Format: ORAL

Frantiek Zedek1, Tammy L. Elliott1,2, Pavel Vesel1, Petr marda1, Flix Forest3, Ilia J. Leitch3, Eimear Nic Lughadha3, Marybel Soto Gomez3, Samuel Pironon3,4, Matilda J. M. Brown3, Jakub merda1, Petr Bure1

1 Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno, Czech Republic 2 Department of Biological Sciences, University of Cape Town, Cape Town 7700, South Africa 3 Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AE, United Kingdom 4 UN Environment Programme World Conservation Monitoring Centre (UNEP-WCMC), Cambridge, Cambridgeshire, CB3 0DL, United Kingdom

Angiosperms, spanning diverse habitats across continents, showcase substantial genome size variations, offering a prime platform to explore global genome size distribution hypotheses. Among these, the large-genome-constraint, mutational-hazard, polyploidy-mediated, and climate-mediated hypotheses stand central. We present the most extensive dataset to date, comprising 16,017 angiosperm species, representing over 5% of the known diversity. Leveraging this dataset alongside comprehensive geographic distribution data, we conducted an in-depth analysis of genome size distribution among angiosperms. Our findings reveal a correlation between small range sizes in angiosperms and larger genomes, supporting the large-genome-constraint hypothesis. Unlike the unimodal U-shape pattern in latitudinal distribution observed in polyploid proportions, we observed the S-shape with the increase in angiosperm genome sizes between the equator and 40-50N/S and a decrease in genome sizes beyond 4050N northwards. Climate, especially temperature, emerges as a dominant factor shaping genome size distribution along this global latitudinal gradient. Conversely, the influence of polyploidy frequency and growth form types appears negligible. Our comprehensive analysis underscores the significant role of climatically mediated non-adaptive processes, including purifying selection, genetic drift, relaxed selection, and environmental filtering, in sculpting the global distribution of angiosperm genome sizes.