Phylogeny of genus Castanea Miller and identification of C. latifolia (Sord.) in 45,000-year-old samples from Venice Lagoon

The phylogeny of the genus Castanea Miller and its biogeographic history are presented. The sequence of the trnL-trnF chloroplast DNA region was determined for 4 species of the genus Castanea and for fossil samples including C. latifolia Sord., a species considered extinct based on palynological evidence. The fossil material was collected from a site of North-East Italy dating back to a period between the final phases of the last Interglacial and the beginning of the last Würmian glaciation (45,000-year-old). The DNA sequences amplified from the fossil sample indicate that they belong to the genus Castanea but not to the extant Castanea species. The optimal solution of phylogeny and dispersal-vicariance analyses indicated that the ancestral area of speciation of Castanea was the Middle East. The lineage first diverged for dispersion into two sublineages, one with an ancestral area in the Middle East and the second with an ancestral area in Eastearn Asia, which later became fragmented by a vicariant event separating the existent species present in the Middle-East, Europe and Eastern Asia. At least a dispersal event from the sublineage Eastearn was directed towards North America.