Population genetic analyses of Ferula gr. communis and Ruta gr. corsica in the Tyrrhenian area

The Western Mediterranean Islands represent a major hotspot of plant diversity in the Mediterranean area and are priority regions for conservation due to their high number of endemic plant species. However, information supporting human decision-making on the conservation of these species is still scarce, especially at the genetic level. In this thesis the first assessment is reported of the genetic diversity and structure of the Corso-Sardinian endemic Ferula arrigonii (Apiaceae) and of Ruta corsica and R. lamarmorae (Rutaceae), endemic to Corsica and Sardinia, respectively. The main aim was to provide suggestions for the conservation of these rare species. In the case of the genus Ferula, the widespread F. communis was also analyzed in order to gain information on its genetic diversity and structure in the Tyrrhenian area and to compare it with the endemic F. arrigonii. Nine populations (179 individuals) of F. arrigonii were investigated by means of AFLP (Amplified Fragment Length Polymorphism) markers. Results indicate that this species is characterized by high levels of genetic polymorphism (about 92% of the fragments were polymorphic), a low inter-population differentiation (Gst = 0.124) and a high intra-population variation (Hw = 0.317). PCoA, Bayesian analysis and neighbor-joining clustering were also employed to investigate the genetic structure of this species. Three genetically distinct groups were detected, although with considerable overlap between sampling sites. The AFLP analysis of 12 populations of F. communis (168 individuals) from four different islands (i.e. Minorca, Corsica, Sardinia and Sicily) and the Tyrrhenian coast revealed that the populations form an homogeneous group irrespective of the geographic provenance, with the only exception of individuals belonging to F. communis subsp. glauca. Genetic diversity values were not significantly different with respect to those of the endemic F. arrigonii. As regards the genus Ruta, a set of 11 microsatellite markers was used to assess the genetic diversity and the spatial structure of the genetic variation of 96 individuals of R. corsica (6 populations) and 63 individuals of R. lamarmorae (3 populations). The markers were highly polymorphic and detected 10 alleles per locus on average. Overall, results showed that both species have maintained relatively high levels of genetic diversity (He = 0.579 and 0.639, Ho = 0.558 and 0.591 for R. corsica and R. lamarmorae, respectively). Pairwise Fst values (0.035 – 0.351) indicated a low-moderate differentiation for most pairs of populations. AMOVA revealed that 80% of the genetic variation resides within populations, while only 4% is due to differences among the two species. The analyses of the spatial genetic structure suggested the clustering of the individuals into two groups, approximately corresponding to taxonomic affiliations.