Preserving Biodiversity

Measuring Biodiversity

Technology has matured to the point where we can begin cataloging the planet’s species in accessible ways; DNA barcoding is one such method.

Learning Objectives

Explain how DNA barcoding aids in measuring biodiversity

Key Takeaways

Key Points

  • DNA barcoding is a taxonomic method that uses a short genetic marker in an organism’s DNA to identify it as belonging to a particular species.
  • Barcoding allows us to classify organisms that would otherwise be difficult to identify, such as in situations where only part of an organism is available, or is too immature to identify by conventional methods.
  • At the present rate of description of new species, it will take close to 500 years before the complete catalog of life is known; however, most species will be extinct before this time.
  • Even with barcoding, it is difficult to know which species are threatened and to what degree they are threatened, a task carried out by the non-profit IUCN (International Union for Conservation of Nature).

Key Terms

  • barcoding: a taxonomic method that uses a short genetic marker in an organism’s DNA to identify it as belonging to a particular species
  • phylogeny: the evolutionary history of an organism
  • taxonomy: the science of finding, describing, classifying and naming organisms

Measuring Biodiversity

The technologies of molecular genetics, data processing, and data storage are maturing to the point where cataloging the planet’s species in an accessible way is close to feasible. DNA barcoding is one molecular genetic method, which takes advantage of the rapid evolution in a mitochondrial gene present in eukaryotes, to identify species using the sequence of portions of the gene. Plants may be barcoded using a combination of chloroplast genes.

DNA Barcoding

DNA barcoding is a taxonomic method that uses a short genetic marker in an organism’s DNA to identify it as belonging to a particular species. It differs from molecular phylogeny in that the main goal is not to determine patterns of relationship, but to identify an unknown sample in terms of a preexisting classification. The most commonly-used barcode region for animals, at least, is a segment of approximately 600 base pairs of the mitochondrial gene cytochrome oxidase I (COI).

Applications include, for example, identifying plant leaves (even when flowers or fruit are not available), identifying insect larvae (which may have fewer diagnostic characters than adults and are frequently less well-known), identifying the diet of an animal (based on its stomach contents or feces), and identifying products in commerce (for example, herbal supplements or wood).

Rapid, mass-sequencing machines make the molecular genetics portion of the work relatively inexpensive and quick. Computer resources store and make available the large volumes of data. Projects are currently underway to use DNA barcoding to catalog museum specimens, which have already been named and studied, as well as testing the method on less studied groups. As of mid-2012, close to 150,000 named species had been barcoded. Early studies suggest there are significant numbers of undescribed species that looked too much like sibling species to previously be recognized as different. These now can be identified with DNA barcoding.

Numerous computer databases now provide information about named species and a framework for adding new species. However, as already noted, at the present rate of description of new species, it will take close to 500 years before the complete catalog of life is known. Many, perhaps most, species on the planet do not have that much time.

There is also the problem of understanding which species known to science are threatened and to what degree they are threatened. This task is carried out by the non-profit IUCN (International Union for Conservation of Nature) which maintains the Red List: an online listing of endangered species categorized by taxonomy, type of threat, and other criteria. The Red List is supported by scientific research. In 2011, the list contained 61,000 species, all with supporting documentation.

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IUCN Red List: This chart shows the percentage of various animal species, by group, on the IUCN Red List as of 2007. The Red List is an online listing of endangered species categorized by taxonomy, type of threat, and other criteria.

Changing Human Behavior in Response to Biodiversity Loss

Human responses to climate change and species loss include national and international legal measures, as well as the creation of preserves.

Learning Objectives

Detail the benefits and limitations of different human responses to climate change and species loss, such as using preserves to conserve species

Key Takeaways

Key Points

  • Legislation throughout the world has been enacted to protect species; the legislation includes international treaties as well as national and state laws.
  • The international response to global warming has been mixed; the Kyoto Protocol, an international agreement that came out of the United Nations climate change convention that committed countries to reducing greenhouse gas emissions, was ratified by some countries, but spurned by others.
  • Many nations have laws that protect endangered species: for example, forbidding hunting, restricting land development, or creating preserves (purchased land for the explicit purpose of attempting to protect species and ecosystems ).
  • Preserves protect biodiversity in many ways, two of which are captive breeding and private farming.

Key Terms

  • endangered species: a species which is in danger of becoming extinct

Changing Human Behavior

Human Responses to Climate Change and Species Loss

Legislation throughout the world has been enacted to protect species and include international treaties as well as national and state laws. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) treaty came into force in 1975. The treaty (and the national legislation that supports) it provides a legal framework for preventing approximately 33,000 listed species from being transported across nations’ borders, thus protecting them from being caught or killed when international trade is involved. The treaty is limited in its reach because it only deals with international movement of organisms or their parts. It is also limited by various countries’ ability or willingness to enforce the treaty and supporting legislation. The illegal trade in organisms and their parts is probably a market worth hundreds of millions of dollars. Illegal wildlife trade is monitored by another non-profit, the Trade Records Analysis of Flora and Fauna in Commerce (TRAFFIC).

Within many countries there are laws that protect endangered species and regulate hunting and fishing. In the United States, the Endangered Species Act (ESA) was enacted in 1973. The U.S. Fish & Wildlife Service is required by law to develop management plans that protect the species listed as at risk in the Act in order to bring them back to sustainable numbers. The Act, and others like it in other countries, is a useful tool, but it suffers because it is often difficult to get a species listed or to get an effective management plan in place once it is listed. Additionally, species may be controversially taken off the list without necessarily having had a change in their situation. More fundamentally, the approach to protecting individual species rather than entire ecosystems is inefficient as it focuses efforts on a few highly-visible and often charismatic species, perhaps at the expense of other species that go unprotected. At the same time, the Act has a critical habitat provision outlined in the recovery mechanism that may benefit species other than the one targeted for management.

The Migratory Bird Treaty Act (MBTA) is an agreement between the United States and Canada that was signed into law in 1918 in response to declines in North American bird species caused by hunting. The Act now lists over 800 protected species. It makes it illegal to disturb or kill the protected species or distribute their parts (much of the hunting of birds in the past was for their feathers).

In relation to global warming, The Kyoto Protocol, an international agreement that came out of the United Nations Framework Convention on Climate Change that committed countries to reducing greenhouse gas emissions by 2012, was ratified by some countries, but spurned by others. Two important countries in terms of their potential impact that did not ratify the Kyoto Protocol were the United States and China. The United States rejected it as a result of a powerful fossil fuel industry, while China did so because of a concern that it would stifle the nation’s growth. Some goals for reduction in greenhouse gasses were met and exceeded by individual countries, but worldwide, the effort to limit greenhouse gas production is not succeeding. The intended replacement for the Kyoto Protocol has not materialized because governments cannot agree on timelines and benchmarks. Meanwhile, climate scientists predict the resulting costs to human societies and biodiversity will be high.

Using Preserves to Conserve Species

The private, non-profit sector plays a large role in the conservation effort both in North America and around the world. The approaches range from species-specific organizations to the broadly-focused groups mentioned above.

Many nations have laws that protect endangered species: for example, forbidding hunting, restricting land development, or creating preserves. Preserves are purchased land for the explicit purpose of attempting to protect species and ecosystems. They also protect biodiversity in many ways, such as through captive breeding and private farming.

Captive breeding is the process of breeding rare or endangered species in human-controlled environments with restricted settings, such as wildlife preserves and conservation facilities. Captive breeding is meant to prevent species extinction and to stabilize the population of the species so that it will not disappear. This technique has worked for many species for some time, such as for Pere David’s deer. However, captive breeding techniques are usually difficult to implement for such highly-mobile species as some migratory birds (e.g. cranes) and fish (e.g. hilsa). Additionally, if the captive-breeding population is too small, then inbreeding may occur due to a reduced gene pool, which may also reduce immunity.

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Captive breeding: Père David’s deer is a species of deer that is currently extinct in the wild: all known specimens are found only in captivity. This species was successfully saved through captive breeding programs after almost being hunted to extinction in China.

Ecological Restoration

The purpose of ecological restoration projects, such as wildlife and ecosystem preserves, is to return ecosystems to pre-disturbance states.

Learning Objectives

Explain the purpose of ecological restoration projects

Key Takeaways

Key Points

  • Ecological preserves, while effective in the short term, are not yet viable, long-term solutions.
  • Some of the limitations on preserves as conservation tools include preserve designs, political and economic pressures, and climate change.
  • Habitat restoration is a promising tool for restoring and maintaining biodiversity; restoration can improve the biodiversity of degraded ecosystems.

Key Terms

  • biodiversity: the diversity (number and variety of species) of plant and animal life within a region
  • keystone species: a species that exerts a large, stabilizing influence throughout an ecological community, despite its relatively small numerical abundance
  • carrion: dead flesh; carcasses

Conservation in Preserves

Establishment of wildlife and ecosystem preserves is one of the key tools in conservation efforts. A preserve is an area of land set aside with varying degrees of protection for the organisms that exist within the boundaries of the preserve. Preserves can be effective in the short term for protecting both species and ecosystems, but they face challenges that scientists are still exploring in order to strengthen their viability as long-term solutions.

Due to the way protected lands are allocated (they tend to contain less economically-valuable resources rather than being set aside specifically for at-risk species or ecosystems) and the way biodiversity is distributed, determining a target percentage of land or marine habitat that should be protected to maintain biodiversity levels is challenging. The IUCN (International Union for Conservation of Nature) World Parks Congress estimated that 11.5 percent of earth’s land surface was covered by preserves of various kinds in 2003. This area is greater than previous goals; however, it only represents 9 out of 14 recognized major biomes. Research has shown that 12 percent of all species live solely outside preserves; these percentages are much higher when only threatened species and high-quality preserves are considered.

Limitations on Preserves

Some of the limitations on preserves as conservation tools stem from preserve designs. Additionally, political and economic pressures typically make preserves smaller, never larger, so setting aside areas that are large enough is difficult. Climate change will create inevitable problems with the location of preserves. The species within them will migrate to higher latitudes as the habitat of the preserve becomes less favorable. Scientists are planning for the effects of global warming on future preserves and striving to predict the need for new preserves to accommodate anticipated changes to habitats. Some argue that conservation preserves reinforce the cultural perception that humans are separate from nature, can exist outside of it, and can only operate in ways that do damage to biodiversity. Creating preserves reduces the pressure on human activities outside the preserves to be sustainable and non-damaging to biodiversity.

Habitat Restoration

Habitat restoration holds considerable promise as a mechanism for restoring and maintaining biodiversity. Restoration ecology aims to return ecosystems to a more natural, pre-disturbance state. Of course, once a species has become extinct, its restoration is impossible. However, restoration can improve the biodiversity of degraded ecosystems.

Reintroducing wolves, a top predator, to Yellowstone National Park in 1995 led to dramatic changes in the ecosystem that increased biodiversity. The wolves, which function to suppress elk and coyote populations, provide more-abundant resources to the guild of carrion (flesh) eaters. Reducing elk populations has allowed re-vegetation of riparian areas, which has increased the diversity of species in that habitat. Decreasing the coyote population increased the populations of species that were previously suppressed by this predator. The number of species of carrion eaters has increased because of the predatory activities of the wolves. In this habitat, the wolf is a keystone species: it is a species that is instrumental in maintaining diversity in an ecosystem. Removing a keystone species from an ecological community may cause a collapse in diversity. Similarly, restoring a keystone species can have dramatic effects. The results from the Yellowstone experiment suggest that restoring a keystone species can have the effect of restoring biodiversity in the community. Ecologists have argued for the identification of keystone species where possible and for focusing protection efforts on those species. It also makes sense to attempt to return them to their ecosystem if they have been removed.

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Yellowstone National Park restoration efforts: (a) The Gibbon wolf pack in Yellowstone National Park represents a keystone species. The reintroduction of wolves into Yellowstone National Park in 1995 led to a change in the grazing behavior of (b) elk. To avoid predation, the elk no longer grazed exposed stream and riverbeds, such as (c) the Lamar Riverbed in Yellowstone. This allowed willow and cottonwood seedlings to grow. The seedlings decreased erosion and provided shading to the creek, which improved fish habitat. A new colony of (d) beaver may also have benefited from the habitat change.

Other large-scale restoration experiments underway involve dam removal. In the United States, since the mid-1980s, many aging dams are being considered for removal rather than replacement because of shifting beliefs about the ecological value of free-flowing rivers and because many dams no longer provide the benefit and functions that they did when they were first built. The measured benefits of dam removal include restoration of naturally-fluctuating water levels (the purpose of dams is frequently to reduce variation in river flows), which leads to increased fish diversity and improved water quality. In the Pacific Northwest, dam removal projects are expected to increase populations of salmon, which is considered a keystone species because it transports key nutrients to inland ecosystems during its annual spawning migrations. In other regions, such as the Atlantic coast, dam removal has allowed the return of spawning anadromous fish species (species that are born in fresh water, live most of their lives in salt water, and return to fresh water to spawn). Some of the largest dam removal projects have yet to occur or have happened too recently for the consequences to be measured. The large-scale ecological experiments that these removal projects constitute will provide valuable data for other dam projects slated either for removal or construction.