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EVOLUTION > Natural Selection (2) > Flashcards

Natural Selection (2) Flashcards

1
Q

Natural selection?

A

= process by which favourable heritable traits become more common in successive generations of a population of reproducing organisms & unfavourable heritable traits become less common.

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2
Q

Explain natural selection.

A

Natural selection enables/cause populations to evolve through traits within those populations being favourable to their environment/fit to survive the environment and is more likely to be passed on to subsequent generations through reproduction.

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3
Q

Thing to consider about favourable?

A

That it may change.

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4
Q

Who/What does natural selection act on?

A

Individuals.

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5
Q

NS attributes? (5)

A

• Differential reproduction of genotypes.
• Non-random process, but no “intent”.
• Acts on mutations (random).
• Acts on the genotype through the phenotype.
• Occurs at different stages of a life cycle.

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6
Q

3 selection types we’ll be focusing on from the adult section of the life cycle?

A

• Variable selection.
• Sexual selection.
• Survival selection.

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7
Q

NS principles? (4)

A

• Acts on individuals.
• Not progressive/linear.
• Can’t predict the future.
• Populations evolve, not individuals.

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8
Q

What do we mean when we say that NS is not progressive/linear?

A

We mean that in NS things change often if not all the time & is unpredictable (not straight to the point).

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9
Q

Results of NS? (2)

A

• Increase in no. of individuals in subsequent generations that possess potentially adaptive characteristics.

• Adaptations to local environment (local adaptation).

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10
Q

Give an eg of how NS can’t predict the future & explain it?

A

Darwin’s finches

• how they responded to seed availability where beak size depended on the types of seeds that where available.

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11
Q

Conditions for NS to occur? (3)

A

• Variation in individual traits.
• Heritable traits/Heritability.
• Difference in fitness (reproduction).

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12
Q

Eg of the 1st NS condition?

A

Beak depth in Darwin’s finches.

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13
Q

What does fitness involve? (4)

A

• Variability.
• Fecundity.
• Longevity.
• Mating success.

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14
Q

Viability?

A

= the probability that an organism is able to survive & pass down their traits to the next generation.

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15
Q

Fecundity?

A

= where an individual is able to produce fertile/healthy gametes to increase the chances of them transferring their traits to the next generation.

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16
Q

Longevity?

A

= the lifespan of individuals before & after mating & whether they will be able to mate successfully before their ultimate deaths.

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17
Q

Mating success?

A

= whether an individual is able to transfer their genetic traits to the next generation & in subsequent generations.

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18
Q

Fitness types? (2)

A

• Absolute fitness.
• Relative fitness (w).

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19
Q

Absolute fitness?

A

= the average no. of offspring produced for genotypes.

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20
Q

Relative fitness?

A

= an individual’s/genotype’s fitness relative to the fitness of other individuals/genotypes in the population.

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21
Q

Main selection types that act on a character that is continuously distributed? (3)

A

• Directional selection.
• Disruptive selection.
• Stabilizing selection.

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22
Q

Eg of Directional NS & explain?

A

Pterosaurs body size.

  • As birds emerged, pterosaurs got bigger.
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23
Q

Eg of Disruptive NS?

A

False Wanderer (butterfly).

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24
Q

Eg for Stabilizing NS & explain?

A

Baby birth weight

  • where average (middle) weight is favoured/healthy.
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25
Q

Results of Disruptive/Diversifying NS? (2)

A

• Increase in extreme traits in population.
• Increase in trait diversity.

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26
Q

Result of Stabilizing NS?

A

Decrease in variation/diversify.

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27
Q

How do we distinguish Stabilizing NS & No selection? (2)

A

• Compare Expected change (random) & Observed change (chi² test).

• If calculated change < expected change = Stabilizing selection is occurring.

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28
Q

What are the applications of evolution? Where can we apply the evolution theory? (4)

A

• Phylogenetics (viruses).
• Genetic counseling (zebra fish).
• Pharmaceuticals (medicinal purposes).
• Artificial selection (wild mustard= provides kale, cabbage, broccoli).

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29
Q

Genetic drift?

A

= the random change in allele frequency.

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30
Q

Frequency-dependent selection (FDS)?

A

= selection that depends on how many morphs/morphologies are present in a population.

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31
Q

FDS types? (2)

A

• Positive FDS (+).
• Negative FDS (-).

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32
Q

+ FDS?

A

= selection where the common morph is favoured.

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33
Q

– FDS?

A

= selection where the rare morph is favoured.

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34
Q

+ FDS attributes? (3)

A

• Eliminates polymorphisms.
• Higher fitness when common.
• Predators avoid common morph & select the rare form.

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35
Q

What does + FDS result in regarding risk?

A

It results in a shared risk among common individuals.

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36
Q

What do we mean by shared risk when talking about + FDS?

A

We mean that if you look like everyone else, there’s a lower risk of getting eaten by prey.

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37
Q

Egs of + FDS? (2)

A

• Aposematism.
• Language.

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38
Q

What does - FDS result in?

A

It results in genotypes (common + rare) reaching an intermediate frequency.

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39
Q

– FDS attributes? (2)

A

• Maintains polymorphisms.
• Results in genotypes reaching an intermediate frequency.

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40
Q

How does -FDS maintain polymorphisms?

A

By producing stable polymorphisms in a population.

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41
Q

Egs of -FDS? (2)

A

• Side-blotched lizards.
• Scale-eating cichlids.

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42
Q

+ FDS in terms of FDS & Mimicry?

A

= selection common mimics survive.

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43
Q

– FDS in terms of FDS & Mimicry?

A

= selection where the rare mimics survive if the common is poisonous.

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44
Q

To better understand FDS & Mimicry refer to what paper?

A

Chouteau et al. 2016.

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45
Q

Things to note for FDS & Mimicry according to Chouteau et al. 2016? (3)

A

• Warning colouration frequency/Common frequency is dependent on predator avoidance knowledge.
• + FDS.
• Tested using Heliconius butterflies.

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46
Q

Mimicry types? (2)

A

• Müllerian mimicry.
• Batesian mimicry.

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47
Q

Müllerian mimicry?

A

= mimicry that involves aposematism/warning colouration.

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48
Q

Müllerian mimicry attributes? (2)

A

• Honest signaling.
• Both groups are toxic/harmful.

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49
Q

What do we mean by “Honest signaling”?

A

= signaling where organisms bravely show predators that they’re poisonous.

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50
Q

Batesian mimicry?

A

= mimicry where the edible/harmless species resembles the toxic/harmful species.

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51
Q

Batesisn mimicry attribute?

A

Deceptive signaling.

52
Q

Eg of Müllerian mimicry?

A

Heliconius species mimicking each other (H. erato & H. melpomene).

53
Q

Egs of Batesian mimicry? (2)

A

• King snakes mimicking coral snakes.
• Barnyard grass mimics rice.

54
Q

Outcomes of NS (2)?

A

• Mimicry.
• Adaptations.

55
Q

Adaptation?

A

= any change in form/function/behaviour that promotes the likelihoods of a species’ existence.

56
Q

Adaptation attributes? (2)

A

• Increases the ability of a species to survive in an environment & more likely to reproduce.
• Has a genetic basis (except for learned behaviour).

57
Q

Why does Barnyard grass mimic rice?

A

To prevent being weeded out of the rice paddy garden.

58
Q

What is adaptation based on?

A

Genetics.

59
Q

What does adaptation exclude?

A

Learned behaviour.

60
Q

How do we identify traits that are adaptations? What questions do we need to ask to identify adaptations? (4)

A

● Is it heritable?

● Is it functional?

● Does it increase fitness?

● How did the trait first evolve?

61
Q

Egs of animal adaptations? (3)

A

• Loose bone attachment in snakes (wide mouth opening).
• Camouflage.
• Finches on Galapagos islands.

62
Q

Camouflage types? (2)

A

• Visual camouflage.
• Chemical camouflage.

63
Q

Visual camouflage?

A

= camouflage that aimed to blend in with the environment.

64
Q

Eg of visual camouflage?

A

Chameleons.

65
Q

Chemical camouflage?

A

= camouflage that aimed to remove scent.

66
Q

Eg of chemical camouflage?

A

Female puff adders when they don’t feel like mating with male puff adders.

67
Q

Eg of plant adaptation?

A

Flowers mimic the form & scent of pollinator mates (orchids mimicking female wasps).

68
Q

If a trait is not an adaptation, then what/where did it arise from? (4)

A

• Chance result of evolutionary history (long term).
• By product of another trait.
• Outdated adaptation (vestigial structure).
• Result of genetic drift (short term).

69
Q

Exaptation?

A

= a trait that acquires a function that it was not originally selected for.

70
Q

Egs of an exaptation? (2)

A

• Feathers.
• Penguin’s wing.

71
Q

Explain the exaptation eg?

A

They were meant for sexual selection & insulation but developed to be adapted for flight.

72
Q

Eg of where these conflicting selection pressures are seen & explain?

A

Guppies.

  • where when a predator is present they are basic/simple fish (to avoid getting eaten).
  • when a predator is absent they are colourful fish (to attract female guppies for mating).
73
Q

Directional selection?

A

= where the extreme phenotype/trait is favoured.

74
Q

Egs of directional selection? (3)

A

• Pink salmon size and net size.
• Pterosaurs body size in Mesozoic period.
• Change in finch beak size over time.

75
Q

Stabilizing selection?

A

= where the trait mean is selected for (average trait is favoured).

76
Q

Stabilizing selection attributes? (2)

A

• Traits in tail of distribution are selected against.
• Decrease in variation.

77
Q

Egs of Stabilizing selection? (2)

A

• Baby birth weight.
• Sickle cell anaemia (heterozygous).

78
Q

Fitness?

A

= number of offspring produced.

79
Q

Generational fitness?

A

= fitness that depends on an organism’s offspring having offspring and so on to perpetuate the gametes.

80
Q

Important thing to note with fitness?

A

Fitness is key to NS.

81
Q

What is relative fitness (w) used for?

A

To evaluate NS as selection occurs through differences among individuals in the population.

82
Q

Disruptive selection is AKA?

A

Diversifying selection.

83
Q

Things to be mindful of with selection types? (2)

A

• Trait distribution in the original population.
• How that changes to identify the type of selection.

84
Q

Directional selection attributes? (3)

A

• Occurs due to competition, migration, human interference, etc.
• Distribution moves in one direction or the other.
• Variation is constant.

85
Q

Disruptive selection?

A

= where the trait mean is selected against.

86
Q

Disruptive selection attributes? (2)

A

• Leads to increase in extreme traits in the population.
• Leads to increase in diversity of traits (increase in variation).

87
Q

Extreme?

A

= tails of the distribution (increase in frequency).

88
Q

Explain the eg for Disruptive selection? (2)

A

• Extreme phenotypes mimic Butterflies not normally predated on because they’re morphologically similar to 2 other toxic species.

• Frequency of alleles in the population changed due to selection for extreme phenotypes.

89
Q

Things to consider for Diversifying selection? (2)

A

• Mean (x bar) = trait predated on.
• Increased frequency of tail phenotypes.

90
Q

Stabilizing selection attributes? (2)

A

• Traits in tail of distribution are selected against.
• Leads to decrease in variation.

91
Q

Why does sickle cell anaemia persist in a population?

A

Because of the heterozygous state which enables detrimental traits to remain in a population.

92
Q

Compare Directional selection; Disruptive selection & Stabilizing selection in terms of variation? (3)

A

● Directional selection = variation is constant.

● Disruptive selection = increase in variation.

● Stabilizing selection = decrease in variation.

93
Q

What do we mean when we say “traits must be heritable”?

A

Offspring should resemble their parents more than organisms within the same environment.

94
Q

Body size in terms of trait types?

A

Continuous trait.

95
Q

Selection types use what type of traits?

A

Continuous traits.

96
Q

Distribution associated with continuous traist?

A

Normal distribution.

97
Q

Why is variation important in a population?

A

It gives natural selection something to acton and ensures the reproductive fitness/success of varying organisms within population.

98
Q

Aposematism?

A

= where the warning colouration indicates that an organism is poisonous to predators, thus predators avoid eating the common & there’s higher fitness for the common.

99
Q

Explain Eg 1 of -FDS?

A

Touches on sperm frequency being the main factor in determining mating success.

100
Q

Side-blotched lizards male types & their description? (3)

A

• Blue = single females.
• Orange = harems.
• Yellow = sneaker male.

101
Q

Yellow male Side-blotched lizard attributes? (4)

A

• Sneaker male.
• Imitates females.
• Don’t defend territories.
• Rare morph.

102
Q

What are the conflicting selection pressures? (2)

A

• SS.
• NS.

103
Q

Eg of + FDS in terms of FDS & Mimicry?

A

Heliconius butterflies.

104
Q

Eg of – FDS in terms of FDS & Mimicry?

A

Monarch & Viceroy butterflies.

105
Q

Arabidopsis thaliana?

A

= small plant from the mustard family important for genetic research.

106
Q

Arabidopsis thaliana attributes? (3)

A

• Selection = trait changes.
• Gave biologists a window to genotypes.
• Helps biologists underpin genotypes & how traits change.

107
Q

Other evolutionary process that affects trait change?

A

Hybridization.

108
Q

Explain graph of butterflies? (4)

A

• Warning colours in butterflies.
• Common morph is favoured.
• Chouteau et al. 2016.
• + FDS.

109
Q

Selection types for continuous traits? (3)

A

• Directional selection.
• Disruptive selection.
• Stabilizing selection.

110
Q

Selection types for discrete traits? (2)

A

• + FDS.
• – FDS.

111
Q

How do you know that a butterfly isn’t part of the population or is a mimic of another butterfly species?

A

The difference in the morphs is in the details.

112
Q

Why is it beneficial to be honest in Müllerian mimicry/Benefit of Müllerian mimicry?

A

Increases their chances of being recognized by predators & being left alone.

113
Q

Why is it beneficial to be deceptive in Batesian mimicry/Benefit of Batesian mimicry?

A

Organism mimic gains protection as predators mistake it for the toxic organism & leave it alone.

114
Q

Can adaptations evolve by chance alone?

A

No.

115
Q

Difference between learned behaviour & Inherited behaviour?

A

● Learned behaviour = develops during an organism’s lifetime.

● Inherited behaviour = behaviour that an organism is born with.

116
Q

If trait is not an adaptation or even not explained by the other 4 reasons, then what is it?

A

Exaptation.

117
Q

What does selection alter/change? (3)

A

• Frequencies.
• Alleles.
• Genotypes.

118
Q

What do we mean by “Is it heritable”?

A

We mean that traits need to be genetically encoded.

119
Q

What do we mean by “Is it functional”?

A

We mean that the trait needs to perform that task it was shaped to do.

120
Q

What do we mean by “Does it increase fitness”?

A

We mean that the trait must help produce more offspring/enable longer lifespan.

121
Q

What kind of question is “How did the trait first evolve”?

A

Pattern question.

122
Q

What kind of question is “Did form & function arise simultaneously”?

A

Process question.

123
Q

Did form & function arise simultaneously?

A

Unlikely.

124
Q

Arabidopsis thaliana common name?

A

Thale cress.

125
Q

Learned behaviour?

A

= behaviour that develops during an organism’s lifetime.

126
Q

Inherited behaviour?

A

= behaviour that an animal is born with.

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