Message in a bottle: the Mediterranean Sea currents acted as protagonists in shaping the distribution of the sea daffodil (Pancratium maritimum, Amaryllidaceae)

The Mediterranean Basin can be considered as a natural laboratory with which to study the effects of sea currents in the dispersal of coastal plant species that use hydrochory. Pancratium maritimum is a perennial geophyte, with a wide distribution along Mediterranean coasts. We aim to provide a timeframe for the origin of the diversification of this plant, to clarify its phylogeographical structure and to investigate the role of currents in the Mediterranean Sea in influencing spatial patterns of its genetic distribution. The phylogeographic history was analysed using 50 populations. A genetic structure analysis and divergence time estimation was performed using plastid sequences. Five haplotypes were detected, of which two were the most abundant; a third was observed in the central Mediterranean, and two rare haplotypes were present in the eastern Mediterranean. The genetic breaks were concordant with the direction of the major Mediterranean currents. The divergence time estimation for the origin of P. maritimum was located at the end of the Neogene (mid Pliocene to mid Pleistocene). We showed the importance of sea currents in the Mediterranean in acting both as a means of dispersal and as a barrier to the distribution and evolution of P. maritimum due to the special adaptations of its seeds.