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Darwin VS. Lamarck

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Darwin VS. Lamarck Chapter 15-2 Jean Baptiste de Lamarck (1744-1829) First to propose the theory of evolution. Lamarck claimed that species are descendents from early ... – PowerPoint PPT presentation

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Title: Darwin VS. Lamarck


1
Darwin VS. Lamarck
  • Chapter 15-2

2
Jean Baptiste de Lamarck (1744-1829)
  • First to propose the theory of evolution.
  • Lamarck claimed that species are descendents from
    early ancestors.
  • Fossil records supported his findings.

3
Lamarcks Theory
  • Lamarck claimed that species changed over time
    due to an acquired trait.
  • Acquired trait- A trait not determined by genes
    but acquired through a life time.
  • Lamarcks theory was later proven false.

4
Charles Darwin (1809-1882)
  • Charles Darwin came up with a different theory to
    explain how evolution takes place.
  • Darwin collected evidence for his theory on his
    journey around the world on a ship called the
    H.M.S. Beagle.

5
Natural Selection
  • Darwins theory was based on the idea of what he
    called natural selection.
  • Natural selection- Organisms best suited to their
    environment reproduce more successfully than
    other organisms. Thus passing down their
    favorable traits to their offspring.

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Voyage of the Beagle
  • One of Darwin's most famous collections from his
    trip was the collection of finches from the
    Galapagos islands.

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The Finches
  • Darwin collected 13 different species of finches
    from the island.
  • Each bird had a distinct bill specialized for a
    particular food source.
  • Darwin later concluded that these 13 species came
    from one common ancestor.
  • Darwin thought that the original ancestors had
    migrated from the nearby coast of South America.

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The Origin of Species
  • Darwin later published his findings in a book
    titled the Origin of Species.

12
Survival of the Fittest
  • We often use the term survival of the fittest
  • What does this mean?

13
Survival of the Fittest
  • Animals with favorable traits will survive and
    pass those genes to the offspring.
  • The contribution of genes an organism gives to
    the next generation is called fitness.

14
Fitness
  • As more favorable genes are contributed to the
    population the organisms will change over time.
  • This is Darwins idea of natural selection.
  • The process by which a population becomes better
    suited to its environment is known as adaptation.

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THE FORMATION OF A NEW SPECIES
  • Chapter 15-3 and 16-3 Notes

19
Homologous Structure
  • Homologous Structure- Similar features that are
    found in a shared ancestor.

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Vestigial Structures
  • Vestigial Structure- Structures that were useful
    to ancestors now have no purpose.

23
Vestigial Structures
24
Vestigial Structures
25
Similarities in Embryology
  • The early stages of different vertebrate embryos
    are strikingly similar to each other.
  • The similar appearance provides further evidence
    that species originated from a common ancestor.

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Similarities in Macromolecules
  • Darwin based many of his conclusions on the
    physical similarities between organisms.
  • Darwin was unable to examine similarities at a
    molecular level.
  • Scientists have later studied the molecular
    similarities between different organisms.

29
Molecular Similarities
  • The similarity in amino acid sequence can
    determine how closely related two species are.
  • And how long ago they branched off the
    evolutionary chain and developed a new species.

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Analogous Structures
  • When organisms that vary greatly anatomically
    evolve similar structures that serve similar
    functions.
  • Example bird wing and insect wing
  • Example bird beak and giant squid beak
  • Share very distant relatives.

33
Co- Evolution
  • The change of two or more species in close
    association with each other is called
    co-evolution.
  • Example Bat and flower

34
Some flowers and bees have coevolved in a way
that their existence depends on each other.
35
Convergent Evolution
  • Selection that causes two species to become very
    similar to each other even though they have very
    different ancestors.
  • Example- Dolphin and Shark

36
Convergent Evolution
37
Divergent Evolution
  • Two or more related populations or species become
    more and more dissimilar.
  • Divergence is nearly always a response to
    differing environmental factors and can
    ultimately result in new species.
  • The rate of divergent evolution among dogs has
    been increased by artificial selection in humans.

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Speciation
  • Speciation- Is the formation of new species which
    results in many related populations of organisms.

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Biological Species Concept
  • The Biological Species Concept states- A species
    is a population of organisms that can
    successfully interbreed but can not breed with
    other groups.

43
Biological Species Concept
  • The biological species concept works great for
    living organisms but is difficult for organisms
    that have since become extinct.

44
Speciation
  • In order for speciation to occur there must be
    isolation.
  • In isolation two parts of formerly interbreeding
    populations stop interbreeding.
  • Why is isolation important for speciation to
    occur?

45
Speciation
  • Two major types of isolation frequently drive
    speciation
  • Geographic Isolation
  • Reproductive Isolation

46
Geographic Isolation
  • Geographic Isolation- Is the physical separation
    of members of a population.
  • Examples
  • Canyon formation
  • Shrinking ponds
  • - Islands

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Reproductive Isolation
  • Reproductive Isolation- Reproductive isolation
    results from barriers to successful breeding
    between population groups in the same area.

51
Reproductive Isolation
  • Examples
  • Offspring does not survive to reproduce
  • Mating call that is not recognized
  • Different mating times
  • Selective mate

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