BIODIVERSITY
The concept of biodiversity has provoked considerable debate and
misunderstanding among the general public, decision-makers, and even
the scientific community. Much has been published on the subject since
its first appearance at the National Forum on BioDiversity in September,
1986, the proceedings of which became the best-seller, BioDiversity. But
what is biodiversity, what threatens it, why is it important, and what are
ecologists doing to better understand it?
What is Biodiversity?
Short for biological diversity, biodiversity includes all organisms, species, and populations; the genetic
variation among these; and all their complex assemblages of communities and ecosystems. It also
refers to the interrelatedness of genes, species, and ecosystems and their interactions with the
environment. Usually three levels of biodiversity are discussed—genetic, species, and ecosystem
diversity.
Genetic diversity is all the different genes contained in all individual
plants, animals, fungi, and microorganisms. It occurs within a species as
well as between species.
• Species diversity is all the differences within and between populations
of species, as well as between different species.
• Ecosystem diversity is all the different habitats, biological communities,
and ecological processes, as well as variation within individual ecosystems.
What are the Threats to Biodiversity?
The loss of biodiversity is a significant issue for scientists and policy-makers and the topic is finding its way
into living rooms and classrooms. Species are becoming extinct at the fastest rate known in geological history
and most of these extinctions have been tied to human activity.
• Habitat loss and destruction, usually as a direct result of human activity and population growth, is a
major force in the loss of species, populations, and ecosystems.
• Alterations in ecosystem composition, such as the loss or decline of a species, can lead to a loss of
biodiversity. For example, efforts to eliminate coyotes in the canyons of southern California are linked to
decreases in song bird populations in the area. As coyote populations were reduced, the populations of
their prey, primarily raccoons, increased. Since raccoons eat bird eggs, fewer coyotes led to more
raccoons eating more eggs, resulting in fewer song birds.
• The introduction of exotic (non-native) species can disrupt entire
ecosystems and impact populations of native plants or animals. These invaders
can adversely affect native species by eating them, infecting them, competing
with them, or mating with them.
• The over-exploitation (over-hunting, over-fishing, or over-collecting) of a
species or population can lead to its demise.
• Human-generated pollution and contamination can affect all levels of
biodiversity.
• Global climate change can alter environmental conditions. Species and
populations may be lost if they are unable to adapt to new conditions or
relocate. courtesy NC Division of Marine Fisheries
Ecological Society of America
Terms
Biodiversity: The range of variation found among microorganisms,
plants, fungi, and animals. Also the richness of
species of living organisms.
Community: Populations of organisms of different species that
interact with one another.
Ecosystem: Any geographic area with all of the living organisms
present and the nonliving parts of their physical
environment. Involves the movement and storage of
energy and matter through living things and activities.
Gene: A unit of inherited material. An organism’s collection
of genes determines what it is, what it looks like,
and often how it behaves.
Organism: An individual living thing.
Population: A group of individuals belonging to one species living
in an area.
Species: A group of populations of similar organisms that
reproduce among themselves, but do not naturally
reproduce with any other kinds of organisms (e.g.,
Haliaeetus leucocephalus--bald eagle; Quercus
rubra--red oak tree).
Where Can I Get More Information?
Ecological Society of America, 1707 H Street, NW, Suite 400, Washington, DC 20006. 202-833-8773. esahq@esa.org;
http://www.esa.org.
U.S. Geological Survey, Biological Resources Division. biologywebteam@usgs.gov; http://biology.usgs.gov/.
U.S. Fish and Wildlife Service. Contact@fws.gov; http://www.fws.gov.
Marine Conservation Biology Institute, 15805 NE 47th Court, Redmond, WA 98052. 425-
883-8914. mcbiweb@mcbi.org; http://www.mcbi.org.
Convention on Biological Diversity, Secretariat, 393, Saint Jacques Street, Suite 300, Montreal,
Quebec, Canada H2Y 1N9. 1-514-288-2220. secretariat@biodiv.org; http://www.biodiv.org.
National Forum on BioDiversity. 1988. BioDiversity. Wilson, E.O., editor. National Academy
of Sciences. Academy Press, Washington D.C.
Prepared by the Ecological Society of America
1707 H Street, NW, Suite 400, Washington, DC 20006
phone 202-833-8773 · fax 202-833-8775
http://www.esa.org · esahq@esa.org
Fall 1997
