Rome, Italy
May 22, 2007
Wild relatives of plants such as
the potato and the peanut are at risk of extinction, threatening
a valuable source of genes that are necessary to boost the
ability of cultivated crops to resist pests and tolerate
drought, according to a new study released today by scientists
of the Consultative Group on
International Agricultural Research (CGIAR). The culprit is
climate change, the researchers said.
According to the study, in the next 50 years as many as 61
percent of the 51 wild peanut species analyzed and 12 percent of
the 108 wild potato species analyzed could become extinct as the
result of climate change. Most of those that remained would be
confined to much smaller areas, further eroding their capacity
to survive. The study also examined wild relatives of cowpea, a
nutritious legume farmed widely in Africa. It found that only
two of 48 species might disappear. However, the authors predict
that most wild cowpeas will decline in numbers because climatic
changes will push them out of many areas they currently inhabit.
"Our results would indicate that the survival of many species of
crop wild relatives, not just wild potato, peanuts and cowpea,
are likely to be seriously threatened even with the most
conservative estimates regarding the magnitude of climate
change," said the study’s lead author, Andy Jarvis, who is an
agricultural geographer working at two CGIAR-supported centers –
the Colombia-based
International Center for Tropical Agriculture and
Bioversity
International, with headquarters in Rome. "There is an
urgent need to collect and store the seeds of wild relatives in
crop diversity collections before they disappear. At the moment,
existing collections are conserving only a fraction of the
diversity of wild species that are out there."
Extinction of crop wild relatives threatens food production
because they contain genes for traits such as pest resistance
and drought tolerance, which plant breeders use to improve the
performance of cultivated varieties. The reliance on wild
relatives to improve their cultivated cousins on the farm is
expected to intensify as climate change makes it too hot, too
cold, too wet or too dry for many existing crop varieties to
continue producing at their current levels.
The results of the study were announced on International
Biodiversity Day, organized by the Convention on Biological
Diversity (CBD).
Jarvis and his colleagues looked specifically at the effects of
climate change on the three crops in Africa and South America.
The scientists focused on the two continents because this
allowed them to consider how known populations of wild plants
would fare in a wide variety of growing conditions. They found
the impact of climate change is likely to be more pronounced in
some species than in others but that, in general, all three
groups of species would suffer.
Though not apparent to the average consumer, the wild relatives
of crops play an important role in food production. All food
crops originated from wild plants. But when they were
domesticated, their genetic variation was narrowed significantly
as farmers carefully selected plants with traits such as those
related to taste and appearance as well as to yield. When
trouble arises on the farm—attacks by pests or disease or, more
recently, stressful growing conditions caused by climate
change—breeders tend to dip back into the gene pool of the
robust wild relatives in search of traits that will allow the
domesticated variety to overcome the threat.
In recent years, genes available in wild relatives have helped
breeders develop new types of domesticated potatoes that can
fight devastating potato blight and new types of wheat more
likely to survive drought conditions. Wild relatives of the
peanut have helped breeders provide farmers with varieties that
can survive a plant pest known as the root knot nematode, and
resist a disease called early leaf spot. In fact, according to
the report, more than half of new domesticated peanut varieties
developed in the last five years have incorporated traits from
wild relatives. Cowpea wild relatives are known to be a
reservoir of genes that could confer resistance to major insect
pests. In the US alone, the value of the improved yield and
quality derived from wild species is estimated to be in the
hundreds of millions of dollars a year.
Jarvis said the vulnerability of a wild plant to climate change
can depend on its ability to adapt by, for example, extending
its range as warming in its native regions becomes too hot to
handle. One reason wild peanut plants appear to be so vulnerable
to climate change is they are largely found in flat lands and
would have to migrate a long way to reach cooler climates, a
predicament exacerbated by the fact that peanuts bury their
seeds underground, a meter or less from the parent plant. That
limits the speed at which seeds can move into more favorable
climates. By contrast, plants in mountainous locations could
theoretically survive by extending their range slightly up a
slope, even by only a few meters, to find cooler weather. What
scientists must do, Jarvis said, is identify which wild
relatives are most likely to suffer from climate change and give
them priority for conservation.
"The irony here is that plant breeders will be relying on wild
relatives more than ever as they work to develop domesticated
crops that can adapt to changing climate conditions," said Annie
Lane, the coordinator of a global project on crop wild relatives
led by Bioversity International. "Yet because of climate change,
we could end up losing a significant amount of these critical
genetic resources at precisely the time they are most needed to
maintain agricultural production.
Research that identifies crop wild relatives threatened by
climate change is part of a broader CGIAR effort to anticipate
and blunt the effects of global warming on agriculture. In the
local, national, and international policy arenas, CGIAR
researchers are generating innovative options to foster
adaptation to climate change. In addition, new research at
CGIAR-supported centers focuses on understanding the impacts of
shifting climate patterns on natural resources, such as water,
fisheries, and forests, and on planning for improved management
of these resources to meet the needs of growing populations as
the climate changes.
Bioversity International is the world’s largest international
research organization dedicated solely to the use and
conservation of agricultural biodiversity. It is non-profit and
independently operated. For more information, please visit
www.bioversityinternational.org.
The CGIAR is a strategic agricultural research alliance
dedicated to generating and applying the best available
knowledge to stimulate agricultural growth, raise farmers’
incomes, and protect the environment. It supports 15 research
centers worldwide conducting groundbreaking work to nourish the
future. These include Bioversity International, CIAT and IITA.
For more information, please visit
www.cgiar.org. |
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