1. Lecture 1: Biodiversity
© Sun Star/Stock Photos Hawaii
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2. The Value of Biodiversity
-total amount of all genetically based variety of all organisms on Earth.
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3. The Value of Biodiversity
Ecosystem diversity
- habitats, communities, and ecological processes in the living world
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4. The Value of Biodiversity
2. Species diversity
-number of different species in the biosphere.
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5. The Value of Biodiversity
3. Genetic diversity
-all the different forms of genetic information carried by all organisms living on Earth today.
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6. The Value of Biodiversity
Why is biodiversity important to humans?
Species of many kinds have provided us with foods, industrial products, and medicines—including painkillers, antibiotics, heart drugs, antidepressants, and anticancer drugs.
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7. Threats to Biodiversity
Human activity can reduce biodiversity in 4 main ways.
There are 4 main threats:
altering habitats
hunting species to extinction
introducing toxic compounds into food webs
introducing foreign species to new environments
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Habitat Alteration
Habitat Alteration
Habitat fragmentation
-Land development often splits ecosystems into pieces
When land is developed, natural habitats may be destroyed.
The smaller a species’ habitat is, the more vulnerable the species is to further disturbance.
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9. Demand for Wildlife Products
Humans have hunted organisms for food or other products  extinction
Throughout history, humans have pushed some animal species to extinction by hunting them for food or other products.
Today, in the U.S., endangered species are protected from hunting.
The Convention on International Trade in Endangered Species, CITES, bans international trade in products derived from endangered species.
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10. 3. Pollution Remember biomagnification? Pollution
Many forms of pollution can threaten biodiversity.
One of the most serious problems occurs when toxic compounds accumulate in the tissues of organisms.
DDT, one of the first pesticides, is a good example of this.
For a long time DDT was considered harmless, and it drained into rivers and streams in low concentrations.
However, DDT has two hazardous properties:
It is nonbiodegradable, which means that it cannot be broken down by organisms.
Once DDT is picked up by organisms, it cannot be eliminated from their bodies.
When DDT enters food webs, it undergoes biological magnification.
In biological magnification, concentrations of a harmful substance increase in organisms at higher trophic levels in a food chain or food web.
In 1962, biologist Rachel Carson wrote Silent Spring, which alerted people to the dangers of biological magnification.
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Introduced Species
4. Introduced Species
Invasive species
-reproduce rapidly because their new habitat lacks the predators that would usually control their population.
Another threat to biodiversity comes from plants and animals that humans transport around the world either accidentally or intentionally.
Hundreds of invasive species—including zebra mussels in the Great Lakes and the leafy spurge across the Northern Great Plains—are already causing ecological problems in the United States.
Example:
The common carp is a fish native to Asia which has been introduced to every part of the world with the exception of Eastern Europe, The Middle East and the poles.
Common carp has been introduced, sometimes illegally, to most continents and some 59 countries. Due to their fecundity and their feeding habit of grubbing through bottom sediments for food they are notorious for altering their environment. In feeding, they may destroy, uproot, disturb and eat submerged vegetation causing serious damage to native duck and fish populations, like canvasbacks
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12. Threats to Biodiversity
These threats can lead to…
Endangered species - a species whose population size is declining in a way that places it in danger of extinction
Extinction - occurs when a species disappears from all of range
As the population of an endangered species declines, the species loses genetic diversity.
The Quagga was a unique variety of Plains Zebra, marked by having stripes only on the front of its body, with hair color transitioning toward a light brown or tan along its rear and underbelly, until becoming white along its legs. This picture represents the only Quagga ever to have been photographed alive, taken at the London Zoo in 1870.
Its unique hide made the Quagga a target for hunters and poachers, and the last known wild Quagga was probably killed in the late 1870’s. The species went extinct on August 12th, 1883, when the last specimen died at a zoo in Amsterdam, The Netherlands.
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