Image Left: A
male Parson's chameleon (Calumma parsonii)
from Madagascar. This is one of 11
chameleons for which museum specimens and
satellite data were used to predict species
distributions. Click Image For High
Resolution Version. Photo:
Christopher J. Raxworthy
Chameleons are well known for their ability
to hide from predators.
But they weren't able to hide from NASA,
which helped researchers discover seven
previously unknown species in Madagascar,
off the east coast of Africa.
The NASA-funded study -- which also
successfully predicted the geographic
distribution of 11 known chameleon species
in Madagascar -- uses a computer model
combined with satellite data from NASA and
other agencies, and data from museum
collections about where species have been
found in the past.
The study, which appears in a mid-December
2003 issue of Nature, offers a method that
may be applied to other species around the
world. Predicting the distribution of
species is one of the most important and
tools for effective conservation, as well as
ecological and evolutionary research.
Until now, scientists were required to
physically visit a locale and painstakingly
find and count species. The new approach
allows them to focus on places with a high
likelihood for a big payoff. This is
especially important for poorly explored
regions with diverse climates and habitats.
It is also important for those who work with
limited budgets, or when there is an urgent
need to include species in conservation
planning.
The lead author of the study is Christopher
Raxworthy, a biologist at the American
Museum of Natural History. He's visited
Madagascar to study chameleons for the last
20 years. He used computer software that
allows users to predict where species might
be found, entering information about
chameleons in that area.
Raxworthy entered data from museum
collections about where these chameleons had
been found in the past. Some of this
information dated back to the 1800s. He also
added the latest satellite images of
Madagascar and more data about the island's
land cover (as viewed from space), rainfall,
cloud cover, average and seasonal
temperatures, and topographic data,
including elevations.
Environmental records came from several NASA
satellites, a Space Shuttle radar mapping
mission, and U.S. Geological Survey and
National Oceanic and Atmospheric
Administration data. The computer then
provided maps of the most likely places
where these chameleons might be found.
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Image Right:
The world's fourth largest island,
Madagascar, is featured in this Moderate
Resolution Imaging Spectroradiometer (MODIS)
image taken by the Terra satellite on
September 10, 2003. The narrow strip of
green along the east coast of the island is
a rain forest. The west coast is lined with
baobabs, a desert tree with a fat trunk, and
thorny forest. Click Image For High
Resolution Version.
Photo Credit:
NASA/MODIS Rapid Response Team
The model was tested with museum records
from different time periods to test its
accuracy. Historical data collected prior to
1978 were separated from more modern data
that came from specimens found since 1988.
The model showed that the historical data
alone was quite accurate (74.7 percent
accuracy), the combination of modern and
historical data was even better (82.8
percent accuracy), while the modern data
alone proved to be the best predictor of
where the 11 chameleon species tested might
live (85.1 percent accuracy). The older
records may have reflected a landscape that
has now been altered, and the modern records
may fit better with the current satellite
data.
Also, in a finding that was completely
unexpected, the computer model highlighted
three areas where scientists had never found
these chameleons. No museum records from
these areas had been entered into the model.
Raxworthy and colleagues initially thought
the new pinpointed regions were due to some
sort of computer error. But in visiting two
of these areas, they instead found habitats
that housed seven new closely-related
species previously unrecorded by western
science.
Madagascar and its surrounding area is one
of 25 biodiversity hotspots -- areas
identified by scientists where diverse local
plant and animal life appears to be
thriving, in spite of human influences
nearby. Unfortunately, these hotspots are
few and far between. Consider that the 25
hotspots contain 44 percent of all plant
species and 35 percent of all land
vertebrate species in only 1.4 percent of
the planet's land area.
Madagascar itself has lost forests at an
alarming rate. Only about ten percent of the
original natural habitat remains.
With so much land being changed, nobody
knows exactly which species of plants and
animals have become extinct, and which
species may still be protected.
Conservationists around the world have been
struggling against time to identify
biologically rich areas to protect before
they are lost.
Hopefully, the new technique will offer
conservationists and scientists a
fast-acting tool in their race against time.
With tropical forests and other highly
bio-diverse areas disappearing around the
world, conservationists may now be able to
identify and protect critical habitat before
it is changed and lost. And many new species
may be discovered in the process.
This work is consistent with a new element
of the NASA Earth Science applications
program focusing on ecological forecasting.
The program uses Earth observation data and
models to forecast species distributions and
how environmental change might affect them.
Krishna Ramanujan
Goddard Space Flight Center, Greenbelt, Md.
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