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BIOS 230 > Exam One Prep > Flashcards

Exam One Prep Flashcards

1
Q

What is the difference between homologous and analogous structures?

A

Ancestry, homologous structures are structures that are shared from a shared ancestor whereas analogous structures are similar structures with no common ancestor.

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2
Q

microevolution

A

allele frequency changes within species over relatively short time

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3
Q

speciation

A

species lineages split to form new species

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4
Q

macroevolution

A

large evolutionary changes above species level, taking place over much longer periods of times

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5
Q

what are the 6 evidences for evolution

A
  1. fossils
  2. homology
  3. biogeography
  4. direct observation
  5. selective breeding
  6. vestigal traits
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6
Q

creationism

A

the belief that the universe and living organisms originate from specific acts of divine creation, as in the biblical account, rather than by natural processes such as evolution

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7
Q

fossil

A

any trace of an organism that lived in the past

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8
Q

transitional fossils

A

fossils that show intermediate states between and ancestral trait and that of their descendants

an example with would be an archaepteryx, demonstrating modern feathers and a dinosaur like skeleton

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9
Q

homology

A

similarity resulting from inheritance of traits from a common ancestor

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10
Q

homologous structure

A

traits derived from a common ancestor

forelimbs of horses, dolphins and humans

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11
Q

analogous structure

A

organisms with similar traits but evolved independently

spikes in porcupines and spikes in a pine tree

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12
Q

developmental homology

A

embryos from different vertebrates showing similarities

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13
Q

molecular homology

A

the nucleotide triplets (codons), universal genetic code demonstrating all life forms are related through common ancestry

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14
Q

biogeography

A

geographic distribution of species on Earth

organisms that live in the same regions are often related

examples would be the hawaiian honeycreepers and marsupials

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15
Q

direct observation examples

A

evolution of antibiotic resistant bacteria, insectiside resistance, industrial melanism ( peppered moth), covid-19

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16
Q

selective breeding

A

also known as artificial selection

selecting mating partners by looking for various traits

domestication of corn

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17
Q

vestigial traits

A

structured that derived from ancestor, no longer in use but present in reduced form

human tailbone, human arrector pili (goosebumps)

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18
Q

malthusian dilemma

A

population when unchecked, increases exponentially and resources are outnumbered

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19
Q

darwin’s interpretation of malthusian dilemma

A

species tend to produce more offspring than the enviornment can support, causing competition for those resources

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20
Q

theory of catastrophism

A

earth was 6000 years oldd, living organisms on the planet were created after the great flood

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21
Q

doctrine of uniformitarianism

A

geological processes that are going on today worked similarly in the past

(understanding history by examining this process and working backwards ?)

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22
Q

Lamarck’s theory

A

transmutation of species and inheritance of aquired characteristics

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23
Q

transmutation of species

A

organisms driven to greater complexity

adapting to enviornment and more complex to transform into another species

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23
Q

inheritiance of aquired characteristics

A

change through use and disuse- characteristics of an organism develop during its lifetime in a response to enviornment and then passed down to offspring

common example is a giraffe stretching its neck to make it longer and passing that trait of a longer neck down to its offspring

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24
Q

darwin’s theory

A

natural selection- those with any change variation that provides advantage will tend to be preserved

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25
Q

darwin’s four postulates

A
  1. principle of variation
  2. principle of heredity
  3. more offspring are produced than can survive
  4. survival and reproduction are not random
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26
Q

epigenetics

A

heritiable changes that do not change DNA sequences

ex: stressed male rodents were able to pass on signs of traumas through their sperm RNA

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27
Q

principle of variation

A

within a population there is a variety of traits

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28
Q

principle of heredity

A

offspring tend to inherit their parents’ characteristics

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29
Q

genotype

A

genetic makeup of a morphological trait

ex: BB, Bb, and bb

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30
Q

phenotype

A

an observed trait, expression of a genotype

ex: flower color

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31
Q

alleles

A

variant form of the same gene that share the same locus on chromosome

ex: B and b

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32
Q

Four Forces of Evolution

A
  1. mutation
  2. genetic drift
  3. gene flow (migration)
  4. natural selection

changes allele frequencies in a population

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33
Q

population

A

a group of individuals of the same species that have a higher change to mate among themselves than individuals from another group

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34
Q

point mutations

A

a single DNA nucelotide that is inserted, deleted, or changed

create new alleles at a genetic locus

ex: sickle cell anemia, color blindness, monarch butterfly resistance to milkweed

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35
Q

effects of point mutations on protein function

A
  1. synonymous mutations
  2. nonsynonymous mutations (missense or nonsense)

mutations caused by changes in DNA sequence

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36
Q

synonymous mutation

A

changes in DNA sequence that do not change the amino acid sequence

also known as silent mutation

probably neutral with regard to natural selection

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37
Q

nonsynonymous mutation

A

changes in DNA sequence that change the amino acid sequence of a protein

two kinds: nonsense and missense

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38
Q

nonsense mutation

A

a codon is changed to a stop codon

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39
Q

missense mutation

A

codon is changed for a codon that codes for a different amino acid

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40
Q

chromosome inversion

A

segment of chromosome is inverted

may not change the genetic information, but the order of genes changed

types: paracentric and pericentric

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41
Q

paracentric inversion

A

inversion that doesn’t include centromere

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42
Q

pericentric inversion

A

inversion includes centromere

easily identifiable through karyotyping

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43
Q

what does chromosome inversion often cause?

A. significant gain in DNA.
B. significant loss in DNA.
C. creation of nonfunctional pseudogenes.
D. suppression of recombination.

A

D. supression of recombination

reduces crossing over within inverted regions and increases it in others

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44
Q

inversion heterozygote

A

one set of chromosomes with normal gene sequence, the other set has inverted gene sequence

rarely produces recombinant gametes

45
Q

gene duplication

A

a region of DNA is duplicated

46
Q

mechanisms of gene duplication

A
  1. unequal crossing over during meiosis
  2. retrostransposition
  3. whole-genome duplication
47
Q

unequal crossing over during meiosis

A

homologous chromosomes misaligned at the prophase stage of meiosis l

results in gene duplication in one chromosome and deletion in the other

48
Q

retrotransposition

A

instead of being translated into proteins they are reverse transcribed into DNA sequence

ex: chondrodysplasia in dogs

49
Q

retrotransposons

A

mobile genetic elements that can cause insertion mutations and gene duplication

also known as jumping genes

50
Q

whole genone duplication

A

entire set of chromosomes is duplicated

51
Q

nondisjunction

A

homologous chromosomes or sister chromatids fail to separate during cell division

52
Q

polyploidization

A

nondisjustion causes this: common in plants that self fertilize, prevents offspring from interbreeding with parent species

different # of chromosomes comapred to parent species (typically double)

common source of speciation in plants

53
Q

Which of the following statements is not true?

A. Duplicate genes usually take on new functions.
B. Chromosome inversion does not cause gene duplication.
C. Whole-genome duplication may cause speciation.
D. Human globin gene family is an example of gene duplication.

A

A. Duplicate genes usually take on new functions.

54
Q

genetic variation

A

genetic differences found in indivudals or populations

measured genetic variation by polymorphism and heterozygosity

55
Q

polymorphism (P)

A

estimate of loci that are polymorphic

high polymorphism = high genetic variabillity

polymorphic locus: the most common allele is no more than 95%

56
Q

heterozygosity (H)

A

% or fraction of loci that are heterozygous

can be applied to individual or population

high heterozygosity = high genetic variation

57
Q

genetic load

A

natural selection is very ineffective at removing rare recessive deleterious alleles from a population

in short- unfavorable alleles

58
Q

sex-linked traits

A

generally is a trait that occurs on the X chromosome

genotype frequency of x-linked traits in males = allele frequency

h-w is then applied differently for these traits

59
Q

what does hardy-weinberg equilibrium demonstrate?

what is its use?

A

evolution won’t occur in a population if its five conditions are met

provides an estimate of expected allele frequency assuming no evolution

60
Q

hardy-weinberg equations

A

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

p^2 is frequency of homozygous dominant
2pq is frequency of heterozygous
q^2 is frequency of homozygous recessive

61
Q

If population meet all HWE assumptions which of the statements is true?

A. The population will evolve way more slowly than normal.
B. The population does not evolve as long as these conditions
hold.
C. Dominant alleles in the population’s gene pool will slowly
increase in frequency while recessive alleles will decrease.
D. The population has an equal frequency of dominant and
recessive alleles.

A

B. The population does not evolve as long as these conditions
hold.

62
Q

Five conditions for HWE

A
  1. No mutation
  2. No genetic drift (i.e. infinitely large population)
  3. Random mating
  4. No migration (no gene flow)
  5. No selection

these are essentially the driving forces of evolution MINUS RANDOM MATING

63
Q

Why is nonrandom mating not a source of evolution?

A

Nonrandom mating changes genotype frequency, but there is no change to allele frequency

64
Q

natural selection

A

surrival and reproductive success due to differences in phenotype

occurs as a result of individual differences in fitness

causes adaptation

65
Q

adaptation

A

how individuals better fitted to surrvive in their enviroment

three main kinds: structural, physiological and behavioral

66
Q

fitness

A

avg # of offspring of a individual with a certain genotype compared to that of another

usually abreviated as

a measure of the contribution of a genotype to the gene pool of the next generation

darwin described this as the abillity to survive, find mate and reproduce

67
Q

general selection model (GSM)

A

predicts changes in allele freq. from one gen to the next due to natural selection

68
Q

w=1

A

genotype with highest fitness and highest reproductive success

w<1 (fitness of other genotypes will be less than 1)

69
Q

selection coeffcient (S)

A

measure of the relative strength of selection acting against a genotype

can be thought of as the reduction in fitness

70
Q

fitness and selection coefficient equation

A

s+w=1 or s=1-w

71
Q

5 general models of natural selection

A
  1. selection against recessive allele
  2. selection against dominant allele
  3. heterozygote had intermediate fitness
  4. heterozygous advantage
  5. selection against heterozygote
72
Q

general model #1:

selection against recessive allele

what happens to the alleles?

A

AA: 1
Aa:1
aa: 1-s

Allele A will be the most common but will not be fixed and by the only one

frequency of allele a will be low but it will not reach 0

73
Q

General Model #2

Selection against dominant allele

A

AA: 1-s
Aa:1-s
aa: 1

allele a will be fixed at this locus
allele A will be removed from the population

74
Q

General Model #3: directional

Heterozygote has Intermediate Fitness

A

AA: 1-s
Aa:1-s/2
aa: 1
(selection for allele a & removes allele A from pop. )
OR
AA: 1
Aa:1-s/2
aa: 1-s
(selection for allele A & removes allele a from pop.)

changes in p and q will be slower

allele that is favored by selection will be fixed, allele A will be fixed

75
Q

General Model #4:

Heterozygote Advantage

A

AA: 1-s
Aa:1
aa: 1- t

t is selection coefficient like s

there are several names for this, heterosis, overdominance

leads to stable polymorphism BOTH alleles remain in population

76
Q

Model of Selection #5

Selection Against Heterozygote
(“Underdominance”)

A

AA: 1-
Aa:1-s
aa: 1- s

leads to disruptive selection, equilibirum is UNSTABLE

whichever allele is at highest frequency will likely become fixed
polymorphism is NOT maintained

77
Q

Frequency dependent selection

A

the fitness of a genotype of allele is affected by its frequency in the population

78
Q

postive frequency dependent selection

A

allele or genotype enjoys higher fitness when it is common

a rare allele will be at a selective disadvantage and CANNOT maintain polymorphism

79
Q

negative frequency dependent selection

A

allele or genotype enjoys higher fitness when it is rare

a rare allele will have an advantage leading to stable polymorphism

ex: scale eating fish, right and left handed fish

80
Q

gene flow (migration)

A

movement of alleles among populations (movement of individuals)

**homogenizes genetic differences and keeps popualtions similar to each other **

81
Q

what are the factors that affect gene flow?

A
  1. vagility
  2. distance
  3. barrier
82
Q

vagility

A

the abillity to move

higher vagility higher gene flow

83
Q

distance

A

between different populations

greater distance, lower gene flow

84
Q

barrier

A

geographical isolation that prevents movements of individuals

stronger barrier, lower gene flow

85
Q

outbreeding depression

A

cross between genetically distinct groups may produce offspring with lower fitness

ex: apline ibex capra ibex- hybrids between the two birthed calves too early causing the entire population to disappear

86
Q

relationship between gene flow and genetic drift?

A

gene flow and genetic drift have opposite effects

87
Q

extinction vortex

A

small populations become increasingly vunerable toward extinction

88
Q

genetic drift

A

random change of allele frequencies over generations due to change or “sampling error”

results in LOSS of genetic variation, effects are strongest in small populations

89
Q

types of genetic drift

A

bottleneck and founder effect

90
Q

bottleneck effect

A

caused by catastrophic effect that greatly reduces population size

ex: australia bushfires 2019-2020
whooping cranes- hunted nearly to extinction, from 6 mitochondrial types, there are now only 1

91
Q

founder effect

A

caused by ecological seperation through migration from orginal population

in simpler terms, small group break off and make new population

allele frequencies of new population will differ than that of the source pop.

92
Q

effective population size (Ne)

A

effect of genetic drift is determined by this

influenced by the mating system (breeding ratio)

93
Q

polygyny

A

males mate with multiple females

94
Q

polyandry

A

females mate with multiple males

95
Q

effective population size equation

A

Ne = (4 * Nm * Nf) / (Nm + Nf)

Nm = number of breeding males
Nf= number of breeding females

96
Q

factors influencing Ne

A
  • influenced by the mating system (breeding ratio)
  • fluctuation census population size over time (bottlenecks lower Ne)
  • variation in family sizes ( if some families have many more offspring, lower Ne)
  • sex ratio (unequak sex ratio lowers Ne)
97
Q

types of nonrandom mating

A
  1. negative assortive mating
  2. positive assortive mating
98
Q

negative assortive mating

A

mates between DIFFERENT phenotpes

progressive incr. in the # of HETEROzygotes

99
Q

positive assortive mating

A

mates between similar phenotypes

progressive incr. in the # of HOMOzygotes

100
Q

inbreeding

A

mating among close relatives, increases homozygosity at all loci

(type of positive assortive mating)

101
Q

self-pollination in plants

A

extreme forms of positive assortive mating and inbreeding

102
Q

what happens to allele frequencies in nonrandom mating

A

NOTHING

p and q remain the same

103
Q

inbreeding depression

A

reduced fitness due to inbreeding

increased homozygosity, expression of deleterious recessive alleles

ex: greater prarie chicken in illinois
florida panther

104
Q

genetic load

A

collection of deleterious recessive alleles

105
Q

genetic rescue

A

augment gene flow into small populations to reduce inbreeding depression

successful cases- greater prarie chicken, florida panther
unsucccessful- outbreeding depression in alpine ibex

106
Q

quantitative genetics

A

looks at the evolution of multilocus traits that show continuous variation

107
Q

quantitative traits

A

product of both genotype and enviornment

has continuous variation, typically are controlled by multiple genes

ex: morphology (size and shape)
physiology ( pressure, temperature)
performance ( speed, puzzle solving)
fitness ( seeds, suriviving offsrping)

108
Q

multilocus trait

A

combination of alleles found at two or more loci in a single individual

109
Q

hertiable variation- individual level phenotype equation

A

Phenotype(P) = genotypic effects (G) + enviornmental effects (E)

for the single locus traits enviornmental effects E= 0

110
Q

Phenotype equation (other ver. )

A

Vp= Vg + Ve

Vp = phenotypic variance
Vg = genetic variance
Ve = environmental variance.

111
Q

heritabillity (h^2)

A

proportion of the variance in phenotype that is transmissible from parents to offspring

influenced by genetic, ranges between 0 and 1, one being that the only influence is genetics

can be used to predict changes in the population as a result of natural selection

BIOS 230 (4 decks)

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