The rest Flashcards
(9 cards)
What’s the equation for the coefficient of inbreeding?
F = ∑ N (1/2)n, where N is the number of loops and n is the number of ancestors in each loop; from the child (not counted) to its parents, and back to the shared ancestor, and back down to the other
parent. Thus, for brother-sister mating:
F = 2 x (1/2)3 = 2 x 1/8 = 1/4
What is inbreeding depression?
Inbreeding is associated with a decrease in fitness termed inbreeding depression. This is caused the increase in homozygosity of rare deleterious alleles.
Give an example of inbreeding in humans.
King Alfonso XII of spain had 8 ancestors where there should have been 128. Finland which has 33 unique genetic diseases such as Variant Late Infantile neuronal ceroid lipofuscinoses VLINCL, which traces back to a single male in a pedigree.
What are runs of homozygosity?
Runs of homozygosity are continuous lengths of homozygous genotypes that are present in an individual due to parents passing on identical haplotypes to their offspring. Runs of homozygosity
are more common in people living on islands of Croatia than the mainland Croatia.
Give a human example of the founder effect
Connexin 26 mutation causing high rates of deafness in Himalayan population.
How is genetic drift quantified?
We can quantify the sampling standard deviation (ie the strength of drift) using the formula √pq/2N (p and q are allele frequencies, N is population size). This means the larger the sample size, the smaller the sampling variance. Similarly, the closer p and q is to 0.5, the smaller the sampling variance.
give examples of positive assortative mating
blue tits who tend to mate with partners of similar brightness. Humans to show positive assortative mating for traits such as height, weight, collar size, skin colour and one of the strongest predictors of all is educational level.
give examples of negative assortative mating
Wolves more likely to mate with individuals of a different coat colour. Similarly, in white
throated sparrows opposite morphs (tan and white) always tend to mate.
How is mutation rate in maize tested?
triploid endosperm every cob a family of seeds; recessive “white” allele, c. Cross cc (female) x CC (male) -> Ccc (coloured). Any mutation in the C allele will lead to a single white seed. Allows mutation rate to be calculated which varies massively across the maize genome.
