The Geography of Phytochemical Races

4.4 South Pacifi c 207
chose to treat the fl avonoid data in terms of classes of compounds, that is, sulfated
versus nonsulfated compounds, rather than as individual compounds (thus
lessening the impact of differences in fl avonol glycoside composition). This treatment
resulted in two most parsimonious trees, cladograms B and C in Fig. 4.14.
In cladogram B, F. cyrtandroides retains its position as sister to the New Zealand
clade, but the positions of F. perscandens and F. excorticata are exchanged. In
cladogram C, F. cyrtandroides is part of an “inner” clade rather than sister to the
New Zealand taxa, suggesting that the Tahitian species was derived from within
the New Zealand species. Additional insights came from restriction fragment
analysis of chloroplast DNA (Sytsma et al., 1991). The single, well-supported,
tree that emerged from that analysis is identical to cladogram C, which is one of
the two most parsimonious trees that emerged from the study of Crisci and Berry
(1990), thus providing additional support for the emergence of F. cyrtandroides
from within the New Zealand group. Sytsma et al. (1991) presented an evolutionary
scenario accounting for the origin of Fuchsia sect. Skinnera. An abbreviated version
follows.
Fuchsia is thought to have originated in warm, temperate forests of South
America during the Eocene or Oligocene (Raven and Axelrod, 1974; Berry,
1982). Originally, Raven (1972) suggested that Fuchsia colonized New Zealand
by long-distance dispersal. More recent microfossil fi nds suggest a different possibility.
The discovery of fossil pollen in New Zealand dated as late Oligocene
and early Miocene (25–30 mya) (Pocknall and Mildenhall, 1984) coupled with
the identifi cation of Fuchsia pollen in Oligocene and Miocene deposits in the
Murray Basin of southeastern Australia (Berry et al., 1990), point to the possibility
of a much older connection for Fuchsia between South America, Antarctica,
and Australasia. With the establishment of Fuchsia in Australia, the stage
was set for its migration across the Tasman Sea to New Zealand, followed by its
eventual extinction in Australia. Fuchsia cyrtandroides, or an immediate ancestor,
is then thought to have differentiated from the F. excorticata and F. perscandens
clade (or ancestor). A large number of cpDNA synapomorphs (19) that
defi ne the F. excorticata – F. perscandens lineage and the number observed in the
F. cyrtandroides DNA (20) suggest a divergence well before the appearance of
Tahiti (2 mya) and Society Islands (4 mya). Sytsma et al. (1991) estimated, on the
basis of base changes in the DNA, that F. cyrtandroides separated from its sister
clade about 10 mya, well before its future home became available. Those workers
also mentioned the possibility that F. cyrtandroides might have existed on
other islands in the southwestern Pacifi c. In this scenario, the absence of sulfated
fl avonoids in F. cyrtandroides was interpreted as a loss, the basal position in the
section being their presence. Similarly, the loss of gynodioecy in F. cyrtandroides
was interpreted as a derived feature. Careful reading of the Sytsma et al. (1991)
paper would repay individuals interested in breeding-system evolution, a topic
beyond the scope of this treatment. As a concluding remark, it can be pointed out
that, despite inconsistencies in the fl avonoid data, this study represents a model
of synthesis in the manner in which information from a variety of disciplines has
been incorporated.