Population Genetics

Question 0

“nothing in biology makes sense except in the light of evolution”

Answer 0

Theodosius Dobzhansky

Question 1

a geneticist codified the definition of evolution as genetics and the origin of species

Answer 1

thomas hunt morgan’s pupil

Question 2

study of genetic variation within species

Answer 2

pop genetics

Question 3

group of freely interbreeding individuals

• composed of local populations (Demes)
• sexually reproducing

Answer 3

population

Question 4

all alleles of every gene in pop

Answer 4

gene pool

Question 5

Mendel focused on observable traits

Answer 5

polymorphism

Question 6

variation in the genetic code of a pop

• > 1 allele
• SNPs (smallest unit of genetic polymorphism)
• 90% of genetic variation in humans

Answer 6

genetic polymorphism

Question 7

no variation

Answer 7

monomorphism

Question 8

change in a single base pair

Answer 8

point mutation

Question 9

don’t alter RNA or polypeptides

Answer 9

silent mutations

Question 10

alter polypeptides

Answer 10

missense mutation

Question 11

change codon to stop codon

Answer 11

nonsense mutation

Question 12

change translation reading frame

Answer 12

frameshift mutations

Question 13

“random” chance (genetic drift)

-selection

Answer 13

ultimate: causes of genetic variation

Question 14

proximate-causes of genetic variation

Answer 14

mutations

Question 15

american scientists mainly discounted selection

-english scientists found several examples of power of selection

Answer 15

atlantic drift

Question 16

early geneticists were trying to disprove darwin’s theory of evolution via natural selection

Answer 16

neutral pop genetics

Question 17

proportion of gene pool that is a particular allele

Answer 17

allele freq.

Question 18

-proportion of individuals in a pop with a particular genotype

Answer 18

genotype freq.

Question 19

hardy-weinberg equation

Answer 19

p^2 + 2pq + q^2 =1

Question 20

p=
q=
p^2=
q^2=
2pq=

Answer 20

freq of an allele
freq of other allele
freq of homozygotes for first allele
freq of homozygotes for second allele
freq of heterozygotes

Question 21

when allele and genotype freq match expectations, pop is not changing
-evolutionary stasis

Answer 21

hardy weinberg equilibrium

Question 22

semi-random generation of NEW alleles

-neutral, beneficial, or deleterious

Answer 22

mutation

Question 23

mechanisms altering existing genetic variation

Answer 23

genetic drift
migration
selection
non-random mating

Question 24

___________ _________ more likely than beneficial mutations

Answer 24

deleterious mutations

Question 25

number of new mutations per generation per gene or DNA segment

Answer 25

mutation rate

Question 26

random fluctuations in allele freq. - no selection - random mating

Answer 26

genetic drift

Question 27

discovery of genetic drift

Answer 27

seawall wright

Question 28

typically leads to loss of allele 0% or allele fixation 100%

Answer 28

genetic drift

Question 29

genetic drift is affected by

Answer 29

pop size initial allele freq # generations

Question 30

probability that a new mutation will be fixed

Answer 30

``` 1/2N= probability of fixation= initial freq N= pop size ```

Question 31

if fixation of new allele does occur, how long does it take? | assumptions?

Answer 31

4N generations on average | -constant pop size, no selection, random mating

Question 32

genetic drift can lead to the fixation of ______,______, or ________ alleles

Answer 32

deleterious, neutral, or beneficial

Question 33

population ___________ -contraction of a pop -genetic drift becomes a strong force "tears of the cheetah" 10-12,000 years ago, a ________ wiped out most genetic diversity

Answer 33

bottleneck

Question 34

small # of individuals colonize new area | -envision the colonization of deserted island

Answer 34

founder effect

Question 35

migration between populations promotes

Answer 35

higher genetic diversity

Question 36

due to migrants that successfully breed and alleles are successfully propagated -tends to homogenize allele freq

Answer 36

gene flow

Question 37

all freq can be used to estimate ________ _____

Answer 37

migration rates

Question 38

________ affects allele freq | -affects the fitness conferred by alleles and genotypes

Answer 38

selection

Question 39

the likelihood that a genotype will contribute to the gene pool of the next generation

Answer 39

fitness

Question 40

selections acts on both new and existing _________ _______

Answer 40

genetic variation

Question 41

our world is constantly changing, thus ...

Answer 41

the effects of selection vary through time

Question 42

alleles and genotypes that confer higher fitness can ________ alleles and genotypes that are deleterious _______

Answer 42

increase | decrease

Question 43

fittest genotype, aa has fitness value of 1 - Aa, on avg contributes 20% _____ offspring to the next generation - AA contributes 90% _____ offspring

Answer 43

``` darwinian fitness (W) fewer ```

Question 44

favors traits at one extreme of phenotypic distribution | -can drive fixation

Answer 44

directional selection

Question 45

under directional selection, the freq of the selected allele ________ over several generations

Answer 45

increases

Question 46

- intermediate phenotypes are the most fit | - tends to decrease genetic diversity

Answer 46

stabilizing selection

Question 47

traits at 2 or more extremes of phenotypic space are most fit

Answer 47

disruptive selection

Question 48

when divergent phenotypes or alleles are equally fit in a homozygous environment -heterozygote advantage (sickle cell disease)

Answer 48

balancing selection

Question 49

neg freq dependent selection | -fitness decreases as allele or phenotype freq increases

Answer 49

balancing selection

Question 50

positive (similar phenotypes mate more freq) | neg (opposites attract)

Answer 50

assortative mating

Question 51

mating btween closely related individuals | -decreases genetic diversity

Answer 51

inbredding

Question 52

mating btween unrelated individuals

Answer 52

outbreeding

Question 53

exon shuffling, horizontal gene transfer, gene introgression, species hybrids

Answer 53

sources of genetic variation

Question 54

results in novel genes and proteins

Answer 54

exon shuffling

Question 55

several causes of exon shuffling..

Answer 55

``` double crossovers duplications transposable elements (jumping genes) ```

Question 56

transposable elements - DNA seq that changes position in the _________ - can make up ______ _______ of genome

Answer 56

genome | large portion

Question 57

organism incorporates genetic material of another that is not the parent 20-30% of prok genetic variation

Answer 57

horizontal gene transfer

Question 58

gene flow btween species | -multiple step process: 1,2,3

Answer 58

genetic introgression 1. produce viable hybrids 2. hybrids backcross (reproduction with non hybrids) 3. backcrossing continues

Question 59

__________ btween two species can create new species if they are in euk, most typical plants

Answer 59

hybridization