Evidence from chloroplast DNA restriction site analysis on the relationships of Scalesia(Asteraceae: Heliantheae)

Chloroplast DNA restriction site variation provided data with which to compare the Galápagos Island endemic Scalesiato potential sister groups within subtribe Helianthinae. Pappobolusis suggested by these data to be the most likely sister group to Scalesia.It is an Andean endemic genus that includes the South American species once regarded as a subgenus of Helianthusand later assigned to Helianthopsis.Two other groups considered as potential sister groups based on their geographic distribution in South America were not placed near Scalesiain the most parsimonious tree. Viguierasect. Diplostichisappears to be relatively basal within subtribe Helianthinae, and the South American species of Viguiera, although previously classified in more than one subgenus, appear to form a single, monophyletic group that is not the sister group to Scalesia.The minimum of ten restriction site differences between Scalesiaand Pappobolusof approximately 525 sites surveyed yielded an estimated sequence divergence of 0.19%, and an estimated time of divergence of approximately 1.9–6.2 million years.