Читать книгу Fundamentals of Conservation Biology - Malcolm L. Hunter Jr. - Страница 69

There are many ways to define species, and decisions on what constitutes a species can have significant ramifications for conservation activities. It is generally desirable for conservationists to seek to maintain all distinguishable taxa, whether or not there is full agreement on definitions of “species,” because they represent significant genetic diversity. Approximately 1.3 million species have been described by scientists, but the actual number of species that exists is certainly much greater because there are large numbers of undescribed species. Although conservation biologists cannot hope to work with each species, it is useful to know the magnitude of what we might lose if environmental degradation continues.

One can argue that every species has intrinsic value; in other words, its importance is independent of its relationships with people and all other species. From this perspective, conservationists usually evaluate the importance of a species relative to how endangered it is. This is the basis for the lists of species jeopardized with extinction maintained by many organizations. Instrumental values, which are based on the usefulness of species, differ greatly among species. Many species have economic value because they provide food, medicine, materials, fuel, recreation, and various services for people. Species also have aesthetic, spiritual, scientific, and educational values that go beyond economics. They have ecological importance to many other species because of their roles in ecosystems, especially if they are dominant or keystone species. They can be of strategic value to conservationists by serving as flagship, umbrella, or indicator species. Some of these instrumental values are currently realized; many of them are potential values because they have not yet been expressed. Finally, species vary in their taxonomic uniqueness, and species that have no closely related species are generally considered more important than species with many close relatives.