Issues in Ecology Number 2 Spring 1997 human-dominated ecosystems is undocumented in addi. As described in the previous section biodiversity tion.natural products extracted from many hundreds of is a direct source of ecosystem goods.It also supplie ies ontribute diver inputs to industrv gums and the genetic and biochemical res that under ssential oils and rings.resins nd oleo curre ultral and pha utical resins,dyes,tannins,vegetable fats and w axes,insect may allow us to adapt these vital enterprises to globa cides,and multitudes of other compounds(Myers 1983: change.Our ability to increase crop productivity in the Leung and Foster 1996).The availability of most of face of new pests.diseases.and other stresses has de these natural products is in decline due to ongoing habi- pended heavily upon the transfer to our crops of gene tat conversion from wild cror relatives that confer resistance to thes challenge Such extractions fro nbiodiversity's Generation and Maintenance of Biodiversity library account for nnual t Biologicl diversity.or biodiversity for short.re fers to the variety of life forms at all levels of organiza 1992).Biotechnology now makes possible even greate tion,from the molecular to the land- use of this natural storehouse of ge. scape level.Biodiversity is generated netic diversity via the transfer to crops and maintained in natural ecosystems of genes from any kind of organisn where organisms counter a wide not simply crop relative and it variety of livi ing cond tions pro 6 play a majd role in fu events that shape their evolution in ture yield increase By the e turn unique ways.Out of convenience or the.farm-evelsae f th necessity.biodiversity is usually quan products of agricultural biotechnol tified in terms of numbers of species ogy,iust now entering the market and this perspective has greatly influ- ce,are expected to reach at least enced atio It is i rtant to ren however, 1991 cited (World Bank tal.1996 In addition to sustaining the produc to humanity are delivered througl tion of conventional crops,the populations of species residing in liv biodiversity in natural ecosystems may ing communities within specific physi include many potential new foods cal settings-in other words.through Human beings have utilized around comple syste 7 000 plant sn ies for food ov systems (Daily and) story and ar .70.000 beings to realize most of the nts are aesthetic,spiritual,and economic ben Wilson 1989).Only about 150 food efits of biodiversity,natural ecosys Figure 4-Harpoon-whaling in olants have ever been cultivated on a tems must therefore be accessible.the The o re a key sourc large scale,however.Currently.82 continued existence of coniferous tree of animal protein for the human popu plant species contribute 90 percen species somewhere in the world would lation. of national per-capita supplies of food not help the inhab itants of a tov ants ott-Allen undated by ng be ause of the clearing of a pin a much smalle er numbe forest upstream.Generally,the flow of ecosystem goods of these supply the bulk of the calories humans consume and services in a region is determined by the type,spa- Many other species,however,appear more nutritious or tial layout.extent.and proximity of the ecosystems sup better suited to the growing conditions that prevail in plying them.Because of this,the preservation of only important regions than the standard crops that dom one minimum viable population of each non-human spe nate world food supply today. Because of increasin and the world' eprtectedra wot iation ofirigate nds and the otential for d security it.Indeed,such a strategy.taken to extreme,would leac may come to depend on drought-and salt-tolerant vari to collapse of the biosphere,along with its life support eties that now play comparatively minor roles in agricul services. ture. As described in the previous section, biodiversity is a direct source of ecosystem goods. It also supplies the genetic and biochemical resources that underpin our current agricultural and pharmaceutical enterprises and may allow us to adapt these vital enterprises to global change. Our ability to increase crop productivity in the face of new pests, diseases, and other stresses has de￾pended heavily upon the transfer to our crops of genes from wild crop relatives that confer resistance to these challenges. Such extractions from biodiversity’s genetic library account for annual increases in crop productiv￾ity of about 1 percent, currently valued at $1 billion (NRC 1992). Biotechnology now makes possible even greater use of this natural storehouse of ge￾netic diversity via the transfer to crops of genes from any kind of organism not simply crop relativesand it promises to play a major role in fu￾ture yield increases. By the turn of the century, farm-level sales of the products of agricultural biotechnol￾ogy, just now entering the market￾place, are expected to reach at least $10 billion per year (World Bank 1991, cited in Reid et al. 1996). In addition to sustaining the produc￾tion of conventional crops, the biodiversity in natural ecosystems may include many potential new foods. Human beings have utilized around 7,000 plant species for food over the course of history and another 70,000 plants are known to have edible parts (Wilson 1989). Only about 150 food plants have ever been cultivated on a large scale, however. Currently, 82 plant species contribute 90 percent of national per-capita supplies of food plants (Prescott-Allen and Prescott-Allen 1990), although a much smaller number of these supply the bulk of the calories humans consume. Many other species, however, appear more nutritious or better suited to the growing conditions that prevail in important regions than the standard crops that domi￾nate world food supply today. Because of increasing salinization of irrigated croplands and the potential for rapid climate change, for instance, future food security may come to depend on drought- and salt-tolerant vari￾eties that now play comparatively minor roles in agricul￾ture. 5 Issues in Ecology Number 2 Spring 1997 Photo by Taylor Ricketts Figure 4-Harpoon-whaling in Flores, In￾donesia. The oceans are a key source of animal protein for the human popu￾lation. human-dominated ecosystems is undocumented. In addi￾tion, natural products extracted from many hundreds of species contribute diverse inputs to industry: gums and exudates, essential oils and flavorings, resins and oleo￾resins, dyes, tannins, vegetable fats and waxes, insecti￾cides, and multitudes of other compounds (Myers 1983; Leung and Foster 1996). The availability of most of these natural products is in decline due to ongoing habi￾tat conversion. Generation and Maintenance of Biodiversity Biological diversity, or biodiversity for short, re￾fers to the variety of life forms at all levels of organiza￾tion, from the molecular to the land￾scape level. Biodiversity is generated and maintained in natural ecosystems, where organisms encounter a wide variety of living conditions and chance events that shape their evolution in unique ways. Out of convenience or necessity, biodiversity is usually quan￾tified in terms of numbers of species, and this perspective has greatly influ￾enced conservation goals. It is im￾portant to remember, however, that the benefits that biodiversity supplies to humanity are delivered through populations of species residing in liv￾ing communities within specific physi￾cal settings in other words, through complex ecological systems, or eco￾systems (Daily and Ehrlich 1995). For human beings to realize most of the aesthetic, spiritual, and economic ben￾efits of biodiversity, natural ecosys￾tems must therefore be accessible. The continued existence of coniferous tree species somewhere in the world would not help the inhabitants of a town in￾undated by flooding because of the clearing of a pine forest upstream. Generally, the flow of ecosystem goods and services in a region is determined by the type, spa￾tial layout, extent, and proximity of the ecosystems sup￾plying them. Because of this, the preservation of only one minimum viable population of each non-human spe￾cies on Earth in zoos, botanical gardens, and the world’s legally protected areas would not sustain life as we know it. Indeed, such a strategy, taken to extreme, would lead to collapse of the biosphere, along with its life support services.