CHAPTER 1 Introduction EDWARD O. WILSON Pellegrino University Professor, Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts “Biodiversity,” the term and concept, has been a remarkable event in recent cultural evolution: 10 years ago the word did not exist, except perhaps through occasional idiosyncratic use. Today it is one of the most commonly used expres- sions in the biological sciences and subsequently has become a household word. It was born “BioDiversity” during the National Forum on BioDiversity, held in Washington, D.C., on September 21-24, 1986, under the auspices of the National Academy of Sciences and the Smithsonian Institution. The proceedings of the forum, published in 1988 under the title BioDiversity (later to be cited with less than bibliographical accuracy by most authors as Biodiversity), became a best- seller for the National Academy Press. By the summer of 1992, as a key topic of the Rio environmental summit meeting, biodiversity had moved to center stage as one of the central issues of scientific and political concern world-wide. So what is it? Biologists are inclined to agree that it is, in one sense, every- thing. Biodiversity is defined as all hereditarily based variation at all levels of organization, from the genes within a single local population or species, to the species composing all or part of a local community, and finally to the communi- ties themselves that compose the living parts of the multifarious ecosystems of the world. The key to the effective analysis of biodiversity is the precise defini- tion of each level of organization when it is being addressed. Even though the study of biodiversity can be traced back as far as Aristotle, what finally has given it such extraordinarily widespread attention is the real- ization that it is disappearing. In the late 1970s and through the 1980s, the first convincing estimates were made of the rate of tropical deforestation, which translates to the areal loss of habitat where most of living diversity is concen- 1 2 / BIODIVERSITY II trated. This information led to disturbingly high estimates of the rates of loss of species in these forests. The magnitude of erosion also drew attention to ongo- ing extinction in other habitats, from deserts to coral reefs, at all levels of bio- logical organization from alleles to entire local ecosystems. It became clear that the decline of Earth’s biodiversity was serious. Worse, unlike toxic pollution and ozone depletion, it cannot be reversed. Scientists who once had devoted their careers to bits and pieces of bio- diversity now became holists, or at least more approving of the holistic approach, and they were energized by a new sense of mission. For the good of society as a whole, they now realized that the classification of such organisms as braconid wasps and lauraceous shrubs mattered. Moreover, the ecologists also were in- cluded: the processes by which natural communities are assembled and their constituent species maintained have central importance in both science and the real world. The study of diversity subsumed old problems in systematics and ecology, and specialists in these and in related fields of biology began to talk in common parlance as never before. Just as significantly, physical scientists, so- cial scientists, geographers, and artists were drawn into the colloquy. The sub- ject consequently has begun to be reshaped into a new, often surprisingly eclec- tic field of inquiry. Today we now hear regularly of “biodiversity science” and “biodiversity studies.” Since the 1986 National Forum on BioDiversity, there has been an exponen- tial rise in research and technical innovation. Scientists appreciate that only a tiny fraction of biodiversity on Earth has been explored, and that its origin and maintenance pose some of the most fundamental problems of the biological sci- ences. These problems are also among the least technically tractable. Those who have cut into the outer surface of ecology and evolution suspect that mo- lecular and cell biology eventually will prove simple by comparison. The present volume is a 10-year report on the state of the art in biodiversity studies, with an emphasis on concept formation and technique. Overall, it makes a striking contrast with the original BioDiversity, showing how extraordinarily far we have come and at the same time mapping how far scientists yet must travel in their reinvigorated exploration of the biosphere. Some scientists and policy-makers have worried that the magnitude of the biodiversity we now know to be present in the world’s habitats is so enormous, the cost of exploring and documenting it so overwhelming, and the number of biologists who can analyze and document it so small that the goal of understand- ing the diversity of the world’s species is unattainable. The central message of this volume is, to the contrary, that the potential benefits of knowing and con- serving this biodiversity are too great and the costs of losing it are too high to take a path of least resistance. By documenting the infrastructure of knowledge and institutions that already are in place, this volume suggests that there is a cost-effective and feasible way of approaching the conservation of the world’s biological resources. The key to a cost-effective solution to the biodiversity INTRODUCTION / 3 crisis lies in the collaboration of museums, research institutions, and universi- ties; the pooling of human and financial resources; and the shared use of physi- cal and institutional structures that are already present. Rather than building the knowledge, institutional and physical infrastructure for documenting bio- diversity from the ground up, we need to build upon preexisting infrastructure and increase support for systematics, training, and museums. This volume is an outgrowth of one such endeavor, the recent establish- ment of a Consortium for Systematics and Biodiversity between the Smithsonian Institution, the University of Maryland at College Park, the U.S. Department of Agriculture Systematics Laboratories, the University of Maryland Biotechnol- ogy Institute, and the American Type Culture Collection. The Consortium, dedi- cated to enhancing the conceptual understanding and documentation of bio- diversity of organisms (from viruses and bacteria to invertebrate and vertebrate animals, protists, fungi, algae and higher plants) in living and nonliving mu- seum collections, represents the type of cooperation that will be necessary for us to cost-effectively understand and protect our natural resources. 4 / BIODIVERSITY II CHAPTER 2 Biodiversity: What Is It? THOMAS E. LOVEJOY Counselor to the Secretary for Biodiversity and Environmental Affairs, Smithsonian Institution, Washington, D.C. Biodiversity has to be thought of in a number of different ways. One would begin by looking at the overall perspective of evolutionary time and more spe- cifically by looking at a great radiation (such as that of the Hawaiian honey- creepers) from a single ancestor. Another way of viewing biodiversity is as a characteristic of natural communities. For instance, a forest in Southern New England characteristically will contain about 20 or 30 tree species, but in a marshy area in Southern New England or farther north, forests are composed of only two or three species. In contrast, a tropical forest, such as in Amazonian Peru, will contain hundreds of species of trees. Therefore, natural communities each have their own characteristic biodiversity, both in terms of numbers and composition of species. Another way of looking at biodiversity is globally and collectively. While the number of species currently described is on the order of 1.4 million, the big question is how many species are there totally? Current estimates of the total number of species run from 10-100 million. One can break it down and look at certain segments of global totals, such as the diversity of higher plants, number of species, or expressed as sheer weight (biomass). The degree of knowledge about biodiversity varies with both location and taxon (classificatory groups of organisms). For example, the British insect fauna is much better known than the Australian insect fauna. (Indeed I believe that there are so many naturalists in Britain that it is impossible for a bird to lay an egg without three people, includ- ing at least one cleric, recording it). Within Australia, vertebrates are better known than insects. That relation is true throughout most of the world, because 7 8 / BIODIVERSITY II we have tended toward vertebrate chauvinism in the exploration of biodiversity (Wilson, 1985). Another way to think about biodiversity is where it is most concentrated. The best known concentration, of course, is in tropical forests—those places near the equator where there is enough moisture sufficiently evenly distributed through the year to maintain a tropical forest formation. These forests comprise roughly 7% of the dry land surface of the Earth and may hold more than 50% of all species. The reality, however, is that we do not know precisely how much biodiversity is concentrated in a particular biological formation. A characteris- tic pattern of biodiversity is a general increase in numbers of species as one approaches the equator. For example, São Paulo, just within the tropics, holds 100 times more species of ants than Tierra del Fuego, and the number at the equator will be even higher than at São Paulo (MacArthur, 1972). This is a pattern that repeats itself again and again for many groups of organisms, but, of course, not all. The marine realm has more representations of the major group- ings of life than those on land, and the realm of soil biology is so poorly explored that it is hard to tell what rich forms of life might exist there. So as we learn more about life on Earth, the relative proportions of where life on Earth is con- centrated can be expected to change.