Chloroplast and nuclear evidence for multiple origins of polyploids and diploids of Hedera (Araliaceae) in the Mediterranean basin.

Chloroplast (trnT-L) and nuclear rDNA (ITS) sequence analyses of the Araliaceae provide strong molecular evidence for the monophyly of the genus Hedera. Phylogenetic reconstructions suggest multiple origins and an active polyploidization process not only in the formation of tetraploids (2n = 96), hexaploids (2n = 144), and octoploids (2n = 192), but also of diploids (2n = 48). A high basic chromosome number of x = 24, extensive polyphyly in widespread diploids, and terminal placement of Hedera in phylogenies of the Araliaceae reveal that extant diploid taxa may be, in fact, assemblages of ancestral polyploids from plants of n = 12. Four major lineages containing four types of chloroplast (chlorotypes I, II, III, and IV), which are defined by different trnT-L nucleotide substitutions and two large insertions (50- and 30-bp), provide evidence for evolutionary processes and historical biogeography in Hedera. We propose a scenario where an initial colonization in the Mediterranean basin by Asian ancestors (carrying the ancestral Araliaceae chlorotype I) is followed by differentiation into the four chlorotypes of the Mediterranean region, and then recolonization of Asia and northern Europe only by chlorotype III. The Macaronesian taxa (Hedera azorica, Hedera maderensis ssp. maderensis, and Hedera canariensis) appear to have originated from a single-colonization event to each archipelago with no further contact either with continental or insular species.

Phylogenetic position of Mediterranean Astereae and character evolution of daisies (Bellis, Asteraceae) inferred from nrDNA ITS sequences.

Phylogenetic analyses of nrITS sequences of Asteraceae revealed that the Bellis group is a natural assemblage comprising all the species of Bellis and Bellium, but not Rhynchospermum. In contrast, we propose to include the genera Bellis, Bellium, and Bellidastrum in the subtribe Bellidinae in the interest of circumscribing natural groups. Our results also suggest an early diversification in the western Mediterranean Basin of two monophyletic lineages, Bellis and Bellium. Three major groups can be distinguished within BELLIS: (1) the B. perennis group, containing five annual and perennial species with three ploidy levels (diploid, octoploid, and decaploid), which are distributed throughout the Mediterranean Basin despite lack of pappus; (2) the Bellis sylvestris group, with five annual and perennial species primarily from the western Mediterranean, in which there are five ploidy levels (diploid, tetraploid, hexaploid, octoploid, and decaploid); and (3) a basal grade consisting of three diploid, perennial species which displays remarkable diversification of morphologies. Striking characteristics, such as an annual life form, polyploidy, and loss of pappus, seem to have occurred in parallel several times and in different geographical areas during the early diversification of Bellis species in the western Mediterranean. Character evolution reconstructions allow us to describe a putative ancestor of the genus Bellis (proto-Bellis).