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Evolutionary Genetics > Lectures 1-10 > Flashcards

Lectures 1-10 Flashcards

(80 cards)

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1
Q

two controversial ideas of evolution

A

concept of a changing universe, a phenomenon with no purpose

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2
Q

early ideas about evolution

A

earth formed according to the laws of physics and chemistry

life emerged as distinct types (not true)

paleontology provided evidence that life changed

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3
Q

fossils

A

fill in the gaps of extinct forms we don’t see today

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4
Q

co-discoverers f natural selection

A

Charles Darwin and Alfred Russell Wallace

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5
Q

darwin

A

voyage on the H.M.S Beagle (1831-1836)

layed the foundation for plant and animal studies

wrote 25 books

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6
Q

importance of islands in evolution

A

their isolation means many of the living organisms found on islands are unique to them (prevents migration)

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7
Q

preservation of favored races in the struggle for life

A

all organisms have descended with modification from common ancestors

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8
Q

founder of taxonomy

A

carl linnaeus

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9
Q

hierarchical system of classification in order from largest to smallest

A

Kingdom-Phyla-class-order-family-genera-species

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10
Q

taxa at the tips of phylogenetic trees

A

are all alive and have been evolving for the same amount of time

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11
Q

Monophyletic group

A

includes an ancestor and all of its descendants (the type we want)

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12
Q

paraphyletic group

A

includes ancestor and some descendants

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13
Q

polyphyletic group

A

includes two convergent descendants bot not their common ancestor

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14
Q

phylogenetic trees

A

hypotheses about relationships between taxa

can be done at any taxonomic level

are constantly reevaluated

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15
Q

homoplasy

A

common problem (only 4 character states so the probability of separate lineages independently arriving at the same character can be high)

when species have the same mutation but were independent events

convergent evolution

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16
Q

significance of genes that differ in rate of evolution

A

slowly evovlving genes are useful for distantly related species

rapid evolving genes are useful for closely related lineages

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17
Q

parsimony

A

simplest explanation is most likely the right one (use when making a tree)

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18
Q

using traits (DNA) in a tree

A

traits that all species share are not useful for inferring phylogenies

traits that only one species has are also not useful

most useful characters are shared derived traits

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19
Q

homology

A

traits that are shared because they are inherited from a common ancestor (homologous)

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20
Q

synapomorphies

A

shared derived traits that evolves in the common ancestor

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21
Q

sources of genetic variation

A

mutation (ultimate source), recombination, gene flow, and hybridization

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22
Q

somatic mutations

A

affect cells in the body of an organism: not heritable

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23
Q

germ-line mutations

A

affects gamettes: heritable and relevant to evolution

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24
Q

rates of mutations

A

depends on type of mutation, the organism and it varies among genes

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25
most common mutation
point
26
point mutation rate in humans
12 mutations/ billion base pairs 3.2 billion bp in haploid genome 36 mutations from each gam
27
most mutations are... because...
mildly bad genomes work very well, billions of years of evolutions more ways to mess things up than to fix them
28
possible gamete combinations in humans
8 million (2^23), meiosis generates variation (independent assortment)
29
where does majority of genetic variation in a populations come from
sexual reproduction
30
evolution
change in allele frequencies through time
31
hardy Weinberg equilibrium equations
q^2 + 2pq + p^2 = 1 p+q=1
32
predicting genotype frequencies, ie. what is the probability that a zygote will be AA
probability of the egg being A * probability of the sperm being A = probability of AA 0.6*0.6=0.36 (p^2)
33
p^2 + 2pq + q^2 = 1 means that
your math is correct not the the population is in HWE
34
5 Hardy-Weinberg equilibrium assumptions
no selection, no mutation, no migration, no chance events, and random mating
35
Hardy-Weinberg equilibrium principle
allele frequencies do not chnge between generations, single generationn of random mating establishes H-W proportions
35
given the number of individuals with each genotype or frequencies. and you are asked whether the population is in HWE
write out observed genotype frequencies use observed to calculate allele frequencies (p + 1/2 2pq, ect) calculate expected genotype frequencies using allele frequencies
36
p and q are
allele frequencies
37
p^2 , 2pq and q^2 are
genotype frequencies
38
2pq has a maximum value of ... when p = q = ...
0.5
39
alleles are lost more rapidly in ..
small populations
40
allele changes are less predictable in ..
small populations
41
properties of genetic drift
one allele will eventually be fixed, tends to remove genetic variation, direction of change can not be predicted and the probability that a particular allele will eventually be fixed is proportional to its frequency in the population
42
rare alleles are primarily found in
heterozygotes
43
drift causes ... but not ...
evolution but not adaptive evolution
44
fitness
the expected reproductive success of an individual with a particular phenotype
45
factors of fitness
survival to reproductive age, mating success and fecundity
46
relative fitness
fitness of a genotype standardized by comparison to other genotypes w calculate the relative fitness of a genotype by dividing it by the fitness of the most fit genotype on the population
47
relative frequency at reproduction is =
new Wa1a1/ bar W
48
natural selection is more powerful in ___ populations because _______ is weaker
large genetic drift
49
s
selection coefficient = fitness disadvantage to genotype Waa= 1-s
50
h
dominance coefficient = proportion of s applies to the hetero genotype WAa = 1 - hs
51
overdominance
heterozygote advantage maintains variation and both alleles
52
underdominance
heterozygote disadvantage removes variation
53
negative frequency dependent selection
an allele becomes lee fit as it becomes more common promotes genetic diversity allele dominance often go through cycles both alleles are maintained
54
positive frequency dependent selection
an allele becomes more fit as it becomes more common leads to unstable polymorphism difficult to study as soon as one allele becomes more common it goes to fixation
55
inbreeding
self fertilization, sib mating, etc. reduces heterozygosity
56
two types of inbreeding
disassortative mating and assortative mating
57
disassortative mating
genotypes that are different may mate one another more often than expected
58
assortative mating
genotypes that are similar may mate more often than expected
59
inbreeding can be eliminated with one ...
round of random mating
60
inbreeding coefficient
probability that two alleles are identical by descent
61
in each round of inbreeding heterozygosity is
reduced by half
62
inbreeding changes
genotypes not alleles/allele frequency (not a type of evolution)
63
F =
1- (Hobs/Hexp)
64
inbreeding depression
reduced vigor, longevity, fertility, etc. by exposing recessive alleles
65
difference between inbreeding and assortative mating
inbreeding acts on the whole genome simultaneously alternative mating, which only acts on the loci associated with the traits (both mate with preference for a genotype)
66
events required for gene flow
gene movement and gene establishment
67
gene movement
movement of individuals and movement of their gametes
68
gene establishment
survival and reproduction
69
direct methods for measuring gene flow
mark recapture in natural populations
70
indirect methods for measuring gene flow
molecular marker variation analyze differences in allele frequencies
71
genetically differentiated
when populations differ in allele frequencies
72
when two adjcent populations are genetically differentiated this tells us that
gene flow has not homogenized them
73
Fst
measurement of differentiation measures variation in allele frequencies among populations ranges from 0-1 compares the average expected heteroxygosity of individual subpopulations (S) to the total expected heterozygosity (T) if the subpopulations are combined = 1 - (Hs/Ht)
74
calculating Ht
calculate the mean of p calculate the mean of q Ht = 2(pmean)(qmean)
75
Fst = 1
most extreme subdivision
76
calculating Hs
calculate 2pq for each population mean (2pq)
77
gene flow balances with ____ causing populations to be ____
genetic drift differentiated
78
genetic drift VS genetic flow
population subdivision enhances the effects of drift (divergence in allele frequencies) gene flow counteracts subdivision by homogenizing allele frequencies (more similar among populations
79
population subdivision causes some level of ____ because ____
inbreeding it has a reduced mating pool and more alleles are identical by descent

Evolutionary Genetics (3 decks)

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