What conservation biology is and why it matters

Conservation biology is the science of understanding and protecting the diversity of life. It draws on ecology, evolution, genetics and physiology, which earlier courses in this program have built up, and it adds something those fields do not require: a commitment to an outcome. Ecologists study how populations grow and how communities assemble; conservation biologists study the same processes in order to slow the loss of species, populations and ecosystems. This first lesson asks what kind of science that makes conservation biology, why people value biodiversity, how different knowledge systems contribute, and how the rest of the course is organized.

A crisis discipline

In 1985 the American biologist Michael Soulé published an essay titled 'What is conservation biology?', which has shaped the field ever since. He described conservation biology as a crisis discipline, comparable to cancer biology or emergency medicine. In a crisis discipline, practitioners must often act before the science is complete, because waiting for certainty would mean losing the very thing they hope to protect. A physician treating a trauma patient cannot wait for a randomized trial; a biologist faced with a population of a few dozen animals cannot wait decades for a full demographic study. Decisions are made under uncertainty, and the costs of being wrong are asymmetric: an unnecessary precaution is usually reversible, but extinction is not.

Soulé also argued that conservation biology is value-laden, and he set out four functional postulates and a normative one. The functional postulates were that the diversity of organisms is good, that the untimely extinction of populations and species is bad, that ecological complexity is good, and that evolution is good. The normative postulate was that biotic diversity has intrinsic value, irrespective of its usefulness to people. Critics then and now have pointed out that these statements are not scientific hypotheses that can be tested; they are commitments. Supporters respond that every applied science has goals of this kind. Public health assumes that human health is worth protecting, and engineering assumes that bridges should stay up. The science within conservation biology must still be rigorous and honest, even when the results are unwelcome.

Roots of the field

Conservation biology as a named field dates from the late 1970s and 1980s. The first International Conference on Conservation Biology was held in San Diego in 1978, and the Society for Conservation Biology was founded in 1985. Its roots are much older. In North America, two traditions of the late nineteenth and early twentieth centuries are often contrasted. The preservationist tradition, associated with John Muir, argued that wild places should be protected for their own sake and for the spiritual benefit they give people. The resource conservation tradition, associated with Gifford Pinchot, the first chief of the US Forest Service, argued that forests, water and wildlife should be managed scientifically to provide the greatest good for the greatest number over the long run. Both traditions shaped the national parks and forest reserves created in Canada and the United States, from Yellowstone in 1872 and Banff in 1885 onward.

The ecologist Aldo Leopold bridged the two traditions. His essay 'The Land Ethic', published in 1949 in A Sand County Almanac, proposed that people should see themselves as members of a biotic community rather than as conquerors of it. Leopold's famous principle was that a thing is right when it tends to preserve the integrity, stability and beauty of the biotic community. Rachel Carson's Silent Spring (1962) then showed the public how pesticides moved through food webs, and helped launch modern environmental law in both countries. The science of island biogeography developed by Robert MacArthur and E. O. Wilson in the 1960s, discussed in BIOL-208, gave conservation biology some of its first quantitative tools, and population genetics, covered in BIOL-322, supplied others.

These historical roots also carry a less comfortable legacy. Many protected areas in North America were created by removing Indigenous peoples from lands they had lived on and cared for over thousands of years, and by banning hunting, fishing and burning practices that had shaped those landscapes. Lesson 11 returns to this history and to the growing role of Indigenous-led conservation today.

Levels of biodiversity

Biodiversity is usually described at three nested levels. Genetic diversity is the variation in genes within and among populations of a species; it is the raw material for adaptation and is lost when populations shrink or disappear, as BIOL-322 showed. Species diversity is the variety of species in a place or on Earth as a whole; it is the level most people think of first and the level at which most laws operate. Ecosystem diversity is the variety of communities and the processes, such as nutrient cycling and disturbance regimes, that connect them. Some authors add functional diversity, the range of ecological roles that species play, and phylogenetic diversity, the amount of evolutionary history represented by a set of species. Lesson 2 shows how each level can be measured.

Conservation can fail at any level. A species can persist while losing most of its genetic diversity, as the northern elephant seal did after being hunted to perhaps a few dozen animals in the 1890s. A species can survive in zoos while its ecological role disappears from the wild. And an ecosystem can lose its character without losing a single species, if the abundances of key species collapse. For this reason conservation biologists increasingly talk about protecting abundance and ecological function, not only the presence of species.

Why biodiversity matters: values

People value nature for many reasons, and conservation biologists find it useful to distinguish three broad families of values. Intrinsic values are the values that nature has in and of itself, independent of any use to people. When someone says that a species has a right to exist, they are appealing to intrinsic value. Intrinsic value cannot be measured in money, and it does not depend on whether a species is useful, beautiful or even known to science.

Instrumental values are the values that nature has as a means to human ends. The most familiar instrumental values are the goods and services that ecosystems provide. The Millennium Ecosystem Assessment, published in 2005, sorted these ecosystem services into four groups. Provisioning services are products such as food, timber, fiber, fresh water and medicines; about half of modern pharmaceuticals were derived from or inspired by natural compounds. Regulating services include pollination, the purification of water by wetlands, the control of floods, the storage of carbon in forests and peatlands, and the control of crop pests by predators. Cultural services include recreation, tourism, inspiration and spiritual experience. Supporting services, such as soil formation and nutrient cycling, underpin all the others.

Relational values are a third category, emphasized in recent work by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) and by researchers such as Kai Chan and colleagues in 2016. Relational values are neither purely intrinsic nor purely instrumental; they reside in relationships between people and nature and among people through nature. A family that has fished the same river for generations, a community whose identity is bound to a mountain, or a nation whose laws and ceremonies are tied to the return of salmon all hold relational values. IPBES now uses the broader term 'nature's contributions to people' to make room for values that do not fit easily into the language of services.

Putting numbers on nature

Because many decisions are made in economic terms, ecologists and economists have tried to estimate the monetary value of ecosystem services. A widely cited study by Robert Costanza and colleagues in 1997 estimated the annual value of global ecosystem services at about 33 trillion US dollars, more than the global economic output of the time, and an updated study in 2014 raised the estimate to well over 100 trillion dollars a year. These numbers are rough, and critics point out that summing the value of services that cannot be substituted for one another has little meaning; without pollination or fresh water there would be no economy to compare them with. Valuation is more useful at local scales, where it can show, for example, that protecting a watershed is cheaper than building a water treatment plant. New York City made this argument in the 1990s when it chose to protect the Catskill and Delaware watersheds rather than build a filtration plant estimated to cost several billion dollars.

Valuation also raises the problem of time. Many benefits of conservation, such as a stable climate or the continued existence of a species, accrue far into the future, while the costs, such as forgone timber harvest, fall now. Economists convert future benefits to present values by discounting, and the choice of discount rate can decide the outcome of an analysis, as the next example shows.

# Present value of a wetland's services compared with a one-time payment for converting it.
# All numbers are invented for illustration.
annual_services = 120_000       # dollars per year of flood control, water filtration and recreation
conversion_value = 2_500_000    # one-time value of draining the wetland for development
years = 100
for rate in (0.01, 0.03, 0.05, 0.07):
    pv = sum(annual_services / (1 + rate) ** t for t in range(1, years + 1))
    choice = "protect" if pv > conversion_value else "convert"
    print(f"discount rate {rate:4.0%}: present value of services = {pv:12,.0f}  -> {choice}")
# value of services 100 years from now, seen from today
for rate in (0.01, 0.07):
    print(f"at {rate:.0%}, one year of services in year 100 is worth {annual_services / (1 + rate) ** 100:9,.0f} today")

discount rate   1%: present value of services =    7,563,465  -> protect
discount rate   3%: present value of services =    3,791,869  -> protect
discount rate   5%: present value of services =    2,381,749  -> convert
discount rate   7%: present value of services =    1,712,310  -> convert
at 1%, one year of services in year 100 is worth    44,365 today
at 7%, one year of services in year 100 is worth       138 today

At low discount rates the stream of services over a century is worth more than the one-time conversion payment, so protection wins; at high rates the same stream is worth less, and conversion wins. The last two lines show why: at 7 percent a year, a benefit received a century from now is worth about one thousandth of its face value today. Some economists argue that discounting the welfare of future generations at market rates is ethically unjustified, and that irreversible losses such as extinction should be treated differently from ordinary costs. This debate is not one that biology can settle, but conservation biologists need to understand it because it shapes real decisions.

Knowledge systems and Two-Eyed Seeing

Western science is one way of knowing about nature. Indigenous knowledge systems, sometimes called traditional ecological knowledge or Indigenous knowledge, are others. They are cumulative bodies of knowledge, practice and belief, passed down through generations and adapted as conditions change, about the relationships of living beings with one another and with their environment. They are often place-based and intergenerational, and they are embedded in law, language and ceremony. Indigenous knowledge has contributed directly to conservation science: for example, Inuit knowledge of polar bear and beluga movements, Cree and Dene knowledge of caribou and the long fire-management traditions of many nations.

In Canada, an influential framework for bringing knowledge systems together is Etuaptmumk, or Two-Eyed Seeing, articulated by Mi'kmaw Elder Albert Marshall. Two-Eyed Seeing means learning to see from one eye with the strengths of Indigenous knowledges and from the other eye with the strengths of Western knowledges, and using both eyes together for the benefit of all. It does not mean absorbing Indigenous knowledge into Western science or treating it as a source of data points; it means respecting each system on its own terms and creating space where both can inform decisions. BIOL-208 introduced Two-Eyed Seeing in an ecological context; in conservation, it appears in species assessments, in co-management boards and in Indigenous-led monitoring.

In the United States, tribal nations are sovereign governments with treaty-reserved rights to hunt, fish and gather on and beyond their reservations, and they manage millions of acres of land and many fisheries. Co-management arrangements between tribes and federal or state agencies are increasingly common: for example, treaty tribes in Washington have co-managed salmon fisheries with the state since the 1974 Boldt decision, and the InterTribal Buffalo Council supports dozens of tribes in restoring bison herds. Tribal wildlife departments run monitoring and recovery programs for species such as the black-footed ferret, Pacific lamprey and Columbia River salmon.

Bringing knowledge systems together raises real questions of power and control. Who owns knowledge shared in an assessment? How is it protected from misuse? Indigenous data sovereignty principles, such as the CARE principles (collective benefit, authority to control, responsibility and ethics), are designed to keep communities in control of data about their lands and peoples, and BIOL-322 discussed similar principles for genomic data. Good practice is to involve communities from the design of a project, not only at the end.

Science, values and advocacy

Because conservation biology has goals, its practitioners face a recurring question: how far should scientists advocate for particular policies? One view holds that scientists should present evidence and let others decide, because advocacy may undermine public trust. Another holds that scientists have a responsibility to speak up when their expertise shows that a course of action will cause irreversible harm. Most conservation biologists take a middle position: they distinguish clearly between what the evidence shows and what they recommend, they disclose their values, and they avoid overstating certainty. Honest reporting of uncertainty, including evidence that a favored intervention does not work, is part of what makes the field credible. Lesson 12 discusses evidence-based conservation in more detail.

Conservation decisions also involve trade-offs among values held by different people. A dam may provide clean electricity and flood control while blocking salmon migration; a mine may provide jobs and minerals needed for batteries while destroying caribou habitat. Conservation biology can describe the biological consequences of each option clearly, estimate the risks to species and ecosystems, and design ways to reduce harm. It cannot by itself decide which values should prevail. That is a matter for democratic processes, Indigenous governance and law, which lesson 9 examines.

Conservation in two countries

The United States spans arctic, temperate, desert and tropical ecosystems, from Alaska to Hawaii and Puerto Rico, and it contains several global centers of species richness and endemism, including the California Floristic Province, the freshwater systems of the southeastern states, which hold more species of freshwater mussels, crayfish and fishes than anywhere else in the temperate world, and the islands of Hawaii, where a large share of the nation's documented extinctions have occurred. Roughly 1,700 species found in the United States are listed as endangered or threatened under the Endangered Species Act. Many wide-ranging species, from caribou to monarch butterflies and migratory birds, are shared with Canada and Mexico.

Throughout the course, examples are drawn from both countries, and legal and policy material is presented for the country whose site you are reading, with comparisons where they help. The science is the same on both sides of the border; what differs is the institutions through which societies act on it.

How the course is organized

Lessons 2 and 3 cover measurement and status: how biodiversity is quantified and what the best global and national data say about its state. Lessons 4 and 5 examine the threats that drive declines, grouped under the acronym HIPPO: habitat loss, invasive species, pollution, human population and consumption, and overexploitation, with climate change and disease as growing and interacting pressures. Lessons 6 and 7 turn to the population and landscape processes that determine whether species persist: small-population dynamics, population viability analysis, metapopulations and connectivity. Lessons 8 to 10 cover responses: protected areas and conservation planning, law and policy, and the recovery of species through captive breeding, reintroduction and restoration. Lesson 11 considers people, from Indigenous-led conservation to working landscapes and environmental justice. Lesson 12 is a capstone on monitoring, evidence and recovery planning, in which you will apply the course's tools to an invented species at risk.