The Geography of Phytochemical Races

234 5 Wide Disjunctions
Southern Hemisphere members of these algal groups ought to be higher because, in
the absence of otters, the plants had to rely solely upon chemical defenses against
herbivores. This suggestion was tested by examining 25 species of algae collected
in New Zealand and Australian waters. The median value for the Australasian species
was 6.20% total phenolics (dry wt.) in contrast to 1.33% for North American
algae (25 species) (Steinberg, 1989).
5.2.13 Cystoseira amentacea (Cystoseiraceae)
Cystoseira amentacea Bory var. stricta Montagne is a brown alga widely distributed
along the coast of the Mediterranean Sea. The complex terpene chemistry of this
species has been reviewed by Valls et al. (1996) who, in the same paper, described
a study of the alga collected at eight sites along the western French Riviera from
Sausset les Pins at the western end of the transect (43°20′N, 5°5′E) to Le Trayas at
the eastern end [Le Trayas lies ca. 10 km to the northeast of Boulouris (43°25′N,
6°49′E), which was also one of the collection sites]. Plant material from all eight
sites gave the same array of compounds: [471], known as cystoketal, and [472], both
of which were known, and the two compounds new to this taxon, [473 and 474].
Plants collected farther to the east near Nice (43°42′N, 7°16′E), however, were
shown to contain the two rearranged meroditerpenes mediterraneol-A [475] and
cystoseirol-D [476] (see Fig. 5.8 for structures and Fig. 5.9 for a map of the area).
Fig. 5.8 Compounds 471–476, terpene derivatives from Cystoseira amentacea