Paleontology (cont.)

Sources of Variation

• gene recombination
  
  - chromosomes - DNA
  - sexual reproduction
  
  • mutations
    

Populations

• gene pool
  
• genotype
  

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Organic Evolution

• results in a change in genetic composition of a population
  
• mutation
  
• gene recombination
  
• natural selection
  

Speciation

• Allopatric Speciation
  
  - geographic barriers
  - peripheral isolates
  

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  (Figure 5.10, p.111)
  

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• Adaptations
  
• Adaptive Radiation
  
  Beach Naupaka Scaevola sericea
  pantropical distribution
  

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  Mountain Naupaka Scaevola gaudichaudiana
  endemic to Kauai and Oahu, Hawaii
  

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  (note half flower on both)
  
• Convergent Evolution
  Ironwood
  Casuarina equisetifolia
  an angiosperm with a conifer morphology

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Phylogeny

Models of Evolution (Figure 5.11, p. 111)

• Phyletic Gradualism
  

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• Punctuated Equilibrium
  

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Evidence for Evolution

• Paleontology
  
  - Marine Invertebrates
  
  -Tertiary Radiolarians
  

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  -ammonoid cephalapods
  

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  chambered nautilus
  

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  Tornoceras uniangulare
  Devonian
  

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  Schistoceras sp.
  Pennsylvanian
  

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  - fossil horses
  

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  (Figure 18.20, p.496)
  

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• biological
  
  - homologous structures
  

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  - vestigial organs
  - biochemistry
  

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last updated 2-22-2001

All original material copyright (c) 1998 by Annabelle Foos. All rights reserved.