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Quantitative Genetics: Understanding Polygenic Inheritance, Heritability, and Twin Studies, Study notes of Genetics

An overview of quantitative genetics, focusing on polygenic inheritance, heritability, and twin studies. Topics include continuous variation, additive alleles, calculating the number of genes, broad sense heritability, narrow sense heritability, and twin studies. The document also covers statistical tools such as mean, variance, and standard deviation, as well as the concept of quantitative trait loci (QTL).

What you will learn

  • What is polygenic inheritance and how does it differ from discontinuous inheritance?
  • What role do twin studies play in understanding heritability and quantitative trait loci (QTL)?

Typology: Study notes

2021/2022

Uploaded on 09/12/2022

ekambar
ekambar 🇺🇸

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Quantitative Genetics
Polygenic inheritance
Continuous variation
Additive alleles
Calculating the number of genes
Heritability
Statistical tools: Mean, variance
Broad sense heritability
Narrow sense heritability
Twin Studies and concordance
Polygenic inheritance
2 or more genes
Show continuous
variation vs
discontinuous
Additive component
Distinct phenotypic
classes
Quantitative traits:
size, weight, height,IQ
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pf4
pf5
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Download Quantitative Genetics: Understanding Polygenic Inheritance, Heritability, and Twin Studies and more Study notes Genetics in PDF only on Docsity!

Quantitative Genetics

  • Polygenic inheritance Continuous variation Additive alleles Calculating the number of genes
  • Heritability Statistical tools: Mean, variance Broad sense heritability Narrow sense heritability Twin Studies and concordance

Polygenic inheritance

  • 2 or more genes
  • Show continuous variation vs discontinuous
  • Additive component
  • Distinct phenotypic classes
  • Quantitative traits: size, weight, height,IQ

Polygenic inheritance

Continuous variation

  • Kolreuter’s cross
  • Dwarf x tall tobacco
  • F1 intermediate
  • F2 intermediate, normal distribution

Calculation of number of genes

  • (1/4)n= ratio of f2 individuals showing extreme phenotype

Statistical Analysis

  • Mean
  • Variance
  • Standard deviation

Heritabilty

  • Genetic contribution to phenotypic

variability

  • Broad-sense Heritabilty
  • Narrow-sense Heritabilty
  • Quantitative trait loci (QTL)

Broad-sense Heritabilty

  • H = proportion of total variance caused by genetic variance
  • H = 1.0, all genetic
  • H = 0 all variation due to environment - Vp= phenotypic var - Vg= genetic var - VE= enviromental var - Vp= Vg + VE - H^2 = Vg/Vp

Narrow-sense Heritabilty

  • Potential response to selection
  • h^2 = M2- M/ M1 – M response/selection differential
  • M= mean of parental
  • M1= mean of selected segment
  • M2= mean of offspring
  • Heritability low for traits essential for survival

Narrow-sense Heritabilty

Twin Studies

H = (Vdz – Vmz)/ Vdz

Quantitative trait loci (QTL)