VARIATION Flashcards
1
Q
VARIATION
A
- differences
- responsible for selection
- key to improvement of a breed/herd
2
Q
TYPES OF VARIATION
A
- phenotypic
- genetic
3
Q
PHENOTYPIC VARIATION
A
- actual variation we observe per trait
4
Q
PHENOTYPE
A
- what we measure or touch
- influenced by genotype and environmental factors
- i.e., growth rate; number of pigs in a litter
5
Q
GENOTYPE
A
- genes that make up animals
6
Q
GENETIC VARIATION
A
- variation controlled by genes
- attributed to different gene action
7
Q
DETERMINANT OF POTENTIAL AMOUNT OF GENETIC IMPROVEMENT
A
- genes passed on from parents to offspring
- amount of genetic variation
8
Q
ALLELES
A
- different forms of the same gene
9
Q
QUALITATIVE/CATEGORICAL TRAITS
A
- controlled by a single gene
- easily fixed in a population
- i.e., polled gene; coat color
10
Q
QUANTITATIVE TRAITS
A
- most economically important traits
- measure on continuous scale
- controlled by many genes
- impossible to eliminate from a population
- i.e., growth rate
11
Q
TYPES OF GENE ACTION
A
- additive
- dominance
- epistasis
12
Q
ADDITIVE GENE ACTION
A
- summing up of effects of alleles of a gene and of effects of genes at different chromosome locations
- influenced by selection programs
- contributes most to genetic variation
13
Q
DOMINANCE GENE ACTION
A
- one allele dominating another at the same locus
- difficult to take advantage of in breeding programs
14
Q
EPISTATIC GENE ACTION
A
- interaction of different genes
- enhance or cancel out each other
15
Q
HERITABILITY
A
- ratio of genetic variation to phenotypic variation
