Nuclear markers (AFLPs) and chloroplast Microsatellites differ between Fagus sylvatica and F-orientalis

Abstract

Former studies based on chloroplast markers and allozymes suggested that postglacial recolonization of central Europe by Fagus sylvatica L. occurred from one or a few undifferentiated refuges. Here, we examine F. sylvatica from Germany and Greece and different provenances of F sylvatica ssp. orientalis (Lipsky) Greut & Burd. (E orientalis Lipsky) with chloroplast microsatellites and AFLP markers. Only such AFLP markers were selected that had shown a differential amplification in F sylvatica and F. orientalis in a preliminary analysis. UPGMA cluster analysis of AFLP data distinguished one F sylvatica group and one F. orientalis group from northern Turkey. Low structuring in the neighborjoining analysis and the lack of diagnostic bands for either taxon suggests a relatively recent differentiation in Fagus orientalis and F sylvatica. High bootstrap values were only found for a separate cluster that comprises F. orientalis from two different forest botanical gardens. Four of these samples have a unique chloroplast type and are genetically very similar (bootstrap value 96) mostly likely due to clonal replication. Only two different chloroplast types (type 1 in Germany, type I and type 2 in Greece) could be detected for F sylvatica. In contrast, F. orientalis from northern Turkey showed different chloroplast types even within one provenance pointing to a glacial refuge in northern Turkey and a bottleneck at the time of postglacial recolonization of central Europe. The classification of ten samples from northern Turkey as F sylvatica by AFLP data, chloroplast markers and morphology questions the interpretation of F orientalis and F. sylvatica as two geographically separated (allopatric) taxa.