Biology 100/101
Lecture 22
Biodiversity II
(Print Version)

Announcements

Objectives

Review of Last Lecture

Why Preserve Biodiversity?

Pharmaceuticals

Foods

Biological Products

Genetic Resources

Ecosystem Benefits

Other Benefits

Keystone Species

Studies of Biodiversity

Lecture Syllabus

IB 100/101 Home Page

Announcements

Text Readings in
Lewis et al.		 Testing Your Knowledge Thinking Scientifically
Chapter 45, Environmental Challenges No questions today No questions today

Information on the topic of biodiversity is presented in several different sections of your text, from chapter opening vignettes to boxed readings. Explore your text to discover these readings!

You may also ask questions and see answers to your classmates' questions in Web Crossing in the "Talk to Jim, Jason, and Ed" discussion.

Objectives:

After studying this material you should be able to:

  1. 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.

  2. Explain what is meant by "The Sixth Extinction" and why this should concern us.

  3. 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.

  4. Explain the potential value of biodiversity in terms of both direct human uses and ecosystem level processes.

  5. Describe the relationship between biodiversity and keystone species.

  6. Explain some of the ways in which biodiversity is being studied.

  7. Understand these terms and the relationships among them:

    8. biodiversity genetic variability species variability
    ecosystem variability keystone species population
    mass extinctions alleles mutations
    bioprospecting gene banks systematic biology
    taxonomy conservation biology hot spots

Review of Last Lecture

Earth's mass extinctions: Figure 16.15 (left) and Figure 16.15 (right)

The Sixth Extinction, by Niles Eldridge. An excellent read!

Endangered or threatened species in Illinois

  • In Illinois, 511 species are threatened or endangered.
  • In Illinois, 115 species have gone extinct.

Losses of biodiversity are irreversible. Replacement of the number of species (though not the same ones) takes approximately 10 million years.

How are species becoming extinct?

Does a loss of one or two species really matter?

How many species can be lost before an ecosystem collapses?

Should we be concerned about this?

Why is Preserving Biodiversity Important?

  1. Pharmaceuticals

  2. Food

  3. Wood and other biological products

  4. Genetic resources

  5. Ecosystem level benefits

  6. Other benefits

Pharmaceuticals

  • 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.

  • 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.

  • Will technological advances in the pharmaceutical industry preclude further natural-products research? Many natural drugs cannot be manufactured synthetically (or, if they are, they do not work as effectively). Natural diversity is valued for the "blueprint" it provides for new synthetic drugs. Some drugs (e.g., taxol) are so unusual structurally, that they would probably have never been discovered in the laboratory.

  • 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.

  • 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.

  • 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 Pharmaceutical Biology and this one from Time magazine.

  • 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:

    • Digitalis (foxglove), for the cardiac stimulant digitoxin.

    • 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.

    • Taxus brevifolia (Pacific yew) for taxol, used to treat ovarian and breast cancer.

    • Cyclosporin, a powerful immunosuppression agent used in organ transplants, was discovered in a Norwegian fungus.

    • The Calophyllum story

  • For more information:

Foods

  • 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).

  • 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!)

  • 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."

  • 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.

  • 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!

  • For more information:

Wood and other biological products

The potential products obtained from biological resources are endless. Some examples include:

  • fuel, construction, paper production

  • new hybrids and varieties of ornamental plants developed and marketed

  • adhesives from barnacles

  • fibers from spider silk

  • natural pesticides from microorganisms

  • petroleum substitutes

Genetic resources

  • Specific habitats (ecosystem diversity) are important for breeding and spawning.

  • Some habitats are genetic reservoirs from which seed and other materials can be obtained.

  • Biotechnological advances permit genetic engineering wizardry (i.e., the transfer of genes from one organism to another without breeding).

Ecosystem level benefits

  • Protection of water resources (vegetation regulates and stabilizes water runoff and increases water yield and quality).

  • 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).

  • Pollution breakdown and absorption (bacteria and other organisms breakdown pollutants; wetlands can act as filters).

  • 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.

  • The removal or disturbance of one part of an ecosystem could affect the functioning of many other parts--recall the intricate web of life.

Other benefits

  • Social benefits
    • Recreation
    • Research opportunities
    • Education
    • Historical and cultural value

  • Evolutionary benefits
    • Maintenance of genetic diversity provides opportunity for evolution instead of extinction

  • Ethics
    • It's the right thing to do.
    • How do we place value on preserving a species or an ecosystem? Do species and habitats differ in their value?

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.

  • The Tree of Life Project and its goals.

  • The All Species Foundation, is a non-profit organization dedicated to the complete inventory of all species of life on Earth within the next 25 years - a human generation.

  • Integrative Biology 260 (formerly Plant Biology 260) introduces the principles and methods of identifying, naming, and classifying flowering plants. It includes a survey of selected flowering plant families and provides information on their interrelationships. The course meets three times a week for lecture and once a week for a two-hour lab. 4 credit hours (counts for Advanced Hours in LAS). Click here for some comments on why you might want to take this course.

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.