Biology Reference
In-Depth Information
Figure 2.34
Eggshells on sticks protecting a garden from the
ojo de malo
(evil eye), Posada San
Sebastian, David, Panama.
with foreign explorers and early missionaries beginning in the 1500s, but
more recent relocations and destruction of native habitats. The cultural di-
versity is likely a consequence of the environmental and landscape hetero-
geneity that includes elevations ranging from 13 m below sea level on the
Valdés Peninsula of Argentina (fi g. 2.38) to the highest peak in the New
World—Cerro Aconcagua in Argentina on the border with Chile (6960 m).
Rainfall varies from the hyperarid Atacama Desert in Chile where it practi-
cally never rains, to the Colombian Chacó where it practically never stops.
Such heterogeneity provides an array of isolated habitats accommodating a
diverse human population.
The habitats support new plants and animals evolving in situ, as well
as others migrating in from elsewhere by abrupt long-distance transport
and more gradually in response to environmental change. There are about
110,000 species of vascular plants in the neotropics, and a third more re-
main to be described. In addition, there are an unknown number of lichens,
bryophytes, fungi, and microorganisms. All twelve of the plant formations
recognized in this text are found in South America, although their compo-
sition and, to some extent, the nomenclature used to describe them must
be distinct because of about 90 million years of separation from Africa,
67 million years from North America, and 32 million years from Australia
