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Reseda sect. Glaucoreseda is a monophyletic group composed of five endemic tetraploid species with a disjunct distribution in the high mountains and plateaus of the Iberian Peninsula and Morocco. It was previously suggested that range shifts induced by Quaternary glaciations played an important role in the speciation of the group. We studied the evolution of R. sect. Glaucoresedain order to infer historical range dynamics and speciation processes, and to understand current distributional patterns. Phylogeographic analyses were performed using nuclear ribosomal ITS and plastid trnL–Fand rps16sequences. Cloning of additive ITS sequences was carried out to elucidate the origin of intra–individual polymorphisms. A dated phylogeny based on ITS and cpDNA (rbcL, matK, trnL–F) sequences was used to estimate divergence times of R. sect. Glaucoreseda. Time estimates using Penalized Likelihood analyses indicate a late Pleistocene diversification of R. sect. Glaucoreseda. Incomplete lineage sorting of ancestral polymorphisms due to recent divergence, rather than rampant hybridisation, is suggested as the main cause of the phylogenetic incongruence detected between nuclear and plastid datasets. Our results support the vicariance hypothesis for population disjunctions in the Iberian Peninsula, in which an ancestral, widespread species could have undergone differentiation by Quaternary interglacial fragmentation. In contrast, long–distance dispersal across the Strait of Gibraltar may have been involved in the colonisation of North African plateaus by R. battandieri.

Arenaria sect. Plinthine is an easily distinguishable morphologically cohesive group encompassing 14 species and five additional subspecies. To explore phylogenetic relationships and search for phylogeographic patterns in a group that is restricted to the western Mediterranean, independent and combined analyses of four datasets (morphological characters and sequences from nuclear and plastid DNA: nrITS, trnT–trnL, trnL–trnF) were conducted using Maximum Parsimony, Neighbour–Joining, Maximum Likelihood and Bayesian Inference. Monophyly of the section is supported by the data, the ITS sequences show full agreement with taxonomy for one third of the taxa, and the high number of trnL–F haplotypes found in SE Spain (7 of 11) is consistent with the fact that this region is one of the hotspots of biodiversity in the Mediterranean. However, a number of less easily interpretable results have been obtained, despite considerable ITS variation (43 parsimony informative characters within the ingroup) and a reasonable intraspecific sampling for this marker. These results are: low resolution at deep nodes of the ingroup, partial discordance between taxonomy and ITS sequences particularly for widespread taxa, and lack of congruence not only between the topologies of the plastid and nuclear trees but also between the two plastid trees. It is proposed that a combination of factors (rampant aneuploidy, polyploidy, hybridization, lineage sorting, and concerted evolution of ITS sequences) are responsible for the incongruent but not totally unexpected results.