href="#ulink_d7a67586-8102-5569-b990-cc32ce76a0a8">Fig. 3.12). Conservationists have also used the umbrella species concept in other ways with mixed results (Roberge and Angelstam 2004; Branton and Richardson 2011), for example, by conserving habitat specialists that will only generate a small umbrella, or, conversely, by identifying suites of umbrella species to generate a broader umbrella. When using the broad umbrella species concept for such specific applications, the conservation “shortcut” might disappear if the exercise requires detailed information on the habitat needs of co‐occurring species (Seddon and Leech 2008).
Figure 3.12 With a geographic range reaching from the Russian Far East south to Indonesia and west to India (formerly to Turkey and Iran), the tiger ranges across a broad set of ecosystems – boreal forests, mangrove swamps, rain forests, dry deciduous woodlands, riparian thickets, and more. Efforts to keep the tiger from going extinct have benefitted other wild creatures throughout much of Asia thus making it a classic umbrella species.
(Martin Prochazkacz/Shutterstock and Ondrej Prosicky/Shutterstock)
Some species are useful to conservation biologists because the health of their populations is an easy‐to‐monitor indication of environmental conditions or of the status of other species; these are called indicator species (Niemi and McDonald 2004). They are the “miners’ canaries” that can warn us about general environmental degradation just as miners used to carry canaries to warn them of poor air quality. The classic example comes from the impact of DDT on peregrine falcons, brown pelicans, and some other birds. DDT caused their eggs shells to thin, resulting in fewer young produced and catastrophic declines of these species. This phenomenon first alerted scientists to a subtle but pervasive and serious impact of DDT and similar compounds for an entire ecosystem and ultimately human health. Smaller species are often sensitive indicators; for example, lichens reflect forest management practices that change a forest’s microclimate (Nascimbene et al. 2013) as well as urban air quality, and aquatic invertebrates are monitored to track water pollution (Sundermann et al. 2013). Some indicator species provide “easy access”; for example, monitoring colonial seabirds to assess the 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.
The Uniqueness Value of Species
Imagine a question on your vertebrate zoology final: What do the aardvark and bowfin have in common? “They are both vertebrate animals” might get you grudging partial credit. “They are the only species in their respective orders: Tubulidentata and Amiiformes” would certainly earn you full credit. These are two special species because they are unique at the taxonomic level of an order, a level of taxonomy that also encompasses such large groups as rodents (Rodentia, c. 2300 species), songbirds (Passeriformes, c. 5300 species), and perches and their relatives (Perciformes, c. 10,000 species) (Fig. 3.13). Similarly, there are dozens of taxonomic families represented by just one or two species. We could argue about artificiality of taxonomic classifications, but in the end we would agree that a white‐eyed vireo is much more similar to a red‐eyed vireo than an aardvark is to one of its nearest living relatives, the African elephant.
Figure 3.13 Which is more important to conserve, the aardvark or the jerboa? 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, pictured here is the four‐toed jerboa) 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.)
In terms of instrumental values, a species that has close relatives is more likely to be replaceable than a species without close relatives. Huckleberries may not taste exactly like blueberries, but they are not a bad substitute. In contrast, nothing tastes very much like a pineapple. There is some bad news lurking here. The process of replacing one species with another one that has similar economic values can spread the web of overexploitation. Whalers started with the species that were most profitable to catch, mainly the right whale (so named because it was the ”right” whale to catch), and, as each species was depleted, they concentrated on the next one in line. This phenomenon is now characteristic of global fisheries in general; as predatory species such as tuna are depleted we move on to species that are at a lower trophic level, a process known as “fishing down the food web” (Pauly and Palomares 2005).
The instrumental values that are determined by a species’ role in an ecosystem may also
