick and Hijmans 2017); we extracted
 estimates of woody cover for each community from a data layer of
 fractional woody cover for sub-Saharan Africa (Venter <em>et
 al.</em> 2018).
description: This 'README_file_Herbivore community assembly.txt' file was
 generated on 2024-01-23 by JOEL O. ABRAHAM GENERAL INFORMATION 1. Title of
 Dataset: Environmental context shapes the relationship between grass
 consumption and body size in African herbivore communities 2. Author
 Information A. Principal Investigator Contact Information Name: Joel O.
 Abraham Institution: Princeton University Email:
 B. Associate or Co-investigator Contact
 Information Name: J. Tyler Faith Institution: University of Utah Email:
 3. Date of data collection (approximate):
 2023-08-01 to 2024-01-13 4. Geographic location of data collection:
 eastern and central Africa; compiled from existing literature/data sources
 5. Information about funding sources that supported the collection of the
 data: Joel O. Abraham was supported by the NSF GRFP J. Tyler Faith was
 supported by NSF grants CNH-1826666 and 2224318 SHARING/ACCESS INFORMATION
 1. Licenses/restrictions placed on the data: None. 2. Links to
 publications that cite or use the data: TBD 3. Links to other publicly
 accessible locations of the data: TBD 4. Links/relationships to ancillary
 data sets: NA 5. Was data derived from another source? YES A. List
 source(s): Cerling, T.E., Andanje, S.A., Blumenthal, S.A., Brown, F.H.,
 Chritz, K.L., Harris, J.M., et al. (2015). Dietary changes of large
 herbivores in the Turkana Basin, Kenya from 4 to 1 Ma. PNAS, 112,
 11467–11472. Fick, S.E. & Hijmans, R.J. (2017). WorldClim 2: new 1-km
 spatial resolution climate surfaces for global land areas. International
 Journal of Climatology, 37, 4302–4315. Rowan, J., Beaudrot, L., Franklin,
 J., Reed, K.E., Smail, I.E., Zamora, A., et al. (2020). Geographically
 divergent evolutionary and ecological legacies shape mammal biodiversity
 in the global tropics and subtropics. Proceedings of the National Academy
 of Sciences, 117, 1559–1565. Venter, Z.S., Cramer, M.D. & Hawkins,
 H.-J. (2018). Drivers of woody plant encroachment over Africa. Nat Commun,
 9, 2272. Wilman, H., Belmaker, J., Simpson, J., Rosa, C. de la,
 Rivadeneira, M.M. & Jetz, W. (2014). EltonTraits 1.0: Species-level
 foraging attributes of the world’s birds and mammals. Ecology, 95,
 2027–2027. 6. Recommended citation for this dataset: Abraham, J.O., Rowan,
 J., O'Brien, K., Sokolowski, K.G., and Faith, J.T.
 (2024).Environmental context shapes the relationship between grass
 consumption and body size in African herbivore communities, Dryad,
 Dataset. DATA & FILE OVERVIEW 1. File List: README_file_Herbivore
 community assembly.txt: README file explaining how the dataset was
 generated and the data contained in the dataset EcoEvo_Abraham et
 al_community level diet data.csv: EcoEvo_Abraham et al_community
 covariates.csv: METHODOLOGICAL INFORMATION 1. Description of methods used
 for collection/generation of data: We quantified local grass dependence
 from a dataset of stable isotope data collected from across eastern and
 central Africa, Cerling et al. (2015). We identified which species were
 missing local data using a dataset of herbivore community composition,
 Rowan et al. (2020). We then computed regional species-level averages for
 those community members missing local diet data, also from the
 aforementioned stable isotope dataset.  We extracted species-level body
 mass estimates from EltonTraits (Wilman et al. 2014). We downloaded
 shapefiles for each community from the World Database on Protected Areas
 (WDPA). Using these shapefiles, we extracted environmental covariates for
 each herbivore community: we calculated mean annual rainfall, mean
 rainfall seasonality, mean annual temperature, and mean temperature
 seasonality for each community from climatic data layers downloaded from
 WorldClim 2.0 (Fick and Hijmans 2017); we extracted estimates of woody
 cover for each community from a data layer of fractional woody cover for
 sub-Saharan Africa (Venter et al. 2018). 2. Methods for processing the
 data: NA 3. Instrument- or software-specific information needed to
 interpret the data: NA - R was used to generate community covariates data
 but is not necessary for using the data 4. Standards and calibration
 information, if appropriate: NA 5. Environmental/experimental conditions:
 NA 6. Describe any quality-assurance procedures performed on the data: NA
 7. People involved with sample collection, processing, analysis and/or
 submission: All data were compiled and extracted by Joel O. Abraham.
 DATA-SPECIFIC INFORMATION FOR: EcoEvo_Abraham et al_community level diet
 data.csv 1. Number of variables: 10 2. Number of cases/rows: 443 3.
 Variable List: Ecosystem - the abbreviation for the herbivore community to
 which the data correspond Protected_area - the name of the protected area
 from which stable isotope data were collected and environmental covariates
 were extracted Type - whether the data were local (directly from Cerling
 et al. 2015), regional (species-level averages derived from Cerling et al.
 2015), or global (pulled from global diet data compilations because that
 species was not present in Cerling's dataset). Species - the
 scientific name of the community member Order - the order to which the
 community member belongs Family - the family to which the community member
 belongs C4_mean - the mean dietary grass fraction estimate for the
 community member C4_SD - the estimated standard deviation in dietary grass
 fraction for the community member C4_N - the number of samples used to
 generate the estimated dietary grass fraction mean and standard deviation
 Body_mass - the body mass of the community member, in kilograms (kg) 4.
 Missing data codes: 'NA' 5. Specialized formats or other
 abbreviations used: NA DATA-SPECIFIC INFORMATION FOR: EcoEvo_Abraham et
 al_community covariates.csv 1. Number of variables: 19 2. Number of
 cases/rows: 23 3. Variable List: Ecosystem - the abbreviation for the
 herbivore community to which the data correspond Community_name - the full
 name of the herbivore community to which the data correspond Park_name -
 the name of the protected area from which stable isotope data were
 collected and environmental covariates were extracted WDPA_PID - the
 unique ID assigned to the protected area by the World Database on
 Protected Areas Latitude - the latitudinal centroid of samples collected
 for each community Longitude - the longitudinal centroid of samples
 collected for each community Complete_community_data - whether or not
 community composition data were available for the community Elephant -
 whether or not elephants were present within a community SpN - the number
 of herbivore species present in the community Woody_cover_mean - the
 average woody cover for the protected area corresponding to the herbivore
 community Woody_cover_SD - the standard deviation in woody cover for the
 protected area corresponding to the herbivore community MATemp_mean - mean
 annual temperature (in degrees Celcius) for the protected area
 corresponding to the herbivore community MATemp_SD - standard deviation in
 mean annual temperature (in degrees Celcius) for the protected area
 corresponding to the herbivore community TempS_mean - mean temperature
 seasonality (measured as the standard deviation of temperature across the
 seasonal cycle) for the protected area corresponding to the herbivore
 community TempS_SD - standard deviation in temperature seasonality (the
 standard deviation of temperature across the seasonal cycle) for the
 protected area corresponding to the herbivore community MARain_mean - mean
 annual rainfall (in millimeters) for the protected area corresponding to
 the herbivore community MARain_SD - standard deviation in mean annual
 rainfall (in millimeters) for the protected area corresponding to the
 herbivore community RainS_mean - mean rainfall seasonality (measured as
 the coefficient of variation [standard deviation divided by the mean] in
 precipitation throughout the year) for the protected area corresponding to
 the herbivore community RainS_SD - standard deviation in rainfall
 seasonality (measured as the coefficient of variation [standard deviation
 divided by the mean] in precipitation throughout the year) for the
 protected area corresponding to the herbivore community 4. Missing data
 codes: 'NA' 5. Specialized formats or other abbreviations used:
 NA