Conclusions

- Global mammal distributions, biodiversity hotspots, and conservation

Conservation biologists and managers must carefully reconsider conservation priorities. They must wrestle with difficult questions not included when efforts are focused solely on hotspots of species diversity, however they are defined. The crucial issue is balancing allocation of effort to conservation of species diversity with protection of population diversity and ecosystem services, especially when the elements to be conserved occur in “coldspots” (29). That means acquiring information on complementarity within and between groups that can be used in making difficult judgments about trade-offs between redundancy and diversity at the species level. For instance, two species of predatory insect may undergo population increases and maintain a pest-control service as a species of insectivorous bat declines. How should the joint distributions of the three be evaluated? This involves the vexed issue of trade-offs between preservation of existence values and ecosystem services, and further problems related to accelerating climate change. Making judgments on ecosystem services involves a similar series of issues at the population level. Indeed, conservation biologists will soon be converging on economists with a strong focus on “elasticity of substitution” (30).

Considering how little is known about the distribution and ecology of most organisms—indeed, of even the best-known groups such as mammals, birds, and butterflies—it is clear that time, funds, and personnel will not be available in the foreseeable future to illuminate these issues in detail except for a small sample of systems. Even the results here, for the mammals, whose distributions are known in more detail than most of the biota, will likely need revision as new biogeographic information becomes available. Therefore research effort must be concentrated on carefully selected test systems. In addition, all conservation biologists should be attempting to find ways of reducing the basic drivers of biodiversity loss: population growth, over-consumption by the rich, and the use of faulty technologies and socio-economic-political systems (30).