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Darwin and Evolution

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Darwin and Evolution Charles Darwin Son of Robert Darwin, a physician and grandson of Erasmus Darwin, also a physician Was to study medicine, stomach not strong ... – PowerPoint PPT presentation

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Title: Darwin and Evolution


1
Darwin and Evolution
2
Charles Darwin
  • Son of Robert Darwin, a physician and grandson of
    Erasmus Darwin, also a physician
  • Was to study medicine, stomach not strong enough
  • Studied Theology, loved natural science

3
Darwins Voyage
  • 1831 - 1836
  • Naturalist on the HMS Beagle
  • Looking for a biblical account of creation
  • Many specimens collected (hares, tortoise,
    finches) and observations made that contradicted
    creationism
  • Put his ideas into an essay, but sat on it for 20
    years for fear of being discredited as a scientist

4
Pre - Post Darwinian Views
  • Earth is young
  • Fixity of species
  • Adaptation due to creator variation-
    imperfections
  • Observations should confirm view
  • Earth is old
  • Species related by descent
  • Adaptation random variations in environmental
    conditions
  • Observations used to test hypothesis

5
Evolution versus Creationism
  • Descent with modification- as descent occurs
    through time so does diversity
  • Explains the unity and diversity of life
  • Living things share common characteristics
    because they are descended from a common ancestor
  • Higher being created the species
  • Fixity of species
  • Each species has ideal structure and function

6
Mid-18th century contributions
  • Carolus Linnaeus taxonomy, scala naturae
    ladder of life simple to complex (humans)
  • Count Buffon French naturalist, work support
    DWM
  • Erasmus Darwin grandfather physician,
    naturalist, work eluded to DWM
  • All these mens work opened the door to the
    thought of evolution but still supported fixity
    of species

7
Late 18th century contributions
  • Georges Cuvier
  • comparative anatomy for classification, founded
    paleontology
  • Fixity of species supporter
  • Tried to explain strata of earth was due to
    catastrophes/mass extinction

8
Cont.
  • Jean Baptist LaMarck
  • First to believe evolution occurs
  • Inheritance of Acquired traits use it or lose
    it environment brings about change
  • Phenotype does not result in genetic changes
  • Giraffe neck length
  • Suntan, muscles

9
Darwins Theory of Evolution
  • Influenced by Charles Lyells Principle of
    Geology
  • James Hutton geological changes occur slowly
    over time, natural process EARTH IS OLD
  • Contradicts Cuvier due to catastrophes

10
Natural Selection Charles Darwin and Alfred
Wallace
  • Idea that those organisms that are best suited to
    their environment will reproduce and pass on
    their traits
  • Alfred Russell Wallace sent Darwin essay on
    Natural selection before he published his own
  • Variations (mutations) are essential to natural
    selection process ex. Independent assortment

11
Natural Selection
  • Thomas Malthus socio-economist
  • human population increase faster than food
    supply struggle for existence
  • Each generation of organisms have same
    reproductive potential, but not all will survive
    to reproduce

12
Natural selection
  • Fitness ability to survive and reproduce in its
    environment relative to others
  • Usually has most resources
  • Survival of the fittest
  • Artificial selection characteristics are
    selected for and select organisms to reproduce.

13
Natural Selection
  • Adaptation trait that helps organism be better
    suited for its environment
  • Flippers water, wont help on land
  • Natural selection occurs because certain members
    of a population happen to have a variation
    (mutation) that allows them to survive and
    reproduce.

14
Darwins Theory of Evolution - Evidence
  • Biogeography study of range and geographic
    distribution of life forms on earth
  • Darwin reasoned related species could be modified
    based on their environment (ex. Tortoises)
  • Observed geographical changes 1st hand and
    collected fossils to support his theory that
    species are not fixed, but change over time.

15
Evidence of Evolution
  • Biochemical evidence
  • Darwin was not aware of biochemical evidence
  • Amino acids- cytochrome c (used in electron
    transport)
  • DNA/RNA/enzymes similarities
  • Introns (junk DNA)
  • Fossils

16
Evidence of Evolution
  • Anatomical structures
  • Homologous structures - similar in structure but
    have different function
  • Vestigial structures features that are fully
    developed in one group of organisms but are
    reduced and may have no function in similar
    groups
  • Embryological development look at dorsal rod
    (notochord), pharyngeal slits (gills)

17
Theory of Evolution
  • Unifying theory in biology
  • Large number of observations
  • have not yet been found lacking or disproven
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