Date: Tue, 21 Jul 1998 21:37:16 -0500
From: Richard Wolfson <firstname.lastname@example.org>
Subject: GE News: Genetic diversity study; Jeremy Rifkin article
Thanks to: email@example.com (Joe Toth) for posting this
"American farmers already know of the problems this can cause, since
they barely avoided a near-disaster because of over-planting of corn
with too little genetic diversity in the 1970s."
Forest fragmentation creating genetic bottleneck
Monday, July 20, 1998
By Environmental News Network staff
(CNN) -- Scientists have recently discovered that the deforestation
of tropical areas may be more devastating than previously thought.
A new study by botanists at the University of Georgia shows for the
first time that trees left standing in pastures can actually
dominate the reproduction in nearby remnant forests, creating a
"genetic bottleneck." The research indicates that the survival of
tropical forests could be far more complex than was known before and
that new approaches to conservation strategies may be needed.
"The key is to understand how much genetic movement there is between
fragments of forest," said Dr. James Hamrick. "When we lose
fragments of forest, we lose genetic diversity. Gene exchange
between fragments helps to maintain this diversity."
The study, by Hamrick and his graduate student Preston Aldrich, was
published in the journal Science.
Genetic diversity is vital in both plant and animal communities.
Farmers have, for hundreds of years, bred crop plants and farm
animals to maintain a healthy diversity of what were, before the
20th century, called traits. Now, with advanced techniques to
determine the exact genetic makeup of individuals, scientists
understand considerably more about how genes drift through
Aldrich and Hamrick studied a tree species called Symphonia
globulifera in a little-examined premontane rain forest area in
southern Costa Rica. S. globulifera is a shade-tolerant canopy tree
with bright red flowers that are pollinated primarily by
hummingbirds. Bats disperse the seeds by eating fruits and then
passing seeds on through guano at their resting sites. Like many
areas in the tropics, the study area consisted of an area of
fragmented forest with a number of large nearby members of the
species standing alone in open pasture land. There were neither
seedlings or saplings of S. globulifera in the pastures, suggesting
poor habitat quality for germination and growth.
The question was simple: What trees are the parents of seedlings
growing in the forest fragments? Finding the answer would have been
nearly impossible even a decade ago until the invention of sensitive
techniques that allow researchers to determine the exact genetic
makeup of individual plants in an ecosystem. Even now, the problem
is daunting, since there were more than 800 possible parent pairs.
"In trying to tell who the parents are, we had to use the same
techniques used in forensic analysis to determine a child's
parents," said Hamrick. "We were able to do this only because
Preston was able to develop the techniques for our specific genetic
The breakthrough came in using segments of DNA called
microsatellites as specific markers for S. globulifera. These
markers allowed Aldrich and Hamrick to determine the pedigree for a
number of seedlings and saplings in a one hectare forest fragment on
their 38.5- hectare research area. (A hectare is a metric unit of
area equal to 2.471 acres.) The scientists knew the genetic
composition of all the adults, 42 individuals, in the study area.
The results of the genetic analysis were startling. Out of nearly
250 seedlings studied from a single forest fragment, some 68 percent
were produced by adults in pastures -- not from adults within the
fragments themselves. Moreover, of the seedlings produced by pasture
trees, 77 percent came from only two trees. Adults left in the
fragment produced less than 5 percent of the seedlings in their own
patches. The importance of the discovery lies in the fact that the
genetic diversity of seedlings in forest fragment may be relatively
"If you looked at the number of seedlings superficially, you might
say that this is a healthy rate of regrowth," said Hamrick. "But in
truth, the effect is ecologically unhealthy due to the potential for
inbreeding in subsequent generations." As humans know, inbreeding
can expose deleterious genes.
The scientists have several theories why the pasture trees have such
an overwhelming impact on gene flow. First, there is little
competition for the pasture trees for sunlight and nutrients, giving
them superior abilities to flower and fruit. Second, the abundance
of flowers may attract more hummingbirds for pollination. Finally,
bats have easy pickings of the fruit and take them from the pasture
trees to the forest fragment, where they eat and then pass seeds
back to soil in guano.
The study has important implications for conservation and forest
restoration. And it shows that the impact of deforestation has been
far more devastating that the simple removal of individual trees. At
least in this species of tree, fragmentation has resulted in the
possibility of a serious loss of genetic diversity in this test
Thus, areas that look healthy in terms of regrowth may not be
healthy at all over the long term. They may be facing serious future
problems due to problems with genetic drift and inbreeding. American
farmers already know of the problems this can cause, since they
barely avoided a near-disaster because of over-planting of corn with
too little genetic diversity in the 1970s.
Still, scientists say it is beginning to become apparent that it
will be difficult to make any kind of blanket statements about gene
movement among populations of forest species. Indeed, botanists say
we are now only beginning to understand what happens to genetic
diversity in natural populations over time -- and why.
"One of the important things this study has shown us is that the
superficial appearance of an area might not be telling you the whole
story," said Hamrick. "Each situation has unique characteristics
that make if very difficult to say that tropical trees in a certain
situation will behave this way or that. Quite simply, our study area
looked healthy, but it wasn't."
EDITORIAL COMMENTARY COLUMN BEWARE THE BIOLOGICAL CENTURY Jeremy Rifkin
07/19/98 St. Louis Post-Dispatch
FIVE STAR LIFT Page B3
While the 20th century was shaped largely by breakthroughs
> in physics and chemistry, the
> 21st century will belong to biology. Scientists are deciphering the
> genetic code of life. Global life science companies are beginning to
> exploit the discoveries in myriad ways. Genes are already being used
> such fields as energy, bioremediation (bugs that eat pollution),
> and packaging materials, pharmaceuticals and medicine. The biggest
> impact, however, is likely to be in agriculture. Life science
> such as Monsanto promise a biological renaissance. Critics worry
> seeding farmland with
> transgenic food crops could spread genetic pollution and
> damage the biosphere. The critics are right.
> It is true, as supporters of genetic engineering say, that
> human beings have been remaking the Earth for as long as we
> have had a history. Until recently, however, our ability to
> manipulate the environment has been tempered by the restraints
> of species boundaries. We have been forced to work narrowly,
> crossing only close relatives in the plant or animal kingdoms.
> But scientists can now manipulate the natural world at the
> most fundamental level - the genetic one. They can take genes
> from unrelated species and create life forms. Scientists have
> taken the gene that emits light in a firefly and inserted it
> into the genetic code of a tobacco plant; the mature plant
> glows 24 hours a day. Other researchers have introduced an
> anti-freeze gene from the flounder fish into the genetic code
> of a tomato plant to protect it from cold spells.
> Over the next 10 years, life science companies plan to
> introduce hundreds of laboratory-conceived transgenic plants
> over millions of acres of farmland. The risks in releasing
> these genetically engineered crops are similar to those in
> introducing exotic organisms. While many have adapted to new
> ecosystems without severe dislocations, a small percentage of
> them have wreaked havoc. Gypsy moth, Dutch elm disease,
> starlings and Mediterranean fruit flies come to mind.
> Whenever a genetically engineered organism is released, there
> is always a small chance that it will run amok. Like exotic
> species, it has been artificially introduced into local
> ecosystems that have developed a complex web of relationships
> over evolutionary history.
> Much of the effort in agricultural biotechnology centers on
> creation of herbicide-tolerant plants. To increase their share
> of the growing global market for herbicides, companies such as
> Monsanto and Novartis have created transgenic crops that
> tolerate their own herbicides. For example, Monsanto's,
> herbicide-resistant patented seeds are resistant to its best-
> selling chemical herbicide, Roundup.
> The life science companies hope to convince farmers that
> herbicide-tolerant crops will allow for a more efficient
> eradication of weeds. If farmers can kill weeds without
> destroying their crops, they may use more herbicides. The
> increased use of herbicides, in turn, raises the possibility
> of weeds developing resistance, which will force an even
> greater use of herbicides.
> New pest-resistant transgenic crops are also being introduced.
> Several plants, including Ciba Geigy's pest-resistant
> "maximiser corn" and Rohm and Haas' pest-resistant tobacco,
> are already available. New evidence points to the likelihood
> of creating "super bugs" resistant to pesticide-producing
> genetic crops.
> The new generation of virus-resistant transgenic crops poses
> the equally dangerous possibility of creating new viruses.
> Some ecologists also warn of the danger of "gene flow" - the
> transfer of transgenic genes from crops to weedy relatives by
> way of cross-pollination. Transgenic genes for herbicide
> tolerance, and pest and viral resistance might escape and
> insert themselves into the genomes of weedy relatives,
> creating weeds resistant to herbicides, pests and viruses.
> Such fears were heightened in 1996 when a Danish research team
> observed the transfer of a transgene from a transgenic crop to
> the genome of a wild weed - something biotech companies have
> ignored as a remote or nonexistent possibility. The insurance
> industry, however, has made clear it would not insure the
> release of genetically engineered organisms into the
> environment against the possibility of "long-term"
> catastrophic environmental damage. Who, then, will be held
> liable for losses if a transgenic plant introduction triggered
> genetic pollution for an indefinite period? The life science
> companies? Government?
> The debate could affect humans more directly. Most new
> genetically engineered crops contain genes from non-food
> organisms including viruses, bacteria, insects and exotic
> animals. With 2 percent of adults and 8 percent of children
> allergic to common foods, consumer advocates argue gene-
> spliced foods need proper labelling. The Food and Drug
> Administration has fallen short of requiring across-the-board
> labelling; The New England Journal of Medicine concluded FDA
> policy "would appear to favor industry over consumer
> The industry has all but dismissed such criticisms. The
> biotech companies may be right. But what if they are wrong?
> A worldwide moratorium should be declared on releasing
> genetically engineered food crops and other gene-spliced
> organisms into the environment pending further study. It would
> be irresponsible and foolish to begin seeding farmland with
> such crops when we have yet to develop a rudimentary risk-
> assessment science by which to regulate these new agricultural
Richard Wolfson, PhD
Consumer Right to Know Campaign,
for Mandatory Labelling and Long-term
Testing of all Genetically Engineered Foods,
500 Wilbrod Street
Ottawa, ON Canada K1N 6N2
tel. 613-565-8517 fax. 613-565-1596
Our website, http://www.natural-law.ca/genetic/geindex.html
contains more information on genetic engineering as well as
previous genetic engineering news items
Subscription fee to genetic engineering news is $35 for 12 months
See website for details.
--Dan in Sunny Puerto Rico--
To Unsubscribe: Email firstname.lastname@example.org with "unsubscribe sanet-mg".
To Subscribe to Digest: Email email@example.com with the command