Signals from the past: preliminary evidence on the role of ancient and historical landscape changes on population genetic structure of Macedonian oak (Quercus trojana Webb.) in Puglia (Italy)

The study aimed at investigating the possible environmental factors that have led to the presence of three genetic pools, defined in previous population genetics analysis, in Macedonian oak germplasm (Quercus trojana Webb) of a disjunct part of the species distribution range (Puglia, Italy). A Paleogeographic analysis and a Landscape genetics approach, based on specific methods for multivariate spatial data analysis, were applied. These allowed to verify the isolation by distance hypothesis and to generate other hypotheses likely to underlie different evolutionary processes (gene selection and gene flow). The results confirm the population genetic structure previously observed and suggest its very ancient origin, probably due to geodynamic and phytogeographic events as from at least late Miocene times, only subsequently influenced by land use changes that in historical times have led to the fragmentation of forests and of Macedonian oak habitat. These are preliminary, yet important, findings relevant to strategies aimed at the conservation and the adaptive forest/landscape management, of this endemic species, in the context of climate change.