环境生态学(双语)Chapter 3

To be accurate but maybe overworked
• High biodiversity ensures us a supply of new
genetic and pharmaceutical material.
• Plants and animals provide people with food and medicine.
As natural systems breakdown, people around the world are forced to find alternative and often more costly ways to maintain adequate supplies of clean water or to deal with increasingly polluted air. The net economic benefits of biodiversity are estimated to be at least $3 trillion per year, or 11 percent of the annual world economic output
What is So Good about Biodiversity?
• That biodiversity should be maintained has become •
an article of faith among conservationists. One of the common answers has been that all nature is interwoven and that if any piece is removed it will start a chain reaction of collapse that will ultimately doom us all. (Better be explained by food web/chain in ecosystems. Every species in food chain play important role to ecosystem, both as prey and predator, it transport food and energy through food chain)
Chapter 3 The great wealth of life: Biodiversity
• Biodiversity is the variety and variability of
life on Earth. • This includes all of the plants and animals that live and grow on the Earth, all of the habitats that they call home, and all of the natural processes of which they are a part. • Also includes variation within a species caused by genetic variation. • The earth supports an incredible array of biodiversity
• The extinction of each additional species
results in the irreversible loss of unique genetic materials, each of which has potential for development of medicines and foods and associated enterprises that create jobs.
How Many Species Are There?
• No one knows • Estimates 4 – 100 million • Nowadays, only 1.4 million (account for
11%) species of plants and animals have been described by science. (table 3.1) • 90% of vertebrates and 83% vascular plants (维管植物) have been described. • Most unknown species are almost certainly shy, rare, small and similar to a known type.
Biodiversity of insects and microbes
• Most of species areon of
• • • • •
total species diversity highly speculative. Estimation of total insect diversity are really just educated guesses. 1982, Terry Erwin re-evaluate the number of insects in a tropical forest system. From his observation, he built an argument that the total number of insect species is likely to be closer to 30 million than to 4 million. Other estimates in Asian and South American forest using similar methods have produced estimates of 5-10 million species. Microbes: another consideration to estimate biodiversity
More ---• While plants and animals keep you well fed and
healthy, trees play an important role in absorbing greenhouse gases. Through photosynthesis, trees absorb and store atmospheric carbon, helping to combat global warming and purifying the air we breathe. Forests also control soil erosion and purify water.
Forty percent of all prescriptions written today are composed from the natural compounds found in different species. An estimated 80,000 edible plants are found in the world, and one in every three mouthfuls of the food you swallow is prepared from plants pollinated by wild insects and animals.
Therefore
• Biodiversity is important as a source of
genetic material and new drugs, increased ecosystem stability, and for ethical and moral reasons. • We are just one species among many, albeit a very powerful one, and that it is our obligation to use our creativity and intellect to sustain life on the planet and not destroy it.
Case study
ecology in action – medicinal drugs
• Most plants known to have medicinal
properties come from the rain forest. Table 3.2. • E.g. Morphine and cocaine as analgesics, as the original formulation of Coca-Cola. • Many tropical insects have pharmaceutical potential.
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Biodiversity Hotspots and Conservation
• To conserve biodiversity, first to decide
which areas should be prioritized for conservation with two considerations (by Norman Myers): 1. How biologically unique is the area? 2. How severe is the threat posed by development?
ecology in action – medicinal drugs
• Many plants and animals defend themselves with
chemicals that evolution has shaped to ward off bacteria, protozoan, and fungal attacks. Therefore, that with some modification these same chemicals are effective in repelling the fungi, bacteria, and protozoa that plague humans. Pharmaceutical researchers are scrambling to collect new products for testing in a wave of chemical prospecting. The knowledge of plants forms the basis of the indigenous social hierarchy. They will not divulge this to outsiders. Collaboration between Merck & INBIO “rain forest friendly”
More
• Any organism could be valuable, although
they do not make the case right now. • Another justification for maintaining biodiversity is that we cannot predict which species will be needed for ecological control. (we will need some species most of which are insect, fungi, and bacteria, to deal with the resistance in pathogens and pest species or exotic species.) • E.g. Fruit farmers are facing to the crisis.