Genetics Flashcards
What is a mutation?
Mutations are changes in the DNA. A single
mutation can have a large effect, but ¡n many cases,
evolutionary change is based on the accumulation of
many mutations.
What is gene flow?
Gene flow is any movement of genes from one
population to another and is an important source of
genetic variation.
What are qualitative traits?
Qualitative traits are characterised by segregation in classical Mendelian ratios, purely genetic.
Eg. coat colour, absence of horns.
What are quantitative traits?
Quantitative traits also referred to as ‘continuous’ traits e.g. Growth rate or milk yield.
.These can be given a numerical value on a
scale and are what population genetics is
mostly involved with. Often polygenic
and depend upon environmental factors
(non-genetic or epigenetic mechanisms).
Define phenotype?
Phenotype = Genetic + Environmental
An observed category or measurable level of performance for a trait in an individual (P)
Define genotype?
The genetic make up of an individual (G)
What does heterosis (aka as hybrid vigour) mean?
Extra performance above above mid-parent mean.
What can be found out from sib testing?
What to breed from based on sibling performance.
What can be found out from progeny testing?
What to breed from based on the performance of an the particular animal’s offspring
What is a generation interval?
The average age of an animal when their offspring are born. Species Average L Poultry 7 months Pigs 9-12 months Sheep 12-24 months Cattle 24-36 months Human 19-30 years
What is the problem of inbreeding?
Inbreeding depression. The ultimate result of continued inbreeding is terminal lack of vigor and probable extinction as the gene pool contracts,
fertility decreases, abnormalities increase and mortality rates rise.
What is a simple definition of inbreeding?
The mating of related individuals. A more appropriate definition is “the mating of individuals more closely related than average for the population”
Define inbreeding depression?
Expression of unfavourable recessive alleles influencing polygenic traits. This can manifest in poor gene combinations that can significantly
decrease performance
What is the inbreeding co-efficient?
The level of inbreeding in an individual is
measured by the inbreeding coefficient
This is the PROBABILITY that both alleles at a
single locus are identical by descent
What methods can be employed to reduce inbreeding?
Deliberately choose less related individuals
Use selected parents once only
Use factorial mating designs
