Theory of Evolution

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Theory of Evolution

• Ch. 15

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(15-1) Evolution

• Change of organisms over generations w/ a strong
  natural modification process
• Change over time

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Scientific Theories

• Explain data
• Generations of predictions
• Falsifiable

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Lamarcks Theory

• Use Disuse parts of body that are used
  extensively become larger stronger while those
  that are not used deteriorate
• Acquired traits

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Lamarck (cont.)

• Ex
• Webbed foot stretching of membrane b/w toes
  (water birds)
• 1st to say
• Organisms change over time
• New organisms are modified descendants of older
  types

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Darwin Wallaces Theory

• Natural Selection organisms best suited to their
  environment reproduce more successfully than
  others
• Survival of the fittest

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Charles Darwins

• Voyage on the Beagle

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Darwins Studying Ground
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Darwins Observations

• 13 similar but separate species of finches
• Specialized for food
• Similarities lead to belief of a common ancestor

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Darwins Conclusions

1. Descent w/ modification
2. Modification by natural selection

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Descent w/ Modification

• Newer species are modified descendants of older
  species
• All species descended from 1 of a few original
  types of life

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Modification by Natural Selection

• How evolution occurs
• Environment limits pop.s growth
• Not all individuals in a pop. are identical
  environment affects them differently

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Natural Selection (cont.)

• Individuals w/ favorable traits reproduce more
  often than those w/ unfavorable traits
• Thus favorable traits will be passed down more
  often

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Adaptation

• Inherited trait that inc. an organisms chance of
  survival in a particular environment
• Based on genes

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Fitness

• Ability to survive to propagate their genes (have
  babies)

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Lamarck vs. Darwin
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(15-2) Evidence of Evolution

• Biogeography
• Geographical distribution of species
• Fossil Record
• Type order of fossils

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Evidence (cont.)

• 3. Homologous structures
• Similar b/c of common ancestry
• 4. Comparative embryology
• Study of structures that appear during embryonic
  development
• 5. Molecular biology
• DNA proteins

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Biogeography

• New organisms arise in same geographic area where
  similar forms already lived
• Ex kangaroos only in Australia

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Fossil Record

• Fossils impressions of organisms from the past
  mineralized in rock
• Links b/w modern forms ancestors

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Distribution of Fossils

• Law of superposition lowest layers of rock are
  oldest
• Fossil-bearing strata show when organisms became
  extinct
• Mass extinction brief period in which large s
  of species disappeared

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Homologous Structures

• May have different functions but have similar
  anatomy
• Shows a common ancestor
• Ex bird beaks forelimbs

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Common Ancestor
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Analogous Structures

• Similar look function, but different
  embryological development anatomy
• Ex bird insect wings

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Vestigial Structure

• Part of an organism w/ little or no function, but
  had a function in an ancestral species
• Ex human tailbone appendix

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Comparative Embryology

• All vertebrate embryos go through a stage in
  which they have gill pouches tails

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Molecular Biology

• The more similar the sequence, the more closely
  related 2 species are to each other
• DNA, RNA, proteins (amino acids)

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Amino Acid Chart
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(15-3) Patterns of Evolution

• Coevolution
• Convergent Evolution
• Divergent Evolution
• Pattern speed result from changes in the
  environment

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Coevolution

• Change of 2 or more species in close association
  w/ each other
• Ex
• Predator-prey
• Parasite-host
• Plant-animal pollinator

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Convergent Evolution

• Organisms appear to be similar but are not
  closely related
• Environment selects similar phenotypes
• Ex shark porpoise

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Divergent Evolution

• 2 or more related populations become more
  dissimilar in response to different habitats
• Adaptive radiation
• Galapagos finches
• Artificial selection
• Domestic dogs

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Divergent evolution of Grand Canyon squirrels
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Peppered Moth Evolution