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Published byLeon Curtis Modified over 9 years ago
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A Short History
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Aristotle Envisioned – scala naturae Fixed species occupied allotted rungs on an increasingly complex ladder of life Linnaeus – Devised a hierarchy for classification King Phillip Came Over For Grape Soda Pre-Darwinian View
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Cuvier – Believed that catastrophic extinctions explained unique sets of fossil species between successive strata James Hutton & Charles Lyell Proposed that profound changes in the earth’s surface can result from slow, continuous actions Pre-Darwinian View
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Jean Baptiste Lemark Inheritance of Acquired Characteristics Proposed the theory of evolution where increasing complexity & more perfect adaptations result from inheritance of characteristics acquired by organisms interacting w/ the environment However, there is NO evidence for inheritance of acquired characteristics Pre-Darwinian View
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Darwin Proposed the idea that new species originate from ancestral forms by the gradual accumulations of adaptations Alfred Wallace Independently arrived at the theory of Natural Selection soon after Darwin Pre-Darwinian View
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Darwinian view of life has 2 parts: Descent with Modification Natural Selection Dual Meaning of Darwinism
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Survival of the Fittest The driving force of Evolution Based on differential success in reproduction Individuals best adapted to the local environment leave more offspring = thereby pass on their adaptive characteristics more frequently Natural Selection
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Fact 1: All species’ population size would increase exponentially if all individuals that are born reproduce successfully Fact 2 Most populations are normally stable in size, except for seasonal fluctuations Fact 3 Natural resources are limited 5 Facts of Nature
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Fact 4 Individuals of a population vary extensively in their characteristics; no 2 individuals are exactly alike Fact 5 Much of this variation is inherited 5 Facts of Nature
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Darwin’s 1 st Inference/Conclusion: Production of more individuals than the environment can support leads to a struggle for existence among individuals of a population, w/ only a fraction of offspring surviving each generation Darwin’s Conclusions
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2 nd Inference/Conclusion: Survival is a struggle that depends on the inherited characteristics of the individual. Surviving individuals will produce more offspring 3 rd Inference/Conclusion: Unequal ability to survive and reproduce will lead to gradual change in a population
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Biogeography of species First suggested common descent – island species are more closely related than those on distant shores Chronological fossil record This supports and is compatible w/ other lines of evidence Taxonomic hierarchy reflects common descent Signs of Evolution
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Homologous structures testify to an evolutionary remodeling process Embryonic Development Reveals homologies not apparent in adult species Closely related species show unmistakable similarities in their DNA and Proteins Signs of Evolution Cont.
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Tree of Life - Cladogram
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