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Natural Selection + Genetic Drift

Natural Selection + Genetic Drift. Robert Bastaja Cole Palmer Tristan Honscheid. Prerequisite: Hardy-Weinberg Equilibrium. A population is in “equilibrium” if: There are NO mutations Mating is RANDOM No NATURAL SELECTION occurs Extremely LARGE populations

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Natural Selection + Genetic Drift

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  1. Natural Selection + Genetic Drift Robert Bastaja Cole Palmer Tristan Honscheid

  2. Prerequisite: Hardy-Weinberg Equilibrium • A population is in “equilibrium” if: • There are NO mutations • Mating is RANDOM • No NATURAL SELECTION occurs • Extremely LARGE populations • NO Gene Flow due to immigration or emigration

  3. Natural Selection • Evolution happens when a population deviates from the Equilibrium. • Individuals with desirable traits better suited for the environment are more likely to survive and reproduce, amplifying that gene in the population, while weeding out the unsuccessful genes.

  4. 1/6 White, 5/6 Red

  5. 0/5 White, 5/5 Red White bugs are easier to spot and will not live to reproduce.

  6. Genetic Drift • Random events may also shape a population. If a storm knocks down the flowers where the bugs were, the frequency of the red bugs may be reduced despite having an advantage. • The white bugs on the nearby flower survive longer.

  7. Effects of Genetic Drift • More significant in small populations: it’s easier to accidentally wipe out a small group and there’s not much diversity to begin with. • Causes allele frequencies to change at random • May suppress diversity • Can cause harmful alleles to become more common (counterevolution)

  8. Gene Flow • When different populations mate (different gene pools), gene flow occurs • Common in Humans: capable of traveling around the world and finding a spouse. • Reduces genetic differences by “blending” populations • May be bad; could transfer a gene that is harmful to the other population.

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