Adil GÜNER, Vehbi ESER - optima

GENETIC DIFFERENTIATION IN SONCHUS SECTION PUSTULATI
THREATENED TAXA (ASTERACEAE)
Jose L. SILVA 1 , José A. MEJIAS
Seville University, Department of Plant Biology and Ecology, Apdo. 1095, 41080 Seville, Spain 1 jlsilva@us.es
Genus Sonchus section Pustulati Boulos consists of three species: S. pustulatus, S. fragilis and
S. masguindalii, which clearly constitute a monophyletic group within the genus (Kim, 2007).
The species are confined to coastal and low altitude rocky walls enclaves from both sides of
Western Mediterranean Basin, although S. pustulatus is the single taxa occurring in northern
side. All species has been considered very scarce in Morocco (Fennane & Ibn Tattou, 1998),
meanwhile S. pustulatus is cataloged as "critically endangered species (CR)" in Spain
(Bañares et al., 2003), where exclusively some hundreds of individuals have been registered.
In order to study the genetic diversity of populations and phylogeographic patterns among
them, we genotyped 167 individuals from seventeen populations using AFLP molecular
analysis technique. Three chosen primer combinations generated 249 unambiguously DNA
fragments. Genetic distances were analysed at different group levels to detect the presence of
specific barriers to gene flow. Different methods such as neighbour-joining, AMOVAs,
principal co-ordinate analysis and Bayesian clustering (STRUCTURE) revealed that
Mediterranean Sea and Gibraltar Strait are acting as an efficient barrier between Moroccan
and Spanish S. pustulatus populations. FST values also indicate that populations from Western
Rif should be considered as a large metapopulation. On the other hand, in S. masguindalii,
eastern populations showed the highest values of rare fragment index (DW), genetic diversity,
and number of polymorphism fragments, indicating a long-term isolation, in spite of the
continuous distribution pattern.
In general, population genetic diversity (Hj) ranges from 0.09 to 0.17, Iberian S. pustulatus
populations showing lowest values of genetic diversity. This factor and the low number of
individuals indicate that these populations show the highest extinction risk in the group.
Keywords: W Mediterranean, ALFP, phylogeography, genetic diversity, conservation.
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