Velocity of the falling dispersal units in Zelkova abelicea: remarkable evolutionary conservation within the relict tree genus.

Members of the genus Zelkova, growing today in distant regions, show remarkable evolutionary conservation of the velocity and flight mechanics of their dispersal units. This is surprising because the Mediterranean and East Asiatic Zelkova species have been separated at least 15-20 mya. Zelkova abelicea, although growing in the Mediterranean with completely different forest structure and composition, still uses the same dispersal mechanism. The dispersal capacity of the genus Zelkova is less efficient than that of other wind dispersed trees, and it presumably evolved for short-distance ecological spread and not for long-distance biogeographical dispersal.