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Goals for this Section:
1. Identify the effects of extinction and extirpation on the amount of biological diversity seen in and ecosystem.
2. Distinguish between artificial and natural selection.
3. Describe the use of biotechnology in various fields.
4. Describe new technologies that are used to recombine genetic material.
5. Evaluate the success and limitations of strategies used to reduce the loss of species diversity.
4.1 – The Reduction of Biological Diversity
Species and ecosystems are being stressed by humans’ demands for natural resources
The result is a decline in the genetic, species, and ecosystem diversity on Earth
The extinction of species, and the reduction in the population of other species reduces biological diversity
Natural Causes of Extinction & Extirpation
Catastrophic Events
Lack of food due to overpopulation
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Natural Causes of Extinction & Extirpation
Disease
Overspecialization
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Effects of Extinctions & Extirpations
Both extinctions & extirpations reduce biological diversity
The main difference is that extinctions reduce biological diversity worldwide, while extirpations reduce biological diversity in a particular area
Often extirpations in one area affect other species in the same area as well
4.2 – Selecting Desirable Traits
Humans have used artificial selection for thousands of years
This produces breeds of plants and animals that have particular desired traits
Biotechnology
Now that we understand how genes within cells work, we can use more “high tech” methods of selecting traits
We can now create clones of organisms that have the traits that we desire
Cloning
We can create clones by taking cells from an organism that we wish to clone
The nucleus of the cell is removed and placed in an egg cell that has had its nucleus removed
This egg cell is then allowed to develop
Artificial Reproductive Technology
In animals, artificial insemination and in vitro fertilization may be used
Both of these techniques increase the likelihood of producing offspring with the desired traits
Genetic Engineering
Genetic Engineering refers to any technology that directly alters the DNA of an organism
We can use genetic engineering to insert DNA from one species into the DNA of another species
For example, we can now produce plants that produce toxins that only affect insects (these toxins were originally coded by genes from bacteria)