Population genetics in companion animals Flashcards
What are the genetic forces that may affect a population (e.g. a certain breed)?
- Genetic drift (and inbreeding)
- Selection
- Migration (out-crossing)
- Mutation (not a big factor)
What is genetic drift and what influences its effect?
It is the change in allelle frequences in a population. Small pop sizes/bottlenecks will see larger fluctuations in allele frequency. This may even lead to the loss of some allelles.
What is coancestry?
The chance of related animals sharing alleles from a common ancestor.
What is the inbreeding coefficient?
The probability that 2 copies of a gene are the same, it gives the probability of the same allelle being passed on.
What is inbreeding depression?
Compromise of a genetic lineage to survive and reproduce. One of the first things to be affected by inbreeding is fertility!
What is the rate of inbreeding?
The change in average inbreeding coefficient over time.
What is the effective population size?
The number of breeding individuals in a random mating population that would have the same rate of inbreeding seen in the real population. (Ne = 1/2xrate of inbreeding)
What are possible solutions to reducing inbreeding?
- Minimise coancestry of matings
- Increase numbers of animals used for mating
- Equalise use of males and females
- Optimise genetic contributions (choosing distantly related animals with quantitative methods)
- Out-crossing
What information can be used to analyse complex diseases?
Phenotypic data
Pedigree information
Genetic variation
Heritability
Genetic correlations between traits
EBVs.
What is heritability?
The proportion of phenotypic variation made up of variation in the genes.
How do EBVs differ to heritability values?
EBVs take into account the phenotypes of related individuals so give a good indicator of the health of an indivisuals genetics. (See lecture slides for example)
How does a GBV differ to an EBV?
EBV uses pedigree information in its analysis whereas GBVs use DNA information.
How can selection intensity be increased?
By changing the threshold for selection based on EBVs etc. So that change comes about more quickly.
