Evolution (5.1)
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HL Evolution/ Natural Selection/ Cladistics Notes
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Charles Darwin and his evidence of evolution
Evolution by Natural Selection was made popular by Charles Darwin (1809-1882) through the publishing of his book On the Origin of Species (1859)
Darwin indicated three pieces of evidence to support his theory:
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Selective Breeding (Evidence #1)
Darwin’s idea of species changing came from his understanding of Selective Breeding.
Selective Breeding is how humans breed organisms in order to gain the traits most desired.
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Geologic Column
The Geologic Column is the term given to the layers of rock within a given area. What is known:
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Fossil Evidence (Evidence #2)
What is a Fossil?Any remains, impression, or trace of a living thing of a former geologic age, as a skeleton, footprint, etc. (dictionary.com)
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Transitional FossilsA fossil that shows a step or stage in the change of heritable characteristics of a specific species or group of organisms.
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Fossils as Evidence
Darwin postulated that if Evolution were occuring, then the fossil record within the geologic column would show the changes between organisms (called transitional fossils).
While many examples exist for changes within groups or families of organsims (dogs, wolves & foxes), few examples have been found to demonstrate links between entirely different groups (wolves & whales)- although there are theories. Fossil Record video |
Converent vs Divergent Evolution
Convergent Evolution
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Divergent Evolution
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Adaptive Radiation
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Homology (Evidence #3)
Homologous Structures
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Analogous Structures
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Rudimentary (Vestigal) Organs
Definition: Reduced structures that serve no function (left over from ancestors
- Examples given
- Teeth in embryo baleen whales but adults are toothless
- Pelvis and thigh bones found in body walls of some whales and snakes who do not walk
- Appendix (appears to have to function)
- Just because we do not know the function doesn’t mean it doesn’t have one
- By claiming it doesn't have one we actually negate the ability of scientists to find one.
- Examples of things we use to think had no function:
- Appendix- reasoned it houses the good bacteria in your intestines
- “Junk DNA” - renamed as the parts of the DNA once considered junk are vital to the regulation and control of our DNA
- Spleen- filters and helps control the immune system
- Tailbones- attachment of tendons, ligaments, and muscle. Allows you to sit.
Peppered Moths
Natural Selection of color in Peppered Moths (Biston betularia) is a famous examples of the change in a gene pool of a species.
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