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Zoology Semester 1 > APS121 Evolution - Hunter > Flashcards

APS121 Evolution - Hunter Flashcards

1
Q

What is the defining concept in biology?

A

evolution

  • Understanding how the circulatory system works is essentially hydrostatic physics. Understanding how blood and haemoglobin work by binding to and releasing oxygen and carbon dioxide is essentially a chemistry problem. Why circulatory systems are different across different organisms is where it becomes exclusively biology
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2
Q

What are the 3 parts to the scientific method?

A

Observation of patterns, hypotheses, tests (to obtain data and evidence) - you try to disprove the hypothesis

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3
Q

What are the 3 theories for the history of life?

A

Creationism, transformism, evolution

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4
Q

How is creationism disproved?

A

Changes are evident in time.
E.g. peppered moths - change in form with changing amounts of industry and carbon particulate matter in the atmosphere, darkening trees - melanic form more common as harder to spot for predators. Now wild type pale form far more common with little industry

e.g. artificial selection - dogs have been artificially selected for 1000s of years - change in form

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5
Q

How do we define a species?

A

Breeding and producing viable offspring

+ morphology

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6
Q

How is transformism disproved?

A

Man has selected new species, for example Primula kewensis - produces viable offspring only with other individuals of the same plant - created by accident while interbreeding similar species of primrose to create new attractive traits - 2 parental species with 18 chromosomes each - one offspring got 36 chromosomes (polyploidy) - consistent only with evolution theory

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7
Q

Are changes in form of a species evident in space?

A

Yes - e.g. clines of red fox in NA (longer, denser fur and smaller ears in colder north, shorter fur and larger ears in warmer south)

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8
Q

What is a cline?

A

A change in a feature across a geographic region (usually linear and latitudinal)

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9
Q

What are ring species?

A

Species can interbreed with adjacent species, but not further distances. E.g. gulls in the northern hemisphere - can all interbreed with adjacent species, except herring gulls and lesser black-backed gulls.

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10
Q

There are much more complex organisms and many more different organisms as time progresses. Which theory is this consistent with?

A

Evolution

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11
Q

What is homology?

A

Identifying traits that have the same ancestry but different forms and functions
- homologous characters are traits that are inherited from a common ancestor (but may have different functions) e.g. parts of reptile jaws converted into parts of the ear in higher apes, or the beaks of Darwin’s finches

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12
Q

Is the form of a species fixed?

A

No

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13
Q

What is gene frequency?

A

A proportional representation of a gene in the population (as a fraction of 1)

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14
Q

How are genes inherited?

A

In a mendelian fashion - dominant and recessive alleles - 2 copies of each gene

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15
Q

In mendelian inheritance, heredity is not…

A

Blending - offspring look like one or other of the parents not an intermediate of the two.

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16
Q

What are the 2 functionally different classes of cells?

A

Somatic (body) and germ (gonads) cells

- the germ cells transmit information from one organism to the next

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17
Q

Any change in soma can’t be transmitted back into…

A

germ line
(if you get fit and muscular it won’t be transmitted back into the germ line)
- this is Weismann’s principle

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18
Q

Mendelian inheritance does not produce a change in gene…

A

frequency

- it does produce a change in genotype frequency, but not individual genes

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19
Q

With an infinite population size there would be no…

A

genetic drift

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20
Q

What is genetic drift?

A

A process by which allele frequencies change as a result of random processes)
- much more noticeable in small populations than large ones

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21
Q

What is a mutation?

A

A heritable change in genetic material - occurs at relatively low frequencies (so unimportant as mechanism of evolution)
- can be single point to entire chromosomal change

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22
Q

What is meiotic drive?

A

When particular sets of genes skew the process of meiosis in their favour - distort segregation so that gametes that don’t carry genes die during gametogenesis - but this is very rare

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23
Q

What is molecular drive?

A

Genes convert other genes into identical copies of themselves - very rare

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24
Q

What is lamarkism?

A

Lamark suggested individuals pass on acquired traits (e.g. blacksmiths’ sons are big and beefy like their parents - but this is actually due to the environment rather than genes) - does not occur

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25
Q

What does HWE assume?

A

Infinite population size, no mutation, mendelian inheritance, no selection, random mating

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26
Q

Selection occurs when…

A

genotypes differ in their ability to pass genes on to the next generation - if a genotype is successful its genes will increase in frequency.

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27
Q

What are the 3 types of selection?

A

Natural, artificial, sexual

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28
Q

How does sexual selection work?

A

Traits make individuals more attractive to members of the opposite sex (can be behavioural or anatomical)
- fighting traits can also allow males to exclude other males from competing for females and allow them to defend females from other males - affect chance of random mating

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29
Q

What is the most common and important mechanism for evolution?

A

Selection (particularly natural and sexual selection)

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30
Q

What is an adaptation?

A

An evolutionary change that fits an organism to its habit or habitat - a directional change with either a positive or negative consequence

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31
Q

What are the 3 main approaches to objectively quantify an adaptation?

A

Optimality approach (relatively weak)
Comparative studies
Experimentation

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32
Q

What is the optimality approach to finding out if a trait is an adaptation?

A

e. g. how would evolution produce a well-designed wing bone in a bird - both strong and light - hollow to be lightweight and internal cross-bracing to increase strength and robustness.
- However more useful when looking at behavioural, rather than anatomical adaptations, e.g. european bee-eaters and central place foraging (they fly out from a central spot, catch food, and fly back to the central spot to eat it). - Timed how long away from nest to estimate the distance travelled to catch food - tend to bring back bees and dragonflies (but dragonflies are 3-4 times more calorific) - optimality theory suggests birds should be willing to expend more energy flying further to catch a dragonfly, as it is gaining more energy - found with shorter flights higher proportion of bees brought back, with longer flights higher proportion of dragonflies brought back - this behaviour is an adaptation

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33
Q

What is the comparative method to finding out if a trait is an adaptation?

A

Do organisms with similar lifestyles evolve similar traits? - compares very taxonomically different organisms to see if they have similar adaptations - if they do it can’t be due to them inheriting it from a common ancestor.
- e.g. bats and oilbirds use echolocation to detect things in a dark environment (e.g. in caves) - 2 very different animals use the same trait to overcome the same problem - therefore can conclude that echolocation is an adaptation to cope with a dark environment

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34
Q

What is the experimental approach to finding out if a trait is an adaptation?

A

Take variable that you think is responsible for the outcome, manipulate that variable, and you see whether that changes the outcome in a way that is consistent with your prediction - if a trait is adaptive, changing that trait should change the nature of the adaptation or the adaptive value of the trait
e.g. peppered moth - took light and dark and put both on both backgrounds, saw which predated by birds - conclude that colours of moths are adaptation to avoid predation

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35
Q

What are the 6 potential mechanisms for adaptation (including 1 that doesn’t exist)?

A
  • Genetic drift
  • Mutation
  • Meiotic drive
  • Molecular drive
  • inheritance of acquired characteristics (doesn’t exist)
  • Selection
36
Q

Which of the potential mechanisms for adaptation are random rather than directional in accordance to the environment?

A
  • Genetic drift
  • Mutation
  • Meiotic drive
  • Molecular drive
37
Q

What is the actual mechanism for adaptation?

A

Selection - better adapted individuals survive longer and mate more frequently so leave more offspring, whereas poorly adapted individuals die sooner and faill to mate so leave fewer offspring - shows directional change in accordance to the environment

38
Q

What are the 3 factors necessary for selection?

A
  • Multiplication (producing offspring through reproduction) - far more offspring are produced than can possibly survive (carrying capacity of the environment reached - struggle for existence)
  • Variation - incredible amount that we might not be attuned to see (e.g. damselfly wings) - less well-adapted will not survive
  • Inheritance - must have heritability for evolution - ability to inherit favourable traits allows species to adapt
39
Q

Selection + inheritance =

A

adaptation

40
Q

Where does new variation come from?

A
  • Recombination (crossing over) - variation but no change in gene frequency
  • mutation - creates variation - not a mechanism for evolution but necessary for it to occur - creates variation on which selection acts
    So source of variation is mutation (random) and the mechanism for variation is selection (directional)
41
Q

Darwinian selection + Mendelian inheritance =

A

Neo-Darwinism

42
Q

What is the commonest type of selection?

A

Stabilising - trait mean stays the same - selection against extremes
e.g. 136 house sparrows + storm –> 72 survived –> found those closer to mean survived more often - small and large died
OR babies + mortality after war

43
Q

Does the mean change in disruptive selection?

A

No - just fewer individuals actually have the mean trait

44
Q

What is Batesian mimicry?

A

Model is distasteful, mimic is palatable but mimics model models to avoid being predated (due to negative association)
- stops working when mimics reach a higher frequency than models - selection keeps model at higher population

45
Q

In Batesian mimicry, how do mimics find a way to reach a decent population level?

A

Mimic different model organisms, e.g. butterfly Papilo dardanus - example of disruptive selection (only acts on females - males stay in their own form)

46
Q

How do we detect selection?

A

Look for correlations between characters and spatial or temporal variation in the environment
Look directly for differences in fitness

47
Q

What is fitness?

A

Genetic contribution to next generations

48
Q

How do you quantify fitness?

A

LRS (lifetime reproductive success) - number of viable offspring left during lifetime - balance between survival and reproduction (fecundity and fertility + number of mates)

49
Q

What are the 2 types of sexually selected traits?

A
  • Intrasexual selection traits (within one sex) - largely competitive traits and usually possessed by the males - for fights and competitive displays
  • intersexual selection traits (between the sexes) - favours traits that females find attractive in males
50
Q

Do sexual and natural selection operate in the same direction?

A

More often than no they operate in different directions - e.g. more colourful more attractive sticklebacks are more visible and vulnerable to predation
- balance each other out to find optimum point for sexual and natural selection

51
Q

Higher mating rates are favoured in…

A

males - can produce many many gametes

  • higher mating rate = higher fitness
  • higher reproductive capacity
52
Q

What does sexual dimorphism mean?

A

Males and females look different

- sexual selection is operating

53
Q

Why does sex role reversal occur?

polyandrous system

A

Due to ecological constraints
e.g. dotterels live in low energy environment - males defend territory - on edge of existence - can only defend territory for one chick - females go from territory to territory finding males to mate with and look after chicks - female more brightly coloured

54
Q

What is polyandry?

What is polygyny?

A

Female has multiple partners

Male has multiple partners

55
Q

Does there tend to be sexual selection in monogamous species?

A

No - tends to be no sexual dimorphism

56
Q

How can males compete? (intrasexual competition)

A

Fighting, stamina tests, mate guarding (pre- or post-copulatory - exclude competing males), sperm competition (selection favours sperm traits that increase chances of egg fertilisation)

57
Q

What are intersexual selection traits driven by?

A

Female choice (epigamic selection)

58
Q

What do females gain from choosing attractive mates?

A
  • access to resources (courtship feeding)
  • Access to good genes - utilitarian (e.g. health conditions) - and more likely to pass on genes by producing more attractive offspring
59
Q

What prevents runaway sexual selection?

A

Natural selection

60
Q

What is it suggested makes attractiveness traits attractive in the first place, before sexual selection enhances them?

A

Survival advantage, e.g. bird tail length

- goes past optimum length due to preference traits in females

61
Q

What is altruistic behaviour?

A

Benefits other individuals at a cost to the altruistic individual

62
Q

Some altruistic behaviour is actually…

A

selfish rather than altruistic

63
Q

Altruism reduces personal…

A

fitness

64
Q

In vampire bats, altruism is…

A

reciprocated

65
Q

Can altruism evolve for the good of the species?

-i.e. group selection

A

No

- “cheating” would occur - end up with whole group of selfish individuals

66
Q

What are some examples of altruistic behaviour?

A 
Alarm calls
Sterile workers
Senescence
Ritualised fighting
Reciprocated feeding (vampire bats)
67
Q

At what level does selection occur at?

A

The level of the gene

68
Q

Altruism is selfish at the level of the…

A

Gene

- help individuals who have the altruistic gene themselves

69
Q

What is Hamilton’s rule (Kin selection)?

A

Altruism evolves when rb>c

Cost of altruism = c
Benefit to recipient = b
coefficient of relatedness = r
r = % of genes shared

70
Q

What are changes within a species referred to as?

A

Micro-evolution

71
Q

What is speciation?

A

The splitting of one species into 2 new species

- also responsible for the formation of other higher taxonomic groups

72
Q

What are macro-evolution processes responsible for generating?

A

Diversity

73
Q

What is gene flow?

What can it counteract?

A

The exchange of genes between populations as a result of movement and interbreeding of individuals
- can counteract disruptive selection and speciation

74
Q

Disruptive selection + little gene flow =

A

Potential for speciation

75
Q

What are the 2 most important changes that occur during speciation?

A

Divergence - species adapt to different environments as a result of disruptive selection
Reproductive isolation - consequence is that populations can’t interbreed - shuts down gene flow

76
Q

What the two theories of speciation differ in the order of?

A

Reproductive isolation and divergence
Allopatric - isolation (due to lack of ability for gene flow) then divergence as a consequence
Sympatric - divergence then isolation

77
Q

What are some types of isolating barriers in allopatric selection?

A

Mountain ranges, land separating marine species as sea levels fall, river cutting between areas of land, area of desert, polar structures
- conditions vary slightly on either side of the barrier, allowing disruptive selection

78
Q

In sympatric speciation what does disruptive selection have to be strong enough to overcome?

A

Gene flow

e. g. grass on sheffield slag heaps and heavy-metal resistant energy consuming genes
e. g. aphids on deciduous and coniferous trees, post-zygotic isolation + temporal

79
Q

Punctuated equilibrium theory suggests that evolution becomes much faster during…

A

Speciation events

  • rapid periods separated by periods of stasis
  • based on fossil record where new forms appear suddenly with no intermediates (although fossil record is not reliable - large gaps, biases etc)
  • opposes gradualism theory
80
Q

Why do gaps appear in the fossil record?

A

Sedimentation is not actually particularly common - happens in only few specific places (rivers, shallow seas etc.)

  • rock strata don’t represent complete history of time (only 1-10%) - long periods where no or very little sedimentation occurs
  • even when sedimentation occurs fossilisation is very rare - must be buried before bones are separated
  • animals without hard parts very very rarely fossilised
81
Q

Which type of selection has lead to “living fossils”

A

Stabilising selection - keeps features the same - long periods of stasis

82
Q

Give an example of divergent evolution

A

Pentadactyl limb

83
Q

What is adaptive radiation?

A

One species adapts in to many species to fill different niches

  • e.g. exploiting new environments
  • e.g. due to reduction in competition from other groups (for example due to mass extinction events)
84
Q

What are local extinctions?

A

Loss of a population from a particular area

85
Q

What are mass extinctions?

A

A period of geological time when extinction rate peaks above the background rate of extinction

  • characterised by breadth and brevity
  • occur quickly (in geological terms)
86
Q

What is the racial senescence theory?

orthogenesis

A

Species evolve and evolve until this drives them to their own extinction
- irish elk, gryphea, ammonites

  • but there is no mechanism for this, it doesn’t actually happen - completely at odds with natural selection
    + some species have not changed for millions of years e.g. nautilus
87
Q

There is a band of rock at the…

A

K/T boundary - find dinosaurs below this boundary but not above - full of iridium (very rare on earth but common in meteors) - distributed around entire surface of earth - caused nuclear winter + cretaceous mass extinction

Zoology Semester 1 (16 decks)

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