A total of 20 men and 20 women volunteer to participate in a statistics project. The height and weight of each subject are given in the table. Draw one histogram for the height of the subjects and a separate histogram for weight. Use different colors for men and women so that you can visually compare the distributions by sex and plot weights in 10-lb intervals (i.e., 90–99 lb, 100–109 lb, 110–119 lb, etc.).
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
Analyzing Trait Variance
Problem 1d
Textbook Question
How do we assess environmental factors to determine if they impact the phenotype of a quantitatively inherited trait?

1
Understand that quantitative traits are influenced by both genetic and environmental factors. To assess the impact of environmental factors, we need to isolate and measure their contribution to the phenotype.
Design an experiment where genetically identical individuals (e.g., clones or inbred lines) are raised in different environments. This ensures that any phenotypic variation observed is due to environmental factors, as the genetic contribution is constant.
Calculate the phenotypic variance (Vp) in the population. This variance includes contributions from both genetic (Vg) and environmental (Ve) factors.
Use statistical methods, such as analysis of variance (ANOVA), to partition the total phenotypic variance into its genetic and environmental components. This allows us to estimate the environmental variance (Ve).
Compare the environmental variance (Ve) to the total phenotypic variance (Vp) to determine the proportion of phenotypic variation attributable to environmental factors. This can be expressed as Ve/Vp.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Quantitative Genetics
Quantitative genetics is the study of traits that are influenced by multiple genes and environmental factors, leading to continuous variation in phenotypes. Unlike Mendelian traits, which follow simple inheritance patterns, quantitative traits require statistical methods to analyze their inheritance and variation. Understanding this concept is crucial for assessing how traits are expressed and how they can be influenced by environmental conditions.
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Phenotype
Phenotype refers to the observable characteristics or traits of an organism, which result from the interaction of its genotype with the environment. In quantitative genetics, phenotypes are often measured on a continuous scale, such as height or weight. Assessing how environmental factors affect phenotypes is essential for understanding the expression of quantitatively inherited traits.
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Environmental Impact Assessment
Environmental impact assessment in genetics involves evaluating how external factors, such as nutrition, climate, and habitat, influence the expression of traits. This assessment can be conducted through controlled experiments or observational studies, allowing researchers to distinguish between genetic and environmental contributions to phenotypic variation. Understanding these impacts is vital for determining the heritability of traits and their potential for adaptation.
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