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Part IV Prospects for the Future A rmed with evidence from the past and present about global pat- terns and processes of extinction, what can be projected for global biodiversity in the near and distant future? Chapters in this sec- tion address several of the many challenges presented by the ongoing extinction crisis, both for the biodiversity sciences per se and for efforts to translate the science into an enhanced societal awareness that might spawn effective conservation policies and actions. Conventional wisdom has been that ecologically important traits (such as an ability to withstand cold climates) are too evolutionarily labile to be of much utility in phylogenetic inference. In Chapter 13, Michael Donoghue challenges this paradigm by reviewing several cases in which higher plant taxa have retained, for long periods of evolutionary time, particular traits that impact their geographic distributions. Donoghue calls this phenomenon “phylogenetic niche conservatism.” His basic idea is that the geography of biodiversity at any horizon in time reflects an interaction between phylogenetic legacy (as registered in the evolved eco- logical characteristics of particular lineages) and contemporary ecological selection pressures. This worldview implies that evolutionary shifts from one ecological setting to another cannot be readily accomplished by many plant taxa, especially if substantial genetic adjustments in physiology are required. Thus, newly opened niches are more likely to be filled by immi- grants from ecologically similar zones than by in situ evolution of local populations. Donoghue addresses some ramifications of phylogenetic 243
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244 / Part IV niche conservatism for the future of plant biodiversity in the face of global climate change and habitat fragmentation. In a somewhat similar vein, Jonathan Davies and colleagues associ- ated with the Andy Purvis group show in Chapter 14 how a phylogenetic modeling approach can help to identify mammalian taxa whose intrinsic biology might lend them especially vulnerable to environmental pres- sures. They begin by combining phylogenetic information from a recently completed Tree of Life for mammals with ecological, life history, and geographic data to examine the origins and current distributions of mam- malian biodiversity. Results from the analysis indicate that evolutionary cradles of origin have shifted over time, and that extinction risks vary according to the type of mammal (e.g., large-bodied versus small-bodied) and also to spatial and temporal differences (often region-specific) in threat intensity. The authors discuss ramifications of such phylogenetic findings for the near- and long-term future of mammalian biodiversity, including how alternative criteria (different “currencies of conservation”) might be used in setting preservation priorities. Before the mid-20th century, scientific analyses of biodiversity rested on appraisals of organismal phenotypes. That situation changed dramati- cally when molecular techniques were introduced that permitted direct assays of genotypes. The molecular revolution in evolutionary biology has provided powerful tools for biodiversity assessments ranging from spe- cies identifications and phylogeny reconstructions to genetic dissections of ontogeny. Projecting forward, in Chapter 15 John Avise describes three opportunities for the field of biodiversity genetics that seem not to have been widely appreciated or discussed: use information from the emerging phylogenetic Tree of Life to erect the first-ever universally standardized scheme of biological classification; identify biogeographic hotspots and centers of origin (including those tracing to the late Tertiary) for various extant biotas; and engage in educational outreach by conveying to stu- dents and the public a sense of wonder and appreciation for the marvelous workings of nature, many of which are being revealed for the first time by genetic appraisals. Capitalizing on these opportunities should be instruc- tive for basic science and also helpful in conservation efforts. In Chapter 16, Michael Novacek expands on the public-outreach mis- sion for conservation biology by emphasizing the need to awaken a broad audience to the ongoing biodiversity crisis. Despite the urgency of current environmental problems, and committed efforts (albeit by relatively small segments of society) over the past 20 years to find solutions, national and international responses to date have been slow to materialize and inad- equate to steward global biodiversity through the crucial 21st century. One major reason is the general lack of understanding and engagement on biodiversity issues by the public, which in polls typically ranks environ-
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Prospects for the Future / 245 mental concerns below other challenges such as terrorism, the economy, and family values. Novacek analyzes this state of affairs and argues that effective ways must be found to tailor biodiversity messages to each target audience. Enlightened environmental measures by corporations and democratic governments will be achieved only if the “power of the people” is marshaled in favor of conservation efforts. In Chapter 17, Peter Bryant canvasses the many ways that the gen- eral public can become engaged in conservation efforts. Using Orange County—the second most populous county in California—as a touch- stone, he explains how local citizens have played and are continuing to play important roles in identifying species of plants and animals, moni- toring the status of local populations, assessing geographic distributions, monitoring migration patterns, contributing to rescue and restoration efforts, educating students, joining conservation organizations, promoting parklands and other preservation initiatives, and otherwise contribut- ing to the assessment and protection of biodiversity. These examples are heartening because Orange County (with three million people and grow- ing) lies in one of the most heavily urbanized regions of North America, yet still retains substantial biodiversity that at least some segments of the public are beginning to appreciate and strive to protect. In Chapter 18, Paul Ehrlich and Robert Pringle close this book by reminding us that “the fate of biological diversity for the next 10 million years will be determined during the next 50–100 years by the activities of a single species” (Homo sapiens). With the projected increase by mid-century of 2.6 billion people to an already overcrowded planet, the prospects for preserving substantial biodiversity are dim, unless societal mindsets and comportments change dramatically and quickly. The authors issue a plu- ralistic call for action on seven fronts: combat the underlying drivers of biodiversity loss (notably human population growth, overconsumption, and the use of malign technologies); promote permanent nature reserves; provide social and economic incentives to preserve wild populations; better align economies with conservation; restore biodiversity on cur- rently degraded lands; vest human occupants of a region with the desire and capacity to protect nature; and, in general, fundamentally transform human attitudes toward nature and biodiversity. These calls are ambitious, but positive societal responses to them are not yet beyond the realm of possibility.
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