Exam 2 Flashcards
Genetic Drift
the process of random fluctuation in allele frequencies due to sampling effects in finite populations
3 general consequences of genetic drift
- allele frequencies fluctuate over time even in absence of natural selection
- some alleles fixed, others lost, and heterzygosity decreases
- separate populations diverge in their allele frequencies and in terms of which alleles are present
the rate of allele fluctuation due to genetic drift depends on
population size
selectively neutral
no fitness difference between alleles so natural selection doesn’t act on them
every finite population will eventually
reach fixation for 1 allele
is it certain which allele will become fixed as a result of genetic drift? why or why not?
no because genetic drift is random
what is the probability that an allele at a neutral loci will become fixed?
equal to the frequency of the allele in the population
how does genetic drift affect heterozygosity?
it reduces it
genetic drift ________ variation within a population but _______ it between populations
decreases, increases
law of large numbers
as size of a random sample increases, the observed frequencies will be very close to the expected
observed heterozygosity equation
Ho= 1 - freq of homozygotes
expected heterozygosity equation
He= 1 - summation pi^2
heterozygosity at ___ generation equation
Ht = (1- 1/2N)^t Ho
effective population size, Ne
relates any real, messy population to an ideal Wright-Fisher population
census population size
number od individuals in the population
