Ecological significance of intraplant variation: Epigenetic mosaicism in Lavandula latifolia plants predicts extant and transgenerational variability of fecundity‐related traits

Abstract

Abstract Intraindividual epigenetic mosaicism is probably widespread among long‐lived plants, yet its ecological significance as a potential source of variation in fitness‐related traits in plant populations remains virtually unexplored. This paper examines the hypothesis that extant epigenetic variation within plants can have both current and transgenerational fecundity correlates which could eventually translate into fitness variations among different parts of the same individual and their respective offspring. Five modules, each consisting of a terminal branchlet bearing one inflorescence and its subtending leaves, were collected from each of 15 wild‐growing Lavandula latifolia (Lamiaceae) plants. They were characterized epigenotypically by the methylation state of methylation‐sensitive amplified fragment length polymorphism (MS‐AFLP) markers, and phenotypically by fecundity‐related traits (inflorescence length, and size, number and mass of seeds produced). Seeds from the different modules were sown in the greenhouse and resulting ‘subprogenies’ characterized phenotypically (germination probability and time to emergence, seedling size, susceptibility to fungal disease). All plants sampled were internally heterogeneous with regard to the methylation state of 1%–13% of MS‐AFLP markers. Predictable relationships were found between epigenotypic and phenotypic variation across the extant modules of individual L. latifolia shrubs. Phenotypes of subprogenies from different modules of the same plant grown under homogeneous conditions in the greenhouse were predictably related to the epigenotype of the maternal module which produced the seeds. Synthesis. The variable epigenotypes of different modules in the same plant not only predicted extant phenotypic variation among the modules themselves, but also phenotypic differences among the subprogenies produced by different modules. These relationships linking intraplant epigenotypic mosaicism with both extant and transgenerational heterogeneity in fitness‐related traits support the ‘epigenetic mosaicism hypothesis’ for plant variation, and also suggest hitherto unexplored ecological consequences of epigenotypically enhanced variation in the context of plant populations and communities.