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Announcements
Objectives
Why
Preserve
Biodiversity?
Pharmaceuticals
Foods
Biological
Products
Ecosystem
Benefits
Keystone
Species
Studies
of
Biodiversity
Lecture
Syllabus
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Announcements
Chapter 42, Preserving
Biodiversity
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Objectives:
After studying this material you should be able to:
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Define the term biodiversity and explain how the three
levels of
biodiversity (genetic diversity, species diversity, and ecosystem
diversity) are related and dependent on one another.
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Explain what is meant by "The Sixth Extinction" and why
this should
concern us.
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Explain how biodiversity is lost, how rapidly it is
currently being
lost, and some of the reasons why we might be concerned about this
loss.
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Understand the problems associated with slowing the rate
of
loss of
biodiversity.
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Explain the potential value of biodiversity in terms of
both direct
human uses and ecosystem level processes.
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Describe the relationship between biodiversity and
keystone
species.
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Explain some of the ways in which biodiversity is being
studied.
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Understand these terms and the relationships among them:
| biodiversity |
genetic variability |
species variability |
| ecosystem variability |
keystone species |
population |
| mass extinctions |
alleles |
mutations |
| bioprospecting |
gene banks |
systematic biology |
| taxonomy |
conservation biology |
hot spots |
What are the material benefits of preserving biodiversity?
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Pharmaceuticals
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Food
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Wood and other biological products
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Genetic resources
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Ecosystem level benefits
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Other benefits
Pharmaceuticals - bioprospecting: the new gold rush
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80% of the people in less-developed countries rely heavily
or
entirely on drugs derived from natural sources (World Health
Organization estimate). More than 20,000 species have been used for
medicinal purposes.
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Of the drugs used in the U.S., 25% are derived from
plants,
13% from
microorganisms (including many antibiotics), and 3% from animals.
Overall, 41% of our prescription drugs have their active ingredients
derived from living organisms.
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Will technological advances in the pharmaceutical industry
preclude
further natural-products research?
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According to the National Cancer Institute, over 70%
of
the
promising anti-cancer drugs come from plants in the rain forest.
See bioprospecting for new pharmaceuticals.
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Who really benefits from the commercialization of
biodiversity? In
the early 1990's, germplasm from developing countries was worth $32
billion per year to the pharmaceutical industry. Now, many tropical
countries are taking real steps to protect their interests. See Shaman Pharmaceuticals.
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An experimental but promising anti-HIV compound called
Prostratin has
been isolated from Homalanthus nutans (Euphorbiaceae). This
plant is only found in the tropical Pacific island of Samoa, where it
has been long used in native herbal medicine. A recent agreement will
return 20% of all commercial revenues from drugs developed from this
plant to the native peoples of Samoa. See this article from Time magazine.
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Relatively few flowering plants (that is, of the ones we
know) have
been examined for their medicinal properties. Up to 1992, only 2% (or
5,000 species) had been examined. A number of these have become
multi-billion dollar commodities:
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Digitalis (foxglove), for the cardiac stimulant
digitoxin.
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Catharanthus roseus (rosy periwinkle), for vincristine &
vinblastine
(two of the most effective anticancer agents ever discovered). These
drugs are used for the treatment of childhood leukemia and Hodgkin's
disease. Who benefitted from this discovery?
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Taxus brevifolia (Pacific yew) for taxol, used to
treat ovarian and breast cancer.
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Cyclosporin, a powerful immunosuppression agent used in
organ
transplants, was discovered in a Norwegian fungus.
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The Calophyllum story
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For more information:
Foods
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30,000 or more plant species have edible parts; 7,000
species are
grown and used as food by humans; 20 species feed the majority (90%) of
the world's population; just 3 species are the major world-wide
staples (rice, wheat, and corn).
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Modern cultivated races vs. "land races." The latter are
grown by
indigenous peoples and are diverse genetically. Only very few varieties
of corn and rice are cultivated widely. The genetic diversity
represented by these cultivated varieties is quite small (yet our
existence is dependent upon them!)
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Wild plant gene pools are important to augment the narrow
genetic
base of established food crops (by providing resistance to disease,
improved agricultural productivity, and different environmental
tolerances). Most improvements in agriculture will depend upon the
survival of these "gene banks."
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In 1970, 15% of the US corn crop was wiped out by leaf
blight.
Mexican wild corn (Zea diploperennis) is a wild relative of
corn.
It was discovered in the 1970's. It has the same chromosome number as Zea
mays and exhibits perennial growth. It occupies 25
acres of
cold mountain land, and was one week away from extinction! This weedy
plant resistant to a number of serious viral corn diseases that infect Zea
mays. Researchers have transferred this viral
resistance to
corn. It may also be possible to produce perennial corn.
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Many presently underutilized food crops have the potential
to become
important in the future. Remember: the relatively few species currently
cultivated have had lots of research and selective breeding applied to
them!
Wood and other biological products
The potential products obtained from biological resources are
endless. Some examples include:
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Protection of water resources (vegetation regulates and
stabilizes
water runoff and increases water yield and quality).
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Soil formation and protection (helps in the formation
and
maintenance
of soil structure and quality, the retention of moisture and nutrient
levels, and the prevention of erosion).
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Pollution breakdown and absorption (bacteria and other
organisms
breakdown pollutants; wetlands can act as filters).
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Recovery from unpredictable events (primary and
secondary
succession). Degraded ecosystems are less likely to recover from
natural
and man-made disasters (genetic variability is depleted and extinctions
occur). Biodiversity promotes stability.
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The removal or disturbance of one part of an ecosystem
could affect
the functioning of many other parts--recall the intricate web of
life.
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Green Facts - Ecosystem Level Services
Economic importance of biodiversity
Keystone Species
What are they, and how are they related to biodiversity?
A keystone species is one that affects the survival
and
abundance of many other species in a community. Its removal results in
a
significant shift in the composition of a community, and sometimes even
the physical structure of the environment.
If the keystone species is returned, the community can be
restored.
How do we study biodiversity?
Taxonomy & Systematic Biology-- To understand
genetic
diversity and genetic relatedness for the construction of evolutionary
histories and to understand how species arise.
Much of our knowledge of biodiversity comes from the basic
activities
of systematic biologists, namely the discovery, inventory, and
description of new species, the determination of their characteristics
and evolutionary relationships to other species, and the organization
of
this knowledge into classification systems. These classifications are
powerful predictive tools that help us to understand, maintain, and
effectively utilize this great biological wealth.
Ecology & Conservation Biology-- The study of the
interrelationships of organisms and their environment. How to protect
and conserve populations, species, and ecosystems under the growing
pressure of human habitation.
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