Why maintain biological diversity? Not only for moral and aesthetic reasons, but also because experts believe that great scientific and economic benefits could be gained
Given the present state of knowledge, genes themselves cannot be manufactured by scientists; they can come only from nature. When a given species of plant or animal, from unicellular all the way up to the most complex organisms, becomes extinct, some of its genetic material is lost forever. And even if scientists learn how to make genes, there is little likelihood that an extinct species could be recreated, since knowledge of its genetic makeup would be lacking. Conceivably, genes that are lost through species extinction may be those that could have conferred resistance to certain pests or diseases on a given food or fiber crop. Others might have contributed to industry, science, or even environmental cleanup. For these and many other reasons, scientists—especially biologists and biochemists—are beginning to look at the accelerating rate of species extinction as an environmental danger. Biologist Paul Ehrlich of Stanford University concurs with this view. He warns that the threat of extinction is indeed global in scope, and that its materialization could lead not only to genetic resource losses, but to deleterious changes in weather patterns and soils, and to the loss of "other 'services' humanity can't do without." Among these "services" might be included the sustenance and improvement of agricultural, forestry, and fisheries production, and the usefulness of various species to act as a buffer against adverse environmental change. For these and many other reasons, scientists are urging worldwide efforts to put a brake on the increasing rate of species extinction—at least, that portion attributable to human activity— and to encourage the preservation of biological diversity. "Biological diversity" can perhaps be defined in 94A
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terms of the total number of species in existence; the variations among individual species; and the relationships between them, sometimes very complex and unique, in different ecosystems. An estimated 5-10 million microbial (both plant and animal) and higher plant and animal species inhabit the earth. Many of them have not yet been classified by science, especially in tropical areas. Scientists believe that between the years 1600 and 1900, about 75 mammal and bird species became extinct. Between 1900 and the present, this extinction rate is believed to have increased to one species a year.
Among human acts held responsible for species disappearances is habitat destruction for purposes of urbanization or agricultural development. Ehrlich believes, however, that if the development of virgin land were to end now, the extinction rate might be slowed somewhat, though not halted. Presently, scientists forecast sharp increases in the extinction rate. For 1990, the rate is projected at 10 000 species/y; by the year 2000, perhaps 20% of all species presently extant will have disappeared, and possibly as many as 30-70% of the world's plant species. That is the view of botanist Billie Lee Turner of the University of Texas at Austin, who is generally
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pessimistic that humanity will do much to try to reverse these projections. A foreign policy interest Concern with species extinction and consequent genetic resource loss was expressed at the Strategy Conference on Biological Diversity. Sponsored by the U.S. Departments of State, Interior, and Agriculture, and the Agency for International Development (AID), the conference was held in Washington in mid-November. Speakers and participants from the U.S. and several other countries considered "steps that the U.S. might pursue domestically and internationally, over the next three to five years, to maintain the earth's biological diversity in a manner that serves a range of economic, social, and ecological interests over the long term." More specifically, aims of the conference were to: • review the scope, magnitude, and sources of worldwide losses of plant and animal species • assess the economic, social, ecological, political, and strategic implications of a continuing decline in species diversity, especially as it may relate to world food supply, energy demand, and commercial output • identify and evaluate scientific knowledge, technologies, and institutions available for conserving biological diversity • review the nature and effectiveness of U.S. government domestic and international programs • recommend initiatives that the U.S. should undertake in order to stimulate and assist an expanded worldwide effort in this area. The agenda covered crop and noncrop plants, including trees; domesticated and wild animals; microbes; aquatic resources; ecosystem mainteSome definitions Biological diversity refers to the numbers of species and genetic types within species, plus maintenance of relationships among the species. Ecological diversity refers to diversity exhibited by a species under different ecological conditions. Genetic diversity refers to the existence of different genetic types of varieties within a given species. A cultiver is an organism that exists or persists because it is cultivated. This term is most often applied to crop plants.
nance; and genetic engineering applications. "Maintenance of world biological diversity has not been a traditional State Department concern; but, as you can see by our sponsoring this conference, our position in this regard is changing," said James Malone, Assistant Secretary of State for Oceans and International Environmental and Scientific Affairs. "Biological diversity has now become a U.S. foreign policy interest, in our view," he added. That the narrowing of biological diversity through extinction is inherently an international problem, and hence, a U.S. foreign policy interest, was underscored by Undersecretary of State James Buckley. Noting that "future generations have a stake in stemming impoverishment of biological resources," he estimated that 40% of all prudent (ethical) drugs come from nature. Buckley also noted that biological resources most needing protection are more often found in less developed countries (LDCs). Cataloging wild "relatives" In tropical LDCs, up to 90% of the indigenous plant and animal species are as yet unclassified by biologists (although some scientists believe that for plants, the 90% figure is an overstatement). If habitat destruction through urbanization and expanded agriculture continues, these species may never be classified. Plants of concern comprise members of all phyla; with animals, although all are under consideration, emphasis is on invertebrates. The focus is on both terrestrial and aquatic environments. Zoology professor Clark Hubbs, also of the University of Texas at Austin, observed that many of the species conservation efforts that have taken place dealt with colorful, conspicuous types of plants and animals, such as Saguaro cacti, or "big cats." Little or no attention has been paid to lower species such as fungi or insects, which might be of very great importance to an ecosystem, particularly in the tropics, he added. As a first step toward slowing down the extinction rate, a systematic cataloging of species, with emphasis on those in tropical areas facing urban or agricultural development, was advocated by some conference speakers. Addressing plant species in particular, Quentin Jones of the U.S. Department of Agriculture (USDA) proposed establishing four categories: • species, especially in tropical areas, for which no information as yet exists • species of which ecological pa-
rameters and geographic distributions are generally known • species that are not cultivars, but might be expected to be useful in the future as crops, or in some other capacity such as watershed stabilizers, revegetation plants, or the like • cultivars grown in commerce for food, fiber, and other purposes, and—very important—their wild progenitors. There was a strong recommendation that special attention be given to wild progenitors and relatives of many cultivars, such as cereal grains, legumes, and the like. For instance, these wild plants could provide genetic material that might furnish the cultivars with increased natural resistance to insects or diseases, the ability to withstand less favorable climatic conditions, or other such desirable traits. Without this diversity of material, the cultivars themselves could lose their adaptability to changes in their environments, perhaps with the consequence that they could become increasingly difficult or actually impossible to continue to cultivate to any large extent. "No useless plant" After species inventory the next step, which must probably be taken simultaneously, is establishing and maintaining genetic material "banks." Turner, of the University of Texas, who directs the University's Plant Resources Center, says that the best such bank for protecting an otherwise disappearing species would be a series of preserved actual habitats, perhaps 30-50 km2 in area. Otherwise, genetic material banks might consist of specially constructed repositories properly maintained under carefully controlled environmental conditions, for both plant and animal species. U.S. agencies and groups maintain such repositories, especially for cultivar varieties. For example, the USDA funds a National Germplasm System that has 450 000 accessions, and adds 7500/y from many different sources. The National Science Foundation sponsors biological diversity research, particularly for tropical areas. AID contributes funds to sponsor germplasm systems at various international agricultural research institutes throughout the world. Also, the International Board for Plant Genetic Resources (IBPGR), a component of the U.N. Food and Agricultural Organization (Rome, Italy), has the task of preserving and expanding the world genetic resource inventory of crops. The IBPGR was founded in 1974, and is devoted to developing international Environ. Sci. Technol., Vol. 16, No. 2, 1982
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Biological diversity could protect crops One possible illustration of the need to maintain biological diversity can be found in cereal grain growing. Corn (maize, Zea mays) for human and animal consumption is a prime example. Without genetic diversity, a given variety of maize could eventually be unable to adapt to changing conditions. For instance, its ability to "fend off" biotic threats, such as weeds, diseases, and insects, and abiotic threats, such as heat, cold, or drought, could be seriously impaired. A source of genetic diversity for maize might be found in five of six teosinte grass species of Mexico and Guatemala, which, according to botany professor Hugh litis of the University of Wisconsin (Madison), may be considered as subspecies, or ancestral forms of Zea mays, now known only as a cultivar. He adds that not only was teosinte an ancestor of maize 8000 years ago, "but it continues to play an important role in maize evolution today." Until recently many in Mexico have regarded teosinte as a pesky field weed to be exterminated. However, on a parcel of land scheduled for development, a botanist found a species that "is resistant to more than half the viruses that plague domesticated maize types, is immune to a range of insects, and thrives in hostile areas where other varieties perish," according to UNEP. Possibly, these desirable traits could be transferred to certain domesticated maize varieties. UNEP notes that had the land parcel—the only known sanctuary of that wild maize species—been developed as scheduled, the plant would probably never have been known, and its genetic resource would most likely have been irretrievably lost. Similarly, ancestral forms and older varieties of wheat grow in various parts of central Asia and Turkey. Stanford's Ehrlich warns that without such genetic renewal with material from the wild, many extensively cultivated wheat varieties (or substitute rye, millet, sorghum, and so on) could lose the genetic capability to adapt to a changing environment.
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collaboration among its members in a global network of institutions active in the exploration, collection, conservation, documentation, and use of plant genetic resources. Other international-level organizations working in species preservation include the U.N. Environment Program, and UNESCO's "Man in the Biosphere" program. On a nongovernmental level, there is the International Union for the Conservation of Nature and Natural Resources. Recounting an ancient Indian proverb that "a useless plant has never been found," T. N. Khoshoo, director of the National Botanical Research Institute (Lucknow, India) said that his country has five national government agencies working to maintain and promote biological diversity. He added that India is establishing, or plans to establish "gene sanctuaries" and biosphere reserves. Khoshoo suggested that where habitat preservation is infeasible for some reason, tissue culture could be an "inexpensive" means of retaining a species' living material. He added that conservation of marine biota and microbe species "is of the utmost importance," perhaps because there are so many such species that have the potential of making important contributions to the world genetic resource base. One example of a benefit that can be derived is additional sources of enzymes for fermentation processes. No bailout The preservation of ecological and genetic diversity, then, transcends aesthetic, moral, or sentimental considerations. According to scientists at the State Department conference, and other experts in the field, it is a matter of absolute necessity for survival. As Stanford's Ehrlich put it, "In most cases, humanity does not know how to substitute for ecosystem services." And some of these may be biological and biochemical services without which human survival could become problematic. Nevertheless, prospects for really large-scale global efforts toward species preservation and resultant ecological and genetic diversity retention are probably dim, especially in tropical areas where they are needed most. Urbanization and rural agricultural development continue; and, if anything, will probably accelerate further. Botany professor Turner of the University of Texas takes the view that it is "probably too late anyway" for significant species preservation and biological diversity maintenance. He
Biological diversity could pay off About 2 5 % of the number of all prescription drugs in the U.S. are derived from higher plants, Norman Farnsworth of the University of Illinois Medical Center (Chicago) estimates. He pegs their total 1980 market value at $8 billion. This does not take into account the value of pharmaceuticals derived" from microorganisms and fungi, for instance. Farnsworth, whose specialty is medicines derived from nature, told ES.ililf Kt-si.irili .mil Iin1li-.lri.il 14M ..
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