genetics 3: genetic decision making in animal breeding Flashcards
1
Q
what are the pressures involved when making a decision about animal breeding
A
- availability of information
- financial and physical resources
- current breeds in use
- local traditions
- market demand
- perosonal preferences
2
Q
what is the breeding pyramid
A
3
Q
why would we cross breeds
A
dramatic and rapid genetic change when there are large genetic differences
- esp if market need to change breed
- costly
- can only be acheived once
4
Q
what is the result of inbreeding
A
the ultimate result of inbreeding is terminal lack of vigour and probable extinction as the gene pool contracts, fertility decreases, abnormalities increase and mortality rates rise
5
Q
is inbreeding a logical breeding strategy
A
- related animals have more alleles in common than unrelated animals
- an individual with outstanding genetic merit is likely to have relatives with higher than average merit
- therefore it is logical to mate related individuals with the aim of increasing the frequency of favourable alleles
6
Q
what is the downside to inbreeding
A
- results in animals with more favourable alleles but also more unfavourable alleles
- known to decrease heterozygous genotypes and increase homozygous genotypes
- leads to serious genetic defects
- can lead to a decline in performance in traits associated with fitness
7
Q
what is inbreeding coefficient
A
- the level of inbreeding in an individual
- this is the probability that both alleles at a single locus are identical by descent
- an individual will always have a higher proportion of homozygous alleles than those identical by descent as not all homozygous genes will be identical by descent
8
Q
list strategies taken to avoud inbreeding
A
- deliberately choose less related individuas
- use more than one male from each selected full sib family
- use selected parents once only
- use factorial mating designs
