Natural Selection (5.2)
SECTION LINKS:For Industrial Melanism Peppered Moth Example Please see Topic 5.1 |
Evolution/ Natural Selection/ Cladistics Notes (includes 5.1, 5.2, 5.4, & HL 10.3)
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What is Natural Selection?
Natural Selection is the selection of an inherited characteristic within a population that becomes more or less frequent within the population due to a selective pressure causing it to become more or less advantagous than other variations.
Natural Section Simulation (PHET simulation) Other examples of Natural Selection |
below is an animation originally produced by UTAH genetics
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Four Principles of Natural Selection
4 key principles must be in place for Natural selection to occur:
- Genetic Variation: A population must already have variation within it for selection to occur
- Overproduction of Offspring: More offspring are produced than necessary to survive to ensure some will survie
- Struggle for Existance: Something must force some organisms can survive others die
- Reproduction: Those organisms that survive reproduce passing on their genes to the next generation.
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Example: Pocket Mice video
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Daphne Major Finch Beaks (Darwin's Finches)
The Grant's reserach with finches on Daphne Major, one of the Galapagos Islands, has helped support the idea that that sifts and changes can be seen within populations through natural selection.
Darwin's Finches |
Antibiotic Resistance
How does antibiotic resistance demonstrate natural selection?
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Growing antibiotic resistance within populations is increasingly problematic. There are some bacteria species that are now resistant to 5 or more drugs. How does this occur? And how does this demonstrate natural selection?
How does it occur? The overuse of antibiotics for diseases such as colds has helped to increase the flood of resistant bacteria. Also not taking all of an antibiotic perscribed will often leave some resistant bacteria behind. Antibiotic Resistance |