Phenotypic rebuilding after fire: Understanding within‐individual variability in a Mediterranean shrub

Abstract Due to the modular nature of plants, plant phenotypes are heterogeneous and dynamic within individuals. Previous studies have shown that certain environmental drivers can modulate variability within plant traits, but the effects of disturbances such as fires remain unknown. Fire may potentially act as a driving force of within‐individual and population‐level dynamics following resprouting. Specifically, we hypothesize that post‐fire resprouting rebuilds plant phenotype by restarting plant development and erasing the previous developmental history. Consequently, we predict that burned (resprouting) and unburned plants differ in their phenotype and that this difference will have fitness consequences. To test this hypothesis, we studied a population of the leguminous shrub Anthyllis cytisoides (Fabaceae) that was partially affected by a wildfire, allowing us to compare resprouting (burned) and undisturbed individuals in close proximity. We measured leaf, flower, seed and fitness traits, as well as global cytosine methylation—an indicator of epigenetic status, at a within‐individual level. Our results show that, for every study trait, burned and unburned individuals differed in at least one of the three dimensions we studied (mean value, total variability, within‐individual variability). Burned plants showed a generalized increase in within‐individual variability, including global cytosine methylation, as well as shifts in the relationship between this trait and several others, such as petal size and leaf shape. This pinpoints a possible epigenetic mechanism in explaining the phenotypic differences. Furthermore, higher seed set and altered floral–fruit set relationships in resprouting plants suggest fitness consequences of these phenotypic changes. Synthesis . We found that burned resprouting individuals of A. cytisoides differed significantly in phenotype, global cytosine methylation, and the relationship between floral phenotype and fitness, compared to neighbouring undisturbed individuals. These findings support the idea that fire can alter the phenotype of individual plants, potentially through epigenetic mechanisms, and suggest that these changes may affect plant–animal interactions.