Adaptive maternal effects in early life history traits help to maintain ecological resilience in novel environments for two contrasting Senecio species

Abstract

AbstractMaternal effects can maintain fitness across environmental conditions regularly experienced by a population. However, the consequences of maternal effects for ecological resilience in novel environments remain poorly understood. We produced seeds by breeding field-collected individuals of two closely related, but ecologically distinct, species of Sicilian daisy (Senecio, Asteraceae) in a quantitative genetics design. Using siblings of the same families, we quantified seedling root morphology in the laboratory, and planted seeds at four elevations that included the native elevation of each species. Seedling survival of both species was high at their native elevations, but declined at the novel elevation furthest from their native range, demonstrating adaptive divergence. Seedling development rate changed with elevation similarly for both species, and aligned with selection for faster development at lower elevation and slower development at higher elevation. Selection on paternal (sire) variance in development rate was consistent across elevation, and opposed phenotypic selection in the novel elevations. By contrast, selection on maternal variance in development rate changed with elevation and aligned with the direction of selection at both the native and novel elevations, suggesting that maternal effects underlying plasticity in development rate can increase fitness in novel environments. Selection on root morphology was only strong for the high elevation species, and occurred in the direction of the native phenotype for maternal variance, but not for sire variance. Together, these results suggest that maternal variation in development time plasticity and root architecture can increase ecological resilience in novel habitats, despite theory suggesting that they may reduce fitness in such situations.