CAN THE SPREAD OF AGRICULTURE IN EUROPE BE FOLLOWED BY TRACING THE SPREAD OF THE WEED SILENE LATIFOLIA - A RAPD STUDY

On the basis of gene frequency data of three flavone glycosylating gen es, populations of the agricultural weed Silene latifolia (Caryophylla ceae) in Europe can be divided into two chemical races: an eastern and a western race. Morphological data also show a clear east-west divisi on. When the two datasets are combined at least nine different geograp hical races can be distinguished using cluster analysis. Because these observations are hard to explain by selection, it has been proposed t hat these different races probably originated as a consequence of migr ation during the spread of agriculture over Europe in the past. To dis criminate between selection and genetic drift many more selectively ne utral easy-to-score characters are needed. In order to test whether ra ndom amplified polymorphic DNAs (RAPDs) might be suitable for this pur pose, we performed a small-scale RAPD analysis on 16 geographical diff erent populations. Using Jaccard's coefficient of similarity, we calcu lated genetic distances by pair-wise comparisons of both unique and sh ared amplification products, and a dendrogram was subsequently constru cted using an unweighted pair-group method with arithmetical averages (UPGMA). On the basis of the dendrogram two clusters were discerned th at clearly coincide with the aforementioned east-west division in popu lations. As there has been little or no artificial selection on this w eed, its migration routes may be a good reflection of the different ge ographical routes agriculture has taken. We propose that a phylogeneti c analysis of RAPD data of many more populations may provide additiona l information on the spread of agriculture over Europe.