Introduction to Quantitative Genetics - GBV

1 Introduction to Quantitative GeneticsFourth EditionD. S. FalconerTrudy F. C. MackayPREFACE TO THE THIRD EDITION ixPREFACE TO THEFOURTHEDITION xACKNOWLEDGEMENTS xiINTRODUCTION xiiifGENETIC CONSTITUTION OF A POPULATION 1 Frequencies of genes and genotypes 1 Mendelian variation in natural populations Causes of changeHardy-Weinberg equilibrium 5 The Hardy-Weinberg law Applications of the Hardy-Weinberg lawMating frequencies and another proofofthe Hardy-Weinberg lawMultiple alleles Sex-linked genes More than one locusNon-random mating 1 9 Assortative matingProblems 202 CHANGES OF GENE FREQUENCY 23 Migration 23 Mutation 24 Non-recurrent mutation Recurrent mutationSelection 25 Change of gene frequency under selection Effectiveness of

2 SelectionNumber of generations required Average fitness and loadEquilibria 3 4 Balance between mutation and selection Changes of equilibriumSelection favouring heterozygotesPolymorphism 42 Problems 453 SMALL POPULATIONS: I. CHANGES OF GENEFREQUENCY UNDER SIMPLIFIED CONDITIONS 48 The idealized population 49 Sampling 5 1 Variance of gene frequency Fixation Genotype frequenciesInbreeding 5 7 Inbreeding in the idealized population Variance of gene frequencyGenotypefrequenciesProblems 634 SMALL POPULATIONS: II. LESS SIMPLIFIEDCONDITIONS 65 Effectivepopulationsize 6 5 Exclusionofclosely related matings Different numbersofmales andfemales Unequal numbers in successive generations Non-randomdistributionoffamily size Minimal inbreeding Overlapping generationsMutation, migration, and selection 7 2 Non-recurrent neutral mutation Recurrent mutation and migrationSelectionRandom drift in natural populations 7 6 Polymorphism 7 8 Neutral theoryProblems 8 15 SMALL POPULATIONS: III.

3 PEDIGREEDPOPULATIONS AND CLOSE INBREEDING 8 2 Pedigreed populations $ 2 The inbreeding coefficientofan individual Coancestry or kinshipRegular systems of inbreeding $ 8 Close inbreeding Fixation Repeated backcrosses Crosses andsubsequent generations Mixed inbreeding and crossing Changeofbase: structured population Mutation Selection favouringheterozygotesProblems - 9 86 CONTINUOUS VARIATION 100 Metric characters 102 Properties of metric characters 10 4 Problems 10 67 VALUESAND MEANS 108 Population mean 10 9 Average effect 11 2 Breeding value 11 4 Dominance deviation 11 6 Interaction deviation 11 9 Problems 1208 VARIANCE 122 Components of variance ' 122 Components as proportionsofthe total Estimationofthe degreeofgenetic determination.

4 VG/VpGenetic components of varianceAdditive and dominance variance Total genetic variance Interactionvariance Variance due to disequilibriumCorrelation and interaction between genotype and environment 131 Correlation InteractionEnvironmental variance 134 Multiple measurements: repeatabilitySummary of variance partitioning 14 3 Problems 14 39 RESEMBLANCE BETWEEN RELATIVES 14 5 genetic covariance 14 6 Offspring and one parent Offspring and mid-parent Half sibs Full sibsTwins General Epistatic interactionEnvironmental covariance 15 5 Phenotypic resemblance 157 Problems 15 810 HERITABILITY 160 Estimation of heritability 16 3 Offspring parent regression Sib analysis Intra-sire regressionofoffspring on dam Combined estimatesTwins and human data 17 1 Assortative mating 17 4 Precision of estimates and design of experiments 177 Offspring parent regression Sib analyses SelectionofparentsProblems 18 111 SELECTION: I.

5 THE RESPONSE AND ITS PREDICTION 184 Response to selection 18 5 Predictionofresponse Selection differential and intensityofselectionImprovementofrespons eMeasurement of response 194 Variabilityofgeneration means Weighting the selection differentialRealized heritability Maternal effectsChange of gene frequency under artificial selection 19 9 Effects of selection on variance 201 Problems 20412 SELECTION: II. THE RESULTS OF EXPERIMENTS 208 Short-term results 208 Repeatabilityofresponse Sampling variance AsymmetryofresponseLong-term results 21 5 Selection limits Mutation Causesofselection limitsNumberof loci(effective factors) and standardized effectsProblem 22613 SELECTION: III.

6 INFORMATION FROM RELATIVES 228 Criteria for selection 229 Simple methods Predictionofresponse Combined selectionRelative meritsofthe methodsIndex selection 240 Construction of an index Accuracy Response to selectionActual achievementsProblems 24514 INBREEDING AND CROSSBREEDING: I . CHANGESOF MEAN VALUE 247 Inbreeding depression 247 The effect of selectionHeterosis 253 Single crossesProblems 26115 INBREEDING AND CROSSBREEDING: II. CHANGESOFVARIANCE 263 Inbreeding 264 Redistribution of genetic variance Environmental variance Uniformityof inbred strainsMutation 269 Subline divergenceCrossing 27 2 Variance between crosses Combining abilityProblems 27 916 INBREEDING AND CROSSBREEDING: III.

7 APPLICATIONS 281 Selection for combining ability Three-way and four-way crosses;backcrosses Reciprocal recurrent selection OverdominanceNaturally self-fertilizing plantsProblems 28 817 SCALE 290 Distribution and variance Interactions ConclusionsProblems 29718 THRESHOLD CHARACTERS 29 9 Liability and threshold Two classes, one threshold Adequacy of theliability model Scale relationships Three classes, two thresholdsSelection for threshold charactersProblems 31 019 CORRELATED CHARACTERS 31 2 genetic and environmental correlations 31 2 Estimation of the genetic correlationCorrelated response to selection 31 7 Indirect selectionGenotype-environment interaction 321 Index selection 32 5 Construction of the index Response Effect of selection on geneticcorrelationsProblems 33220 METRIC CHARACTERS UNDER NATURAL SELECTION 33 5 Natural selection 33 5 Fitness and its componentsRelationships between metric characters and fitness 33 7`Fitness profiles'Responses to natural selection 33 9 Fitness Correlated responses Strength of selectionEquilibrium populations 342

8 Fitness Major components Characters with intermediate optimaCharacters with minimum fitness of intermediates Neutral charactersOrigin of variation by mutation 34 8 Mutational varianceMaintenance of genetic variation 35 1 Balance between neutral mutation and random driftMutation-selection balanceProblems 35421 Quantitative TRAIT LOCI 356 Major genes 35 6 Methods of detectionMethods for mapping QTLs 35 9 Marker loci QTL genotypes Single marker analysis Intervalmapping analysisGenetical and statistical considerations 36 6 Experimental design Multiple tests Maximum likelihoodestimation Multiple QTLsExperimental results 37 0 Number of loci Gene effects ConsistencyFrom QTL to gene 37 5 Problem 37 7 APPENDIX TABLES 37 9 GLOSSARY OF SYMBOLS 38 1 Equivalence of symbols used by Mather and Jinks 38 3 SOLUTIONS OF PROBLEMS 38 5 REFERENCES 43 7 INDEX 459