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Exploring Genetic Equilibrium Challenges in Natural Populations

Understand Darwin's Five Points and reasons why genetic equilibrium does not exist in nature. Explore factors like mutation, gene flow, genetic drift, and more affecting the balance of genetic information within populations.

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Exploring Genetic Equilibrium Challenges in Natural Populations

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  1. Population Genetics Unit 5 – Lecture 4

  2. Darwin’s Five Points • Observations regarding natural selection: • populations have variations • some variations are beneficial / favorable • more offspring are produced than survive • those that survive will have favorable traits • because of this, a population will change over time

  3. Genetic Equilibrium • Recall – natural selection affects POPULATIONS not individuals • Gene Pool – the collection of genes within a population • allelic frequency – the frequency of certain alleles within a population

  4. Genetic Equilibrium – cont’d • Genetic Equilibrium – a steady-state of genetic material/information within a population • no new traits added, none removed • doesn’t really happen in nature [will discuss why soon]

  5. Genetic Equilibrium – cont’d • Hardy-Weinburg Law • can find out how many alleles are in population if you assume that there is genetic equilibrium at any single point in time

  6. Discuss • List and explain Darwin’s Five Points. • Name and explain reasons why genetic equilibriumdoes NOT exist in nature.

  7. Genetic Equilibrium – cont’d • Genetic Equilibrium could be achieved if: • there is a large breeding population • no selection • all traits must be as favorable than others to maintain the same amounts of each allele • random mating exists • if there is sexual selection, certain traits would be favorable…which would change the amounts of each allele in the population

  8. Genetic Equilibrium – cont’d • Genetic Equilibrium could be achieved if: • no change due to mutations • any loss or gain of alleles would change the genetic ratios • no immigration or emigration • when organisms leave, they take with them their traits • when organisms arrive, they bring in new traits

  9. Genetic Equilibrium – cont’d • Genetic Equilibrium does not exist because of… • selection • natural or otherwise – changes amount of certain genes • mutation • loss or gain of info – changes amount of certain genes • gene flow • emigration / immigration

  10. Genetic Equilibrium – cont’d • Genetic Equilibrium does not exist because of… • genetic drift • small populations exist in which certain genes are more prevalent than in the general populus • American Indians do not have blood group B • Amish – marry within their own community, so more likely to have certain recessive conditions likepolydactyly [extra fingers]

  11. Genetic Equilibrium – cont’d • Genetic Equilibrium does not exist because of… • natural disasters / mass illness • cause the “bottleneck” effect

  12. Discuss • Again, summarize the reasonswhy genetic equilibrium does NOT exist in nature.

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