1 Domestication, breeding and genetics

Question 1

According to Galton (1865), what are three key conditions that make an animal species suitable for domestication?

Answer 1

Hardy, comfortable with humans, and useful to humans.

Question 2

Name two modern techniques used in genetic improvement of livestock.

Answer 2

Artificial insemination (AI) and embryo transfer.

Question 3

What is a “breed” in the context of domestic animals?

Answer 3

A group of domestic animals with a homogeneous appearance, behavior, and other traits that distinguish it from others of the same species.

Question 4

What is the term for the physical location of a gene on a chromosome?

Answer 4

Locus

Question 5

What do you call two identical alleles at the same locus (e.g., AA or aa)?

Answer 5

Homozygote

Question 6

What type of gene action is demonstrated when a heterozygote shows a phenotype intermediate between the two homozygotes?

Answer 6

Additive gene action (or co-dominance)

Question 7

Which type of inheritance results in a heterozygote performing better than either homozygote?

Answer 7

Overdominance (e.g., Inverdale allele in sheep)

Question 8

What is the difference between sex-linked and sex-limited genes?

Answer 8

Sex-linked: Genes located on sex chromosomes

Sex-limited: Traits expressed in only one sex (e.g., milk production in cows)

Question 9

What happens when a sheep carries two copies of the Inverdale (FecX) allele?

Answer 9

The ewe is infertile (FecX/FecX = ❌)

Question 10

What type of mutation is a single base change in the DNA sequence?

Answer 10

SNP (Single Nucleotide Polymorphism)

Question 11

What is genomic imprinting, and which parent’s allele is expressed in Callipyge sheep?

Answer 11

Genomic imprinting is when only one parental allele is expressed; in Callipyge sheep, the paternal allele causes muscle hypertrophy.

Question 12

What does the Hardy-Weinberg equation
𝑝2+2pq+q 2=1 predict in a population?

Answer 12

The expected genotype frequencies under stable conditions with no evolutionary forces.

Question 13

What is the main difference between qualitative and quantitative traits?

Answer 13

Qualitative traits are controlled by one or a few genes (e.g., coat color).

Quantitative traits are polygenic and influenced by the environment (e.g., milk production).

Question 14

What does a Punnett square help you determine in livestock breeding?

Answer 14

The possible genotypes and phenotypes of offspring based on parental alleles.

Question 15

Name one genetic mechanism that creates diversity in offspring during sexual reproduction.

Answer 15

Recombination (or segregation)