Quantitative Trait Loci Analysis in Animals

Author: Weller   J.I.  

Publisher: CABI Publishing‎

Publication year: 2010

E-ISBN: 9781845937348

P-ISBN(Paperback): 9781845934675

Subject: S815 livestock management

Keyword: Science Applied Sciences Life Sciences Biology Molecular Biology Genetics (Non-medical) Zoology and Animal Sciences

Language: ENG

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Description

Quantitative Trait Loci (QTL) is a topic of major agricultural significance for efficient livestock production. This advanced-level textbook covers all the statistical methods that have been used or proposed for detection and analysis of QTL and marker- and gene- assisted selection in animal genetics and breeding, as well as new advances that have revolutionized the field since the first edition.

Chapter

1 Historical Overview

1.1 Introduction

1.2 From Mendel to Sax

1.3 Quantitative Genetics 1920–1980, or Who Needs Mendel?

1.4 QTL Detection 1930–1980, Theory and Experiments

1.5 From Biochemistry to Biotechnology, or More Markers Than We Will Ever Need

1.6 Genetic Mapping Functions

1.7 Physical and Genetic Mapping, Questions of Scale

1.8 Summary

2 Principles of Parameter Estimation

2.1 Introduction

2.2 Desired Properties of QTL Parameter Estimates

2.3 Moments Method of Estimation

2.4 Least-squares Parameter Estimation

2.5 Least-squares Solutions for a Single Parameter

2.6 Least-squares Solutions for the General Linear Model

2.7 Maximum Likelihood Estimation for a Single Parameter

2.8 Maximum Likelihood Multi-parameter Estimation

2.9 Confidence Intervals and Hypothesis Testing for MLE

2.10 Methods to Maximize Likelihood Functions

2.11 Derivative-free Methods

2.12 Second Derivative-based Methods

2.13 First Derivative-based Methods (Expectation-maximization)

2.14 Bayesian Estimation

2.15 Minimum Difference Estimation

2.16 Summary

3 Random and Fixed Effects, the Mixed Model

3.1 Introduction

3.2 The Mixed Linear Model

3.3 The Mixed Model Equations

3.4 Solving the Mixed Model Equations

3.5 Some Important Properties of Mixed Model Solutions

3.6 Equation Absorption

3.7 Multivariate Mixed Model Analysis

3.8 The Repeatability Model

3.9 The Individual Animal Model

3.10 Grouping Individuals with Unknown Ancestors

3.11 The Reduced Animal Model

3.12 Maximum Likelihood Estimation with Mixed Models

3.13 Estimation of Variance Components, Analysis of Variance-type Methods

3.14 Maximum Likelihood Estimation of Variance Components

3.15 Restricted Maximum Likelihood Estimation of Variance Components

3.16 The Problem of Variance Components Outside the Parameter Space

3.17 Summary

4 Experimental Designs to Detect QTL: Generation of Linkage Disequilibrium

4.1 Introduction

4.2 Assumptions, Problems and Types of Effects Postulated

4.3 Experimental Designs for Detection of QTL in Crosses Between Inbred Lines

4.4 Linear Model Analysis of Crosses Between Inbred Lines

4.5 Experimental Designs for Detection of QTL in Segregating Populations: General Considerations

4.6 Experimental Designs for Detection of QTL in Segregating Populations: Large Families

4.7 Experimental Designs for Detection of QTL in Segregating Populations: Small Families

4.8 Experimental Designs Based on Additional Generations: Inbred Lines

4.9 Experimental Designs Based on Additional Generations: Segregating Populations

4.10 Comparison of the Expected Contrasts for Different Experimental Designs

4.11 Gametic Effect Models for Complete Population Analyses

4.12 Summary

5 QTL Parameter Estimation for Crosses between Inbred Lines

5.1 Introduction

5.2 Moments Method of Estimation

5.3 Least-squares Estimation of QTL Parameters

5.4 Least-squares Estimation of QTL Location for Sib-pair Analysis with Flanking Markers

5.5 Linear Regression Mapping of QTL with Flanking Markers

5.6 Marker Information Content for Interval Mapping, Uninformative and Missing Marker Genotypes

5.7 Maximum Likelihood QTL Parameter Estimation for Crosses Between Inbred Lines and a Single Marker

5.8 Maximum Likelihood Tests of Significance for a Segregating QTL

5.9 Maximum Likelihood QTL Parameter Estimation for Crosses between Inbred Lines and Two Flanking Markers

5.10 Estimation of QTL Parameters by the Expectation-maximization Algorithm

5.11 Biases in Estimation of QTL Parameters with Interval Mapping

5.12 The Likelihood Ratio Test with Interval Mapping

5.13 Summary

6 Advanced Statistical Methods for QTL Detection and Parameter Estimation

6.1 Introduction

6.2 Higher-order QTL Effects

6.3 QTL Interaction Effects

6.4 Simultaneous Analysis of Multiple Marker Brackets

6.5 Principles of Composite Interval Mapping

6.6 Properties of Composite Interval Mapping

6.7 Derivation of Maximum Likelihood Parameter Estimates by Composite Interval Mapping

6.8 Hypothesis Testing with Composite Interval Mapping

6.9 Multi-marker and QTL Analysis by Regression of Phenotype on Marker Genotypes

6.10 Estimation of QTL Parameters in Outbred Populations

6.11 Analysis of Field Data, Daughter and Granddaughter Designs

6.12 Maximum Likelihood Analysis of QTL Parameters for the Daughter Design with Linkage to a Single Marker

6.13 Non-linear and Linear Regression Estimation for Complex Pedigrees

6.14 Estimation of QTL Allelic Frequencies in Segregating Populations

6.15 Maximum Likelihood Estimation with Random Effects Included in the Model

6.16 Incorporation of Genotype Effects into Animal Model Evaluations When Only a Small Fraction of the Population Has Been Genotyped

6.17 Maximum Likelihood Estimation of QTL Effects on Categorical Traits

6.18 Estimation of QTL Effects with the Threshold Model

6.19 Estimation of QTL Effects on Disease Traits by the Allele-sharing Method

6.20 Summary

7 Analysis of QTL as Random Effects

7.1 Introduction

7.2 ML Estimation of Variance Components for the Haseman–Elston Sib-pair Model

7.3 The Random Gametic Model of Fernando and Grossman, Computing G[sub(v)]

7.4 Computing the Inverse of G[sub(v)]

7.5 Analysis of the Random Gametic Model by a Reduced Animal Model

7.6 Analysis of the Random Gametic QTL Model with Multiple QTL and Marker Brackets

7.7 Computation of the Gametic Effects Variance Matrix

7.8 The Gametic Effect Model for Crosses Between Inbred Lines

7.9 REML Estimation of the QTL Variance and Recombination for the Model of Fernando and Grossman

7.10 REML Estimation of the QTL Variance and Location with Marker Brackets

7.11 Bayesian Estimation of QTL Effects, Determining the Prior Distribution

7.12 Formula for Bayesian Estimation and Tests of Significance of a Segregating QTL in a Simulated Granddaughter Design

7.13 Comparison of ML and Bayesian Analyses of a Simulated Granddaughter Design

7.14 Markov Chain Monte Carlo Algorithms, Gibbs Sampling

7.15 Summary

8 Statistical Power to Detect QTL, and Parameter Confidence Intervals

8.1 Introduction

8.2 Estimation of Power in Crosses Between Inbred Lines

8.3 Replicate Progeny in Crosses Between Inbred Lines

8.4 Estimation of Power for Segregating Populations

8.5 Power Estimates for Likelihood Ratio Tests: General Considerations

8.6 The Effect of Statistical Methodology on the Power of QTL Detection

8.7 Estimation of Power with Random QTL Models

8.8 Confidence Intervals for QTL Parameters, Analytical Methods

8.9 Simulation Studies of Confidence Intervals

8.10 Empirical Methods to Estimate Confidence Intervals, Parametric and Nonparametric Bootstrap and Jackknife Methods

8.11 Summary

9 Optimization of Experimental Designs

9.1 Introduction

9.2 Economic Optimization of Marker Spacing When the Number of Individuals Genotyped Is Non-limiting

9.3 Economic Optimization with Replicate Progeny

9.4 Selective Genotyping

9.5 Sample Pooling: General Considerations

9.6 Estimation of Power with Sample Pooling

9.7 Comparison of Power and Sample Sizes with Random Genotyping, Selective Genotyping and Sample Pooling

9.8 Sequential Sampling

9.9 Summary

10 Fine Mapping of QTL

10.1 Introduction

10.2 Determination of the Genetic Map Critical Interval for a Marker Locus with a Saturated Genetic Marker Map

10.3 Confidence Interval for QTL Location with a Saturated Genetic Marker Map

10.4 Fine Mapping of QTL via Advanced Intercross Lines

10.5 Selective Phenotyping

10.6 Recombinant Progeny Testing

10.7 Interval-specific Congenic Strains

10.8 Recombinant Inbred Segregation Test

10.9 Fine Mapping of QTL in Outcrossing Populations by Identity by Descent

10.10 Estimation and Evaluation of Linkage Disequilibrium in Animal Populations

10.11 Linkage Disequilibrium QTL Mapping, Basic Principles

10.12 Linkage Disequilibrium Mapping, Advanced Topics

10.13 Summary

11 Complete Genome QTL Scans: The Problem of Multiple Comparisons

11.1 Introduction

11.2 Multiple Markers and Whole-genome Scans

11.3 QTL Detection by Permutation Tests

11.4 QTL Detection Based on the False Discovery Rate

11.5 A Priori Determination of the Proportion of False Positives

11.6 Analysis of Multiple Pedigrees

11.7 Biases with Estimation of Multiple QTL

11.8 Bayesian Estimation of QTL from Whole-genome Scans, Theory

11.9 Bayesian Estimation of QTL from Whole-genome Scans, Simulation Results

11.10 Summary

12 Multitrait QTL Analysis

12.1 Introduction

12.2 Problems and Solutions for Multitrait QTL Analyses

12.3 Multivariate Estimation of QTL Parameters for Correlated Traits

12.4 Comparison of Power for Single and Multitrait QTL Analyses

12.5 Pleiotropy Versus Linkage

12.6 Estimation of QTL Parameters for Correlated Traits by Canonical Transformation

12.7 Determination of Statistical Significance for Multitrait Analyses

12.8 Selective Genotyping with Multiple Traits

12.9 Multitrait LD Mapping

12.10 Summary

13 From the QTL to the Gene

13.1 Introduction

13.2 The Molecular Basis of QTL Discovered So Far

13.3 Determination of QTL Candidate Genes

13.4 Determination of Concordance

13.5 QTN Validation by Other Statistical Methods

13.6 QTN Validation by Functional Studies

13.7 Summary

14 Principles of Selection Index and Traditional Breeding Programmes

14.1 Introduction

14.2 Selection Index for a Single Trait

14.3 Changes in QTL Allelic Frequencies Due to Selection

14.4 Multitrait Selection Index

14.5 The Value of Genetic Gain

14.6 Dairy Cattle Breeding Programmes, Half-sib and Progeny Tests

14.7 Nucleus Breeding Schemes

14.8 Summary

15 Marker-assisted Selection: Theory

15.1 Introduction

15.2 Situations in which Selection Index Is Inefficient

15.3 Potential Contribution of MAS for Selection Within a Breed: General Considerations

15.4 Phenotypic Selection Versus MAS for Individual Selection

15.5 MAS for Sex-limited Traits

15.6 Two-stage Selection: MAS on Juveniles, and Phenotypic Selection of Adults

15.7 MAS Including Marker and Phenotypic Information on Relatives

15.8 Maximum Selection Efficiency of MAS with All QTL Known, Relative to Trait-based Selection, and the Reduction in RSE Due to Sampling Variance

15.9 Marker Information in Segregating Populations

15.10 Inclusion of Marker Information in ‘Animal Model’ Genetic Evaluations

15.11 Genetic Evaluation Based on Dense Whole-genome Scans

15.12 Velogenetics: the Synergistic Use of MAS and Germ-line Manipulation

15.13 Summary

16 Marker-assisted Selection: Current Status and Results of Simulation Studies

16.1 Introduction

16.2 Modelling the Polygenic Variance

16.3 The Effective Number of QTL

16.4 Proposed Dairy Cattle Breeding Schemes with MAS: Overview

16.5 Inclusion of Marker Information into Standard Progeny Test and MOET Nucleus Breeding Schemes

16.6 Progeny Test Schemes, in Which Information on Genetic Markers is Used to Preselect Young Sires

16.7 The Current Status of MAS in Dairy Cattle

16.8 Selection of Sires Based on Marker Information Without a Progeny Test

16.9 Computation of Reliabilities of Genetic Evaluations Based on Complete Genome Scans

16.10 Long-term Considerations, MAS Versus Selection Index

16.11 MAS for a Multitrait Breeding Objective with a Single Identified QTL

16.12 MAS for a Multitrait Breeding Objective with Multiple Identified QTL

16.13 Summary

17 Marker-assisted Introgression

17.1 Introduction

17.2 Marker-assisted Introgression: General Considerations

17.3 Marker-assisted Introgression of a Major Gene into an Inbred Line

17.4 Marker-assisted Introgression of a QTL into a Donor Population Under Selection

17.5 Marker-assisted Introgression for Multiple Genes

17.6 Summary

Glossary of Symbols

Latin Symbols

Greek Symbols

Other Symbols

References

Author Index

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Subject Index

A

B

C

D

E

F

G

H

I

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M

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Q

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