Download evolution

Darwin’s theory of natural selection:
• Population grow exponentially
• Over population results in competition and
struggle for existence
• In any population, there is unequal abilities
for individuals
• Only the best fit survive and pass their traits
• Evolution occurs when advantageous traits
accumulate in a population
Please see video
Figure 17.15
Figure 17.16
Figure 17.17
Condition for Hardy – Weinberg
equation:
1. Large population
2. No evolution: Population
is stabilized, in equilibrium
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•
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No genetic drift
No gene flow
No mutation
No non-random mating
No natural selection
Cause of Evolution
• Genetic drift
– Bottle neck effect
– Founder’s effect
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Gene flow
Mutation
Non-random mating
Natural selection
Habitat isolation:
Two species of
Garter snake
Thamophis
Terrestrial
Water
Temporal isolation:
Spotted skunk
S. gracilis
mates in summer
S. putorius
mates in winter
Behavioral isolation
Blue-footed boobies
Please see video
Mechanical isolation
Monkey flower Mimulus
Gametic isolation
Reduced hybrid viability
Salamander Ensatina
Reduced hybrid fertility
Hybrid breakdown
22
9
Types of Evolution
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Directional
Diversifying
Stabilizing
Heterozygotic
supriority
• Minority advantage
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Divergent
Convergent
Parallel
Reciprocal
Adaptive radiation
Figure 18.6
Figure 18.2
http://www.faceresearch.org/demos/average
(Works when in slide show)
1930. JBS Haldane
Heterozygotic superiority
SS
ss
Ss
Sickle cell anemia
Normal
Disease
Normal
Malaria
S
R
R
Australian Mole
North American Mole
The same evolutionary forces
acted on humans