Module 14

Question 1

Quantitative Genetics

Answer 1

The study of quantitative traits, which can be anatomical, physiological, behavioral, and disease-related

Question 2

Frequency Distribution

Answer 2

A normal distribution of quantitative traits following a bell-curve model

Question 3

Polygenic Inheritance

Answer 3

Influenced by two or more genes, exhibits a continuum of phenotypic variation

Question 4

Quantitative Trait Loci (QTL)

Answer 4

Location on chromosomes harboring one or more genes affecting the outcome of a quantitative trait, identified by genetic mapping

Question 5

The more ____ and ____ variability of a quantitative trait, the greater phenotypic variance will be presented

Answer 5

genetic and environmental

Question 6

QTLs are mapped by:

Answer 6

• Taking two highly inbred strains of diploid species
• Producing heterozygous F1 offspring
• Then backcrossing the F1 to the parent generation to produce the F2 offspring
• Identify which genes are associated with a specific phenotype

Question 7

Heritability

Answer 7

The amount of phenotypic variation within a group of individuals due to genetic variation

Can be either broad or narrow sense

Question 8

Broad Sense Heritability

Answer 8

Takes into account different types of genetic variation possibly affecting phenotype

Question 9

Narrow Sense Heritability

Answer 9

Heritability of a trait based on additive (genetic) allelic effects

Question 10

Genotype-Environment Interaction

Answer 10

Certain environmental factors can positively influence some genotypes (ex. plants and mineral content of soil)

Question 11

Genotype-Environment Association

Answer 11

Certain genotypes can be preferentially found in specific environments (ex. studied in genetically identical twins)

Question 12

Selective Breeding

Answer 12

Modification of phenotypes in plant and animal species of economic importance by human intervention (artificial selection)

Question 13

Selection Limit

Answer 13

Selective breeding for certain phenotypes plateaus once an individual becomes monomorphic for all relevant alleles (ex. corn oil content)

Question 14

Heterosis

Answer 14

When two inbred strains are crossed to each other, offspring are more vigorous than either parent (“hybrid vigor”)

Question 15

Dominance Hypothesis

Answer 15

Proposed by Davenport, effects of dominant alleles explain the favorable heterozygote outcome

Question 16

Overdominance Hypothesis

Answer 16

Proposed by Shull and East, resulting hybrids are heterozygous for one or more genes displaying overdominance