Exam 1 Lecs - 3 Flashcards
population genetics is study of … of populations, including … and … in genotype and phenotype frequency in responses to the processes of …, …, etc
genetic composition; distributions; changes; natural selection; drift
… = population of gametes
gene pool
Gene frequency = …
allele frequency
P for ….
Q for …
R for …
homozygous dominant;
heterozygous;
homozygous recessive
A = p = …
a = q = …
P + R + Q = …
p + q = …
P + 1/2Q;
R + 1/2Q;
1;
1;
the following can change the gene pool: ... ... ... ... etc
nonrandom mating;
migration;
mutation;
drift;
migration is always from the perspective of individuals …
entering the population
conditions in which there is no evolution: no ... ... no ... no ... ... population such that there's no ...
selection; random mating; mutation; gene flow; infinitely large; drift
If there’s no evolution, frequencies …
… - used to determine expected genotype frequencies if the population isn’t evolving
stay constant;
Hardy Weinberg;
In the case of no evolution, the genotypes represent a …
Hardy Weinberg is important historically bc it indicates that there’s no tendency for … to …
random sample of gametes;
the dominant allele; increase in frequency
an elementary population genetics model has 4 main steps: ... rule ... ratios add ... of each ... any selection by ...
mating;
mendelian;
frequencies; genotype;
differential survival
the simplest model of selection is for … at …
one favored allele;
one locus
chance of survival varies from … - …
represents …
for non-favored genotype: …
for favored genotype: …
0; 1;
relative fitness;
1-s;
1
chance of survival:
s is the … - proportion of individuals with that particular genotype that …, chance of …
selection coefficient;
died;
dying
hardy equation adjusted for differential survival between birth and adults:
…
if is is 0 –> …
p^2 + 2pq + q^2(1-s);
hardy weinberg equilibrium
…, representing selection, between birth and adulthood
differential survival
can’t use a term like directional selection when dealing with …, rather than …, traits
categorical;
continuous
when heterozygote is fitter than either homozygote: selection can maintain a ... Genotype AA - fitness: 1 -s Aa: fitness = ... aa: fitness = ... example of this is ...
polymorphism;
1;
1 - t;
sickle cell
when heterozygote is fitter than either homozygote:
… : … : ….
p^2(1-s): 2pq: q^2(1-t)
Even with heterozygous advantage, frequency of hetero … over several generations; however, it remains … than predicted frequency with Hardy
decreases; higher
to eliminate an allele from a population, … must be lower as well as the …
heterozygous fitness;
homozygote
…: no selection on the population
- in a very large population with no selection, will …
- in a small population, … is observed –> … shift over generations
selective neutrality;
remain in hardy;
drift;
genotype frequencies
selective neutrality
in a small population, drift is observed –> genotype frequencies shift over generations:
in very small populations, … shift randomly as well
allele frequencies
extreme case of founder effect: …
founder effect totally changes … at …
single fertilized female;
allele frequency; random
founder effect totally changes allele frequency at random:
- no …
- founding individuals are not representative of the …
selection;
entire original population
founder effect totally changes allele frequency at random:
can determine if the alleles are present/not in the population by calculating the chance of … (chance that all the individuals in the founding population have the …)
= …
homozygosity;
same alleles;
(p^2)^N + (q^2)^N
founder effect totally changes allele frequency at random:
- can have some alleles being … from one generation to the next with a founder effect
fixed
Founder events:
Afrikaner ethnicity - … people colonized …, descended from one shipload of immigrants
Dutch;
South Africa
Afrikaner ethnicity - Dutch people colonized South Africa
- carried rare alleles, including that for …
- in a normal population this allele is in low frequency
- in this area, frequency of this allele is … due to the founder event that occurred –> most cases of the disease in the modern population can be traced back to …
Thus, with founder events you can have, by random, an increased frequency of an allele that doesn’t …
Huntington’s disease;
higher than expected;
a single Dutch man;
increase fitness
One gene can be … by random drift:
- if the population remains small for several generations, one allele can become …
- frequency of a gene in a small population is as likely to … as to … since its random
substituted for another;
fixed;
decrease;
increase
one gene can be substituted for another by random drift:
- frequency of a gene in a small population is as likely to decrease as to increase since its random - thus, possible for a gene to be carried up to much … frequencies, including …(…) –> … in population
higher frequencies;
1;
fixing;
losing variation
balance between population size and …
- with a small population over enough time, you’ll have … and/or … of an allele - in all cases
… influences this as well
number of generations;
fixation;
loss;
initial frequency
over time with drift, you … bc you’re increasing the frequency of one of the alleles
maximum heterozygosity is when frequency of p and q are …
decrease heterozygosity;
equal;
expected heterozygosity in a population:
H = …
1 - (p^2 + q^2)
