Evolution

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Evolution
Lec 13 15Feb02
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The ecological theater
The evolutionary drama
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Evolution by Natural Selection is not
random
Selection is non-random
non-random
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How are complex structures designed by natural
selection?
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Eyes have evolved in many animals
In single celled animals
light meters
direction detectors
In multicellular animals
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Eyes have evolved in many animals
a shadow detector
a pinhole camera
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Octopus eye
is a camera eye
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Octopus eye
Vertebrate eye
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Convergent Evolution
Octopus eye
Vertebrate eye
a direct eye
a backwards retina
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How did eyes evolve?
A better question is how do genes control the
construction of an eye?
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A better question is how do genes control the
construction of an eye?
If a characteristic is genetically controlled
it has evolved
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Nature red in tooth and claw?
not necessarily
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e.g. mutualism
Nature red in tooth and claw?
not necessarily
often cooperation
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Mutualism
mycorrhizal fungi
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Mycorrhizal fungi
share nutrients with tree roots
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e.g. mutualism
Nature red in tooth and claw?
not necessarily
often cooperation
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Cleaning symbioses
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Cleaning symbioses
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Symbiosis
living together
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often cooperation
Nature red in tooth and claw?
not necessarily
e.g. pollination
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Wind-pollinated plants
have inconspicuous flowers
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Pollination
An example of coevolution
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Bees see ultraviolet light
nectar guides
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Honeybees learn
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Honeybees learn
and communicate
flower location to fellow workers