BIO 317
Conservation of Wildlife Resources
Sustaining Wild Species
Status of Wild Species - Extinction Rates
Significance of this Mass Extinction
An unprecedented biological collapse has begun worldwide, and only unprecedented
effort will curtail the massive wave of extinctions. Furthermore, climate
change from carbon dioxide emissions is likely to accelerate the demise
of many forms of life. Although species are disappearing most rapidly from
the world's tropical forests, biological diversity is diminishing all over
the globe. For example:
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Three-fourths of the world's bird species are declining in population or
threatened with extinction.
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Amphibians (frogs,
salamanders, and related species) are declining worldwide.
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About 20% of all reptiles and 1/3 of all fishes are threatened
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In the United States, about 3,000 plants, nearly one in every eight native
species, are considered in danger of extinction. More than 700 are likely
to disappear in the next 10 years.
Without immediate reductions of greenhouse gas emissions, however, the
impacts of global warming will probably make the world's current biological
collapse pale in comparison. Rapidly rising temperatures will overwhelm
many species' and ecosystems' ability to adapt. Widespread die-offs of
forests, tundra, and coral reefs, disruption of animal migrations, and
the loss of mangroves and other wetlands to rising seas are likely in coming
decades if actions are not taken soon to slow global warming.
Endangered & Threatened Species
http://endangered.fws.gov/wildlife.html#Species
Why
be concerned about wild species?
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Bioethics
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Many people believe that every creature, after adapting for thousands or
even millions of years to fit a constantly changing environment, has an
intrinsic value. Exterminating other forms of life is not only shortsighted,
but wrong—especially since the species could never be replaced. Mankind
would also lose; being accustomed to diversity in nature, the quality of
human life would be diminished.
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Ecological value
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No creature exists in a vacuum. All living things are part of a complex,
delicately balanced network called the biosphere. The earth's biosphere
is composed of ecosystems, which include plants and animals and their physical
environment. The removal of a single species within an ecosystem can set
off a chain reaction affecting many other species. It has been estimated,
for example, that a disappearing plant can take with it up to 30 other
species, including insects, higher animals, and even other plants. The
full significance of an extinction is not always readily apparent; much
remains to be learned, and the full long-term impacts are difficult to
predict.
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Medicinal
value
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Each living thing contains a unique reservoir of genetic material that
has evolved over eons of time. This material cannot be retrieved or duplicated
if lost. So far, scientists have partially investigated only a small fraction
of the world's species and have begun to unravel a few of their chemical
secrets to determine, among other things, possible benefits to mankind.
No matter how small or obscure a species, it could one day be of direct
aid to all of us. It was "only" a fungus that gave us penicillin, and certain
plants have yielded substances used in drugs to treat heart disease, cancer,
and a variety of other illnesses. At least a quarter of all prescriptions
written annually in the United States contain chemicals discovered in plants
and animals. If these organisms had been destroyed before their chemistries
were known, their secrets would have died with them.
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Agricultural value
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Many seemingly insignificant forms of life are beginning to show important
utilitarian benefits in areas such as agriculture. Some farmers are beginning
to use insects and other animals that compete with or prey on certain crop
pests, as well as using plants containing natural-toxin compounds that
repel harmful insects. These are called "biological controls," and in many
cases they are a safe, effective, and less expensive alternative to synthetic
chemicals.
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It has been estimated that there are almost 80,000 species of edible plants,
of which fewer than 20
produce 90% of the world's food. If underutilized species are conserved,
they could help to feed growing populations. One grain native to the Great
Lakes States, Indian wild rice, is superior in protein to most domesticated
rice, and its increasing commercial production is earning millions of dollars
annually. Crossing it with a related but endangered species, Texas wild
rice, could perhaps result in a strain adaptable to other regions. Plant
collectors are now seeking out remaining wild strains of many common crops,
such as wheat and corn, for work on new hybrids more resistant to crop
diseases, pests, and marginal climatic conditions.
Factors contributing to the decline & extinction of wild
species
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Primary causes = human population growth & economic/political sytems
that place little value on other species
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These factors lead to:
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Habitat
loss & degradation
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Human activities that cause habitat destruction, degradation and fragmentation
include:
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intensive corporate farming,
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urbanization,
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logging,
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grazing,
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mining,
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road building,
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damming and channelizing of streams,
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pollution,
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the introduction of non-native
species,
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fire suppression, and
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recreation.
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Habitat fragmentation
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Habitat fragmentation involves the breaking up of large areas of habitat
into small, unconnected habitat "islands." These habitat fragments are
often too small to support viable populations of many plant and animal
species. Less than half of the earth's remaining forests are large enough
to support many of the plant and animal species that depend on a woodland
habitat.
Forest fragmentation and loss in Saline and Gallatin
counties, southern Illinois. Prior to 1820, both
counties were completely forested. By 1980, most of the
forest habitat in these counties had been
converted to agriculture and other purposes. Instead
of one large contiguous forest area, the landscape
now consists of several isolated, mostly small, forested
blocks.
(Source: http://www.npwrc.usgs.gov/resource/othrdata/manbook/intro.htm#fig01)
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Predator & pest control
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the near extinction of the swift
fox on the Great Plains is partially blamed on the indiscriminate use
of poison and trapping to kill coyotes.
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Predator control programs (and loss of habitat) almost caused the extinction
of the red wolf
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Many
species of wild cats are declining, in part, because of predator control
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Pet & decorative plant trade
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The trade in wild plants and animals and their derivatives is big business,
estimated to be worth billions of dollars and involve hundreds of millions
of plants and animals every year. Most of the trade is legal but a significant
portion of it is not. The trade is diverse, ranging from live animals for
the food and pet markets to ornamental plants and timber. An array of wildlife
products and derivatives, such as food, exotic leather goods, musical instruments
and even medicines, can be found in markets around the globe. As a result
of this trade:
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The Convention on International Trade in Endangered Species of Wild Fauna
and Flora (CITES)
is an international agreement that came into force in 1975. It is also
known as the Washington Convention from the name of the city in which it
was adopted in 1973. To date, 146 countries have signed the treaty.
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Introduced
species
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Climate change
Methods for Trying to Prevent Extinction
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Zoos & Botanical Gardens
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zoos may play a role in conserving a few species but are not equipped to
play a major conservation role
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The Species Approach
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identify a particular species, then expend resources necessary to try &
prevent extinction
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The Ecosystem Approach
Useful links:
U.S. Fish & Wildlife
Service Endangered Species Program
Why
are we not astonished?
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