P10-Lecture 3- Darwin & Natural Selection Jan.29

P10-Lecture 3- Darwin & Natural Selection Jan.29 -...

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Unformatted text preview: Darwin and Evolution Darwin and Wallace A simple, simply brilliant, idea Organisms share common ancestries Adaptations lead to diversity in life 1874- 65 years old Prevailing views before 1800 s Species constant x The Greeks 3 Variation not important 3 just imperfection s Place on scale of complexity x Scala naturae- Aristotle Brief overview: "Design" s "Design" x Paley and Natural Theology History of Evolution Theory s Extinction x Georges Cuvier (1769-1832) 3Catastrophism 3 Founded the study of paleontology 3 Established extinction as a fact: Caused by localized catastrophes xCuvier and his Ibises: 3Saw no evidence of change over time Believed in functional integration determines 3 3"Function form." History of Evolution Theory s Constancy of species x Lamarck (1744-1829) 3 1st to believe evolution occurs. 3 Inheritance of acquired characteristics 3 Spontaneous generation and a drive for perfection History of Evolution Theory s Age of the Earth x Hutton (1726-1797) x Gradualism and an old Earth x Planted idea of gradual change over long periods of time 3 "Father of Geology" History of Evolution Theory s Age of the Earth x Charles Lyell (1797-1875) x Expanded Hutton's idea of gradual change over long periods of time x Uniformitarianism and an old Earth x Present is key to understanding the past Charles Darwin s A lifelong Naturalist (1809- 1882) s Trained in medicine and for the clergy x 1831 - Boards the H.M. S. Beagle at age 22 for a five year voyage x Not yet an evolutionist x Interested in: 3 Variation 3 Biogeography s Darwin's basic argument: 3 1. Variation - observable, but under appreciated 3 2. Heritable variation - Already known that this could happen, but not known how (see Mendel!) 3 3. Struggle to exist Influenced by Malthus 3 4. Differential reproductive success 3 5. Change in population's characteristics = evolution Charles Darwin, from his autobiography. (1876) s "In October 1838, that is, fifteen months after I had begun my systematic inquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from longcontinued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The results of this would be the formation of a new species. Here, then I had at last got a theory by which to work". Darwin x But was part of a large s Slow to publish his essay intellectual group s Amassed a great deal of evidence and experiments over the next 15 years. Darwin and Wallace s Alfred Wallace independently came up with essentially the same idea xCo-published with Darwin Darwin's Accomplishments s Established occurrence of evolution. x An old idea, but Darwin provided overwhelming evidence and a very clear argument x Widely accepted after 1859 s Proposed a plausible mechanism for evolutionary change and design: 3 Natural Selection x Huxley - "How stupid of me not to have thought of that." x Not widely accepted at first Evidence for evolution Paving the way for evolution s Previous Western views: x Earth young (less than 6000 years) x Species unchangeable and immortal 3 Variation just "noise"; no extinction x Organisms a product of "design" Paving the way for evolution s Emerging views in the early 1800's: x Earth very old 3 Gradualism, Uniformitarianism x Species can change plausible mechanism known then... 3 Extinctions occur x Many characteristics of organisms very difficult to explain as a product of design alone. 3 No Evidence For evolution s "Groups within Groups" x Make sense as a result of "community of descent" Evidence For evolution s 1. Homology x Structural similarities under different uses easily explained by common ancestry. E.g., morphology; comparative anatomy See Fig. 24.9 Evidence For evolution s 1. Homology x E.g. developmental patterns x embryology See Fig. 24.8 Evidence For evolution s 2. Fossil record x Earth is old (as measured by various methods) x Extinction has occurred x General pattern 3 Simpler organisms first, then more complex. See Fig. 27.8 Evidence For evolution s 2. Fossil record 3 Living x Law of Succession- species usually preceded by fossil forms in the same area 3 E.g. Marsupials Evidence For Evolution s 2. Fossil record x Transitional forms... ? Evidence For evolution s 2. Fossil record 3 Linking x Transitional forms: closely related species - Humans (Lucy) 3 Documenting major transitions - Origin of whales 3 Linking major groups - origin of birds, mammals Evidence For evolution Evidence For Evolution See 24.4 Evidence For evolution Evolutionary history of the horse as seen in fossil record supports common ancestry. ...
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This note was uploaded on 05/11/2010 for the course BIOLOGY 100 taught by Professor Richard during the Spring '10 term at George Mason.

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