Abiotic factors modulate phenotypic plasticity in an apomictic shrub [Miconia albicans (SW.) Triana] along a soil fertility gradient in a Neotropical savanna

Abstract

Phenotypic plasticity is an important means by which plants cope with environmental heterogeneity; therefore, understanding variation in plant traits in heterogeneous habitats is important to predict responses to changing environments. In this study, we examined the patterns of intraspecific variation in leaf traits of Miconia albicans (Melastomataceae), a widespread, obligatory apomictic shrub, across a soil fertility gradient in the Cerrado (Brazilian savanna). We predicted high plasticity because selection favours high phenotypic plasticity in asexual populations with low genetic variability. Leaves were sampled in campo sujo (grassland), cerrado (savanna) and cerradão (woodland) in south-eastern Brazil during both dry and rainy seasons to calculate leaf area, specific leaf area, leaf tissue thickness, trichome and stomata density. We found significant between-season variation in leaf traits, indicating that the production of season-specific leaves is a strategy to cope with the strong seasonality. Both multivariate analysis and the relative distance plasticity index indicate lower plasticity during the dry season, especially under shade. Our results show that the phenotypic plasticity can be modulated by changes in abiotic factors and the combination of shade and drought can limit the expression of phenotypic plasticity.