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Chapter 6B: Population Genetics

Chapter 6B: Population Genetics. The Gene Pool. Population A group of individuals of the same species that lives in the same area Gene pool All alleles that all members of a species can possess. Genetic Variation.

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Chapter 6B: Population Genetics

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  1. Chapter 6B:Population Genetics

  2. The Gene Pool

  3. Population • A group of individuals of the same species that lives in the same area • Gene pool • All alleles that all members of a species can possess

  4. Genetic Variation • Variations are differences in the genotypes among individuals in the same gene pool. • Variations can occur in three ways.

  5. Genetic Variation • Random fusion of two gametes • Segregation and exchange of information during meiosis • Mutations

  6. Mass Selection • The selection of desirable breeding stock from the entire population • Used to breed for desirable traits

  7. Hybridization • The crossbreeding of two genetically unrelated individuals • Offspring is called a hybrid. • Heterosis or hybrid vigor • When offspring have superior characteristics to the parents

  8. Inbreeding • The mating of an organism with itself or a close relative • Can be used to produce pure strains • Organisms that are homozygous for certain traits

  9. Studying Populations

  10. Hardy-Weinberg Principle The frequency of alleles and the ratio of heterozygous to homozygous individuals remains constant unless the population is affected by outside factors.

  11. Genetic equilibrium • Condition in which allele frequencies within a population do not change • Allele frequency • The number of times an allele occurs in a gene pool compared to the number of times other alleles occur

  12. Hardy-Weinberg Principle Five factors must be met for genetic equilibrium to exist.

  13. Hardy-Weinberg Principle • Random mating • Large population • No movement into or out of the population • No mutations • Equal chances of surviving and reproducing

  14. Nonrandom Mating • Most species do not mate randomly. • Geographic barriers • Selecting of mates • Inbreeding

  15. Small Population • When there is a change in a small population, the results are amplified. • Genetic drift

  16. Migration • Most populations have individuals moving into or out of the population. • This means that there is genetic information coming into and going out of the population (gene flow).

  17. Mutation • This is the only method whereby new alleles can be produced.

  18. Selection • Not all of the members of a population will reproduce. • This may cause some of the alleles in the gene pool to be lost.

  19. Genetic change = evolution • Population changes never create new kinds of organisms. • They only involve either the rearrangement of already existing alleles or the loss of genetic information. • Therefore, they are not valid support for evolution.

  20. Eugenics

  21. Eugenics • “Good origins” • Efforts to improve the human gene pool • Genetic screening

  22. Eugenics • A Christian Consideration • Sanctity of human life • Dominion mandate • Salvation through Christ alone

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