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In the Light of Evolution: Volume II—Biodiversity and Extinction
Human population densities in Africa are higher where biodiversity is higher, suggesting that biodiversity is itself a better index for comparative wealth than we once had realized (Balmford et al., 2001). Biodiversity enrichment, in its transformed mode, means arable land, a great enticement for needy and opportunistic nations. Such pressures lead to conflict. Many important areas rich in biodiversity lie on international borders, especially tropical rain forests between nations that have not always maintained the most peaceful relations. History shows that people have made war over gold, oil, and water; they may do so over biodiversity.
The Ecological Argument
That species are the fabric of ecosystems, which in turn provide essential services, is a powerful concept, but one that may escape many of those unfamiliar with biological principles. Again, in many instances, it is best to enter these discussions from a practical and experiential starting point, often with a focus on current news. For example, animal pollination of plants is not only central to the function of terrestrial ecosystems, but it is also essential to the survival, sustainability, and economies of human populations (McGregor, 1976; Southwick and Southwick, 1992). The distressing recent decline in the health and number of managed bee colonies in the U.S. (Allen-Wardell et al., 1998; Oldroyd, 2007) can be mitigated by greater reliance on wild populations of pollinators, so long as we maintain the natural habitats adjacent to agricultural areas that are necessary to support these wild species (Kremen et al., 2002; Ricketts et al., 2004). Thus, an effective public message is one demonstrating that putting more biodiversity into service can improve crop yield and save more than a little biodiversity-enriched land in the process.
This argument relates to one that inculcates a more general appreciation for the preservation of the natural world: pollination of plants by diverse species is not only important in food production of humans but is also critical to the sustainability of many terrestrial ecosystems. In other words, the world that is so familiar to us is strongly shaped by an extraordinary collaboration between flowering plants and pollinating insects (as well as some mammals and birds), a proof of concept with a 100 million-year-old history (Novacek, 2007). Huge losses of species that participate in this system have the potential to disrupt ecosystems in ways documented for plants and insects at the time of the end-Cretaceous extinction event (Wilf et al., 2006). That history records such disruptions is a lesson of the past that people respond to; it induces them to think about what life might be like in a similarly degraded world of the future.