9/15/20111Darwin’s Theory of Evolution Artificial Selection9/15/20112Natural SelectionExtinctionSelective Factors that Drive Natural Selection• Climate and Weather• Availability of food• Predators and Diseases• Competition for mates9/15/20113Key Inferences from Darwin’s Observations• Observation 1: Members of a population often vary in their traits, that were inherited from parent to offspring.• Observation 2: All species have the ability to overproduce.• Inference 1: Individuals whose inherited traits give them a higher probability of survival tend to leave more offspring. • Inference 2: Favorable traits will accumulate in a population over generations. Studying fossils provides strong evidence for evolutionReinforcing the evolutionary view of lifeComparative anatomy: • Similarities in characteristics that results from common ancestry is known as Homology.9/15/20114Homologous structuresEvolutionary TreeThe Evolution of Populations9/15/20115Mutation and sexual reproduction• Mutation:• Sexual reproduction:Hardy-Weinberg Equation• pp + 2pq + qq = 1• p is the dominant allele frequency• q is the recessive allele frequency• The equilibrium must satisfy 5 main conditions• 1. Very large population• 2. No gene flow between populations• 3. No mutations• 4. Random mating• 5. No natural selectionMechanisms of Microevolution• Bottleneck effect Founder effect9/15/20116Natural selection can alter variation in a population in three waysSexual Dimorphism Intrasexual selection9/15/20117Intersexual
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