Reconstructing Evolutionary Histories: A Comprehensive Review of RASP for Historical Biogeography and Trait Evolution

Understanding how species originate, diversify, and change across geographic landscapes is a major topic in evolutionary biology. The rapid increase in phylogenetic and biogeographic datasets has driven need for integrative analytical platforms capable of reconstructing ancestral states while accommodating ambiguity. RASP (Reconstruct Ancestral State in Phylogenies) has developed as a frequently utilized tool for historical biogeography, enabling users to apply likelihood-based models, Bayesian frameworks, and parsimony approaches within a unified graphical environment. RASP 4 includes considerable developments, including generalized statistical integration across posterior trees, parallel computing capabilities, phylogenetic signal assessment, continuous and discrete trait evolution tools, and tree-comparison metrics. This paper synthesizes the theoretical underpinning, methodological framework, and practical functioning of RASP, stressing its implementation of BioGeoBEARS models (DEC, DIVALIKE, BAYAREALIKE), Bayesian Binary MCMC, and S-DIVA. Applications across plants, animals, fungi, and vertebrates indicate its capacity to infer biogeographic history, discover vicariance and dispersal mechanisms, and clarify evolutionary patterns under difficult topography or ecological circumstances. Case studies with Turkish Astragalus and Gundelia taxa indicate RASP`s usefulness in places with significant endemism and environmental variation, while examples from Malagasy lizards and fungal infections highlight its versatility in addressing phylogenetic and ecological concerns. Although RASP enables sophisticated visualization, model testing, and uncertainty integration, its output remains subject to geographic coding accuracy and model assumptions. Nevertheless, expanding genomic datasets and developing evolutionary models assure that RASP will continue to function as a crucial tool in biogeography, trait evolution, and macroevolutionary study.