Upper Rhine Valley: A migration crossroads of middle European oaks Authors: Charalambos Neophytou & Hans-Gerhard Michiels Authors’ affiliation: Forest Research Institute (FVA) Baden-Württemberg Wonnhaldestr. 4 79100 Freiburg Germany Author for correspondence: Charalambos Neophytou Postal address: Forest Research Institute (FVA) Baden-Württemberg Wonnhaldestr. 4 79100 Freiburg Germany Telephone number: +49 761 4018184 Fax number: +49 761 4018333 E-mail address:
[email protected] Short running head: Upper Rhine oak phylogeography 1 ABSTRACT 2 The indigenous oak species (Quercus spp.) of the Upper Rhine Valley have migrated to their 3 current distribution range in the area after the transition to the Holocene interglacial. Since 4 post-glacial recolonization, they have been subjected to ecological changes and human 5 impact. By using chloroplast microsatellite markers (cpSSRs), we provide detailed 6 phylogeographic information and we address the contribution of natural and human-related 7 factors to the current pattern of chloroplast DNA (cpDNA) variation. 626 individual trees 8 from 86 oak stands including all three indigenous oak species of the region were sampled. In 9 order to verify the refugial origin, reference samples from refugial areas and DNA samples 10 from previous studies with known cpDNA haplotypes (chlorotypes) were used. Chlorotypes 11 belonging to three different maternal lineages, corresponding to the three main glacial 12 refugia, were found in the area. These were spatially structured and highly introgressed 13 among species, reflecting past hybridization which involved all three indigenous oak species. 14 Site condition heterogeneity was found among groups of populations which differed in 15 terms of cpDNA variation. This suggests that different biogeographic subregions within the 16 Upper Rhine Valley were colonized during separate post-glacial migration waves.