The global distribution of angiosperm genome size is shaped by climate

O_LIAngiosperms, which inhabit diverse environments across all continents, exhibit significant variation in genome sizes, making them an excellent model system for examining hypotheses about the global distribution of genome size. These include the previously proposed large-genome-constraint, mutational-hazard, polyploidy-mediated, and climate-mediated hypotheses. C_LIO_LIWe compiled the largest genome size dataset to date, encompassing >5% of known angiosperm species, and analyzed genome size distribution using a comprehensive geographic distribution dataset for all angiosperms. C_LIO_LIWe observed that angiosperms with large range sizes generally had small genomes, supporting the large-genome-constraint hypothesis. Climate was shown to exert a strong influence on genome size distribution along the global latitudinal gradient, while the frequency of polyploidy and the type of growth form had negligible effects. In contrast to the unimodal patterns along the global latitudinal gradient shown by plant size traits and polyploid proportions, the increase in angiosperm genome size from the equator to 40-50{degrees}N/S is probably mediated by different (mostly climatic) mechanisms than the decrease in genome sizes observed from 40-50{degrees}N northwards. C_LIO_LIOur analysis suggests that the global distribution of genome sizes in angiosperms is mainly shaped by climatically-mediated purifying selection, genetic drift, relaxed selection, and environmental filtering. C_LI