Fundamentals of Conservation Biology. Malcolm L. Hunter, Jr.. Читать онлайн. Newlib. NEWLIB.NET

Автор: Malcolm L. Hunter, Jr.
Издательство: John Wiley & Sons Limited
Серия:
Жанр произведения: Биология
Год издания: 0
isbn: 9781119144175
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health of the marine realm is often easier than deploying oceanic survey vessels (Cury et al. 2011). Indicator species may also reflect undisturbed ecosystems that are prime candidates for reserves. If, for example, you find an area with a sizable population of curassows, chachalacas, or guans (a family of large, delicious birds that are avidly sought by hunters throughout Latin America), you can be fairly confident that it is not heavily hunted and therefore might be a relatively easy place to establish a reserve (Thiollay 2005).

      Realized Values and Potential Values

      When we assess the instrumental values of species, we generally focus on their usefulness here and now, but this is a shortsighted viewpoint as revealed in our discussion of medicinal research and biodiversity. Our rudimentary understanding of biology and ecology leaves an enormous gap between the currently realized value of a species and its potential future value. This gap is particularly wide because we have only a vague idea of what our future lives will be like – technologically, culturally, and ecologically. Consider the bacterium, Thermus aquaticus, which grows in the boiling hot springs of Yellowstone National Park and appears to be mere “slime.” This bacterium has proven fundamental to an extraordinary revolution in biotechnology. Everything from using DNA fingerprinting to identify criminals to discovering the molecular basis of major diseases to develop new treatments originally depended on an enzyme from Thermus aquaticus that is capable of remaining functional at very high temperatures while replicating DNA strands (Brock 1997). Before this discovery one could hardly have imagined its utility. It may be even harder to guess at the potential importance that any species might assume in the future. It would certainly have taken a very prescient biologist to guess that the shrew‐like proto‐mammals that scurried around the ankles of dinosaurs would eventually become the Earth‐dominating Homo sapiens. Or that those wolves skulking around the edge of our campfires 20,000 years ago, hoping for some food scraps, would become our beloved Chihuahuas and Great Danes.

      The core idea in this section is nicely captured in a phrase that could be a motto for conservation biology: keep options alive. We must take this approach because we know so little. We can never say of any species that it lacks value.

Photos depict a key consideration is that the aardvark (left) represents a very distinct evolutionary lineage, reflected in being the only member of its taxonomic order. In contrast there are about 30 species of jerboa (right) and they are among the roughly 2300 other members of the rodent order.

      (Eric Isselee/Shutterstock [left] and reptiles4all/Shutterstock [right])

      The uniqueness of a species is a value that amplifies all of the other values elaborated previously. Even a conservationist focused only on intrinsic values would probably give somewhat more importance to a spectacled bear (the only member of its genus) than a polar bear (one of four members of the genus Ursus), because the spectacled bear is far more different from other bears than the polar bear is. (For more insights on setting conservation priorities based on taxonomic relationships see early papers by Vane‐Wright et al. 1991, Crozier 1992, Faith 1992, and more recent work such as Jetz et al. 2014 and Winter et al. 2013.)

      The instrumental values that are determined by a species’ role in an ecosystem may also be influenced by a species’ uniqueness. Although the exact ecological role or niche of each species in an ecosystem may be different from that of every other species, there is often considerable overlap or redundancy in the functional roles of species. For example, no other forest herb may fill the exact niche of a Canada mayflower, but there are other species that are also fixing carbon, providing a substrate for soil fungi, providing food for pollinating insects and fruit‐consuming small mammals, and so on. If these functional overlaps are sufficient, then it is likely that the ecosystem would not be profoundly changed by the disappearance of its Canada mayflower population. On the other hand, if a species is both very distinctive and has a keystone or dominant role, then its disappearance would most likely cause significant changes to an ecosystem. For example, the loss of elephants from African ecosystems can profoundly affect vegetation structure (Asner and Levick 2012) because no other species can deliver the ecological services, mainly disturbance, herbivory, and seed dispersal, that elephants do.

      CASE STUDY 3.1 The Neem Tree

Photo depicts a variety of neem products.

      (StockImageFactory.com/Shutterstock)

      The most remarkable thing about the neem is the myriad ways it is used as a health product. People use neem products to treat boils, burns, cholera, constipation,