Endangered Species
Article by: Laura Hood Watchman, Defenders of Wildlife, Washington, DC.
Donald W. Linzey, Wytheville Community College, Wytheville, Virginia.
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A species of animal, plant, or other living organism that is in
serious danger of extinction throughout all or a significant portion
of its range. When a species is categorized as endangered, its num-
bers are so small that the species is at risk of extinction. To conserve an
endangered species, whether animal (Fig. 1), plant, or another living
organism, an adequate number of populations must be maintained
within a sufficient amount of protected habitat, with the goal of
minimizing the likelihood of future extinction. "Threatened species" is
a related term, referring to a species likely to become endangered, at
least locally, within the foreseeable future.
Species diversity
The term species is defined in a variety of ways. Most commonly, and
for purposes of protecting from extinction, species are defined us-
ing the biological species concept: a species is a distinct population
or series of populations within which there is a significant amount of
gene flow and which is reproductively isolated from other populations
under natural conditions. Species extinction is a natural process. In fact,
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• Species diversity
• Causes of species loss
• Habitat destruction
• Invasive species
• Pollution
• Overexploitation
• Strategies for protection
Fig. 1: The Florida panther is an example of an endangered animal species, which
is protected from hunting and other threats by law.
(Credit: George Gentry/U.S. Fish and Wildlife Service)
Key Concepts
• A species is a distinct population or series of populations within which there is a
significant amount of gene flow, and which is reproductively isolated from other
populations under natural conditions.
• Species that are categorized as endangered have populations so small that
the species is at risk of extinction.
• A related category is threatened species, which are species that are likely to
become endangered, at least locally, within the foreseeable future.
• The regions with the highest number of endangered species are those with
the greatest species diversity.
• To conserve endangered species, an adequate number of populations must
be maintained within a sufficient amount of protected habitat, with the goal
of minimizing the likelihood of extinction.
• The main factors that cause species to become endangered are habitat destruction,
introduction of invasive species, pollution, and overexploitation.
