Population Genetics II: Genetic Drift Flashcards
genetic drift
a change in allele frequencies across generations due to random error in gamete sampling
binomial distribution
the discrete probability distribution of the # of successes in a sequence of N independent yes/no experiments, each of which yields success with probability p or failure with probability q
what does genetic drift lead to?
leads to the loss of genetic variation within a population
what is the amount of possible change in allele frequencies per generation proportional to?
population size
what is the probability of fixation of an allele equal to?
the initial frequency of the allele
is genetic drift more likely to remove low frequency alleles or high frequency alleles?
low frequency alleles
what does genetic drift create?
differences among populations
how to calculate the variance among populations increases across generations
var p(t) = p0q0 (1 - e^-t/2N)
key point of variance among populations increasing across generations
genetic diversity is lost within populations, while diversity between populations increases
Missouri Ozark Mts
- 8000-4000 years ago: Desert
- 4000-present: Savanna
- lizards live on rocky outcrops in the Savanna
- 1950s: fire supression
- result: populations small and isolated
does genetic drift change mean allele frequencies among populations?
no
does genetic drift raise or lower heterozygosity?
lower
equation: genetic drift lowers heterozygosity
Hg+1 = Hg [1 - 1/2N]
Hg
heterozygosity in the current population
Hg+1
heterozygosity in the next generation
