Global Range Size Project

Range-size-project🌍 Global Plant Range Size Project This repository contains the full code and analysis pipeline for the study "Hemispheric asymmetry in climatic drivers of plant latitudinal range size", which investigates global patterns in plant geographic distributions and the ecological, climatic, and evolutionary factors that shape them.📊 Overview We analyze the latitudinal range sizes of 47,675 vascular plant species using a combination of trait-based modeling, structural equation modeling (SEM), and phylogenetic signal analysis. Our objectives are to:Test Rapoport’s rule in both hemispheres.Identify climatic drivers of latitudinal range size using SEM.Assess evolutionary lability of range size via phylogenetic signal tests.Investigate plant trait associations with range size (growth form, leaf size, structure, phenology).🧪 Major ComponentsData Preparation Climate and occurrence data were grouped by range edge (e.g., extent.ymax or extent.ymin) into 1°/0.5° bins.Mean climatic variables and latitudinal range sizes were computed per bin for SEM input.Predictor Selection A Random Forest model was applied separately for Northern and Southern Hemisphere data to identify the top climatic variables influencing range size.Stepwise regression was used to refine the variable list before SEM modeling.Structural Equation Modeling (SEM) SEMs were implemented using the lavaan package in R.Model refinement was based on modification indices (MI), model fit statistics (CFI, RMSEA, SRMR), and ecological plausibility.For the Southern Hemisphere, latent variables were constructed to represent drought and thermal variability.