Phylogenetic constraints and edaphic factors drove Neogene diversification of the Eurasian herb, Paris L.: The significance of genome size variation in genomic gigantism

Gao, Xiaoyang

PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY

2026

694

Liu, CN

Genome size (GS) variation is of fundamental biological importance, yet its evolutionary drivers and ecological implications remain uncertain. In this study, we focus on Paris L., a giant-genome angiosperm genus boasting a staggering 29-152 pg/1C range, which represents an exemplary paradigm for addressing these issues. Specifically, we present GS quantified across the entire genus via flow cytometry, and integrated phylogenetic reconstruction, geographic distribution patterning, and environmental correlation analyses to provide a comprehensive synthesis of GS evolution within an ecological context. We detected extensive GS variation across taxonomic hierarchies and revealed significant phylogenetic signals, indicating evolutionary conservatism tempered by adaptive shifts across lineages. Pronounced adaptive deviations are evident along geographic gradients, with GS increasing with longitude yet decreasing with latitude and altitude. GS exhibits significant correlations with root zone soil properties, particularly fertility and structural parameters. Variance partitioning demonstrates that soil physicochemical variables independently explain over 78.44% of GS variation, overwhelmingly surpassing phylogenetic effects. These patterns reflect edaphic niche conservatism within a deeptime landscape shaped by late Miocene tectonic and climatic shifts that may have underpinned GS diversification. Our findings elucidate the intricate synergy of phylogenetic inertia and powerful environmental selection, with persistent edaphic heterogeneity likely contributing to lineage-specific differentiation in GS. Our findings highlight a dynamic interplay between neutral and adaptive processes in GS diversification, offering novel insights into the underlying eco-evolutionary mechanisms underpinning genomic giants in angiosperms.