mechanisms & applications of evolution mechanisms of evolution (how it happens) 1.natural...
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Mechanisms & Applications of Evolution
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Mechanisms of Evolution(how it happens)
1. Natural Selection (“survival of the fittest”)
The development of the natural selection theory:
• 1700s- Lamark was the first person to state that organisms change over time, and that new organisms are modified descendants of older organisms (with is theory of acquired traits)
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Natural Selection
• 1800s- Charles Darwin sailed on the H.M.S. Beagle and gathered data from organisms (fossils, finches, etc.)
• From this data, Darwin inferred that all species had descended from one or a few original types of life.
• Darwin also concluded that the way species/organisms change over time was by natural selection
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Natural Selection
The process of natural selection:• There must be variation in the traits of a population.
(This variation is caused by organisms having different genes.)
• There must be environmental pressures that favor one variation of the trait over the other.
• Organisms with the better traits will survive better and longer, reproduce, and pass those good traits on to their offspring.
• The result will be a population better suited for the environment.
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Natural Selection
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Mechanisms of Evolution
2. Geographic Isolation– Organisms of a population can become isolated
from one another by a geographic barrier– If they are no longer able to reproduce, they
may become two separate species.– The formation of a new species is called
speciation.
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Applications of Natural Selection(Why is this important to us now?)
1. Antibiotic-resistant bacteria (ex. MRSA)• Bacteria reproduce and mutate at a very high rate.
• Some bacteria’s DNA has mutated to be resistant to many known antibiotics.
• When the resistant bacteria reproduce, they pass this ability onto their offspring.
• Bacteria can also pass the resistance to other bacteria through conjugation (bacteria’s sexual reproduction).
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Applications of Natural Selection
• To help prevent the development of antibiotic resistant bacteria,
– Don’t overuse antibiotics (they DO NOT kill viruses!)
– Use a variety of antibiotics (not just the same one over and over again)
– Finish the whole dose of antibiotics
• Bacteria are also becoming resistant to cleaners!!! (Don’t overuse antibacterial soaps and cleansers.)
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Applications of Natural Selection
MRSA infections, if severe, can cause “flesh eating disease”.
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Applications of Natural Selection
2. Pesticide-resistant insects• Same mechanisms as above.
• To help prevent this,– Don’t overuse pesticides (or don’t use them at all!)
– Raise/buy organic food
– Use biocontrols (such as lady bugs)
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Applications of Natural Selection
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Convergent Evolution
• Organisms from different ancestors develop similar characteristics
Ancestor A Ancestor B
Different organisms that look similar
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http://cas.bellarmine.edu/tietjen/Evolution/convergent_evolution_examples.htm
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Divergent Evolution
• Organisms with a common ancestor develop different characteristics (adapted to their environments)
Common Ancestor
Organism A Organism B
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Coevolution• Two organisms that live closely together
both adapt to changes in the other organism– Ex.: giant hawk moth and Madagascar orchid– Ex.: bats and cactus flowers
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