Patterns%20of%20Evolution - PowerPoint PPT Presentation

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Patterns%20of%20Evolution

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Divergent Evolution There is isolation of a population from the main gene pool, with first geographical and then reproductive barriers, resulting in a new species. – PowerPoint PPT presentation

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Title: Patterns%20of%20Evolution


1
Patterns of Evolution
2
Divergent Evolution
  • There is isolation of a population from the main
    gene pool, with first geographical and then
    reproductive barriers, resulting in a new species.

3
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4
Adaptive Radiation
  • This is the evolution from a common ancestor of
    different forms adapted to different ecological
    niches.
  • E.g. Darwins Finches
  • when the ancestors of the finches were blown to
    the Galapagos Islands, they found many unoccupied
    niches that in there homeland had been filled by
    other birds.

5
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6
Adaptive Radiation
  • Lacking competition, the finches spread out and
    filled the vacant niches.
  • Natural selection led to selection for different
    adaptations as they did so.
  • After enough time, they had so diversified that
    they had formed different species.

7
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8
Convergent Evolution
  • This is the independent evolution of similar
    adaptive features in originally different
    species.
  • It happens because they have adapted to the same
    environment.
  • e.g. Dolphins, Ichthyosaurs and Sharks look
    similar because of being adapted to a water
    environment.

9
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10
Convergent Evolution
  • Plants that live on mountains tend to have small,
    scale-like leaves, often with hairs and closely
    fitted to the stem, and they have a
    close-to-the-ground, compact growth habit,
    forming cushions or mats of vegetation.
  • Although they may have originated from different
    species, they start to look alike.

11
Parallel Evolution
  • This is the evolution of similar features, not
    present in the ancestral form, in 2 or more
    closely related species.
  • e.g. the loss of wings on off-shore windy
    islands by some insects and birds.

12
Local Case Studies
  • Pg 236 240 text book
  • Hebes and Molluscs
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