FIGURE 2.

Overview of parental Ruppia lineages and two distinct groups of hybrids detected using two sets of microsatellite markers in the Camargue area. It is important to note that parental species only amplified using markers designed for that particular species while hybrids were amplified using both primer sets. Panels (A,B) show the amplification success of different lineages with the R. maritima specific markers and the R. spiralis specific markers, respectively. The markers in bold are the three assumed cross-amplifying markers, and where used in both sets of markers. In panels (C,D), we see the clustering of different genetic lineages based on the alleles detected using both marker sets in a principal component analysis. Finally, panels (E,F) show the results of a complementary DAPC. This analysis shows the assignment of different genotyped individuals to clusters defined by the method. The principal component analysis (C,D) and the discriminant analysis of principal components (E,F) confirm the strong genetic differentiation between the hybrid populations and the pure species as well as the presence of two hybrid clusters. Based on the alleles present in the parental species, one group is expected to have a local origin, the other is presumably foreign. The eight samples of population D1b turn out to be backcrosses between the hybrids and R. maritima: they cannot be distinguished from pure R. maritima with the R. maritima markers, but group together with the hybrids when we used the R. spiralis markers.