Genetic differentiation of Rosa rubiginosa L. in two different Argentinean ecoregions

We analyzed genetic differentiation of Rosa rubiginosa by RAPD from populations growing in two Argentinean ecoregions, Chaco Serrano and Patagonian Steppe. Leaf material was collected during the spring and summer of 2006. UPGMA dendrogram and PCoA clearly suggest a geographical differentiation of the provenances of R. rubiginosa populations. AMOVA analyses revealed high genetic variation within populations (71%) and low variation between populations (29%), in agreement with values estimated by the Shannon–Weaver index. Genetic differentiation between populations estimated by AMOVA was ?_PT = 0.29 (P < 0.001). Nei’s Gst (0.2205) was lower for interpopulation variation. The low interpopulation value obtained suggests genetic homogeneity between the populations. The presence of specific monomorphic bands accounts for the genetic differentiation between populations. The high percentage of within-population genetic diversity suggests the introduction of genetic variation into both ecoregions. From the present results we can conclude that we observed two independently established populations with high similarity between them and a strong intrapopulation differentiation. The empty niche hypothesis for explainging invasion success might explain the invasiveness of R. rubiginosa in Argentinean ecoregions.