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Genetik > 1 > Flashcards

1 Flashcards

1
Q

allele

A

two or more alternative forms of the same gene

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2
Q

polymorphism

A
  • coexistence of multiple forms or variations of a gene within a population
  • contributing to genetic diversity and adaptation to different environmental conditions
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3
Q

what is a molecular marker

A
  • a locus on the gene
  • it identifies a chromosome or DNA sequence or polymorphism
  • marker helps to (1) quantify the genetic diversity (2) measure inbreeding (3) identify remained individuals
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4
Q

conservation

A
  • study of marine plants and animals resources and ecosystem. functions
  • protection and conservation through planned management
  • aim: prevent exploitation
  • preserving
  • restoring
  • molecular marker important e.g. to characterize larval biodiversity
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5
Q

management

A
  • aim: maximum ecosystem services and functions and resilience
  • aim: preserve interconnections among species and their environment
  • mol. marker important e.g. for estimating the number of genetically isolated pop.
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6
Q

aquaculture

A
  • farming of aquatic organisms
  • intervention to enhance production (e.g. regular stocking, feeding, predator-protection)
  • mol. marker e.g. to preselect parental pairs for avoiding genetically coded anomalies
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7
Q

what does population genetics do?

A

study the distribution and change in frequencies of alleles

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8
Q

what is the Hardy Weinberg theorem?

A
  • main concept of population genetics
  • conditions:
    (1) large population
    (2) mating randomly
    (3) no mutation
    (4) no selection
    (5) no migration
  • then allelic frequencies do not change over the generations
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9
Q

ecological paradigm as definition of a population

A
  • qualitative and more of a demographic definition
  • population is a group of individuals
    of the same species that co-occurs in space and time
  • they have the opportunity to interact with each other
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10
Q

evolutionary paradigm as definition of a population

A
  • quantitative and more of a genetic definition
  • population is a group of individuals
    of the same species
  • they live close enough for any member of the group to mate with another member
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11
Q

metapopulations

A
  • populations of populations
  • groups that are more or less in contact
  • groups exchange more or less individuals
  • metapopulations between extremes such as isolation or panmixia
  • different degrees of connectivity
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12
Q

gene flow

A
  • movement of genetic material among population
  • organisms move among different populations through mechanism of migration
  • NOT same as migration
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13
Q

does migration mean there is gene flow?

A
  • no
  • when migration occurs it can be that there is no gene flow because sometimes migratory animals can NOT mate with new population
  • in that case there is
    (1) no exchange of genetic material
    (2) no variation in allelic frequencies
    (3) no gene flow
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14
Q

Dispersal

A
  • natal dispersal: permanent move away of individuals from birth site to their breeding site
  • breeding dispersal: movement from breeding site to another
  • dispersal defined as any movement that has the potential to lead to gene flow
  • influences the distribution of biodiversity
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15
Q

what topics of study does “dispersal” affect?

A
  • climate change
  • planning MPA
  • habitat restoration
  • population viability analysis (PVA)
  • invasive species
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16
Q

what is dispersal in water?
what are the main types?

A
  • active or passive movement of larval stage
  • types
    (1) clumped dispersal (exploitation of local food)
    (2) uniform dispersal (typ. for birds)
    (3) random dispersal (typ. for invertebrates)
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17
Q

are the 3 types of dispersal in water like migration?

A
  • no
  • there is no seasonality in movements
  • not related to a stage of life
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18
Q

migration
(different types of migration)

A
  • permanent, cyclical or seasonal movement away from origin
  • impacts social and genetic structure of pop.
  • obligate: individuals MUST migrate
  • facultative: individuals CAN migrate
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19
Q

vertical migration

A
  • traveling a few hundred meters up and down the water column
  • e.g. krill
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20
Q

tidal migration

A
  • migrating following the tide to and from the coast
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21
Q

connectivity
(what types?)

A
  • how freely individuals can can move in space and reach different habitats
  • and have access to different resources
  • types
    (1) potential connectivity = per capita probability to disperse between sites
    (2) realized connectivity = number of propagules that disperse
    (3) structural connectivity = structurally connected by a corridor
    (4) functional connectivity = varying connectivity depending on temporal and spatial factors
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22
Q

connectivity-model

A
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23
Q

dispersal and migration easier or harder in water? leads to?

A
  • easier
  • greater level of gene flow with larger spatial scale
  • lower sensitivity to habitat fragmentation
  • higher resilience on external sources of recruitment
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24
Q

is panmixia in the ocean easier or harder to have? why?

A
  • easier
  • because of
    (1) the higher gene flow
    (2) larger population sizes
    (3) lower genetic differences between pop.
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25
Q

what are abiotic characteristics that prevent panmixia?

A
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26
Q

important type of connectivity in the ocean

A
  • currents
  • current-based
  • most effective
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27
Q

what is the Lagrangian particle model?

A
  • 3D-hydrodynamical model to study dispersal and connectivity
  • release of particles
  • particles tracked
  • study movement
  • aim: predict passive movement of animals
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28
Q

what is the Eularian model?

A
  • 3D-hydrodynamical model to study current based dispersal and connectivity
  • recording the arrival of particles at certain tie in certain area
  • how do they move? what direction?
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29
Q

allelic frequencies in HWE

A
  • p = frequency of allele A
  • q = frequency of allele B
  • p + q = 1
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30
Q

genotype frequencies in HWE

A

(p+q)^2 = 1

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31
Q

what is tested with HWE?

A
  • differences between the observed (sample) and expected (HW law) genotype frequencies
  • if not under HWE –> selection is acting by favoring ONE allele, not both
32
Q

what is the opposite of what is expected by HW?
Panmixia

A

inbreeding

33
Q

what is the opposite of what is expected by HW?
infinite population

A

genetic drift

genetic drift can lead to fixation or the loss of alleles, especially in SMALL populations. In an infinite population, as compared to small popuations there would be no loss, the random and undirectional effect of genetic drift would not have any impact

34
Q

what is the opposite of what is expected by HW?
no mutation

A

mutation

35
Q

what is the opposite of what is expected by HW?
no migration

A

migration

36
Q

what is the opposite of what is expected by HW?
mortality and fertility not related to genotype

A

selection

37
Q

what are the evolutionary forces acting on genetic variability?

A

(1) genetic drift
(2) gene flow
(3) selection
(4) mutation

38
Q

genetic drift

A
  • fluctuation of allelic frequencies
  • random, by chance
  • depending on pop.-size (more evident in smaller pop.)
  • NO adaptive change
  • it causes a lot of genetic variability (loss of alleles/ reduction in allelic frequencies)
39
Q

in what 2 events is genetic drift involved?

A
  • genetic bottleneck
  • founder event
40
Q

when is the genetic drift stronger?

A

when the effective population size is smaller (Ne)

41
Q

what is the effective population size?

A
  • the number of individuals in a pop. that contribute to the next generation
  • the ones that can mate
  • a measure of size in the gene pool
  • Ne usually smaller than N
42
Q

what is population differentiation?

A
  • when 2 pop. have different pressures from evolutionary forces (e.g. lack of gene flow)
  • results in differences in genotypic and allelic frequencies
43
Q

genetic bottleneck

A
  • is a dramatic reduction of the number of individuals in a pop.
  • does NOT depend on genotype
  • result: change in allelic frequencies –> resulting pop. is not representative for original pop.
  • resulting pop. has small Ne
  • higher risk of inbreeding
  • recovery longer than one generation
  • result: loss of rare alleles, but heterozygosity remains
  • allelic variability is lost faster than heterozygosity
44
Q

founder event

A
  • when a few individuals colonize a new area
  • does NOT depend on genotype
  • depends on population size (more evident in smaller pop.)
  • result: change in allelic frequencies –> resulting pop. is not representative for original pop.
45
Q

migration and gene flow
(considered together)

A
  • exchange of alleles between populations
  • due do migration and spread of new alleles, there is changes is allelic frequ.
  • that prevents allele fixation
46
Q

does migration always produce a gene flow?

A
  • no
  • reproduction might not occur between residents and immigrants
  • increase in heterozygosity is a random event
47
Q

what 2 consequences does migration lead to?

A
  1. an INCREASE in genetic variability WITHIN populations (new alleles from immigrants)
  2. a DECREASE in genetic variability BETWEEN populations (homogeneity effect)
48
Q

what if genetic drift is the only force acting on 2 diff. alleles?

A
  • after some generations it leads to fixation
  • fixation depends on starting allelic frequencies
    also depends on population size
  • genetic drift DECREASES variability WITHIN pop.
  • genetic drift INCREASES variability BETWEEN pop.

(–> opposite of migration)

49
Q

what if genetic drift + migration are forces acting together on two diff. alleles?

A
  • random gene exchange
  • migration counter acts genetic drift
  • balances variability
  • variability does NOT INCREASE BETWEEN pop.
50
Q

what does the occurrence of gene flow depend on?

A

depends on
(1) distribution
(2) number
(3) isolation of diff. pop

51
Q

what models can we use to show the different way, gene flow can occur in?

A
  • Wright’s Island model
  • Stepping Stone model
  • IBD
52
Q

Wright’s Island model

A
  • N equal
  • m equal
  • geographic distances ignored
53
Q

Stepping Stone model

A
  • N equal
  • m equal
  • geographic distances different

(it’s easier for an individual migrate from pop1 to pop2 or from pop3 to pop4 but it’s more difficult migration from pop1 to pop3 or pop4 and so on)

54
Q

Isolation by Distance (IBD)

A
  • N equal
  • m different
  • geographic distance different

(individual in pop1 can migrate only to pop2 but are not able to exchange genetic material with pop3)

–> when 2 population are separated by a great distance (IBD) we can have no gene flow at all and the two populations start to differentiate

55
Q

natural selection

A
  • directional + local
  • NOT random
  • favorable alleles become more frequent
  • leads to diff. mortality and fertility rate of specific genotype
  • it is NOT evolution because it is a mechanism, not a process
  • it is an adaptive evolutionary mechanism
  • it can cause evolution
  • faster than genetic drift
56
Q

in what directions can natural selection act?

A

(1) negative: removing mutations (because deleterious)
(2) positive: leads to increase of allele frequency if it is a benefit for population

57
Q

stabilizing selection

A

favors individuals around mean

58
Q

directional selection

A

favors individuals at one side of the distribution

59
Q

disruptive selection

A

favors individuals at both extremes of the distribution

60
Q

What acts faster? natural selection or genetic drift? why?

A
  • natural selection acts faster
  • it acts directly on individual’s fitness
  • not by chance, as genetic drift
  • it acts locally on specific target gene
  • it can INCREASE variability BETWEEN pops.
61
Q

non-random mating

A
  • when there is preferential reproduction
    (1) assortative mating: individuals with same genotype (increases homozygote)
    (2) disassortative mating: never between same genotypes or morphs (increases heterozygotes)
  • non-random mating acts on single locus/ on a local scale
62
Q

inbreeding

A
  • reproduction between related individuals
  • acts on genomic levels
  • leads to more homozygotes
63
Q

outbreeding

A
  • reproduction between unrelated individuals
  • acts on genomic levels
  • leads to more heterozygotes
64
Q

sexual selection

A
  • individuals of same sex have higher mating success over the other ones
  • correlated to present or absent particular trait
65
Q

mutation

A
  • only way to create new alleles
  • allelic frequencies change when alleles disappear or new ones are introduced
  • change in 1 base of genome (can be more)
  • can be lost or fixed
  • is an error in the DNA-replication that causes a structural change
66
Q

when is a mutation lost or fixed?

A
  • depends on selection and genetic grift
  • if mutations are harmful: lost
  • if mutations are beneficial: fixed
67
Q

what happens after a fixation of a mutation?

A
  • it produces new polymorphisms
68
Q

translocation

A
  • when a mutation affects entire chromosome-complements
  • causes movement of nucleotides from one to another part of the genome
69
Q

does the genetic variability WITHIN the population DECREASE or INCREASE, if “genetic drift” occurs?

A

decrease

70
Q

does the genetic variability WITHIN the population DECREASE or INCREASE, if “mutation” occurs?

A

increase

71
Q

does the genetic variability WITHIN the population DECREASE or INCREASE, if “gene flow” occurs?

A

increase

72
Q

does the genetic variability WITHIN the population DECREASE or INCREASE, if “selection” occurs?

A

both

73
Q

does the genetic variability BETWEEN the population DECREASE or INCREASE, if “genetic drift” occurs?

A

increase

74
Q

does the genetic variability BETWEEN the population DECREASE or INCREASE, if “mutation” occurs?

A

increase

75
Q

does the genetic variability BETWEEN the population DECREASE or INCREASE, if “gene flow” occurs?

A

decrease

76
Q

does the genetic variability BETWEEN the population DECREASE or INCREASE, if “selection” occurs?

A

both

Genetik (11 decks)

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