|
|
|
|||
|
|
|
|
||
 |
 |
 |
|
 |
|
 |
|
 |
|
Freezing Seeds, Saving Species(Any time you see a link, you can click it for more information on that word or topic) What's the Problem? Every day that passes, an entire species of American plant life dies out forever. In other parts of the world, the rate is far greater with 20,000 species facing imminent extinction. These figures represent a tremendous loss to the health of the world's people, to agriculture, to industry, to grazing, not to mention the sheer beauty lost forever. Plants contribute to nearly everything we use daily; from our homes and furniture to the food we eat, from clothing and cosmetics to the oxygen we breathe. When we think of saving endangered species from severe population loss or even from extinction, we usually think of endangered animals - birds such as the whooping crane, mammals such as the giant panda, or reptiles such as the crocodile. Yet many species of plants are struggling to survive as well. Wherever we look today, rare and potentially valuable plants are in danger of extinction. What Makes Plants so Valuable? When we consider the benefits we derive from plants, it is clear that their needs for survival merit our attention, too. Humans are among the many species whose food chain begins with plants. We consume food in order to provide energy for our bodies. But the amount of energy in the universe is finite; quite simply, in order for us to use it, we need to get it from somewhere else. Like most other creatures on earth, we depend on energy captured from the sun's rays. Most of the energy we get this way comes to us by way of plants. They capture it in the process of photosynthesis and use it to grow. We then meet our energy needs and our nutritional requirements from the plants, either directly, when we eat the plants, or indirectly, when we consume animals who themselves have plants at the beginning of their food chains. Of course, plants give us much more than energy and nutrition. They play a large role in regulating and maintaining the temperature and the liquid and gas makeup of the atmosphere. By absorbing water and by holding soils in place, they prevent flooding. They provide natural beauty, materials for shelter and clothing, and components of soaps, oils, resins, and cosmetics we use every day. One-fourth of all prescription drugs come from plants - some from quite rare and endangered ones. Plants are disappearing forever at the rate of several species per day. Many more are in danger of extinction, and the rate is likely to go up as human activities continue to destroy or change the plants' natural habitats. Even when a species survives, the loss of even part of its natural habitat means that it has fewer defenses against pests, diseases, and environmental changes (such as in the temperature, or the amount of sunlight or water available) for the future. In the course of evolution, plants, like all living things, draw on their range of genetic resources - on the variety of different individuals in the species with different strengths and weaknesses - in order to meet new challenges in their environments. The less there is of such genetic diversity, the more likely the species is to face endangerment or even extinction. There are many reasons to protect endangered plants and their habitats. Even for food plants found widely throughout the world, rare strains exist that hold the genetic keys to healthier and more nutritious varieties. One very important reason to save plant species is to give us time to learn what use we can make of their medical and other properties. For thousands of years, people have relied on plants to treat illness. Today, a quarter of all prescription drugs are derived from plants. In many parts of the world where access to modern medicine is scarce, plants are the only source of medicine. The plant that the Mexicans call babasco, which they say is good for the heart, is the source of a modern contraceptive, for example. The Chinese have derived remedies from the gingko tree for centuries. Recently, a substance was found in the gingko that is now used in coronary care. Many other important discoveries about the healing properties of plants have been made in just the last few decades. Plants are efficient and creative factories of new chemicals; because these chemicals have evolved in order to protect the plant from environmental dangers, they often turn out to be useful to humans as well. Several of the most important drugs used in cancer and leukemia therapies today come from rare species of plants found only in small corners of the world. But identifying and testing plant chemicals is a slow and painstaking process. Saving endangered plants provides us with the opportunity to investigate them, and therefore with the chance to feed more people and to conquer more disease. What's the Story? By training, Harold Koopowitz is a neurobiologist, someone who studies the brains and nervous systems of animals. As a child, he collected wildflowers in his native South Africa, and he continued his hobby when he moved to the United States to pursue his profession. When he learned about the high rates of endangerment and extinction faced by plants, he decided to devote some of his scientific ingenuity to protecting them.
His first step was to establish an arboretum (a special garden, usually for rare trees and other plants) at the University of California at Irvine. Many of the flowers that Koopowitz grows at the arboretum, such as moraeas, gladioli, aloes and orchids, are native to South Africa, where they face an uncertain future. One component of the arboretum's activities is a cryogenic seed bank. A gene bank is what scientists call any effort to conserve genetic diversity, in order either to keep species from becoming endangered or extinct, or to preserve the variety within a species. For both plants and animals, the ideal gene bank is a natural habitat that is protected from destruction, such as a nature reserve. This kind of protection is said to be "in situ" - meaning that it takes place within the species' native habitats. Many people around the world are committed to in situ conservation, but their efforts are not always entirely successful. So, others devote themselves to "ex situ" efforts - protection outside the species' native habitats. For plants, the best ex situ gene bank is an arboretum or an experimental garden, farm, or forest, in any of which the growing conditions resemble as closely as possible the various species' natural habitats. Many of the plants that Koopowitz grows in the arboretum he directs are wildflowers whose native habitats are at risk. But even these measures cannot always keep pace with the high rates of endangerment and extinction. They require valuable and expensive open land - land that might otherwise be used for farming, housing, or industry - and their maintenance requires much time and expertise. There is always a risk that the cultivated plants will not survive. Koopowitz's cryogenic seed bank is a kind of ex situ gene bank that takes little space and is easy to maintain. It involves, simply enough, collecting and labeling seeds and placing them in a freezer that is kept at minus 40 degrees centigrade. Finding the proper storage conditions and temperature and testing how well the seeds hold up after various lengths of time in the freezer took a lot of experimenting, but the technique is now a proven one. Koopowitz started the first cryogenic seed bank in the United States, and he has since encouraged many others to follow his example. He has also been a leader in convincing other arboreta and botanic gardens to expand beyond their traditional role – providing a place for the study of plant species and their growth – and to get more directly involved in the conservation of endangered plant species. While the preservation of natural habitats is still the most important goal, ex situ measures such as these are needed while those habitats remain at risk. How's it Work? In Dr. Koopowitz's own words: "We were setting up a model system which meant that we wanted to be able to attract the attention of other gardens and institutions. And we ended up choosing a group of plants from South Africa, where the climate is almost identical to Southern California, and has spectacular flowers. And we decided then that we would go out and try to get representatives of all of the species. We would grow them here; we would build up stocks of seeds; we could then process the seed and freeze it. By processing, I mean we take the seed, dry it partially, and then we can freeze it at minus 40 degrees centigrade. Once it's frozen, the seed can literally live for centuries, and we think that this is a very economical way of preserving plants. If you just try and grow them in captivity, you're liable to lose them eventually. But by having a collection in a deep freeze, it's safe there for a long period of time." In the years since Koopowitz began his work at Irvine, his dream of seeing other gardens get involved with this endeavor has indeed come true. Koopowitz's book, called "Plant Extinctions: A Global Crisis" has helped to publicize the dangers that plants face. In other writings and in lectures, he informs weekend hikers and wildflower lovers of what they can do to protect plants. He advises them to watch which wildflowers they pick, to be careful of the plants' habitats, and not to buy seeds collected in the wild. "When we started this project about ten years ago, we were the only garden in the Western Hemisphere that was at all concerned about saving endangered plant species; and we've built up a collection of about 5,000 accessions, 200 of which are critically endangered. We are now only one of several gardens that are concerned with plant preservation. There's the Berry Arboretum in Oregon that saves the flora of the Pacific Northwest, and there's something called the Center for Plant Conservation -- which controls a consortium of botanic gardens all across the country that are concerned with saving the endangered flora of the United States." The efforts of Koopowitz and others to slow the rate of plant extinctions will give us the opportunity to learn more about the medicinal properties of plants. "One of the most important of the modern medicinal plants is the Periwinkle, Catharanthus roseus, originally from the island of Madagascar. And this plant has in its leaves a large number of alkaloids used for combating cancer. Before we had this plant, a person who contracted leukemia had an 80% chance of dying within the first few years. Now, a person who gets leukemia has a good chance of surviving and being almost cured. But we don't cure everybody who gets leukemia. There may be in the forests of Madagascar a relative of these periwinkles which have much better chemicals which will allow one to cure cancer completely. There's also a good chance that that plant is one of the plants that went extinct yesterday, because the forests of Madagascar are nearly all gone." The National Cancer Institute, in the United States, has recently sent botanists around the world -- to the Amazon, to Africa, and to Southeast Asia -- in an effort to collect endangered plants and screen them for their value in the treatment of cancer. Koopowitz's work is important not only because it can help save a given species from being wiped out entirely, but also because it can also help preserve variety within a species -- what is known as genetic diversity. Without a diversity of genes in its population, a species is helpless when it comes time to evolve a new way to capture food in its environment, or to develop a new defense against a pest or predator. That's bad not just for the plant, but also for us: what makes plants such good sources of food and medicine is precisely the fact that, in response to changes in their environment, they are machines of biochemical ingenuity. There are many reasons to save endangered plants, and several ways to do so. There are traditional means -- protecting their habitats, growing them in arboreta -- and there are new techniques, such as Koopowitz's cryogenic gene bank. When we save an endangered plant, we save a part of our future. The work of Koopowitz and others raises the odds that a beautiful wildflower will be there for our children to enjoy, and preserves the chance that we might find a new source of food or a cure for a dreaded disease. |
||
Activities and Puzzles
|
||
No
activities for this case study yet