Fine-scale response to landscape structure in Primula vulgaris Huds.: does hedgerow network connectedness ensure connectivity through gene flow?

Variation in pollen flow, mating performances, and seed dispersal were examined using direct and indirect approaches in contrasted hedgerow networks (i.e., dense vs. sparse) of the distylous Primula vulgaris. Seed dispersal reached negligible distances, and no difference was observed between the two hedgerow networks. On the contrary, pollen flow through Bombylius sp. activity was impeded in the dense hedgerow network. Furthermore, P. vulgaris was found to be partially self-compatible in our study site. The lower pollen flow in the dense hedgerow network, and especially in small populations, is likely to have unusually favoured self-compatibility and hence selfing in P. vulgaris short-style morph. In addition, the inbreeding depression values recorded were higher in the dense hedgerow network. Our results suggested that a dense hedgerow network does not necessarily ensure connectivity in Primula vulgaris in terms of gene flow. This study provides evidence for considering landscape structure in the microevolutionary processes.