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Mechanisms of Evolution

Mechanisms of Evolution. Mechanisms of Evolution. There are several: Natural Selection Gene Flow Genetic drift Mutations Non-random mating. 1. Natural Selection:. Variation exists within a population More offspring are born than can survive

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Mechanisms of Evolution

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  1. Mechanismsof Evolution

  2. Mechanisms of Evolution There are several: • Natural Selection • Gene Flow • Genetic drift • Mutations • Non-random mating

  3. 1. Natural Selection: • Variation exists within a population • More offspring are born than can survive • Phenotypic differences result in differential reproductive success • Individuals that do survive, pass heritable traits on to offspring • Over time (many generations) this could lead to changes in the population

  4. Natural Selection

  5. 2. Gene Flow: • Is the movement of alleles into or out of a population (immigration or emigration). • Gene flow can introduce new alleles into a gene pool or can change allele frequencies. • Example: • Plant pollen being blown into a new area

  6. Gene Flow

  7. 3. Genetic Drift • The change in allele frequencies as a result of random chance. • Affects small populations.

  8. Examples of Genetic Drift • B) Population Bottleneck: • Occurs when a population undergoes an event in which a significant percentage of a population or species is killed or otherwise prevented from reproducing. • The event may eliminate alleles entirely or also cause other alleles to be over-represented in a gene pool. EX. Cheetahs

  9. 4. Mutations • Are inheritable changes in the genotype. • Provide the variation that can be acted upon by natural selection. • Mutations provide the raw material on which natural selection can act.

  10. 5. Non-Random Mating • In animals, non-random mating can change allele frequencies as the choice of mates is often an important part of behavior. • **Dog Breeders**

  11. Mimicry Coral snakes (venomous) and king snakes (non-venomous) The harmless king snake mimics the poisonous coral snake, causing would-bepredators to avoid them. http://3.bp.blogspot.com Monarchs (toxic to predators) and viceroys (non-toxic) The viceroys mimics the coloration and pattern of the unpalatable monarch, also avoiding would-be-predators. http://fish.mongabay.com Camouflage: A flounder will be less conspicuous to predators and to would-be prey if it blends in with its environment. http://conservationreport.files.wordpress.comCompare/contrast mimicry and camouflage. Pick an organism and explain the benefit of that animal or pl

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