High atop Sierra de Manantlan, near Guadalajara, Mexico, jaguars and ocelots stealthily roam, and crested wild game birds scrabble through a landscape splashed with delicate orchids and giant magnolias. These and 10,000 other kinds of living things on the mountain are safe now from the onrush of development, people and destruction - protected in one of Mexico's newest and most celebrated preserves.
But when the Sierra de Manantlan Biosphere Reserve was created in 1987, it was not because of the wildlife or even the exotic flowers. Instead, the centerpiece of this ruggedly beautiful reserve is a scruffy, weedy plant, named teosinte, that if noticed at all would seem more like a blight than a natural treasure.Teosinte (pronounced tee-oh-SIN-tay) is a wild relative of corn, and this particular variety grows on 15 acres on Sierra de Manantlan and no where else in the world. It has genetic traits found in no other plants - traits that could prove vital to corn fields across the world. It has resistance to diseases that commonly afflict other varieties, and it is a perennial plant that - unlike most domesticated varieties - does not have to be replanted year in and year out.
The discovery of teosinte and the creation of the 350,000-acre reserve to protect it offer a prime illustration of the pivotal role genetic science is playing in efforts to uncover nature's secrets and preserve its bounty.
Increasingly, decisions about conservation, management and use of natural resources are being shaped by an understanding of genes and their role in adaptation and survival. Genes are tiny chemical instructions in the cells of all living things that serve as the building plans of life. Genes determine whether the tomato has a thick, bright red skin or a thin, green one; whether a giraffe will be slow or fleet of foot; and whether a child will have brown or green eyes.
Each species needs genetic diversity - that is, a wide variety of genes among its members - and the more diversity of species, the better for all. Left alone, nature controls the pools of genes a species has for coping with diseases, fending off pests and responding to changes in their environment. Family members with genes best suited to the environment will survive to pass along their genes to future generations.
If all family members are genetically alike, all will respond to changes in their environment in the same way. If one cannot survive, all will perish.
Humans have been able to exploit nature's storehouse of genes to recover from pestilence and bad crop years, improve food production and develop "wonder" drugs. But human beings are depleting nature's storehouse at a devastating rate. Already, 95 percent of all the species that ever lived on Earth have become extinct. While much of the loss is part of nature, biologists and other scientists record with alarm the loss of tens of thousands more species each year. And millions of other species - from micro-organisms to insects to mammals - become endangered daily as man further encroaches on their natural habitats.
There is no time to waste, say most genetic conservationists. By the end of this century, at the current rate of habitat destruction and narrowing of the genetic pool, another million species of plants, animals, insects, fish and birds will have become extinct. As the global genetic pool becomes more shallow, the paths to adaptation, evolution and survival become more precarious.
Loss of biological diversity jeopardizes the world's ability to feed itself, deprives us of potentially life-saving or -enhancing materials and can upset the social, economic, political and cultural structures that rule the relationships between nations and peoples. It closes the door on choices.
"My guess is we've got another decade to collect genetic diversity, or the game's over," said Cary Fowler, director of the Rural Advancement Fund International, a Pittsboro, N.C.-based organization concerned with the worldwide loss of genetic resources in plants and animals.
Worldwide, genetic conservation efforts have been fragmented by international squabbling, primarily between the developed nations and the Third World, site of the greatest natural diversity. Critics contend that many of the industrialized world's policies toward lesser-developed nations actually speed the destruction and loss of diversity.
A gene overlooked today, however, could be the basis of tomorrow's wonder drug, fiber or food.
For the pharmaceutical industry, the genes of wild, exotic plants and even animals, have been a surprise treasure trove. In recent years, two anti-cancer drugs have been developed from the periwinkle native to Madagascar. And only now is modern science beginning to prove the validity of many ancient folk remedies brewed, distilled, or pounded from native and often wild plants.
Though many see biotechnology, or genetic engineering, as a fallback position to genetic conservation, it just is not so, say the experts. Biotech companies that create new drugs, or even develop new varieties of plants and animals, do not create brand new genes, as such, but manipulate existing genetic materials.
"If the periwinkle had been obliterated," said Ronald Cape, founder and chairman of Cetus, a biotechnology company in Emeryville, Calif., "those two cancer drugs wouldn't be available. To invent those molecules out of whole cloth - well, it wouldn't happen."
So far, the bulk of genetic conservation has been in hot-house approaches: zoos for animals and seed "banks" for plants. Such off-site preservation methods often rely on current and usually incomplete assessments of genetic value.
Banks and zoos also often ignore the interdependency of plants, animals and insects on each other for survival. The Sierra de Manantlan Biosphere Reserve is a frontispiece in the genetic conservation movement because the teosinte is not being saved in isolation: The reserve was deliberately created to save the habitat along with a rare species.
The Mexican teosinte is special because, while others in its family of wild maize relatives are also perennial, only this teosinte has genetic characteristics that allow it to be crossed with domestic corn to produce a perennial offspring. It may take another five to ten years to breed a viable, commercial strain of domestic corn with the teosinte's valuable genes, yet the discovery of the wild plant has brought the dream of a perennial corn into the realm of possibility.
Hopes for perennial corn aside, the preservation of teosinte is another bit of insurance for the survival of all corn by keeping its genes available in the species' gene pool to guard against the unexpected.
In Ireland in the 1840s, the unexpected was a fungus that was transported by ship from North America - an invasion as deadly as it was surreptitious. The fungus found a easy target in the potato fields that were the backbone of Irish agriculture; all the potatoes were nearly identical genetically, and all susceptible to the fungus. It swept through the fields.
Since then, farmers, plant breeders, pesticide makers and scientists have learned a great deal about protecting crops. Now, farmers know how to control the fungus that devastated the Irish potato fields, as well as many other diseases, parasites and environmental conditions that endanger food crops. Using biotechnology techniques of isolating and transferring specific genes, scientists and plant breeders are even learning to engineer plants that "manufacture" their own resistance.
But the most important lesson of the Irish potato famine is that without genetic diversity, there can be no real protection of food crops.