Life‐history traits and survival responses to light and water of the rare endemic species <i>Cuphea gaumeri</i> Koehne (Lythraceae)

Abstract Endemic plant species represent a particular conservation challenge because they are often more susceptible to threats such as changes in climatic regimes. Therefore, it is essential to understand the role of variations in climatic variables in the life‐history traits of endemic species. Cuphea gaumeri , a rare tropical endemic of the Yucatán Peninsula, Mexico, occurs in heterogeneous habitats, including evergreen and seasonally dry forests. We conducted a factorial experiment to evaluate the effects of light (sunlight vs. shade) and water availability on four demographic traits: germination, growth, reproduction, and survival. Germination percentage increased at high levels of water availability, and higher water levels reduced the number of days to germination regardless of light conditions. Plant growth increased under shaded conditions with medium to high water availability, highlighting the interaction between light and water. Time to reproduction was delayed in plants exposed to low water availability, whereas plants with higher water levels reproduced earlier, regardless of light conditions. Survival probabilities were highest for plants grown in sunlight with high water availability. This suggests that water can mitigate the stress caused by sunlight exposure by supporting metabolism and reducing light stress, which ultimately enhances plant performance and survival. Overall, the responses of C. gaumeri suggest adaptation to the seasonal flooding of its native habitats, resembling those observed in riparian species. These findings underscore the role of water availability in shaping life‐history traits and highlight the importance of protecting seasonally flooded habitats. These insights can guide conservation strategies for tropical endemic species facing micro‐ and macro‐environmental changes.