Shifting in the shadows: Morphofunctional variations of <i>Miconia sellowiana</i> Naudin (Melastomataceae) associated with cave environments

Caves present unique ecological conditions that influence the distribution and adaptation of species, yet studies on cave-associated vegetation remain limited. This study investigated how cave conditions affect the functional traits of Miconia sellowiana Naudin (Melastomataceae), comparing individuals from the cave interior with those from the adjacent understory. Our objective was to understand how these environments influence the species' morpho-functional characteristics and ecological relevance, aiming to identify physiological responses to the constraints of each habitat. Based on this, we hypothesize that caves act as distinct environmental filters compared to the understory, selecting for unique morphological and physiological variations. Leaf morpho-functional traits were evaluated, including macroscopic dimensions (length, width, and leaf area) and microscopic characteristics, such as the anatomy of the central vein, mesophyll, and epidermis. Samples were fixed, processed for histological sections, and analysed by optical and electron microscopy. Statistical analysis included PCA to identify morpho-functional patterns and Student's t-tests/Wilcoxon tests to compare variables between habitats. Cave individuals had thinner leaves, with fewer layers of photosynthetic parenchyma, smaller relative phloem area in the central vein, lower stomatal density, and reduced leaf area and length compared to understory individuals. Low light availability, high humidity, shallow soils, and nutrient scarcity in caves likely limit the development of thicker leaves and affect stomatal density, vascular tissue, and leaf size. These results suggest that cave environments drive morpho-functional and physiological variations in surrounding plants. This study fills gaps in the literature and highlights ecological mechanisms that sustain life in subterranean ecosystems.