Phenotypic plasticity in amphibious plants across a latitudinal (climatic) gradient

Temporary ponds are vital ecosystems in the Mediterranean basin, supporting many specialized species. Plants must endure significant interannual fluctuations in pond hydrology and may face increased stress from climate change. While research has largely focused on community‐level dynamics, we still lack a clear understanding of how species respond to hydrology and the relative roles of plasticity versus adaptation in their responses. We studied selected vegetative (height, number of leaves, leaf area) and reproductive (number of fruits, number of seeds/spores per fruit, number of seeds/spores per plant, seed/spore size and seed mass) traits of six characteristic species (of the genera; Baldellia, Damasonium, Elatine and Isoetes ) in 20 temporary ponds along a 750 km north–south latitudinal (climate) gradient (31°–35°N) in Morocco (mean annual precipitation range 264 to 856 mm). Traits were assessed on both field‐collected specimens and those grown from seeds/spores in mesocosms under uniform experimental conditions. Our results showed a significant correlation between latitude and plant traits in the field. From north (humid) to south (dry), plants became shorter, with fewer and smaller leaves, fewer fruits, smaller seeds/spores, lower mass per fruit/sporangium, and fewer seeds per plant. Reduced growth and fecundity along the gradient likely result from limited and variable flooding in the south, increasing plant stress. However, these differences in traits were not observed when the plants were grown under common garden conditions. This pattern strongly suggests that differences in plant traits across the six species are mainly due to phenotypic plasticity to local hydrological conditions, although potential genetic differentiation cannot be excluded. In conclusion, phenotypic plasticity, likely favored by large interannual variations in hydrological conditions, may enhance species resilience to climate change and may aid in population transfers for restoration projects.