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Biosci 202 > Final exam - LM4 > Flashcards

Final exam - LM4 Flashcards

1
Q

How is genetic variation measured

A

polymorphisms

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2
Q

Measures of genetic diversity

A
  • allele frequency
  • heterozygosity
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3
Q

Forces which can act on allele frequency

A
  • mutation
  • selection
  • migration
  • random sampling/genetic drift
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4
Q

What does inbreeding change

A

genotype frequency but not allele frequency

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5
Q

Hardy weinberg

A

p2 + 2pq + q2 = 1

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6
Q

What does it mean if expected > observed in hardy weinberg

A

indicates inbreeding as loss of heterozygosity

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7
Q

Conditions of hardy weinberg

A
  • no mutations
  • no inbreeding
  • no random genetic drift
  • no gene flow
  • no selection
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8
Q

Inbreeding on heterozygosity and homozygosity

A
  • increases homozygosity
  • decreases heterozygosity
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9
Q

Inbreeding coefficient

A

the probability of homozygosity by descent

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10
Q

Unrelated parents inbreeding coefficient

A

0

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11
Q

parent-offspring or brother-sister inbreeding coefficient

A

1/4

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12
Q

half sib inbreeding coefficient

A

1/8

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13
Q

first cousin inbreeding coefficient

A

1/16

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14
Q

Relative risk

A

F/q

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15
Q

Inbreeding deepression

A
  • increased homozygotes for deleterious and lethal alleles
  • decreased adaptiveness
  • can only tolerate small range of environmental conditions
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16
Q

What does genetic drift cause

A
  • loss of heterozygosity
  • change in allele frequency
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17
Q

what does a loss of heterozygosity cause

A

decreased variation in allelic polymorphism

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18
Q

Selection

A
  • differential rates of survival and reproduction resulting in changes of allele frequency
  • successful individuals leave more copies of their alleles for next generation
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19
Q

fitness

A

observed/expecred

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20
Q

Types of natural selection

A
  • directional
  • stabilising
  • disruptive
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21
Q

directional selection

A
  • fitness of one homozygote is larger than other possibilities
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22
Q

stabilising selection

A

heterozygotes have greatest fitness

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23
Q

disruptive selection

A

homozygotes have greater fitness than heterozygotes

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24
Q

heterozygotes > homozygotes

A
  • balanced polymorphism
  • overdominance
  • heterozygote advantage
  • stabilising selection
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25
Q

homozygotes > heterozygotes

A
  • unstable
  • selection against heterozygotes
  • underdominance
  • disruptive
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26
Q

Discrete traits

A

few genes for phenotype

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27
Q

Quantitative traits

A

continuous phenotype, many genes acting together

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28
Q

What is a quantitative trait described by

A

mean and standard deviation

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29
Q

Familial variation

A
  • relatives resemble one another more than randomly selected individuals
  • shared genotypes
  • relatives tend to have similar enviro conditions
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30
Q

Heritable

A

variation in phenotype caused by variation in genotypes

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31
Q

Additive gene action

A

combination of alleles contribute to trait

32
Q

Phenotypic variance

A

genetic variance and enviro variance

33
Q

Genetic variance

A

additive gene variance and dominance variance

34
Q

Broad sense heritability

A
  • genetic variance/phenotypic variance
  • proportion of variance due to genetic differences rather than enviro
35
Q

Narrow sense heritability

A
  • additive genetic variance/ phenotypic variance
  • used to compare offspring and parents
36
Q

Why is narrow heritability used rather than broad heritability

A

parents pass a single allele so dont pass dominance effect on so only additive effects

37
Q

Heritability in a stable environment

A

higher heritability as enviro variance is low

38
Q

Selection differential

A
  • difference between optimum (parents) and mean of population
  • selected parents - average
39
Q

selection response

A
  • difference between mean trait value for off spring and previous generation
  • narrow x selection differential
40
Q

How is the location of major genes inferred

A

association mapping with gene markers

41
Q

Quantitative trait locus

A

a gene affecting a complex phenotype

42
Q

2 methods of detecting a major QTL

A
  • linkage mapping for families
  • association mapping in populations
43
Q

How to know if something is a QTL

A

different genotypes have different mean phenotypes

44
Q

Genetic markers

A
  • RFLP
  • Microsatellites
  • SNPs
45
Q

Linkage disequilibrium

A
  • non random association of alleles across nearby loci in genome
  • marker is a good prediction of causative agent
  • marker must be very tightly linked so isnt broken up during meiosis
46
Q

Linkage equilibrium

A

random association

47
Q

3 types of information in molecular archive

A
  • approximate time of existence of a molecular ancestor common to the sequences that are being compared
  • probable AA sequence of ancestral protein
  • lines of descent along which given changes in AA occured
48
Q

Pan selectionist view

A
  • speed and direction of macroevolution determined by natural selection and not mutation
  • neutral mutations are rare so random genetic drift plays no role in evolution
49
Q

Neutral theory

A

-diversity from evolution greater than just that from selection
- alleles have equal fitness
- most diversity is from random mutation and random genetic drift

50
Q

challenges in identifying neutral mutations

A
  • estimation of fitness
  • distinguishing neutral from deleterious or beneficial
51
Q

Why do different proteins evolve at different rates

A

depends on how any changes can be made without affecting function

52
Q

Rate of clock

A

D/2T

53
Q

complications of molecular clock

A
  • relative rate isnt constant between all species as influenced by metabolism, generation time, DNA repair
  • calculation of rate is dependent of correct phylogeny
54
Q

Phylogenetic tree

A

evolutionary history of a group of organisms can be represented as a branching diagram

55
Q

3 types of homology

A
  • orthologous
  • paralogous
  • xenologous
56
Q

Orthologous homology

A

homologous gene that diverge via speciation

57
Q

Paralogous homology

A

gene that diverge via gene duplication events

58
Q

Xenologous homology

A

genes that diverge via lateral gene transfer between genomes

59
Q

Manuka species

A
  • native in both NZ and AUS
  • using molecular clock with 12 fossils diverged 16MYA
  • whole genome sequencing found that NZ manuka arrived 9-12MYA
  • species are distinct with different chemical compositions and morphological differences
  • regional differences are genetic
60
Q

speciation

A

the evolutionary process by which populations evolve to become distinct species

61
Q

Allopatric speciation

A
  • species seperate as reproductively isolated
  • unique mutations will eventually occur in each species making them genetically different
62
Q

Stochastic lineage sorting

A
  • divergence between gene sequences can occur at different time than speciation
  • random due to genetic drift but eventually an allele gets fixed
63
Q

modern phylogenetics

A

have become phylogenomics which is a comparison of whole genome sequences which averages out the stochastic sorting of individual genes

64
Q

Hybridisation

A
  • can be random or non random
  • makes gene sequences look more similar between species
  • non random = selection
65
Q

Human evolution

A
  • homo erectus evolved 2MYA and migrated out of Africa
  • modern humans arose in Africa 200,000YA then migrated out of africa to replace homo erectus
  • neanderthals appeared 400,000YA and likely hybridised with modern humans
  • neanderthal hybridisation occcured randomly and non randomly of the lipid catabolism genes
  • also seen denisovan hybridisation
66
Q

Problem with ancient DNA

A

degrades fast so there is an effective time limit

67
Q

Nuclear DNA via mitochondrial DNA

A
  • nuclear DNA has less copies
  • amplification of nuclear DNA via PCR is vulnerable to contamination
68
Q

3 requirements for evolution via natural selection

A
  • variation in trait must exist
  • variation must be heritable
  • differential survival and reproduction on the basis of the variable trait
69
Q

What is adaptive evolution

A

the incorporation of beneficial alleles

70
Q

purifying selection

A

remove negative mutations and keep positive mutations

71
Q

Adaptive evolution in australian sheep blowfly

A
  • introduced to NZ
  • lay eggs in sheep flesh
  • develped resistance to insecticide by 2 changes in amino acids
72
Q

Adaptive evolution in E.coli

A
  • order in which the antibiotic resistant alleles are important to giving the E.coli fitness
73
Q

Evo devo

A

regulatory genes affecting the timing and distribution of gene expression throughout an organisms development

74
Q

Adaptive regulatory evolution in drosophila

A
  • melangaster and biarmipes have different phenotype
  • biarmipes has a black patch on its wing
  • in biarmipes the regulatory sequence in the wing for the gene is upregulated so increased melanin deposits
75
Q

adaptive regulatory evolution in stickleback fish

A
  • in deep water they will have pelvic spines
  • shallow fish have no pelvic spines
  • deep water fish keep spines as similar selection pressures as ancestors
  • in shallow fish the regulatory gene is off
76
Q

Types of gene duplication

A
  • polyploidy = whole genome duplication
  • misalignment of DNA during meiosis
  • retrotransposition
77
Q

Types of duplicated genes

A
  • neofunctionalization =genes evolve to a new function
  • deleterious will be deactivated = pseudogene
  • subfunctionalization = function split between 2 copies where each copy performs only part of function

Biosci 202 (4 decks)

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