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B3.5 Flashcards

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1
Q

Define Gene Flow

A

The movement of alleles between populations

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2
Q

Define Genetic Drift

A

The random changes in allele frequencies in a population due to chance events. In a small population it is possible some alleles may be lost or fixed.

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3
Q

Define Bottleneck Effect

A

Occurs when there is a dramatic or sudden reduction in population size. Gene pool is limited to alleles possessed by surviving individuals and genetic diversity is lost even when population returns to original numbers.

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4
Q

Define Founder Effect

A

Occurs when a small number of individuals leaves the original population and starts a new population elsewhere. Founder population have different allele frequency to original population. No gene flow and selection pressures may cause populations to diverge.

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5
Q

When did New Zealand split from pangea?

A

Around 65 million years ago

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6
Q

What implication did New Zealand’s lack of mammals after splitting from pangea have for the fauna?

A

Some birds evolved to be ground-dwelling and flightless. In others, gigantism or dwarfism evolved.

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7
Q

How did other species reach New Zealand?

A

Floating vegetation or being caught in strong winds.

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8
Q

When did the Oligocene Drowning occur?

A

Approximately 25 million years ago

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9
Q

What resulted from the Oligocene Drowning?

A

A large biotic bottleneck as land area was reduced, causing huge death of organisms. This causes greatly reduced genetic diversity. After the water levels decreased, the species diversified over time due to mutations.

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10
Q

When did the Southern Alps form?

A

Around 5 million years ago

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11
Q

What was the impact of the formation of the Alps? What was the SI like before?

A

Prior to the Alps, the SI was flat and had a stable, calm environment. After the Alps rose, the west became rainy and wet while the east became dry. This meant that individuals became genetically isolated in different environmental conditions, although some insects and birds are able to cross the ecological borders. This caused genetic drift and potentially speciation.

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12
Q

What happens during an ice age?

A

Water level recedes, exposing land bridges and encouraging gene flow between populations. Water based species may be cut off as channels dry out, isolating some populations.

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13
Q

What happens during an interglacial warming?

A

Water level increases, covering land bridges and isolating some land species. Encourages gene flow between water based species as channels appear.

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14
Q

Evolution

A

The change in allele frequencies in a gene pool from one generation to the next

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15
Q

Gene Pool

A

The sum total of all the genes possessed by all the interbreeding individuals in a population

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16
Q

Stabilising natural selection

A

Favors the average phenotype over either extreme

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17
Q

Directional natural selection

A

Favours the phenotype of one extreme over the average or other extreme

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18
Q

Disruptive natural selection

A

favours both extremes over the average phenotype

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19
Q

Fitness

A

The ability of an organism to survive in its habitat and maximise the number of offspring surviving to reproductive age

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20
Q

Natural selection

A

The probability of survival and relative reproductive success among the members of a species in the specific environment they are living in

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21
Q

Selection pressures

A

Environmental factors that favour certain phenotypes/genotypes which allow some individuals in a population to successfully reproduce and therefore increase the chance that certain alleles will be passed on to the offspring

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22
Q

Mutation

A

A permanent change in the DNA

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23
Q

Population

A

A group of organisms of the same species living together

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24
Q

Species

A

A group of organisms that can interbreed and produce fertile offspring

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25
Q

Divergent evolution

A

Where ancestral stock is divided into 2 or more lines with dissimilar characteristics

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26
Q

Convergent evolution

A

Groups initially exhibiting different characteristics become increasingly similar (because they are exposed to the same selection pressures)

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27
Q

Co-evolution

A

Evolution of species in tandem because of their interdependence- eg. flowers and honey-eaters

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28
Q

Adaptive radiation

A

Evolution of a number of new species from an ancestor species because new niches have become available

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29
Q

Homologous structures

A

Different functions but the same evolutionary origin eg. wing of a bat and leg of a dog (ie. exposed to different selection pressures)

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30
Q

Analogous structures

A

Different evolutionary origins but the same function (eg. the wing of a bat and the wing of an insect) ie. exposed to the same selection pressures (occurs due to convergent evolution)

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31
Q

Speciation

A

Formation of a new species

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32
Q

Allopatric speciation

A

Formation of 2 new species from a single species due to geographic isolation of two populations

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33
Q

Allopatric species

A

2 closely related species that are geographically isolated from each other

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34
Q

Sympatric speciation

A

Formation of 2 new species from a single species when the two populations are NOT separated by a geographic barrier

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35
Q

Sympatric species

A

2 closely related species that are not geographically isolated from each other

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36
Q

Reproductive isolating mechanism

A

Any structure or function that is genetically determined and prevents interbreeding between organisms

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37
Q

Pre-reproductive isolating mechanism

A

Factors that prevent mating

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38
Q

Post-reproductive isolating mechanism

A

Factors that prevent the production of offspring by parents, F1 or F2 generation if mating occurs

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39
Q

Polyploid

A

Organisms having pore than 2n complete sets of chromosomes in a somatic cell

40
Q

Autopolypoloidy

A

A polyploidy organism where only one species contributes chromosomes

41
Q

Allopolyploidy

A

A polyploidy organism where two different but clearly related species contribute chromosomes

42
Q

Genetic equilibrium

A

When a population experiences no changes in allele frequency

43
Q

Deme

A

One of a number of populations that is genetically semi-isolated from similar populations

44
Q

SubSpecies

A

A division of a species because of being incompletely reproductively isolated- partly on its way to forming a new species

45
Q

Phylogenetics

A

Classifying organisms according to their evolutionary relationships based on genetic data

46
Q

Cladistics

A

Classifying organisms according to their evolutionary relationships based on derived characteristics and anatoms

47
Q

Punctuated equilibrium

A

The sudden formation of a number of new species from an ancestral species after a long period of stasis (or a long period of stasis after the sudden appearance of a number of new species from one common ancestor)

48
Q

Gradualism

A

The evolution of new species by gradual accumulation of small genetic changes over long periods of time

49
Q

What are the seven types of evidence for evolution?

A
  • Comparative Anatomy
  • Vestigial Organs
  • Fossil Record
  • Biogeography
  • Biochemical Evidence
  • DNA Evidence
  • Embryology
50
Q

What are the two types of comparative anatomy?

A

Homologous and Analogous structures

51
Q

How do vestigial organs evidence evolution?

A

They are organs or structures which have become reduced or lost their function- eg. tail bone in human or leg bones in whales

52
Q

What are fossils?

A

Preserved remains, impressions or traces of animals, plants and other organisms which lived millions of years ago.

53
Q

How do fossils evidence evolution?

A

Can be used to compare anatomies of organisms to see similarities and differences compared to other organisms both living and ancestral.

54
Q

How does biogeography evidence evolution?

A

Species which are more closely related are found as native species to land masses once joined (eg. ratites only found in places once belonging to Gondwana)

55
Q

What are the two faces of biochemical evidence?

A

Amino acid sequencing and Immunological comparison

56
Q

What is amino acid sequencing and how does it evidence evolution?

A

The comparison of amino acid sequences in proteins between species. Haemoglobin most used. Differences between sequences indicate mutation which are the only way to change the sequence- the more differences= more time so less related- longer since common ancestor.

57
Q

What is immunological comparison and how does it evidence evolution?

A

Blood from a species (1) is injected into a very different species (2) which produces anti-1 antibodies. These anti-1- bodies are extracted and added to different species’ blood. The more precipitate is formed from the reaction, the more the different species’ blood recognizes human protein and so is more similar.

58
Q

What is embryology and how does it evidence evolution?

A

Embryology is the comparison of embryos to see their similarity throughout gestation. The more similar later in development, the more related the species.

59
Q

How does sympatric speciation occur?

A
  • Polyploidy
  • Niche Isolation
  • Sexual selection
60
Q

What is the process of Allopatric speciation?

A
  1. Initially ancestral species occupies a broad area
  2. Geographic barrier forms, gene flow between populations ceases as they become geographically isolated
  3. Gene pools become different over time due to different selection pressures- environmental conditions.
  4. Two populations become increasingly different, sub species.
  5. When populations come back together, they can’t interbreed to produce viable fertile offspring.
    NOTE: First geographic isolation then reproductive isolation
61
Q

What are the 6 different pre-zygotic isolating mechanisms?

A
  • Geographic Barriers
  • Ecological Barriers
  • Temporal Differences
  • Structural Differences
  • Gamete Incompatibility
  • Behavioral Differences
62
Q

What are geographic barriers?

A
  • Shift in continental plates
  • Mountain ranges
  • Climate Chance
  • Desert Formation
  • Seas & Islands
  • Land is species live in water
  • Rivers
63
Q

How do ecological barriers reproductively isolate species?

A

Organisms develop genetic differences to cope with different niches/habitats. May live in same area but different habitats.

64
Q

Why are pre-zygotic mechanisms preferable to post-zygotic mechanisms?

A

They require less energy- allow species to move on and reproduce with members of same species.

65
Q

How do temporal differences isolate species?

A
  • One could be nocturnal the other diurnal

- May be active at different times due to availability of food (eg. fruits) or different tides

66
Q

How do structural differences isolate species?

A

Shape of genitals makes mating impossible

67
Q

How does gamete incompatibility isolate species?

A

Sperm’s enzymes are wrong to break through egg or other chemicals not correct so gametes cannot fuse.

68
Q

How do behavioral differences isolate species?

A

Different courtship rituals or vocalizations. If one species does not recognize the other’s rituals, reproduction will not occur.

69
Q

What are the post-zygotic mechanisms?

A
  • Hybrid Inviability
  • Hybrid Sterility
  • Hybrid Breakdown
70
Q

What is hybrid inviability?

A

When zygote forms but dies (mismatching of chromosomes)

71
Q

What is hybrid sterility?

A

Hybrid forms but is infertile (uneven number of chromosomes so cannot produce gametes)

72
Q

What is hybrid breakdown?

A

F1 Hybrids are fertile but their offspring F2 are infertile.

73
Q

What is a cline?

A

A gradient of variation in a population of a species due to having an extended geographic range. Neighboring speices can interbreed, but two extremes can’t.

74
Q

What is a ring species?

A

A circular gene pool with interbreeding in a smooth graduation of characteristics. Series would be considered a single species except that the overlapping ends of the ring are reproductively isolated.

75
Q

What would happen if intermediate populations in cline/ring species became extinct?

A

The two extreme populations would differentiate

76
Q

What are the steps in allopolyploidy?

A
  1. Two different but closely related species produce gametes which fertilize each other (eg. AA + BB -> AB)
  2. The hybrid produced is sterile and grows vegetatively
  3. A nondisjunction event happens during the hybrid’s growth, causing chromosomes not to separate.
  4. This causes a new fertile species with twice the no. of chromosomes produced.
77
Q

Why is a hybrid sterile?

A

Because it does not have homologous pairs of chromosomes so cannot form gametes.

78
Q

What are the steps of autopolyploidy?

A
  1. Chromosomes are contributed by one species
  2. A non-disjunction event occurs during meiosis which means chromosomes canot separate.
  3. If this happens in one ‘parent’, a sterile hybrid is formed (eg. AAA). Another nondisjunction event is needed to produce a new speices (6n)
  4. If this happens in both ‘parents’ a fertile species is formed (4n)
79
Q

How else can tetraploids form?

A

Spindle failure during meiosis in AA. The polyploidy then divides normally with AAAA.

80
Q

What are the advantages of polyploidy for plant breeders?

A
  • Greater vigor
  • Greater size- larger flowers, sell for more
  • Grow faster so grown in shorter time period- more can be sold
  • Produce more flowers and fruit so more money
  • More hardy so tolerate harsh conditions better. Less loss of plants so money saved
81
Q

What are the advantages of polyploidy for wild plants?

A
  • Greater vigor
  • Larger in size, larger flowers so seen more easily by pollinators. Increased pollination and seed production, survival of species
  • Grow faster so establish more quickly
  • Produce more flowers so more fruit and seeds so increased chance of successful dispersal
  • More hardy so tolerate harsh conditions more. Reproduce.
82
Q

What are methods of inducing polyploidy?

A
  • Using colchicine, prevents spindle fibres from forming
  • Exposing to higher tan usual temperatures-
  • Decapitation- bud removed and some new shoots developing from scar tissue could be tetraploids.
83
Q

What are the patterns of evolution?

A 
Divergent Evolution (inc. Adaptive Radiation)
Convergent Evolution
Co-Evolution
Sequential Evolution
Parallel Evolution
84
Q

What is divergent evolution?

A

Occurs when an ancestral species evolves into two or more species which have become specialized to occupy different ecological niches

85
Q

What evidence supports divergent evolution?

A

Homologous structures- same ancestral origins but different functions.

86
Q

What is a NZ example of divergent evolution?

A

kea and kaka evolving from protokaka

87
Q

What is Adaptive Radiation?

A

When one ancestral species evolves into many species due to the availability of many new niches. This is a form of divergent evolution.

88
Q

What is a NZ example of Adaptive Radiation?

A

Birds all evolving to become flightless.

Ratites

89
Q

What is convergent evolution?

A

When two or more species evolve from different ancestors but develop similar features in response to similar niche requirements (get more and more similar)

90
Q

What evidence supports convergent evolution?

A

Analogous structures (different evolutionary origins but evolve for the same purpose)

91
Q

What is a NZ example of convergent evolution?

A

New Zealand Seal, Little Blue Penguin and Hector’s Dolphin all have flippers to move efficiently through the water.

92
Q

What is co-evolution?

A

When 2 different species are ecologically intimate and this influences each others’ evolution. - can be predator prey, or mutualistic relationship

93
Q

What is an NZ example of co-evolution?

A

Wood rose and short tailed bat- only bat can pollinate flower, only wood rose produces bat’s favorite nectar.

94
Q

What is sequential evolution?

A

When the population of an entire species changes so much over time without a split, they gradually more to a new species.

95
Q

What is parallel evolution?

A

The development of similar anatomical or physiological features by related groups of organisms separated by a geographical barrier. This feature was not present in the ancestral species.

Biology Scholarship (4 decks)

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