Data from: Tropical bird species have less variable body sizes

Processed data and covariates for each bird sister species pairThis file contains all data (variability of body mass across species ranges) and covariates assembled for each tropical-nontropical bird sister species pair identified from a global bird phylogeny. Detailed metadata for each column, including description, units, and data source, are in another associated file: bird_sister_species_column_metadata.txt.bird_sister_species_data.csvColumn metadata for bird sister species dataThis is a tab-delimited .txt file with column metadata (description, data source, and units) for each of the columns in the bird_sister_species_data.csv file also archived with this submission.bird_sister_species_column_metadata.txtRaw body mass data for bird speciesThese are raw body mass measurements from the vertnet.org specimen database that have already been subject to extensive quality control. All columns other than species binomial and mass in grams have been stripped away; this is the minimal information required to do the bootstrap resampling to recreate the analysis in the manuscript.raw_body_mass_data.csvstepAICc R functionThis is a modified version of the stepAIC() function from the R package MASS which uses AICc (Akaike's corrected information criterion) rather than AIC to select the predictor to add at each step.stepaicc.rCode to reproduce analyses in paperThis R script was tested with R version 3.3.3 on 13 December 2017. It loads the two .csv files also archived with this submission and reproduces the analyses in the paper: t-test, bootstrap sampling of the individual measurements to correct for unequal sample sizes, multiple regression, and model selection.bird_sister_species_code.r