Lecture 11 Flashcards
in DNA fingerprinting, why do you need to look at a lot of loci to prove someone is guilty?
with only a few loci, it is possible that many people will have the same combination of alleles at the diff loci
with more loci, it is easier to find a match to just 1 person bc less likely that more than 1 person will have same combo
is inbreeding random? what does this mean about frequencies?
inbreeding is NON-RANDOM –> HW frequencies don’t apply
what phenomenon occurs in inbreeding?
alleles are IDENTICAL BY DESCENT
what does it mean for alleles to be identical by descent?
2 alleles at a locus that are copies of an allele found in an ancestor
what is the inbreeding coefficient, F?
overall probability that the 2 alleles inherited by an individual will be IBD
how do the numbers of homozygotes and heterozygotes change when there’s inbreeding vs random mating?
inbreeding makes MORE homozygotes and FEWER heterozygotes
do genotype or allele frequencies change in inbreeding (vs random breeding)?
only GENOTYPE frequencies change
what is inbreeding depression?
inbred individuals have reduced viability/survival
why does inbreeding depression occur?
deleterious conditions often require 2 copies of the mutation to reduce survival and inbreeding causes increased homozygosity
what are the 4 factors that influence allele frequencies? are they independent of each other?
- mutation
- migration
- genetic drift
- natural selection
is mutation a major force in influencing allele frequencies?
no, mutation rate is very low
what is the rate of mutations per base pair per generation?
10^-9 mutations/bp/generation
what is migration?
new alleles are introduced from a diff population
2 types of migration
- unidirectional
- bidirectional
describe unidirectional migration
similar to mutations, new alleles are introduced every generation
describe bidirectional migration
species becomes HOMOGENIZED and prevents populations in a species from diverging
what type of populations does genetic drift occur in?
small populations only!
what occurs in genetic drift?
slowly an allele is lost as small population is maintained
how does genetic drift affect genetic diversity?
genetic diversity is lost with genetic drift
if genetic drift and migration were occurring simultaneously, how would the population diverge compared to just genetic drift alone?
both genetic drift and migration –> migration would slow down the loss of alleles and population would diverge less quickly
genetic drift –> alleles would be lost and population would diverge quickly
