The Geography of Phytochemical Races

92 2 Examples Within Continents
Lake County just south of Lower Lake, and lies at a distance of about 40 km from
population B, the northernmost of the Sonoma County sites. Populations D1 and D2
lie about 9 km west of population C and are separated from each other by about 300 m.
It is very likely that these two populations were at one time a single large population,
but construction of California Rt. 29, with associated roadside maintenance, has effectively
separated them (refer to any California atlas for details). Other sites reported in
the literature, or represented by voucher specimens, could not be located, owing to the
heavy impact of commercial development in this area of California.
The pigment profi le of L. burkei collected from these sites consists of three quercetin
glycosides and eight patuletin glycosides (patuletin is 6-methoxyquercetin)
plus traces of two unidentifi ed fl avonol glycosides. Only quercetin and patuletin
3-O-glucosides were present in all members of all populations. Clear-cut differences
among the populations were observed with glycosides of both fl avonols. Some populational
variation was also observed at all fi ve sites. These results are summarized
in Table 2.18. Populations D1 and D2 are very similar to each other, which is not
surprising in view of their close proximity; in fact, they may at one time have been
part of a much larger population that was disrupted by road construction. Populations
A and B, the two populations from Sonoma County, are also very similar to
each other and are markedly different from the D populations. Despite the fact that
population C lies geographically much closer to the D populations than it does to
populations A and B, it is the pigment profi le of these latter two that it most closely
resembles, although it clearly exhibits its own characteristic pattern of compounds.
Examination of the table reveals that all differences, both within and among populations,
are based upon the nature of the glycosides accumulated. Without additional
information on the history of the species, the relative ages of the populations, and the
genetic control of the glycosylation reactions, it is not possible to draw any conclusions
regarding relationships among these fi ve groups of plants. This would seem to
be an excellent example of a system for which a population phylogeny would likely
be very revealing. With the ever-increasing pressure of development, however, systems
of this sort are disappearing and taking their genetic histories with them.
Table 2.18 Flavonoid variation in a small area, the case of Lasthenia burkei (after Bohm and
Banek, 1986)
Population No. b Flavonoid Derivativea PT PD PI PX QD PG PX ?G ?X PJ QG PG QN
Sonoma Co. (A) 24 ndc 24d 24 24 nd 24 24 17 17 3 24 2 2
Sonoma Co. (B) 24 1 24 24 24 nd 24 24 19 19 4 24 8 8
Lake Co. (C) 24 1 24 24 24 9 24 24 21 21 nd 24 nd nd
Lake Co. (D1) 18 4 nd 1 nd 18 18 nd 18 nd nd 18 18 18
Lake Co. (D2) 18 2 nd 4 nd 18 18 nd 18 nd nd 18 18 18
a P = Patuletin; Q = quercetin; ? = unidentifi ed fl avonol; T = triglycosides; D = diglycoside; X = xyloside;
G = glucoside; I and J = isomeric glucosides; N = glucuronide.
b No. = Number of plants sampled in each population.
c nd = Not detected.
d Number of plants exhibiting the compound.