Ecophysiological differentiation between life stages in filmy ferns (Hymenophyllaceae)

Desiccation tolerance was a key trait that allowed plants to colonize land. However, little is known about the transition from desiccation tolerant non-vascular sensitive vascular ones. Filmy ferns (Hymenophyllaceae) represent useful system investigate how water-stress strategies differ between and stages within single organism because they have vascularized sporophytes nonvascular gametophytes are each capable of varying degrees tolerance. To explore this, we surveyed 19 species (22 taxa including varieties) filmy on Moorea (French Polynesia) used chlorophyll fluorescence measure light responses. We conducted phylogenetically informed analyses identify differences in physiology life growth habits. Gametophytes had similar or less (ability recover 2 days at ? 86 MPa) lower photosynthetic optima (maximum electron transport rate photosystem II level 95% rate) than sporophytes. Epiphytes were more terrestrial both stages. Despite their lack greater physiological tolerances, several occurred over wider elevational range conspecific Our results demonstrate fern niche requirements, point importance microhabitat shaping evolution water-use plants.