Genetic Variation III Flashcards
How is inbreeding measured?
Via a coefficient of inbreeding ‘F’ which ranges from 0 to 1. If 0 this means that mating occurs randomly in large population.
Value of 1 means all alleles are identical by descent.
How are inbreeding coefficients measured?
By pedigree analysis or from reduction of heterozygosity in population.
What happens in the case of inbreeding?
Repeated generations of inbreeding will eventually split a heterozygous population into a series of completely homozygous lines.
What is the correlation between F and IQ?
for every 10% increase in F the mean Iq of children dropped 6 points.
Mortality increases with close inbreeding - children of 1st cousins have 40% increase in mortality over that in unrelated individuals.
How many genes are shared between 1st degree, 2nd degree, and 3rd degree relatives?
1st degree: 1/2
2nd degree: 1/4
3rd degree: 1/8
What is the coefficient of relationship?
Proportion of alleles shared by 2 persons as a result of common genetic descent from one or more recent common ancestors (R)
What is the coefficient of inbreeding?
Probability that a homozygote has identical alleles at a locus as a result of common genetic descent from a recent ancestor.
What is the coeffecient of relationship and coefficient of inbreeding in children of parents that are 1st cousins?
If parents are 1st cousins -> R = 1/8 and F = 1/16
How are the coefficient of relationship and inbreeding related?
Inbreeding coefficient is always half that of inbreeding.
What is a consanguineous union?
A union between people that are biologically related as second cousins (F>= 0.0156) or closer.
What processes are affecting the frequency of alleles in the next generation?
Selection
Mutation
Migration
Mating pattern
Random genetic drift
How is the fitness of an individual influenced by genotype?
Different genotypes have different rates of survival and reproduction. This means that they have different fitness.
What happens to genetic frequency of characters that are more successful at survival and reproduction?
They will increase and be selected for.
What is a selective sweep?
in genetics, a selective sweep is the reduction or elimination of variation among the nucleotides near a mutation in DNA. It results from a beneficial allele’s having recently reached fixation due to strong positive natural selection.
What kind of positive selection does MHC undergo?
Strong positive selection to maximise genetic variation. Individuals that are heterozygous are thus better protected from pathogens.
