Biology Reference
In-Depth Information
bian Chocó. The mountains also block moisture from the east, and their up-
lift is one in a series of events that created on the coast farther to the south
one of the driest regions on Earth—the Atacama Desert. Thus, in addition
to infl uencing global patterns of climate through an effect on atmospheric
circulation, other consequences of uplift were changes in the confi guration
of the Amazon Basin and its present-day drainage patterns and topography:
the Colombian Chocó with its exceptionally high rainfall, and the Atacama
Desert with its almost unique lack of rainfall. The biotas supported in each
region are all in signifi cant measure a result of the evolution of the Andes
Mountains (Antonelli et al. 2009).
The Lowland Neotropical Rain Forest
[The rain forest is] the most remarkable expression of nature to grace the surface
of the planet in four billion years of life's history.
—NORMAN MYERS,
“Four for the Forest's Future,” 1991
The rain forest often makes a deep impression on fi rst-time visitors when
they are given a few moments of solitude in its vast silence. The sensory
experience is profound and unfamiliar: gigantic trees dripping with mois-
ture and festooned with ferns, lichens, bryophytes, and lianas—“twiners
entwining twiners,” as Charles Darwin put it—grasses the size of bamboos,
ferns as large as small trees, leaves one can stand under, water lilies one
can stand on, enormous water snakes (
Boa aquatica
), and butterfl ies and
tarantulas seven inches across; the oddities of strangler fi gs, sloths, and
the nasty little piranhas; the beauty of passion fl owers (
Passifl ora
) and 750
species of the spectacular jacaranda family (Bignoniaceae); the estimated
10,000 New World orchids (of more than 22,000 species worldwide); and
large fl owers white in color, scented, and open at night to be pollinated by
bats. There are fl owers of the orchid
Ophrys
and others that mimic the fe-
male species of wasps and bees, complete with pheromones, and pollinated
by males of the species. The forest is mostly evergreen, without periods of
noticeable leaf fall, and regeneration occurs unobtrusively throughout the
year. This subdued change from season to season may have contributed to
an impression in the minds of earlier visitors that the rain forest was equally
unchanging from epoch to epoch. Flowering is often in brilliant but widely
scattered patches (fi g. 2.46).
In a somewhat more sober and quantitative characterization, the low-
land neotropical rain forest is typically found on level terrane between 10°N
