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The Received View of Evolution

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Title: The Received View of Evolution


1
The Received View of Evolution
20.04.2005
  • 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
  • genes eye concept (Williams, Dawkins)
  • Hierarchical view

12
2.3 The Received View and its Challenges
  • The genes 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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