A quantitative classification of distribution types for global seed plant genera: Spatial patterns and macroecological implications

Distribution types reflect the modern geographic patterns of biological lineages and serve as spatial proxies for their evolutionary and biogeographic histories. Here we present a comprehensive quantitative classification of 13,485 seed plant genera, grouping them into 26 distribution types across five major categories: “Worldwide Distribution”, “Tropical Regional Distribution”, “Tropical Intercontinental disjunction”, “Temperate–Boreal Distribution”, and “Temperate Intercontinental Disjunction”. The concentrated regions of genera corresponding to each regional distribution type align closely with globally recognized Biodiversity Hotspots, validating that genus-level distribution types can effectively identify areas of high biodiversity. Climatic niche analyses reveal that worldwide genera show a distinct temperate affinity, suggesting that these genera likely achieved their current distribution through an “out of temperate” expansion pathway. Furthermore, our findings provide quantitative support for the hypothesis that tropical alpine systems served as dispersal stepping-stones, facilitating floristic exchange between the Northern and Southern Hemispheres (i.e., amphitropical floristic exchange). This genus-level distributional framework provides a standardized reference for comparative macroecological and biogeographic research on global floras.