Fuentes de variación en el tamaño de la semilla de la herbácea perenne Helleborus foetidus L. (Ranunculaceae)

Abstract

Seed size is one of the plant traits more thoroughly studied in plant sciences due to its pivoting ecological position between dispersal processes and emergence, survival and establishment of plant species. Frequently, most seed size variation is located within plant, exceeding variation between plants and between populations. Resource allocation and type of pollination are some of the main causes of within-plant variation in seed mass. This work explores seed mass variation in Helleborus foetidus trying to assess the relative importance of its possible causes. We thoroughly sampled seed size in two hellebore populations by partitioning its variance in the hierarchic levels of population, plant, flower, carpel, and within carpel. Our results show that the most important source of variance is the within-plant variation. Among the factors most likely responsible for variability at this level, our study suggests that resource allocation exerted the strongest influence. In particular, some evidence points towards a relevant role of the post-anthesis flower functionality on the resource allocation to seeds. Although needing further experimental research, we suggest that such functionality is due to the photosinthetic ability of the perianths of Helleborus foetidus flowers. Some variables related to the reproductive effort accounted for the between-plant variation in mean seed mass. Particularly, a trade-off between seed mass and seed production and the costs related to the pollination type are also contribute to the variation of seed size at this level.