The Geography of Phytochemical Races

264 6 Oceanic Islands
Fig. 6.8 Map of the Juan Fernandez Islands (Mt = Masatierra, Mf = Masafuera), Tristan da Cunha
(T.d.C.), and Inaccessible Island in relation to South America. The location of the Falkland Islands
(Islas Malvinas) is included
relationships among endemic taxa on the Juan Fernandez Islands and likely ancestral
species on the mainland. Much of these efforts have been joint ventures of
botanists from North American universities, the Universidad de Concepción, Chile,
and, more recently, the University of Vienna, with the overall aim of preserving this
highly unusual area from further devastation at the hand of mankind (or the feet of
goats). In several of the systems described below, we have the luxury of both micro-
and macromolecular information which, in addition to providing as many sources
of data as possible, offer an opportunity to assess the relative contribution of each
type to the problems at hand.
6.4.1 Dendroseris (Asteraceae)
Dendroseris D. Don. (Asteraceae: Lactuceae), with 11 species, is the largest endemic
genus on the Juan Fernandez Islands. It also counts among its members some of the
rarest species in the archipelago; Stuessy et al. (1998) reported that only three plants of
D. neriifolia (Dcne.) Hook. & Arn. existed at the time of their discussion of plant conservation
problems in the islands. Sanders et al. (1987) placed the species in three subgenera,
Dendroseris with four species, Phoenicoseris with three, and Rea with four. Eight
of the species are restricted to the older island, while three species, one from each subgenus,
occur only on the younger island: D. macrophylla D. Don (subgen. Dendroseris),
D. regia Skottsb. (subgen. Phoenicoseris), and D. gigantea Johow (subgen. Rea).
The fl avonoid profi les of all species were studied by Pacheco et al. (1991a), who
identifi ed a series of apigenin and luteolin 7-O-mono- and 7-O-diglucosides and
a quercetin 3-O-mono- and 3-O-diglucoside. The somewhat unusual chemistry of
these compounds, three of the apigenin derivatives were 7-O-monoglucosides and
four of the luteolin derivatives were 7-O-monoglucosides, suggesting an array of
isomers for each, has been commented on (Bohm, 1998b). Differences among the
subgenera with regard to fl avone profi les were not very signifi cant, whereas quercetin