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Biology 152 > Evolution > Flashcards

Evolution Flashcards

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1
Q

Charles Darwin

A

Travelled around the world on the HMS Beagle and developed the first theory of evolution

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2
Q

What are the three key ideas of evolution?

A

Common ancestry, populations evolve, natural selection

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3
Q

What important observation did Darwin make while on the HMS Beagle?

A

Species (living and fossil) tend to live near their closest relatives because they descended from a common ancestor that lived in that area

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4
Q

T/F: common ancestry requires evolution

A

True

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5
Q

How did Darwin believe evolution occurred?

A

A mutation within one subject of a population that was passed on through generations

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6
Q

Natural selection

A

Genetic variants that are better adapted will tend to increase in frequency in a population

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7
Q

What are the three big ideas of evolution?

A

Common ancestry unites all life, populations evolve, natural selection provides direction

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8
Q

What are the four types of evidence for common ancestry?

A

Geographic distributions, fossil record, unexpected similarities among living species, treelike patterns of variation

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9
Q

Biogeography

A

Closely related species live near each other

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10
Q

Why is biogeography unlikely for separate ancestry?

A

It is very unlikely that hundreds of species of one animal would have ended up in only one fraction of the world rather than all over

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11
Q

How do fossils support common ancestry?

A

When they fit into ancestry trees based on geographics, morphology, and temporals

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12
Q

How do fossils support common ancestry through morphology?

A

There are features present in the fossils that very closely resemble features seen in species present today

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13
Q

How to fossils support common ancestry through temporals?

A

The order in which they received their traits makes sense in matters of time

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14
Q

Transitional fossil

A

A fossil that shows some but not all the derived features of a living group

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15
Q

Describe “deep” similarity to the evidence of common ancestry

A

Organisms share structural features but it is especially compelling when those same features serve different functions among different species

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16
Q

Vestigial structure

A

Structure that is non-functional in one species but functional in another related species

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17
Q

Describe the connection of “badly designed” structures to common ancestry

A

There are poorly designed structures that are shared among species that is only possible if they descended from the same ancestor

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18
Q

Speciation

A

The formation of a new/distinct species in the course of evolution

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19
Q

How does speciation occur?

A

Geographic isolation

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20
Q

Geographic isolation

A

Geographics separates part of a population so interbreeding can no longer occur, gene flow ends and differentiation occurs, differences accumulate until they reach a threshold to be considered a new species

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21
Q

Clade

A

An ancestral node and all of its descendants, all taxons and their CA

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22
Q

T/F: all members of a clade share a more recent CA with each other than anyone outside the clade

A

True

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23
Q

Topology

A

The branching pattern of a phylogenetic tree

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24
Q

Relatedness

A

The recency of common ancestry

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25
Q

T/F: relatedness refers to sharing of traits

A

False, refers to sharing of recent CA

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26
Q

T/F: a phylogenetic tree shows advancements

A

False, no species is more advanced than another (no goal to evolution, all equal)

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27
Q

Parsimony

A

Hypothesis in which history favors the path of fewest evolutionary changes as most likely being true

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28
Q

Convergence

A

“Same” character state could evolve independently in two different lineages

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29
Q

Reversal

A

A character state can evolve to resemble the state seen in an ancestor

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30
Q

Parsimony uninformative

A

Patterns in character traits that do not help choose the most parsimonious tree

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31
Q

Parsimony informative

A

Have at least two character states each present in at least two taxa

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32
Q

T/F: only genetic changes count as evolution

A

True, it implies a change in population gene frequency

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33
Q

What does it mean when a population has 50/50 gene frequency? (H-W assumptions)

A

There is no mutation, no emigration, the population is very large, mating is random, and there’s no difference in the success of alleles

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34
Q

What conditions allow evolution to occur?

A

Mutation, migration, when there is differences in success of alleles, mating is non-random, and the populations are finite

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35
Q

T/F: evolution by genetic drift depends on genetic variation and removes genetic variation

A

True

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36
Q

T/F: smaller populations lose variation faster

A

True, shown as large jumps in graph, shorter generations, and become genetically identical

37
Q

Natural selection

A

Biased genetic drift that results in adaptations, increases frequency of one allele consistently

38
Q

Fitness

A

Average reproductive output of individuals with a certain genotype

39
Q

What does reproduction require?

A

Surviving, ***producing offspring, and finding a mate (unless asexual)

40
Q

Explain evolution and relative fitness

A

Evolution only cares about alleles relative to one another— one allele assigned 1.0 while other value is determined relative to it

41
Q

Genetic drift

A

Change in frequency of an allele due to random effects of limited population size

42
Q

Directional allelic selection

A

Rapid fixation of a favored allele, removes variation faster than genetic drift
w11 > w12 > w22 (or signs flipped)

43
Q

When does directional selection overpower genetic drift?

A

Large populations, the favored allele begins at a high frequency

44
Q

HW equilibrium equations

A

p^2 + 2pq + q^2 = 1

p+q=1

45
Q

Balancing allelic selection

A

Alleles and low frequency have an advantage and tend to reach a stable, balanced state
w11 < w12 < w22

Slow rate of fixation/loss

46
Q

Disruptive allelic selection

A

Disfavor of the more rare allele and prevents evolution of potentially beneficial alleles generated by mutation
w11 > w12 > w22

Heterozygotes have lowest fitness

47
Q

How do complex traits evolve?

A

Directional selection acts over long periods of time causing mutant alleles at many loci to increase in frequency and go to fixation

48
Q

Quantitative genetics

A

Model for how a phenotype responds to selection when the first trait is controlled by many alleles and many loci

49
Q

How much of a trait can be acted on by selection?

A

Only variation that is due to loci with alternative alleles, NOT environmentally induced variation

50
Q

Heritability

A

Measure of how much of the variation in a trait in a population is explained by genetics (assumes environment is not inherited)

51
Q

What is the heritability value of trait variation that can only be explained by environment?

A

h^2= 0.0

52
Q

What is the heritability value when trait variation is explained only by genetics?

A

h^2= 1.0

53
Q

Formula for strength of selection

A

(Mean of reproducing individuals) - (mean of entire population)

54
Q

Formula for response to selection

A

(Mean of offspring generation) - (mean of parent generation)

55
Q

Formula for response to selection

A

r= (h^2)s
Heritability x strength
h=0 — no response to selection

56
Q

Directional phenotype selection

A

One extreme is favored, mean frequency of the population moves, variance decreases

57
Q

Stabilizing phenotype selection

A

Favors phenotypes near the mean, decreases variance, more narrow bell curve but same mean

58
Q

Disruptive phenotype selection

A

Either extreme is favored, disfavors phenotypes near mean, increases variance

59
Q

Allopatric speciation

A

Geographical separation results in a split in linage to form new species

60
Q

How does sympatry speciation occur?

A

Through disruptive selection and assortative mating

61
Q

Assortative mating

A

Individuals mate with preference to those similar to them

62
Q

How do multi-part features arrive without planning ahead?

A

Exaptation= a trait arose for one reason, was maintained, and then became necessary for another function

63
Q

How are exaptation traits explained by directional selection?

A

These traits reduce the ability to survive by making organisms more visible (only in males)

64
Q

Sexual selection

A

Selection for improved mating success even at the expense of survival that is driven by female choice or male conflict

65
Q

Runaway sexual selection

A

Feedback loop of: females prefer one trait, selection favors that trait, selection favors females with preference, which prefer the same one trait…etc
** why extreme phenotypes exist

66
Q

Why does runaway selection occur mainly in polygamous species?

A

Males have high variance in reproductive success in which few have many offspring (had a trait that was preferred by females)

ex: male bird spends weeks building nest to attract females

67
Q

Altruistic trait

A

Organism reduces own fitness to increase the fitness of another

  • applies to the entire population
  • explained by directional selection
68
Q

Group selection

A

Traits that improve the net success of a population are favored even if it is disadvantageous to some members of the population

69
Q

When does group selection favors altruism?

A

When there are local groups that differ in frequency of altruistic vs selfish genotypes (groups with more altruism do better)

70
Q

Individual selection

A

Alleles that improve individual fitness in a population will tend to increase in frequency

71
Q

Describe LUCA

A

A complex prokaryotic cell that was a chemoautotroph

72
Q

Chemoautotroph

A

Organism that uses redox chemistry to convert carbon dioxide into sugars

73
Q

Define life

A

A self-supporting system of chemicals that can evolve adaptively

74
Q

Hadean earth

A

Period of earth that contained lots of carbon and reducing gases (H2, NH3, H2S) but NO oxygen gas

75
Q

How did organic molecules become organized into life?

A

Chemicals were passed on without genes or cells by sticking to surfaces to grow, spread, and adapt into cellular components

76
Q

Surface metabolism theory

A

Chemical networks arose spontaneously on mineral surfaces through a reverse Krebs cycle

77
Q

How did cells/genetics originate?

A

Mineral surfaces can appear/disappear/change as well as movement of auto catalytic systems to other surfaces to multiply

78
Q

Characteristics of bacteria

A

Diverse metabolism, essential for nutrient cycling, and many symbiotic associations

79
Q

Symbiosis

A

Interaction between two organisms living in close contact

80
Q

Mutualism

A

The interaction is good for both organisms

81
Q

Parasitism

A

The interaction is good for one but not the other

82
Q

Characteristics of Archaea (except eukaryotes)

A

Can live in extreme environments, some mutualists but few parasites, metabolically diverse, similar to eukaryotes

83
Q

Characteristics of oxygenic photosynthesis

A

Made possible by Cyanobacteria, oxygen is the electron donor and is oxidized, takes a lot of energy, and requires two photo systems

84
Q

How did the oxygenic photosynthesis originate?

A

A photosystem I bacteria taking up the DNA of a photosystem II bacteria (or vice versa)

85
Q

What are the consequences of oxygenic photosynthesis?

A

Oxygen accumulated in the atmosphere with iron to produce ozone, allowed for the origin of aerobic respiration

86
Q

Characteristics of eukaryotes

A

Called are 10x larger than prokaryotes, endomembrane system, microbial top predators, many origins of multicellularity

87
Q

Endosymbiotic theory of the endomembrane system

A

A proteobacterium was engulfed by a eukaryote (already had a nucleus)

88
Q

Autogenous theory of endomembrane system

A

A genome formed a double membrane that split into two (mitochondria and a mass), the mass develops into a nucleus

Biology 152 (3 decks)

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