DOI: 10.5061/dryad.44j0zpckm
title: Plant size, latitude, and phylogeny explain within-population variability in herbivory

description: Interactions between plants and herbivores are central in most ecosystems,
 but their strength is highly variable. The amount of variability within a
 system is thought to influence most aspects of plant-herbivore biology,
 from ecological stability to plant defense evolution. Our understanding of
 what influences variability, however, is limited by sparse data. We
 collected standardized surveys of herbivory for 503 plant species at 790
 sites across 116° of latitude. With these data, we show that
 within-population variability in herbivory increases with latitude,
 decreases with plant size, and is phylogenetically structured. Differences
 in the magnitude of variability are thus central to how plant-herbivore
 biology varies across macroscale gradients. We argue that increased focus
 on interaction variability will advance understanding of patterns of life
 on Earth.
description: # Plant size, latitude, and phylogeny explain within-population
 variability in herbivory --- This dataset and set of scripts was produced
 by the members of The Herbivory Variability Network. It examines global
 and phylogenetic patterns of herbivory via 790 suveys of 503 plant
 species. Our website is [herbvar.org](https://herbvar.org). We are funded
 by the US National Science Foundation Research Coordination Networks
 program. The Principal Investigators (PIs) of the project are William
 Wetzel (), Phil Hahn, Brian Inouye, Nora
 Underwood, and Susan Whitehead. The steering committee is the PIs and
 Karen Abbott, Emilio Bruna, N. Ivalú Cacho, and Lee Dyer. Our contact
 information is [here](https://herbvar.org/leadership.html). For the full
 list of HerbVar members, please see [this
 webpage](https://herbvar.org/CollaboratorDirectory.html). This version of
 the dataset and analysis is associated with the following paper: The
 Herbivory Variability Network et al. 2023. Plant size, latitude, and
 phylogeny explain within-population variability in herbivory. Science 382:
 679-683. ##
 Description of the data and file structure There are three csv data files
 in the dataset. Each represents a different biological scale: plant
 individuals, plant populations, and plant species.
 data_plant_level_prep_2023-01-01 10-15-19.csv -- each row is a plant
 individual data_survey_level_prep_2023-01-01 10-15-19.csv -- each row is a
 plant population data_species_level_prep_2023-01-01 10-15-19.csv -- each
 row is a plant species ## Column name definitions
 **data_plant_level_prep_2023-01-01 10-15-19.csv** | Col name | Definition
 | | ------------- | -------------------------------------------------- | |
 surveyID | ID for the population survey | | Genus\_sp | Genus and species
 of the plant surveyed | | plantFamily | Taxonomic family of the plant
 species | | percHerbPlant | The percent of leaf area damaged by herbivores
 (%) | | Lat | The latitude of the survey site (decimal degrees) |
 **data_survey_level_prep_2023-01-01 10-15-19.csv** | Col name | Definition
 | | ------------------------ |
 ------------------------------------------------------------------------------------------------ | | surveyID | ID for the population survey | | date | The date of the survey (month/day/year) | | Lat | The latitude of the survey site | | Lat\_abs | The absolute value of the latitude of the survey site (decimal degrees) | | Lat\_abs\_scale | The scaled absolute value of the latitude of the survey site (decimal degrees) | | hemi | The hemisphere of the survey site (north or south) | | Genus\_sp | Genus and species of the plant surveyed | | plantFamily | Taxonomic family of the plant species | | Biome | The biome of the survey site | | growthForm | The growth form of the plant species | | growthForm\_simp | A simplified version of the growth form of the plant species | | sizeDiameterMean | The mean height for most plant species or mean diameter for prostrate species (cm) | | sizeDiameterMeanLog | Log of sizeDiameterMean | | sizeDiameterMeanLogScale | Scaled log of sizeDiameterMean | | plantMean | The mean percent herbivory in the survey (%) | | plantMeanProp | The mean proportion herbivory in the survey | | plantMeanPropLogit | The logit mean proportion herbivory in the survey | | plantGini | The Gini coefficient of herbivory in the survey | | plantGiniAdj | The adjusted Gini coefficient of herbivory in the survey (see methods) | | plantGiniAdjLogit | The logit adjusted Gini coefficient of herbivory in the survey (see methods) | | propPlantsHerb50 | The minimum proportion of plant individuals with &gt;= 50% of the population's proportion herbivory | | focalPlantCoverMean | The average cover of the focal plant species within the survey | **data_species_level_prep_2023-01-01 10-15-19.csv** | Col name | Definition | | ------------------ | ---------------------------------------------------------------------------------------------------------- | | Genus\_sp | Genus and species of the plant surveyed | | plantFamily | Taxonomic family of the plant species | | plantMean | The mean percent herbivory averaged across the surveys of each species (%) | | plantMeanProp | The mean proportion herbivory averaged across the surveys of each species | | plantMeanPropLogit | The logit mean proportion herbivory averaged across the surveys of each species | | plantGini | The Gini coefficient of herbivory averaged across the surveys of each species | | plantGiniAdj | The adjusted Gini coefficient of herbivory averaged across the surveys of each species (see methods) | | plantGiniAdjLogit | The logit adjusted Gini coefficient of herbivory averaged across the surveys of each species (see methods) | ## Code/Software Our analysis scripts are also available at our [public GitHub repository for this paper](https://github.com/HerbVar-Network/HV-Large-Patterns-MS-public). It includes six R scripts. | Script | Purpose | | -------------------------------------- | -------------------------------------------------------------------------------------------------------------------------- | | 01 - HV MS1 Load data and build tree.R | Loads the data files, builds the phylogenetic tree, and sets priors for all beta models | | 02 - HV MS1 Overall means.R | Calculates model predicted means for mean herbivory and the Gini coefficient of herbivory, plus one more summary statistic | | 03 - HV MS1 Geographic analyses.R | Models geographic patterns in herbivory means and the Gini coefficient, including with latitude and biome | | 04 - HV MS1 Plant trait analyses.R | Models patterns in herbivory with plant size and plant growth form | | 05 - HV MS1 Phylogenetic signal.R | Calculates phylogenetic signal in mean herbivory and the Gini coefficient | | 06 - HV MS1 Sensitivity analyses.R | This script examines the sensitivity of our results to within-survey sample size |