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The Received View of Evolution

20.04.2005. The Received View of Evolution. Sex and Death: An Introduction to Philosophy of Biology. Contents. 2.1 The Diversity of Life 2.2 Evolution and Natural Selection 2.3 The Received View and its Challenges. 2.1 The Diversity of Life. “design space” (Dennett, 1995)

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The Received View of Evolution

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  1. 20.04.2005 The Received View of Evolution Sex and Death: An Introduction to Philosophy of Biology

  2. Contents 2.1 The Diversity of Life 2.2 Evolution and Natural Selection 2.3 The Received View and its Challenges

  3. 2.1 The Diversity of Life “design space” (Dennett, 1995) • All possible and actual “designs” • Regarding these we are highly atypical • Eukaryotic + simply life cycle + huge Diversity and Disparity (Gould) • Diversity: number of species in existence • Disparity: amount of organisms that have fundamentally different designs

  4. 2.1 The Diversity of Life ? ? Why are some areas in design space occupied and some not? • Process Structuralists • Design space is highly constrained • Historical relativity • There are so many designs, that there was no time to realize them all.

  5. 2.1 The Diversity of Life ? ? Why do organisms come packed into species? • Life without species is possible • No sharp distinction between spiecies and varieties

  6. 2.2 Evolution and Natural Selection Basic elements of evolutionary theory (Mayr) • The living world is not constant • Evolution. change has a branching pattern • New species form when a population splits • Evolution. change is gradual • Adaptive change through natural selection

  7. 2.2 Evolution and Natural Selection • Natural selection is the inevitable result of • Phenotypical variation • Differential fitness • Heritability Are the forces that induce genetic variation deterministic? ? ?

  8. 2.2 Evolution and Natural Selection Cumulative selection • Innovation is the result of a sequence of selective episodes • Conditions: • Direction of selection is constant • Low mutation rate • Each intermediate stage must be fitter than its predecessor (adaptive landscapes)

  9. 2.2 Evolution and Natural Selection Speciation • Cumulative selection in different environments results in reproductive isolation • Hybrid matings will be penalized

  10. 2.3 The Received View and its Challenges • 3 important debates • Units of selection • Selection and evolution • Evolution within Biology

  11. 2.3 The Received View and its Challenges ? ? What is being selected • “gene’s eye” concept (Williams, Dawkins) • Hierarchical view

  12. 2.3 The Received View and its Challenges The “gene’s eye” • Only genes are passed on directly from one generation to the next • Genes are replicators and use organisms as “vehicles” • Natural selection acts through vehicles and targets the replicators • Problem: gene – trait relationship

  13. 2.3 The Received View and its Challenges Hierarchical view • organisms are not the only entities that form populations (hives, colonies, species) • Selection can operate simultaneously at different levels

  14. 2.3 The Received View and its Challenges Selection and Evolution • Four major issues • Does the received view overstate the importance of adaptation? • Relationship of selection and other factors • Methodological issues • The proper scope of evolutionary explanations

  15. 2.3 The Received View and its Challenges The Importance of Adaptation  Fitness advantages only make survival more likely !

  16. 2.3 The Received View and its Challenges Relationship between selection and other factors • Selection is historical, it is constrained by inheritances of the population • Some patterns seem to be independent of selection: • Evolution after the Cambrian explosion

  17. 2.3 The Received View and its Challenges Methodological issues • How can we test our ideas? • How much evidence is needed to support a hypothesis?

  18. 2.3 The Received View and its Challenges Scope of evolutionary explanations • Sociobiology (Wilson) • Explaining social / psychological processes with evolutionary mechanisms is possible vs. • This attempt is mistaken in principle. Since there is culture these rule do not apply to us anymore

  19. 2.3 The Received View and its Challenges Evolution within Biology • Evolution and Ecology • Ecology describes the environment which generates selective pressure • Evolution and molecular Biology • Genetics did not make Evolutionary Theory futile • Different levels of explanation

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