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Theories of Evolution A gradual change over time.

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1 Theories of Evolution A gradual change over time

2 Plato (427-347 B.C.) Aristotle (384-322 B.C.) Two philosophers that observed the variations of animals in nature. Aristotle noticed that animals could be arranged in increasing order of complexity calling it Scala Naturae or Natures Scale.

3 Carlous Linnaeus (1708-1778), Swedish botanist, he wanted to discover the proper place for organisms in Scala Naturae – Never considered evolution was the cause. George-Louis Leclerc (1707 – 1788) French naturalist, spent his life writing a 44 - volume natural history of plants and animals. Provided evidence of descent of structural modifications but did not believe in evolution but instead special creation.

4 Erasmus Darwin (1731 – 1802) Charles’ grandfather He believed plants and animals had changed over time. He also noted the presences of vestigial organs. But didn’t understand how evolution could have occurred.

5 Georges Cuvier (1769-1832) Studied taxonomy and comparative anatomy. Founded the science of paleontology using fossilized bones to deduce the structure of animals. He believed in special creation and believed the change in organisms over time was due to catastrophes – where organisms were killed and God created new ones to replace them. Jean Baptiste Lamark (1744 - 1829) First biologist to believe that evolution did occur and linked diversity to environmental adaptation. He concluded that simple organisms gave rise to more complex forms. To explain this he came up with the idea of The Inheritance of Acquired Characteristics. Unfortunately this was incorrect.

6 Charles Lyell (1797-1875) James Hutton Two geologists that influenced Darwin Proposed the earth went through slow gradual change over time. Working with Hutton’s ideas he developed the theory of Uniformitarianism that states that the changes that take place occur at a slow uniform pace so the earth must be very old.

7 Charles Lyell (1797-1875) incorporated Hutton's ideas into a theory known as Uniformitarianism.

8 Alfred R. Wallace (1823-1913) Thomas Malthus A socio-economist that studied populations and the reproductive potential of humans. He said death and famine were inevitable because the human population increases faster than its food supply. Other influential people English naturalist working in South America and the south pacific islands. He noted like Darwin changes he had observed. He said the world could be divided into six biogeographical regions separated by impassible barriers. One barrier in the south pacific is named after him – The Wallace Line

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10 Charles Darwin ( 1809 - 1882 ) Here at age of 31 Published his book – The Origin of the Species by Natural Selection in 1859

11 Voyage of Darwin on the HMS Beagle He was recommended for the voyage by John Henslow a teacher at Christ College from where Darwin got his BA.

12 HMS Beagle

13 Galapagos Islands This was the major turning point in Darwin observations

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15 Common ancestor from mainland Adaptive Radiation

16 Galapagos Tortoise, Geochelone nigra Galapagos tortoise distribution Galapagos means Tortoise in Spanish

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18 Darwin & Wallace both believed in the forces of natural selection drove evolution and described the process in 5 steps. 1.The members of a population have inheritable variations. 2. In a population, many more individuals are produced each generation that the environment can support. 3.Some individuals have adaptive characteristics that enable them to survive and reproduce better than other individuals. 4.An increasing proportion of individuals in succeeding generations have the adaptive characteristics. 5.The result of natural selection is a population adapted to its local environment. Fitness is the reproductive success of an individual in the population. The most fit individual is the one that can get the most resources and convert them into offspring which increases the percentage of genes in the gene pool of the population. Evolution is the modification of the gene pool.

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20 Gradualism


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