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human genetics > Week 3- evolutionary genetics > Flashcards

Week 3- evolutionary genetics Flashcards

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Biology 101 flashcards
1
Q

what is a scientific theory

A

an explanation supported by evidence

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2
Q

what did Darwin hypothesised

A

that present-day species are descendants of ancient ancestors that have evolved

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3
Q

why do populations change over generations

A

to become more adapted to their environment

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4
Q

what species are naturally selected

A

when there is a frequently recurring struggle for existence, any being that varies slightly in a manner profitable to itself, will have a better chance of surviving

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5
Q

when was the origin of species discovered

A

1859

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6
Q

what is natural selection

A

organisms with certain inherited traits are more likely to survive and reproduce that those with other traits.
Frequency of alleles in a population can change over time

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7
Q

what theory did Alfred Wallace come up with

A

similar conclusion to Darwin- survival of the fittest

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8
Q

what was Darwin

A

A naturalist

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9
Q

what tends to happen to closely related species that occupy different ecological settings

A

they have different characteristics

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10
Q

what happens to populations that are physically isolated

A

tend to differ

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11
Q

what were Darwins theories

A
  • All species derive from very different species living in the past
  • Species change over time because bearers of different traits have different probabilities of contributing offspring to the next generation
  • Splitting of single species into two or more species has occurred (Speciation)
  • Evolution occurs by the gradual transformation of populations over long periods of time
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12
Q

what processes are required in natural selection

A
  • competition
  • variation
  • heritability
  • iteration
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13
Q

why is there competition in natural selection

A

Many more individuals are born than survive

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14
Q

why is there variation in natural selection

A

Individuals vary in traits directly related to their ability to survive and reproduce

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15
Q

what is heritability in natural selection

A

advantageous traits are passed on to offspring

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16
Q

what is iteration in natural selection

A

process is repeated generation after generation over long periods of time

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17
Q

what does the modern synthesis theory state

A

genes are responsible for the inheritance of characteristics

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18
Q

what does the modern synthesis combine

A

Darwinian selection and Mendelian inheritance

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19
Q

what is the basic explanation of modern synthesis

A

populations evolve, not individuals. speciation is usually due to the gradual accumulation of small genetic changes

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20
Q

what does the Modern Synthesis Theory suggest that genes are responsible for

A

the inheritance of characteristic

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21
Q

what does the Modern Synthesis Theory suggest that speciation is due to

A

the gradual accumulation of small genetic changes

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22
Q

what do fossils show

A

that species existed in the past that no longer exist today, and species exist today that did not exist in the past

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23
Q

what do fossils provide solid evidence towards

A

the fact that organisms from the past are different to those we see today; they show a progression of evolution

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24
Q

what are vestigial structures

A

an anatomical feature or behaviour that no longer seems to have a purpose in the current form of an organism

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25
Q

how did blind cave fish lose their complex eye structure

A

adaptation to cave dwelling

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26
Q

what is the vestigial genes in blind cavefish

A

one of the genes responsible for eye loss in cavefish also increases the number of taste buds on the ventral surface of the head, which helps them find food more effectively

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27
Q

what would natural selection for the increase in taste buds in cavefish promote

A

blindness

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28
Q

what is homologous

A

Similarities because they derive from a common ancestral source

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29
Q

analogous

A

Similarities because they perform a similar function and not because they come from a common ancestor

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30
Q

what are homologous structures

A

similar structures in organisms with shared ancestry

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31
Q

where are homologous structures derived from

A

the same common ancestor but may not have the same function

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32
Q

what are analogous structures

A

Less-related species living in similar environments have similar body forms, though often involving different body parts.

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33
Q

how are analogous structures formed

A

From variations in a population, the environment selects those that best help an organisms survive in that environment.

34
Q

what can spines be used for in different species

A

insulation, camouflage, signalling, sensing, and defence

35
Q

what does embryological similarities demonstrate

A

a shared set of genes between groups of organisms, suggesting common ancestry.

36
Q

26

A
37
Q

what does comparative genomics demonstrate

A

shared genes for many traits between related species, suggesting descent from a common ancestor

38
Q

what does the direct observation of change over time show

A

through artificial selection experiments, the mean phenotype can be rapidly advanced, and phenotypes can be produced that are well beyond the range of variation in a base population.

39
Q

what is contemporary evolution/ evolution in ecological time

A

evolutionary change in response to changing environmental conditions

40
Q

what is one of the outcomes of evolutionary change

A

the development of species

41
Q

what are species

A

a group of organisms that can potentially interbreed with one another to produce viable, fertile offspring.

42
Q

what is the outcome of different species interbreeding

A

often produce sterile or less viable offspring

43
Q

what are the mechanisms of reproductive isolation

A
  • prezygotic
  • potzygotic
44
Q

what is the pre zygotic mechanism

A

prevent members of different species from mating to produce a zygote

45
Q

how does the prezygotic mechanism work

A
  • habitat isolation
  • temporal isolation
  • behavioural isolation
  • gametic isolation
  • mechanical isolation
46
Q

what is postzygotic mechanism

A

keep hybrid zygotes from developing into healthy, fertile adults

47
Q

32

A
48
Q

what is speciation

A

the process where one species can no longer reproduce with and therefore is different from another species

49
Q

what is allopatric speciation

A

geographic separation of populations from a parent species

50
Q

what is sympatric species

A

remaining in one location

51
Q

how does allopatric speciation occur

A

evolution into two or more descendant species after a period of physical separation caused by a geographic barrier leading to reproductive isolation

52
Q

what are some some examples of geographical barriers that leads to allopatric speciation

A
  • mountain range
  • body of water
  • changed landscape
  • crossing a pre-existing barrier
53
Q

what is sympatric speciation

A

divergence without geographic seperation

54
Q

how does sympatric speciation happen

A
  • mutation/polymorphism within a species
  • polyploidy
54
Q

how does sympatric speciation happen

A
  • mutation/ polymorphism within a species
  • polyploidy
55
Q

what is polyploidy

A

heritable condition of possessing more than two complete (homologous) sets of chromosomes

56
Q

what is microevolution

A

changes in allele frequencies in a gene pool from generation to generation

57
Q

what are the causes of microevolution

A
  • genetic drift
  • natural selection
  • gene flow
  • mutation
  • non-ramdom mating
58
Q

what does a reduction in genetic variation lead to

A

inability to adapt to new selection pressures, because genetic variation that selection would act on may have drifted out of the population

59
Q

what 2 factors may cause genetic drift

A
  • bottleneck effect
  • founder effect
60
Q

what is the bottleneck effect

A

leads to reduced genetic variability following some large disturbances that removes a large portion of the population. The surviving population often does not represent the allele frequency in the original population

61
Q

what is the founder effect

A

when a few individuals from a large population colonise an isolated habitat which may lead to reduced variability

62
Q

what is natural selection

A

differential success in reproduction based on heritable traits results in selected alleles being passed to relatively more offspring

63
Q

when does natural selection occur

A

when one allele (or combination of alleles of different genes) makes an organism more or less able to survive and reproduce in a given environment

64
Q

which mechanisms cause natural selection

A
  • directional selection
  • disruptive selection
  • stabilising selection
65
Q

what is directional selection

A

where one extreme phenotype is more fit than all the other phenotypes

66
Q

what does directional selection favour

A

individuals at one end of the phenotypic range and is most common during times of environmental change or when moving to new habitats

67
Q

what is disruptive selection

A

where both extreme phenotypes are more fit than those in the middle

68
Q

what does disruptive selection favour

A

extreme over intermediate phenotypes, and occurs when environmental change favours an extreme phenotype

69
Q

what is stabilising selection

A

where the intermediate phenotypes are more fit than the extreme ones

70
Q

what does stabilising selection favour

A

intermediate over extreme phenotypes and reduces variation and maintains current average

71
Q

what is gene flow

A

movement of alleles between populations

72
Q

what tends to happen to gene flow over time

A

reduction in variation

73
Q

what does natural selection normally select

A

pre-existing traits (alleles)

74
Q

what is a mutation

A

a change in an organism’s DNA and is represented by changing alleles

75
Q

what is the original source of variation

A

mutations

76
Q

how do mutations affect the composition of the gene pool

A

mutations can be transmitted in gametes to offspring

77
Q

what is non-random mating mating

A

when individuals choose mates non-randomly with respect to genotype

78
Q

what is positive non-random mating

A

same genotypes

79
Q

what is negative non-random mating

A

different genotypes

80
Q

what is inbreeding

A

mating with close relatives

human genetics (9 decks)

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