The Geography of Phytochemical Races

3.4 South America 171
Mediterranean sites in Chile and the steppe ecotone of Argentina, and a second
group from mesic sites in the Argentinean lakes area and Chilean rain forest. The
latter group was distinguished on the basis of their 20-carbon unsaturated acids.
3.4.3 Araucaria araucana (Araucariaceae)
Another example from South America involves Araucaria araucana (Molina)
K. Koch. This tree occurs in the Andean cordillera between 37°27′S and 40°03′S,
where it occurs on both sides of the crest of the range, and disjunctly in the
Cordillera de Nahuelbuta of the Chilean coastal mountains. The species is considered
a Chilean National Monument and is listed internationally as an endangered
species. In an attempt to learn something about variation within this species,
Rafi i and Dodd (1998) examined foliar wax alkanes extracted from 40 individuals
representing four natural populations. The major hydrocarbons identifi ed were
heptacosane (27 carbons), nonacosane (29 carbons), hentriacontane (31 carbons),
and tritriacontane (33 carbons), with the 29-carbon compound present in highest
concentrations in all populations. Numerical analysis of the data set, and construction
of a dendrogram based on a cluster analysis of Nei’s genetic distance
measure revealed that there was a greater difference between west side Andean
populations of A. araucana than there was between Andean populations and populations
from the coastal mountains. These results are in accord with the hypothesis
that plants living in more arid habitats produce higher percentages of longer-chain
hydrocarbons. Chemotypes were not detected in this species.