Darwins theory of natural selection Population grow exponentially

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

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Condition for Hardy – Weinberg equation: 1. Large population 2. No evolution: Population is stabilized, in equilibrium • • • 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 • • 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

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Types of Evolution • • Directional Diversifying Stabilizing Heterozygotic supriority • Minority advantage • • • Divergent Convergent Parallel Reciprocal Adaptive radiation

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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