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E. Dilemmas
1. Evolution of complex traits
E. Dilemmas
1. Evolution of complex traits
E. Dilemmas
1. Evolution of complex traits
2. Where are the continuous sequences of transitional
forms?
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E. Dilemmas
1. Evolution of complex traits
2. Where are the continuous sequences of transitional
forms?
-the fossil record is incomplete – not all species leave a fossil
-Keep looking…
E. Dilemmas
1. Evolution of complex traits
2. Where are the continuous
sequences of transitional
forms?
1861:
Archeopteryx Lithographica
E. Dilemmas
1. Evolution of complex traits
2. Where are the continuous sequences of transitional
forms?
3. What is the source of heritable variation???
E. Dilemmas
1. Evolution of complex traits
2. Where are the continuous sequences of transitional
forms?
3. What is the source of heritable variation???
- Natural selection should “weed out” poorly
adapted forms over time, making the organisms in the population
more similar (less variation).
Why is there still so much variation in natural populations?
E. Dilemmas
1. Evolution of complex traits
2. Where are the continuous sequences of transitional
forms?
3. What is the source of heritable variation???
- selection should eliminated variation
- and if heredity is governed by blending traits, then how is
variation produced generation after generation?
E. Dilemmas
1. Evolution of complex traits
2. Where are the continuous sequences of transitional
forms?
3. What is the source of heritable variation???
- selection should eliminated variation
- and if heredity is governed by blending traits, then how is
variation produced generation after generation?
- Darwin’s explanation - Lamarckian “use and disuse”,
and ‘gemmules’…
F. Darwinian Evolution
1. Darwin’s Model
Sources of Variation
Causes of Change
????????????????  VARIATION  NATURAL SELECTION
(use and disuse??)