-ppt-

WELCOME TO AN SC 221Introduction to Animal Genetics

Lecture 1

Introduction to Animal Genetics

Three Sections of the Course

Qualitative Genetics

Three Sections of the Course

• Modes of Inheritance -- predict progeny phenotypic distribution based on parental genotypes

Qualitative Genetics

Population Genetics

Three Sections of the Course

• Modes of Inheritance -- predict progeny phenotypic distribution based on parental genotypes

• Gene and genotypic frequencies -- predict direction and magnitude of changes in a population

Quantitative Genetics

Three Sections of the Course

• Assessing genetic merit -- describe traits with statistics to predict next record, genetic merit, response to selection

P = G + E

P = G + E

Phenotype: observed expression of a trait

P = G + E

Phenotype: observed expression of a trait

Genotype: composite of all genes that influence a trait

P = G + E

Phenotype: observed expression of a trait

Genotype: composite of all genes that influence a trait

Environment: all non-genetic factors that influence a trait

Types of Traits

Qualitative Quantitative

Types of Traits

Qualitative

• few loci

Quantitative

• many loci

Types of Traits

Qualitative

• few loci

• discrete phenotypes

Quantitative

• many loci

• measured phenotypes

Types of Traits

Qualitative

• few loci

• discrete phenotypes

• little or no effect of the environment

Quantitative

• many loci

• measured phenotypes

• environmental effect can be larger

PREDICT

OUTCOME

UNDERSTANDING GENETIC PRINCIPLES OF

INHERITANCE

What’s new in genetics?

What’s new in genetics?• gene mapping

• using maps to find genes

• sequenced human DNA

• gene therapy

• application to human well being and animal productivity/health

Horns

No Horns

Gene interactions:

Epistasis

Harlequin Double Merle