Table of contents
- 1. Introduction to Genetics51m
- 2. Mendel's Laws of Inheritance3h 37m
- 3. Extensions to Mendelian Inheritance2h 41m
- 4. Genetic Mapping and Linkage2h 28m
- 5. Genetics of Bacteria and Viruses1h 21m
- 6. Chromosomal Variation1h 48m
- 7. DNA and Chromosome Structure56m
- 8. DNA Replication1h 10m
- 9. Mitosis and Meiosis1h 34m
- 10. Transcription1h 0m
- 11. Translation58m
- 12. Gene Regulation in Prokaryotes1h 19m
- 13. Gene Regulation in Eukaryotes44m
- 14. Genetic Control of Development44m
- 15. Genomes and Genomics1h 50m
- 16. Transposable Elements47m
- 17. Mutation, Repair, and Recombination1h 6m
- 18. Molecular Genetic Tools19m
- 19. Cancer Genetics29m
- 20. Quantitative Genetics1h 26m
- 21. Population Genetics50m
- 22. Evolutionary Genetics29m
20. Quantitative Genetics
Heritability
1:25 minutes
Problem 11b
Textbook Question
Textbook QuestionIn selective breeding experiments, it is frequently observed that the strains respond to artificial selection for many generations, with the selected phenotype changing in the desired direction. Often, however, the response to artificial selection reaches a plateau after many generations, and the phenotype no longer changes as it did in past generations. Once a plateau has been reached, is the heritability of the trait very high or is it very low? Explain.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Heritability
Heritability is a measure of how much of the variation in a trait can be attributed to genetic differences among individuals in a population. It is expressed as a value between 0 and 1, where a higher heritability indicates that genetics play a larger role in the trait's expression. In the context of selective breeding, high heritability suggests that the trait can be reliably passed on to future generations, while low heritability indicates that environmental factors may have a greater influence.
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Response to Selection
The response to selection refers to the change in the average phenotype of a trait in a population as a result of selective breeding. Initially, when a trait is under strong selection pressure, significant changes can occur. However, as breeding continues, the rate of change often slows and may plateau, indicating that the population has reached a limit in the trait's expression due to genetic constraints or reduced genetic variation.
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Genetic Variation
Genetic variation is the diversity in gene frequencies within a population, which is essential for evolution and selective breeding. When a population has high genetic variation, there are more alleles available for selection, allowing for continued improvement of traits. Conversely, if a plateau is reached in selective breeding, it often signifies that genetic variation for the trait has been exhausted, leading to a low heritability and limited potential for further change.
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