Exam 1 Lecs - 3 Flashcards by Gail I

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

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… = population of gametes

gene pool

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Gene frequency = …

allele frequency

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P for ….
Q for …
R for …

homozygous dominant;
heterozygous;
homozygous recessive

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A = p = …
a = q = …
P + R + Q = …
p + q = …

P + 1/2Q;
R + 1/2Q;
1;
1;

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the following can change the gene pool: 
... 
... 
... 
... 
etc

nonrandom mating;
migration;
mutation;
drift;

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migration is always from the perspective of individuals …

entering the population

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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

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If there’s no evolution, frequencies …

… - used to determine expected genotype frequencies if the population isn’t evolving

stay constant;

Hardy Weinberg;

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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

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an elementary population genetics model has 4 main steps:
... rule
... ratios
add ... of each ... 
any selection by ...

mating;
mendelian;
frequencies; genotype;
differential survival

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the simplest model of selection is for … at …

one favored allele;

one locus

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chance of survival varies from … - …
represents …

for non-favored genotype: …
for favored genotype: …

0; 1;
relative fitness;
1-s;
1

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chance of survival:

s is the … - proportion of individuals with that particular genotype that …, chance of …

selection coefficient;
died;
dying

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hardy equation adjusted for differential survival between birth and adults:
…
if is is 0 –> …

p^2 + 2pq + q^2(1-s);

hardy weinberg equilibrium

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…, 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)