exam 3 ppt 7 Flashcards
definition of gene pool
all the alleles present in all individuals in a species
what does genetic variation in a population refer to?
refers to multiple alleles within a gene pool
in HWE formula, what does pq represent?
represents heterozygotes
is “populations must select their mates” an assumption of HWE?
no
what genotype is represented by p^2?
homozygous dominant
what genotype is represented by 2pq?
heterozygous
what genotype is represented by q^2?
homozygous recessive
what does HWE describe?
HWE describes situations in which allele and genotype frequencies do not change
5 assumptions in HWE
1) individuals must mate at random, 2) no natural selection, 3) no genetic drift, 4) no gene flow, 5) no mutation
what does the assumption mean in HWE that there is no natural selection?
there can be no differences in the survival and reproductive success of individuals
what does the assumption mean in HWE that there is no genetic drift?
the population must be sufficiently large to prevent sampling errors
what does the assumption mean in HWE that there is no gene flow?
populations must not be added to or subtracted from by migration
what does the assumption mean in HWE that there is no mutation?
no new alleles can be introduced into the gene pool
if a population is NOT in HWE, this tells us…
a population is evolving
what is HWE a starting point for?
a starting point to determine if the population is: undergoing natural selection, migrating, experiencing genetic drift, experiencing new mutations, not mating randomly
what happens to allele frequencies if the population is not evolving?
allele frequencies stay the same from one generation to the next
if you are not told to assume HWE, can you use p^2 + 2pq + q^2 =1 to work backwards?
no
how do we know if differences are different enough to cause evolution?
using chi square test
definition of chi squared
test of goodness-of-fit of null hypothesis that observed and expected frequencies are the same
degrees of freedom =
n-1, where n is the number of possible dats points
equation for chi square test
(observed - expected)^2 / expected
definition of p-values
how likely it is due to random chance (0.05 and less= statistically significant)
P > 0.05=
observed and expected values are not significantly different
