24.1 Quantitative Characteristics Vary Continuously and Many Are Influenced by Alleles at Multiple Loci The Relationship Between Genotype and Phenotype.

Slides:

Advertisements

Similar presentations

15 The Genetic Basis of Complex Inheritance

Advertisements

Chapter 7 Quantitative Genetics

GENETICS AND VARIABILITY IN CROP PLANTS. Genetics and variability of traits are grouped by:  Qualitative traits Traits that show variability that can.

Quantitative traits.

Qualitative and Quantitative traits

Chapter 6: Quantitative traits, breeding value and heritability Quantitative traits Phenotypic and genotypic values Breeding value Dominance deviation.

Quantitative genetics

Chapter 7 Quantitative Genetics Read Chapter 7 sections 7.1 and 7.2. [You should read 7.3 and 7.4 to deepen your understanding of the topic, but I will.

Quantitative Genetics Up until now, we have dealt with characters (actually genotypes) controlled by a single locus, with only two alleles: Discrete Variation.

1 15 The Genetic Basis of Complex Inheritance. 2 Multifactorial Traits Multifactorial traits are determined by multiple genetic and environmental factors.

The Inheritance of Complex Traits

Four Basic Types Of Measurement: Categorizing –Nominal Ranking –Ordinal Determination of the size interval –Interval Determination of the size of ratios.

Quantitative Genetics Theoretical justification Estimation of heritability –Family studies –Response to selection –Inbred strain comparisons Quantitative.

Lecture 5 Artificial Selection R = h 2 S. Applications of Artificial Selection Applications in agriculture and forestry Creation of model systems of human.

Quantitative Genetics

Chapter 5 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning Chapter 5 Complex Patterns of Inheritance.

BIOE 109 Summer 2009 Lecture 7- Part II Selection on quantitative characters.

NORMAL DISTRIBUTIONS OF PHENOTYPES Mice Fruit Flies In:Introduction to Quantitative Genetics Falconer & Mackay 1996.

Quantitative Genetics

Review Session Monday, November 8 Shantz 242 E (the usual place) 5:00-7:00 PM I’ll answer questions on my material, then Chad will answer questions on.

ConceptS and Connections

Breeding and Genetics 101.

4 Quantitative Inheritance in Plant Breeding

Chapter 5 Characterizing Genetic Diversity: Quantitative Variation Quantitative (metric or polygenic) characters of Most concern to conservation biology.

© 2006 Jones and Bartlett Publishers Chapter 15Complex Inheritance 15.1quantitative traits 15.2gene/environment interactions 15.3artificial selection.

Genetics of Quantitative Traits. Quantitative Trait Any trait that demonstrates a range of phenotypes that can be quantified Height Weight Coloration.

Trait evolution Up until now, we focused on microevolution – the forces that change allele and genotype frequencies in a population This portion of the.

Quantitative Genetics. Continuous phenotypic variation within populations- not discrete characters Phenotypic variation due to both genetic and environmental.

Quantitative Genetics

Lecture 24: Quantitative Traits IV Date: 11/14/02  Sources of genetic variation additive dominance epistatic.

Lecture 21: Quantitative Traits I Date: 11/05/02  Review: covariance, regression, etc  Introduction to quantitative genetics.

Genetic Variation There are two main sources of genetic variation:

Chapter 22 - Quantitative genetics: Traits with a continuous distribution of phenotypes are called continuous traits (e.g., height, weight, growth rate,

NORMAL DISTRIBUTIONS OF PHENOTYPES Mice Fruit Flies In:Introduction to Quantitative Genetics Falconer & Mackay 1996.

IV. Variation in Quantitative Traits A. Quantitative Effects.

STT2073 Plant Breeding and Improvement. Quality vs Quantity Quality: Appearance of fruit/plant/seed – size, colour – flavour, taste, texture – shelflife.

Active Lecture PowerPoint ® Presentation for Essentials of Genetics Seventh Edition Klug, Cummings, Spencer, Palladino Copyright © 2010 Pearson Education,

Quantitative Genetics

Section1: Genetic Variation

NORMAL DISTRIBUTIONS OF PHENOTYPES

Bio 508: Evolution Robert Page Slides Courtesy of Dr. Voss

Evolution by Natural Selection as a Syllogism

Genotypic value is not transferred from parent to

NORMAL DISTRIBUTIONS OF PHENOTYPES

Genetics: Analysis and Principles

Quantitative and Behavior Genetics

Quantitative genetics

Quantitative Variation

Quantitative genetics

Statistical Tools in Quantitative Genetics

Spring 2009: Section 5 – Lecture 1

Genotypic value is not transferred from parent to

The Genetic Basis of Complex Inheritance

Bellringer Imagine that you are in charge of a goat ranch. The cost of fencing is high, so you must implement a breeding program that will produce shorter-legged.

15 The Genetic Basis of Complex Inheritance

Genetics of qualitative and quantitative phenotypes

Section1: Genetic Variation

Complex Traits Qualitative traits. Discrete phenotypes with direct Mendelian relationship to genotype. e.g. black or white, tall or short, sick or healthy.

Pak Sham & Shaun Purcell Twin Workshop, March 2002

CH22 Quantitative Genetics

Alternative hypotheses (i. e

Lecture 5 Artificial Selection

Pi = Gi + Ei Pi = pi - p Gi = gi - g Ei = ei - e _ _ _ Phenotype

Statistical Tools in Quantitative Genetics

Genotypic value is not transferred from parent to

Chapter 7 Beyond alleles: Quantitative Genetics

Heritability h2 = VA/Vp Proportion of total phenotypic variance attributed to variation in breeding values. Expresses the extent to which genes are transmitted.

Genetics of Quantitative Traits

Heritability h2 = VA/Vp Proportion of total phenotypic variance attributed to variation in breeding values. Expresses the extent to which genes are transmitted.

Polygenic Inheritance

Presentation transcript:

24.1 Quantitative Characteristics Vary Continuously and Many Are Influenced by Alleles at Multiple Loci The Relationship Between Genotype and Phenotype For continuous characteristics: several different genotypes produce same phenotype.

Types of Quantitative Characteristics Meristic characteristics Determined by multiple genetic and environmental factors, and can be measured in whole numbers. Animal litter size. Threshold characteristics Measured by presence or absence Susceptibility to disease

Types of Quantitative Characteristics Polygenic inheritance Refers to quantitative characteristics controlled by cumulative effects of many genes. Each character still follows Mendel’s rules. Kernel color in wheat.

Determining Gene Number For a Polygenic Characteristic (1/4) n = number of individuals in the F2 progeny. N = gene number.

24.2 Statistical Methods Are Required for Analyzing Quantitative Characteristics Distribution Frequency distribution Normal distribution: a symmetrical (bell- shaped) curve. Samples and populations Population: group of interested individuals Sample: small collection of individuals from the ppulation.

24.2 Statistical Methods Are Required for Analyzing Quantitative Characteristics The mean: the average The Variation and Standard Deviation Variance: the variability of a group of measurements Standard deviation: the square root of the variance.

Correlation Correlation: when two characteristics are correlated, a change in one characteristic is likely to be associated with a change in the other.

Correlation Correlation coefficient: measures the strength of their association Correlation doesn’t imply a cause-and-effect relation. It simply means that a change in a variable is associated with a proportional change in the other variable.

Regression Regression: Predicting the value of one variable, if the value of the other is given. Regression coefficient: represents the slope of the regression line, indicating how much one value changes on average per increase in the value of another varible.

Concept Check 3 In Lubbock, Texas, rainfall and temperature exhibit a significant correlation of Which conclusion is correct? a.There is usually more rainfall when the temperature is high. b.There is usually more rainfall when the temperature is low. c.Rainfall is equally likely when the temperature is high or low.

Concept Check 3 In Lubbock, Texas, rainfall and temperature exhibit a significant correlation of Which conclusion is correct? a.There is usually more rainfall when the temperature is high. b.There is usually more rainfall when the temperature is low. c.Rainfall is equally likely when the temperature is high or low.

24.3 Heritability Is Used to Estimate the Proportion of Variation in a Trait That Is Genetic Heritability: The proportion of the total phenotypic variation that is due to genetic difference.

Heritability Phenotypic variation : Vp Genetic variance: Vg Va: additive genetic variance Vi: genic interaction variance Vd: dominance gentic variance

Heritability Phenotypic variation : Vp Genetic variance: Vg Environmental variance: Ve Genetic-Environmental Interaction Vge Vp = Vg + Ve + Vge Vp = Va + Vd + Vi + Ve + Vge

Heritability Broad-Sense Heritability H 2 = Vg/Vp If H 2 = 0, then none of the phenotypic variance is caused by genetic variance. If H 2 = 1, then the phenotypic variance is 100% caused by genetic variance.

Locating Genes That Affect Quantitative Characteristics Mapping QTLs

24.4 Genetically Variable Traits Change in Response to Selection Response to selection: the extent to which a characteristic subjected to selection changes in one generation. Artificial selection: Selection by promoting the reproduction of organisms with traits perceived as desirable.