Flavonoid Evolution in Dendroseris (Compositae, Lactuceae) From the Juan Fernandez Islands, Chile

Abstract

Leaf flavonoid chemistry was examined from the three subgenera and 11 species of the endemic genus Dendroseris (Compositae, Lactuceae) of the Juan Fernandez Islands, Chile. Eight of the species are restricted to the older island (Masatierra, ca. 4 million years old), which is also closer to the mainland. Three species, one from each subgenus, are restricted to Masafuera, which is younger geologically (1–2 million years old) and 145 km further west of Masatierra. A total of 16 compounds was identified, with the 7‐0‐glucosides of the flavones apigenin and luteolin accounting for 12 of the constituents. Two glucosides of the flavonol quercetin were detected. Despite considerable interpopulation variation within species, six of the taxa have distinctive flavonoid profiles. Although there are few absolute differences among the subgenera, they can be distinguished chemically. Subgenus Rea contains the greatest number of compounds, and a previous cladistic analysis based on morphological features suggested this subgenus as most primitive. Subgenus Phoenicoseris is considered highly derived morphologically, and it has a reduced flavonoid chemistry. Very little reduction in flavonoid diversity was seen in the morphologically specialized subg. Dendroseris as compared to subg. Rea. A trend in reduction of numbers of compounds was seen for two of the three species on the younger island of Masafuera when compared to their presumed ancestors on Masatierra. Flavonoids of selected species of Hieracium and Hypochaeris, presumptive mainland progenitors of Dendroseris, reveal a close chemical affinity with the former genus.

Plastid Phylogenomics of Dendroseris (Cichorieae; Asteraceae): Insights Into Structural Organization and Molecular Evolution of an Endemic Lineage From the Juan Fernández Islands

“…In addition, our current study suggested that D. litoralis is more closely related to D. macrantha than to D. marginata. It has been demonstrated that, based on morphological traits, D. macrantha is most closely related to D. macrophylla on the geologically younger island Masafuera (Alejandro Selkirk), while flavonoid profiles provided no specific insights (Pacheco et al, 1991). The current study strongly suggests a sister relationship between D. litoralis and D. macrantha (100% BS).…”

“…Plant materials of seven Dendroseris species were collected previously in the field during four expeditions of the Universidad de Concepción, Chile and the Ohio State University, United States to the Juan Fernández Islands. As acknowleged in the previous studies (Crawford et al, 1987(Crawford et al, , 1992Pacheco et al, 1991), the CONAF (Corporación National Forestal) of Chile issued the permission to collect in the Robinson Crusoe National Park. Our current samples of Dendroseris are representatives of those previous collections.…”

“…The current study strongly suggests a sister relationship between D. litoralis and D. macrantha (100% BS). However, this relationship contrasts with morphological traits: D. litoralis has shorter morphological distance with D. marginata (two features) compared to the distance with D. macrantha (four features) (Sanders et al, 1987;Pacheco et al, 1991). It is probable that the close relationship of D. litoralis and D. macrantha based on the plastid genomes could be the result of past gene flow since D. macrantha is from cultivated material in the village and also morphology, especially leaf margin, is suggestive of gene flow event (TF Stuessy, personal observation).…”

“…Dendroseris on the Juan Fernández Islands has been the subject of numerous systematic and biogeographic studies over several decades as one of the most striking examples of adaptive radiation on oceanic islands in the Pacific Ocean (e.g., Skottsberg, 1953 , 1956 ; Carlquist, 1967 ; Sanders et al, 1983 , 1987 ; Crawford et al, 1987 , 1992 ; Sang et al, 1994 ; Anderson et al, 2001 ; Bernardello et al, 2001 ). Despite the morphological, anatomical, and ecological divergence, Dendroseris has been strongly supported as a monophyletic group by several molecular markers ( Sanders et al, 1983 , 1987 ; Crawford et al, 1987 , 1992 ; Spooner et al, 1987 ; Pacheco et al, 1991 ; Sang et al, 1994 ; Kim et al, 1996a , b ; Esselman et al, 2000 ). Although the monophyly of Dendroseris was well-established, phylogenetic relationships among the three traditionally recognized taxonomic groups and species remained uncertain probably due to their rapid speciation.…”

Genetic consequences of cladogenetic vs. anagenetic speciation in endemic plants of oceanic islands

“…This latter genus is of interest as it has derived cladogenetically on the older island with three independent dispersals to the younger island and three anagenetic speciations there ( Sanders et al . 1987 ; Pacheco et al . 1991 ; Sang et al .…”