The Geography of Phytochemical Races

3.3 Europe 163
Fig. 3.11 Compounds 278–285, fl avonoids from Pinus halepensis
amounts, ca. 16.6% in Greek populations, to the lowest amounts, ca. 10.2%, in the
northernmost populations. The authors reasoned that since loss of trihydroxylated
B-rings is considered an advanced feature of fl avonoids (Harborne, 1967; Swain,
1975) the Greek population, with the highest concentration of myricetin, must represent
the “archetype population” of the species. With the lowest concentrations of
myricetin, the Italian and French populations would, therefore, represent the more
advanced state. This trend in fl avonoid oxidation level was taken to indicate that
Aleppo pine occupied regions in the Middle East during the height of glaciation
and that migration, after retreat of the ice, followed a pathway westward across
North Africa to western Europe. Migration into southern Europe was a later event,
although Kaundun et al. (1998a, b) offered no estimate of the time involved. This
conclusion is in line with that of Shiller et al. (1986) based on terpenoid data, but
is contradicted by the conclusion of Nahal (1962) and Panestos (1975) who suggested,
on the basis of palynological and morphological evidence, respectively,
that Aleppo pine originated in southern and central Europe. Macromolecular data
would likely resolve this issue.
In a study of isozymes of P. halepensis, Shiller et al. (1987a, b) found alleles
characteristic of P. brutia in trees from the Greek province of Chalkidiki. Other features
suggested that these two species had undergone hybridization in this area [see
Kaundun et al. (1998a) for further references]. The fl avonoid profi le of trees from
that area (Kaundun et al., 1998a, b) was typical of P. halepensis, however, which
was unexpected in light of their earlier work documenting differences between
the fl avonoid profi les of the two species (Kaundun et al., 1997). Two explanations
were offered: (1) hybridization does occur in the area, but offspring exhibit only the
P. halepensis profi le; or (2) hybridization does not occur. The author would like to
suggest that a third explanation might be equally possible. The differences between
the two species lie in relative quantities of quercetin and myricetin: quercetin is a
major component in P. brutia, with myricetin present in much smaller amounts,
whereas in P. halepensis the situation is reversed. It is well known (Levy, 1976) that
hybrids often exhibit fl avonoid profi les that differ from both parents, a phenomenon
that might result from disruption of control systems caused by mixing of genomes.