Conservation biology
Conservation biology is a multidisciplinary field focused on understanding and preserving biodiversity, including species, ecosystems, and ecological processes. It emerged from the conservation movement of the early 20th century, influenced by key figures like Aldo Leopold and Theodore Roosevelt. The field gained momentum in the 1960s and 1970s amid significant ecological discoveries and growing environmental advocacy. Conservation biologists primarily work to protect endangered and threatened species, as defined by organizations like the U.S. Fish and Wildlife Service, which tracks species at risk of extinction.
One major challenge in this field is habitat fragmentation, which reduces the available space for species to thrive and can hinder genetic diversity. Conservation efforts often involve determining a minimum viable population (MVP)—the smallest population size needed to maintain genetic diversity and prevent inbreeding. Additionally, creating and managing reserves is crucial, as these protected areas help sustain both endangered species and their habitats. Effective management may require controlling invasive species and maintaining appropriate environmental conditions to ensure the long-term viability of these ecosystems. Through these efforts, conservation biology aims to combat the ongoing loss of biodiversity and promote sustainable relationships between humans and the natural world.
Subject Terms
Conservation biology
Biological scientists throughout the world are interested in and involved in conservation biology as a means of preserving biodiversity. Evolutionary biologists, botanists, ecologists, and geneticists, as well as those in applied science management fields such as wildlife management, fisheries, and forestry, all play important roles in the broad context of conservation biology.
Background
Conservationbiology is a multidisciplinary field that incorporates the knowledge base and skill sets of all the biological sciences in order to design and implement methods that will attempt to ensure the long-term continuation of species, ecosystems, and ecological processes.
Historical Perspective
Conservation biology as a scientific discipline has its roots in the movement of the early twentieth century. Wildlife scientists such as Aldo Leopold, foresters such as Gifford Pinchot, and progressive politicians such as Theodore Roosevelt wielded tremendous influence in both conservation and efforts. In the 1960s and 1970s, there was phenomenal growth of community data and important ecological theories, such as island biogeography, promoted by Robert H. MacArthur, Edward O. Wilson, and Daniel Simberloff. Social trends of this time period also contributed to the development of this field, as many people embraced the environmental movement, and, accordingly, a number of significant pieces of environmental legislation were passed. As more and more species either neared extinction or became extinct, the movement to “save the planet” became ever more insistent.
Consequently, much of the focus of conservation biology since the 1970s has been on saving endangered and threatened species. The United States Fish and Wildlife Service (USFWS) defines an endangered species as one that is in danger of extinction throughout all or a significant portion of its range. A threatened species is likely to become endangered in the foreseeable future. According to the International Union for Conservation of Nature and Natural Resources, better known as the IUCN, the number of threatened mammals increased by 22 percent from 2007 to 2022. Threatened species refer to those that are critically endangered, endangered, or vulnerable. For some organisms, the percentage was much higher. For example, the number of endangered insects increased by 276 percent, the number of endangered fish species increased by 196 percent, and the number of endangered reptile species increased by 336 percent. In 2022, 16,900 species were on the IUCN's Red List as being threatened. This was double the number of threatened species on the list in 2007.
Minimum Viable Populations
In the past in Europe and North America, most extinctions or local extirpations of species occurred because of overhunting. Examples of this in North America include the bison, cougar (in the eastern United States except for the remnant Florida panther population), red wolf, and passenger pigeon. In Europe, the wolf, wild boar, goshawk, and capercaillie were gone by the nineteenth century.
Although overhunting is still a reason for species decline in some parts of the world, today the primary cause for the large number of endangered and threatened species is habitat fragmentation. This occurs when a large area of habitat is divided into a number of smaller patches comprising a smaller total area. Often these smaller patches are unsuitable for species of the original habitat, and thus dispersal of species into the “new” habitat can be low. Conservation biologists face the challenge of preserving as many individuals of the endangered or threatened species as possible within a suitable habitat, thereby enabling genetic diversity within the species to continue. As a result of fragmentation, conservation biologists are often trying to discover a minimum viable population (MVP) number for each imperiled species. Although the number of five hundred individuals has often been used as a base guideline for MVP, many scientists argue that the specific number of individuals needed to ensure genetic diversity varies by species and that no set number applies to all species.
If the MVP becomes too low, serious genetic problems within the population may occur, as the number of individuals is simply too low to prevent inbreeding. Probably the best known example of this is the cheetah, a species in which almost all the individuals are now related to one another. Biologists have noted deleterious genetic effects such as sperm malformation and high infant mortality within the cheetah population. With species that have greatly reduced population numbers, conservation biologists are faced with the management challenge of reducing inbreeding, encouraging outbreeding if enough individuals remain, and seeking to enable members of the species to migrate, if possible.
Reserves
Along with determining MVPs for endangered and threatened species, biologists seek to meet the management goals mentioned above by creating or maintaining suitable reserve sites. As with deciding on MVP, determining the necessary size and shape of a reserve can be extremely difficult and is again species dependent. Based on their research, several conservation biologists have suggested that a circular shape for is best in order to minimize dispersal distances and to minimize the amount of edge habitat. Within both temperate and tropical forest areas, negative edge effects include temperature and humidity changes, wind exposure, tree mortality, and penetration of light into formerly shaded areas.
Many researchers recommend single large reserve areas for large herbivores, large carnivores, and birds, rather than a number of small reserves, unless an extensive corridor of suitable habitat can connect the small reserves. The efforts of national conservation organizations are often necessary to establish and maintain large nature reserves, whereas regional and even local groups may be able to keep smaller reserves going for species that do not require large expanses of habitat in which to survive.
Active management of reserves is usually necessary in order to provide continued suitable habitat for endangered and threatened species. Often exotic vegetation must be removed from reserves, or a certain successional stage of vegetation must be maintained. Elimination of exotic animal species, such as wild boars or brown-headed cowbirds, may be needed. Once land has been set aside for the preservation of imperiled species, conservation biologists must be vigilant in its management in order to preserve the of the area.
Bibliography
Blackledge, Steve. "Endangered Species Can't Wait for Protection." Environment America, 22 Feb. 2024, environmentamerica.org/articles/endangered-species-cant-wait-for-protection/. Accessed 23 Dec. 2024.
Groom, Martha J., Gary K. Meffe, and C. Ronald Carroll. Principles of Conservation Biology. Sunderland, Mass.: Sinauer Associates, 2006.
Guynup, Sharon. "Global Studies of 71,000 Animal Species Finds 48 Percent Are Declining." Mongabay, 5 June 2023, news.mongabay.com/2023/06/global-study-of-71000-animal-species-finds-48-are-declining/. Accessed 23 Dec. 2024.
Pullin, Andrew S. Conservation Biology. New York: Cambridge University Press, 2002.
Soulé, Michael E., and Gordon H. Orians. Conservation Biology: Research Priorities for the Next Decade. Washington, D.C.: Island Press, 2001.