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Population Genetics

Population Genetics. The study of allele frequencies within a population. Gene Pool. All of the genes of a population of organisms Organisms that are the most successful at reproducing contribute most to the gene pool. Evolution. Any change in the frequency of any allele within a gene pool

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Population Genetics

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  1. Population Genetics The study of allele frequencies within a population

  2. Gene Pool • All of the genes of a population of organisms • Organisms that are the most successful at reproducing contribute most to the gene pool

  3. Evolution • Any change in the frequency of any allele within a gene pool • Populations undergo evolution • Individualsdo not undergo evolution

  4. Factors Affecting the Allele Frequency • Mutation • Especially important for organisms with short generation times

  5. Factors Affecting the Allele Frequency • Migration • Movement of organisms into or out of the population

  6. Factors Affecting the Allele Frequency • Genetic Drift • Random change in allele frequencies • Occurs mostly in small, isolated populations

  7. Factors Affecting the Allele Frequency • Selection • Environmental pressures • Competition • Climate change

  8. Factors Affecting the Allele Frequency • Nonrandom mating • Preferences in selection of a mating partner

  9. SPECIES Species: A group of organisms so similar to one another that they can interbreed and produce fertile offspring Kingdom Phylum Class Order Family Genus Species

  10. Speciation • Speciation is the evolution of new species through time • Speciation occurs most rapidly in a small population

  11. Mechanisms of Speciation • Artificial Speciation • New species have been developed by man • Intentional mutations • Cross breeding • Genetic engineering

  12. Mechanisms of Speciation • Natural Speciation by Isolation of Small Populations • Geographical Isolation • Geographical barriers separate two populations • Mountain ranges • Deep canyons • Bodies of water • Ecological Isolation • Organisms of two populations require different habitats

  13. Mechanisms of Speciation • Behavioral Isolation • Changes in habits that identify one population with another • Mating rituals • Methods of communication

  14. Mechanisms of Speciation • Seasonal Isolation • Reproductive cycles do not coincide • Plants that flower at different times • Animals that mate or nest build at different times

  15. Mechanisms of Speciation • Mechanical Isolation • Physical characteristics that keep organisms from interbreeding • Difference in size • Difference in reproductive anatomy • Inability of sperm to penetrate the egg

  16. Observations From the Fossil Record • Species often remain stable for millions of years with little or no noticeable change • Species may disappear rapidly and new species may appear just as fast

  17. Population Evolution

  18. Punctuated Equilibrium Long periods of stability followed by short periods of rapid change

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