Contrasting genome-size constraints relate to divergent elemental strategies in bryophytes and tracheophytes

Genome size (GS) varies widely across plant lineages, yet its ecological consequences remain unclear. Here, we first examined how GS and climatic variables relate to the size of the reproductive unit and biogeochemical niche (i.e., elemental hypervolume) in bryophytes and tracheophytes (vascular plants). GS is positively associated with pollen and seed size in vascular plants but does not influence spore size in bryophytes. Moreover, GS was positively related to elemental flexibility in bryophytes but not in vascular plants, whereas climatic factors showed the opposite pattern. Elemental and climatic hypervolumes are coupled in vascular plants but decoupled in bryophytes. Overall, regardless of whether GS is an adaptive trait or not, GS can impose ecological and physiological constraints through lineage-specific effects on propagule size and physiological flexibility, reflecting the distinct evolutionary pathways followed by bryophytes and vascular plants during the colonization of land.