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Evolution Flashcards

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Biology 101 flashcards
1
Q

What is the definition of evolution?

A

A change in biological entities over time (over generations)

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2
Q

What was the belief before evolution?

A

the chain of being - ladder of increasing complexity

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3
Q

who is Carolus Linnaeus?

A
  • father of taxonomy (biological classification)
  • promoted hierarchal, nested classification
    (note that linnaues was a taxonomist, not an evolutionist, he did not believe natural selection)
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4
Q

What are fossils?

A

-rocks of different age in the same location containing different species from differing

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5
Q

What did Lamarck propose about fossils and evolution?

A
  • observed progressions of similar species in the fossil record
  • proposed new species arise by modification of existing species (A turns into B turns into C)
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6
Q

What were Lamarck’s ideas about pattern of evolution?

A

He proposed the living world was made up of many separate lineages with independent origins and each lineage progressed for perfection/complexity (he was wrong)

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7
Q

What were lamarcks ideas about the process of evolution?

A

the Use and Disuse of parts idea with inheritance of aquired characters. an individual will evolve and then pass those changes onto their offspring

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8
Q

Were Lamarck’s ideas correct?

A

No!

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9
Q

What did Darwin propose?

A

Natural selection

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10
Q

What was Darwins idea on the pattern of evolution?

A
  • Living things were united in one branching tree of relationships
  • new lineages made by the splitting of existing lineages
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11
Q

What does the splitting of a lineage have to do with relation?

A

An earlier split results in greater difference while a later split results in a more common ancestor which allows for there to be more similarities between species

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12
Q

** note that after the splitting they share common ancestors (similar) but also are independent after the split

A
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13
Q

What was Darwin’s idea on the process of evolution?

A

-Darwin proposed natural selection

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14
Q

What are the aspects of natural selection?

A

1) Heritable variation
2) excess production
3) differential success

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15
Q

What is heritable variation?

A
  • Individuals in a population are born with traits
  • Many traits can be passed on from parents to offspring
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16
Q

What is excess production?

A
  • In any population more offspring produced than needed to maintain it
  • when resources are limited, offspring fail to survive
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17
Q

What is differential success?

A
  • due to differing traits some individuals are more likely to survive (fitness)
  • these traits increase in frequency while unfavourable traits are less frequent (evolution)
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18
Q

What is artificial selection?

A

Artificial selection on heritable variation present in existing species
- show plausibility of natural selection

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19
Q

What is adaptation?

A

Natural selection over time creates organisms well suited to their environment

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20
Q

What are some examples of natural selection in action

A

Drug resistance in pathogens, positive resistance, host switching insects, warfarin resistance, soapberry bug

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21
Q

What is required for a good visual of natural selection?

A

strong selective pressure and short generation times
- this is so we can see the changes in a generation obviously and quickly rather than waiting for light changes over generation, like the neck length of giraffes

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22
Q

Describe how warfarin resistance in rats demonstrates natural selection?

A

Rats that are exposed to warfarin have resistance increase rapidly in the population because they build resistance and the weak die. -

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23
Q

Does natural selection create variations?

A

No! Natural selection only works on pre existing variations (rat mutation)

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24
Q

Is natural selection beneficial in these rats?

A

Not necessarily. Natural selection does not always act to improve the rat, simply based on the environment. In the rat’s case, when they were no longer exposed to warfarin they were not able to create vitamin K as effectively, resulting in malnourishment

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25
Q

How does the soapberry bug represent natural selection?

A

Soapberry bugs switched from one flower to another, so the shorter beaks were more common and ling beak populations fell.

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26
Q

What selection is the soapberry bug representative of?

What is it?

A

Directional selection
- This is a favoured phentoype causing the allele frequency to continuously shift in one direction

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27
Q

What are 3 examples of evidence of the tree of life model?

A

1) Homology
2) biogeography
3) fossil records

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28
Q

What is homology?

A
  • A similarity resulting from common ancestry
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29
Q

What is an example of homology and why does it prove the tree of life?

A

one example is the structure of forelimbs of mammals. They are built very similarly, indicating that most humans have a common ancestor with this bone structure.

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30
Q

What are vestigial structures?

A

Structures with little to no functions, going back to common ancestors both would descend from an organism that has a functional use for that structure

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31
Q

What is molecular homology?

A
  • homologies (similarities) at the biochemical level
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32
Q

What is an example of molecular homology?

A

The universal genetic code (the coding for nucleotide bases) is universal in all living organisms due to shared ancestry ie: genetic code codes for the same proteins

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33
Q

How can molecular homology describe relations between species?

A

Once relationships are identified based on similarities, the slight differences in gene sequence can differentiate between organisms

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34
Q

What is Biogeography?

A
  • The geographic distribution of organisms
  • some taxa are endemic (restricted to certain locations)
    -Descent from a common ancestor that lived in that reason indicates tree of life because its not found anywhere else
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35
Q

How does the fossil record indicate the phylogenetic tree?

A
  • Descent with modification predicts transitional forms
  • order of appearance in the fossil record demonstrates transitional forms in which groups with major adaptation can reveal changes over time
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36
Q

What is an example of the fossil record indicating common ancestors?

A

Whales: A series of transitional forms links modern whales to land-dwelling sea animals

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37
Q

What is the definition of a population?

A
  • A localized group of interbreeding and interacting individuals
  • each species is made up of one too many populations
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38
Q

What are fixed alleles?

A

Whole population is homozygous at locus

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39
Q

What are polymorphic loci?

A

2+ alleles in a population, each present at some frequency

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40
Q

What are sources of genetic variation?

A

New alleles arise by mutation in existing alleles+ microevolution

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41
Q

What are the kinds of mutations and their description?

A

Neutral: Most mutations don’t meaningfully affect fitness
Deleterious mutations: Reduce fitness, harmful alleles
Beneficial alleles : very few, can increase fitness
(alleles can be introduced through gene flow)

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42
Q

What is microevolution?

A

-Change in the frequency of alleles over generations

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43
Q

What is the Hardy Weinberg principle?

A

Describes the expected relationships between alleles and genotype frequencies when there is no evolution

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44
Q

** Review hardy Weinberg notes from class and in textbook. Since it’s an equation it’s important to practice.

A
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45
Q

What are the uses for the hardy Weinberg principle?

A

1) Estimating allele and genotype frequencies
ex: cystic fibrosis
2) Populations with genotype frequencies that conform to the equation are said to be in hard weinbverg equilibirum

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46
Q

What assumptions are made for the Hardy Weinberg principle?

A

1) No net mutations
2) Random mating
3) No natural selection
4) Very large population size
5) No migration

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47
Q

What occurs when the hardy Weinberg assumptions are violated?

A

This indicates evolution is occurring

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48
Q

What are the 3 causes of microevolution?

A

Genetic drift, gene flow, Natural selection

NOTE: Natural selection is the only adaptive form of evolution

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49
Q

Which causes of evolution result in adaptive evolution?

A

only Natural selection

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50
Q

What effect does gene flow have on microevolution?

A
  • Dispersal of gametes
  • gene flow from population with different allele frequencies, changes in allele frequencies
  • gene flow can introduce new alleles to a population
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51
Q

What is random genetic drift?

A
  • ‘sampling error’ : random changes in allele frequencies over generations
  • can lead to fixation of alleles
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52
Q

How is genetic drift affected by population size?

A
  • rate of drift rated to population size, faster in small populations than large
  • this is because smaller populations have less variation and, therefore, a lower ability to adapt to changing conditions.
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53
Q

What is a genetic bottleneck?

A

breeding population is very small for a time, genetic drift powerful, many alleles of extinct/change
- lower genetic diversity overall, rare alleles change in frequency

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54
Q

What is the founder effect?

A

Special case of the bottleneck, previously rare Allene’s end up being much more common in new population

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55
Q

How can genetic diversity increase?

A

genetic diversity can be increased by adding individuals from other populations

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56
Q

What is the definition of a species? What are some ways to classify them?

A
  • It is difficult to classify a species universally.
    -morphological species is based on morphological similarities, historically the most commonly used concept
  • Molecular sequences are also used
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57
Q

What is inter-fertility?

A

Populations that interbreed to produce fertile offspring

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58
Q

What is reproductive isolation?

A

Populations which do not normally interbreed in nature with other species (few hybrids)

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59
Q

Why is biological species concept not always applicable

A

It is difficult to use in concepts with fossils and asexual species

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60
Q

How are biological species classified in terms of similarity?

A

Species are not classified based on similarities rather on inter-fertility
ex: If similar looking birds do not breed between each other, they are classified as different species

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61
Q

What is speciation?

A

Splitting on the tree of life ie: species splits into different versions, becomes common ancestor

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62
Q

What can cause speciation?

A

Reproductive barriers,allopatric speciation, sympatric speciation

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63
Q

what are reproductive barriers?

A

Barriers inhibit gene flow between populations, allowing evolutionary divergence

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64
Q

What is a prezygotic barrier?

A

A form of reproductive barriers, acts before fertilization, prevents mating in the first place
- if the offspring is healthy as an adult, then the parents are of the same biological species

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65
Q

What is a post zygotic barrier?

A

Acts after fertilization
-if zygote is sterile, parents classified as different biological species

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66
Q

What are some examples of pre zygotic barriers?

A
  • habitat isolation
  • temporal isolation
  • behavioural isolation
  • mechanical isolation (reproductive organs don’t fit)
    -Gametic isolation (gametes don’t recognize each other)
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67
Q

What are some examples of post zygotic barriers?

A
  • Hybrid inviability
    -hybrid infertility (mules are sterile due to only having 63/64 chromosomes)
    -hybrid breakdown
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68
Q

How do reproductive barriers arise?

A
  • Some may rise accidentally as a result of evolution in isolation
  • May evolve through natural selection in order to reduce interspecies mating that lowers reproductive success
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69
Q

What forms of speciation lead to evolutionary change?

A

Allopatric speciation and sympatric speciation

70
Q

What is allopatric speciation?

A

Geographic barrier blocks gene flow between population

71
Q

What is sympatric speciation?

A

New species arise within range of parent population

72
Q

What is polygenic inheritance?

A

Phenotypes influence by several genes (alleles at several loci)
-the inheritance of a trait governed by more than one gene

73
Q

NOTE: the curve changed based on where the curve faces the most selection pressure (directional pressure)

A
74
Q

What are the modes of selection?

A

1) Directional selection
2) stabilizing selection
3) Disruptive selection

75
Q

What is directional selection?

A

One end of distribution selected against : classic response to changing environment

76
Q

What is stabilizing selection?

A

Extreme phenotypes selected against, often due to different opposing forces
ie:intermediate selection

77
Q

What is disruptive selection?

A

Intermediate phenotypes selected against, plays a role in some speciation events

78
Q

What is sexual selection?

A
  • a special case of natural selection, competition for mating opportunities results in adaptations that increase mating success (sometimes may reduce survival)
79
Q

What are the forms of sexual selection?

A

Intrasexual selection and intersexual selection

80
Q

What is intrasexual selection?

A

Competition within one sex (usually males) fighting for opportunities

81
Q

What is intersexual selection?

A

One sex (usually female) chooses mate from competing members of other sex

82
Q

What is sexual dimorphism?

A
  • adaptations benefit only one sex, so it is common to see only one sex receives the adaptations that both sexes have the gene for
  • sexual selection: increases chances of survival
  • natural selection: differences occur from simple natural selection for other fitness reasons

Can occur from sexual or natural selection

83
Q

How can sexual dimorphism evolve?

A

From both sexual selection or natural selection.
Sexual selection (male peacocks) for mating purposes
Natural selection (larger female raptors) for survival purposes

84
Q

How can rare alleles be preserved?

A

Diploidy (two alleles) ‘hides’ recessive alleles from selection when rare (consider a single alleles in a population, difficult to remove because its masked and not common)

diploidy: the presence of 2 alleles = one can mask another

85
Q

What is reinforcement?

A

this is when natural selection imposes reproductive barriers in order to reduce interspecies mating that Lowes reproductive success

86
Q

What may occur when two allopatric populations reestablish contact?

A

1) complete reproductive barriers evolve: Populations are biological species
2) partial reproductive barriers evolved = formation of hybrids

87
Q

What types of hybridization are there?

A

Fusion, reinforcement, and lon-lasting hybrid zone

88
Q

What is fusion?

A

Hybrids form readily, have high fitness, the species merge into one again

89
Q

What is reinforcement?

A

Hybrids have low fitness, natural selection barriers strengthen, hybridization ends resulting in two biological species

90
Q

What is long-lasting hybrid zone?

A

Hybrids between species have variable fitnesses

91
Q

What is allopolyploid speciation?

A

One example of polyploid speciation, and hybrid speciation first hybrid is infertile, however potential mitotic or meiotic errors occur form a viable fertile hybrid

92
Q

What is one exception to the ‘tree of life’ model?

A

allopolyploid speciation (rare hybrids form fertile hybrid)

93
Q

What occurs after species separation?

A

Natural selection to different environments, genetic drift

94
Q

In what populations is genetic drift more significant?

A

Smaller populations experience genetic drift greater, because the changes can be expanded faster

95
Q

What are systematics?

A
  • the study of the diversity of life
    -Two components: taxonomy and phylogenetics
96
Q

What is taxonomy?

A

Naming and identification of taxa (species and groups of species)

97
Q

What are phylogenetics?

A

Estimation of evolutionary trees (phylogenies)

98
Q

What are the 3 important hierarchies to know in taxonomy?

A

Family, Genus, Species

99
Q

How does taxonomy and the tree of life relate?

A

Hierarchal taxonomy is consistent with the tree of life (recall that Linnaeus’ model corroborated Darwin’s model)

100
Q

What should taxonomy reflect ideally?

A

Taxonomy should reflect phylogeny, specifically taxa should be monophyletic groups where possible

101
Q

Describe the 3 aspects of the phylogenetic tree?

A

tips = species
branch points ie: internal nodes = recent ancestors
branches = connecting these

102
Q

What are sister taxa?

A

Species which are closest in ancestry

103
Q

How many ways can a phylogenetic tree be drawn?

A

As many ways so long as the branches are not ‘broken’

104
Q

What is a cladogram?

A

An evolutionary tree whose branch lengths have no meaning

105
Q

What is a phylogram?

A

an evolutionary tree whose branch lengths represent evolutionary change

106
Q

What are the different types of groups to be found on a phylogenetic tree?

A

1) monophyletic
2) paraphyletic
3) polyphyletic

107
Q

What are monophyletic groups?

A

Called clades
an ancestor and all of it’s descendants

108
Q

What are paraphyletic groups?

A

an ancestor and some, but not all, of it’s descendants

109
Q

What are polyphyletic groups?

A

A group that does not contain the ancestor itself

110
Q

What group are reptiles considered to be?

A

A paraphyletic group ( to be monophyletic birds would need to be included)

111
Q

How do we infer phylogenies?

A

Character states, morphological features, distribution of character states among organisms

112
Q

What is an out group?

A

Present to distinguish between ancestral and derived states
- choose an animal that is not like the others

113
Q

What does a 0 indicate in relation to the outgroup?

A

If an organism has traits that the our group also has, this means this trait is ancestral and therefore a 0 it placed. We can observe which animals on the tree have changes or no based on these inferences.

114
Q

What causes character state distributions to be inconsistent on the same tree?

A

due to convergent evolution or reversal (the loss of a derived state)

115
Q

How can we determine which phylogenetic tree is the best ?

A

The simplest tree, with the least amount of changes. This can be determined from looking at the trees and determining the minimum number of changes required for a characteristic and adding them up
- the tree with the fewest changes ( ie: parsimonious) is the best

116
Q

What is the 1st ‘rule’ of checking phylograms?

A

are the organisms that share a derived state a clade?
If yes, they both have traits from one common ancestor

117
Q

What is the 2nd ‘rule’ of phylograms?

A

If only one species has a derived state can always explain its lineage (1 change)

118
Q

What is reversal?

A

This is a potential change on the tree that can reverse the derived state back into ancestral state

119
Q

What is molecular sequence data?

A
  • phylogenies of living taxa are usually estimated by comparing molecular sequences
  • a site in DNA sequences is a character
120
Q

What are phylogenies of genes?

A
  • we can trace history of gene duplication or transfer between genomes
121
Q

What is lateral/horizontal gene transfer?

A
  • transfer of genes between species
  • quite common in unicellular organisms
122
Q

What are fossils?

A
  • preserved remnant of past life
123
Q

What kind of materials can fossils be found in?

A
  • mineral components, petrified organic material;. casts, trace fossils 9footprints, etc)
124
Q

What can fossils reveal?

A

Can provide information on past ecosystems and dating of geological record

125
Q

What rock are fossils most likely to be found in?

A

Sedimentary rock -layers upon layers, eventually revealed due to geological formation/weathering exposes the bottom

126
Q

What are Index Fossils?

A

Common widespread fossils characteristic of earth’s history
- crucial for relative dating in geological record, reveals information about the earth at the time!

127
Q

What is the geological record?

A

The timeline of the earth
- earth is ~4.6 billion years old,
- microbial life arose 3.5 billion years ago

128
Q

What are the last 3 eras of the earth called?

A

Phanerozoic eon - divided into 3 eras, each era subdivided into several periods

129
Q

What percentage of fossils exist from the past?

A

we have roughly fossils from the last 15% of the timeline

130
Q

What are mass extinctions?

A

Many species go extinct in a very short period of time

131
Q

How many mass extinctions have there been?

A

5 ‘big ones’, marking end of eras/periods

132
Q

What are the causes of mass extinctions?

A

large environmental changes (eg: massive volcanic activity, asteroid/comet)

133
Q

What is the most devastating extinction?

A

The end permian mass extinction
- 550 million yeas ago, extinction of ~90% of species on earth, many families went extinct

134
Q

What is the end cretaceous mass extinction?

A
  • 65 millions years ago, most recent big mass extinction
  • caused extinction of ~50% of species, notably dinosaurs (apart from birds) went extinct
135
Q

What are adaptive radiations?

A
  • rapid speciation and evolutionary changes in underexploited habitats
  • increase in species with common ancestor because many changes occur to a species as they adapt to a new environment
136
Q

What are the two forms of adaptive radiations?

A
  • regional : colonization of new islands
  • world-wide - following mass extinction species, only surviving lineages can radiate, replacement in fossil record
137
Q

What did Darwin’s theories propose about how complex adaptations evolve?

A

Darwinian evolution proposes that evolution occurs through many small steps, and every step should improve fitness

138
Q

What are the mechanisms for the evolution of complex adaptations?

A

1) functioning intermediates
2) modification of existing structures (exaptation)
3) evolution of developmental regulation

139
Q

What are functioning intermediates?

A
  • Simple forms pf complex structure are functioning
  • evidence: organs of different complexity in related species
  • step wise evolution plausible (each is better than the last)
140
Q

What is the modification of existing structures that leads to complex adaptations?

A

exaptation: structures adapted for one function are coincidentally useful for another function

141
Q

What is exaptation?

A

when structures adapted for one function are useful for another. one example is dinosaurs feathers, which were originally simple structures used for warmth or other functions, and over time increased in complexity to form wings and flight
-a feature that performs a function but that was not produced by natural selection for its current use

142
Q

What is developmental regulation?

A
  • mutations affecting genes that control development
  • small genetic changes can result in large, calculated changes in phenotypes
143
Q

What are homoeotic genes and what do they prove?

A
  • Hoxgenes control identity of segments along the developing animal body, mutations in fruit fly created new pair of wings
  • Homeotic genes are master regulator genes that direct the development of particular body segments or structures.
144
Q

How are new genes formed?

A

gene duplication and horizontal gene transfer

145
Q

How does gene duplication work?

A

1) part of chromosome
2) gene duplication
3) over time, independent evolutionary change occurs

146
Q

What is subfunctionlaization?

A

An example of gene formation, when a gene initially has 2 functions, and then eventually these functions are split onto two different genes for specifically one function

147
Q

What are paralogs?

A

Two related genes in one genome
- genes historically duplicates of one another in the same gene
- they are homologs but different versions of the same gene

148
Q

Are paralogs homologous?

A

They are homologous because they are still derived from one common ancestor, however the creation happened from an initial duplication

149
Q

What is a common example of paralogs?

A

hemoglobin and myoglobin began as one carrying unit

150
Q

What is another form of gene duplication?

A

lateral/horizontal gene transfer
-the acquisition of genetic material from another organism without being its offspring

151
Q

What are the three major lineages of life?

A

the 3 domains: bacteria, eukarya, archaea

  • note: bacteria and archaea are both forms of prokaryotes
152
Q

Why are prokaryotes important?

A
  • on earth for ~3.5 billions years, responsible for most biological activity in ecosystems (ocean, soil) cause many diseases/infections, more [orkryotes than cells, useful for biotechnology
153
Q

Describe bacteria?

A

Includes most well known prokaryotes, all known disease causing

154
Q

What is the bacterial cell envelope like?

A

usually two bounding membranes - plasma membrane and outer membrane
- peptidoglycan wall between the membranes (complex polymer of sugar and amino acids)

155
Q

What are the two membranes that form the bacterial cell envelope?

A

plasma membrane and outer membrane

156
Q

What lipid is found in the bacterial cell envelope?

A

peptidoglycan - complex of sugars and amino acids

157
Q

What are the important bacterias to note ?

A

1) spirachetes
2) gram positive bacteria- no outer membrane , cause many diseases/infections
3) cyanobacteria- photoautotrophs (oxygenic photosynthesis - produces oxygen)
4) protobacteria - very diverse ex: E.Coli

158
Q

What are Archaea?

A
  • a form of prokaryotes, many are extremophiles
  • many are menathogens -produce methane as waste
159
Q

What is the archaean membrane like?

A
  • no outer membrane, no peptidoglycan
    cell membrane lipids are chemically different from bacteria and eukaryotes
  • note the lipids have branches (hydrocarbon branches)
160
Q

Which of the 3 domains are more closely related?

A

archaea are most closely related to eukaryotes than to bacteria

161
Q

What are the steps to the origin of eukaryotic cells?

A

put this in later lol

162
Q

What are some similarities between prokaryotes and mitochondria/plastids ?

A
  • divided by binary fission, have prokaryotic like ribosomes, have their own genomes- encode some rans and some proteins are translated on organelle ribosomes
163
Q

What are protists?

A

eukaryotes Responsible for most of eukaryotic diversity, abundant in ecosystems, important photosynthesizes, major predator of prokaryotes
-parasites cause some major diseases (malaria)

164
Q

What are the origins of animals and fungi?

A
  • phylogenies of molecular show that animals and fungi closely related, but individually evolved from single celled protists
    -Plants evolved from photosynthetic green algae protists
165
Q

What are are the things of the eon?

A
  • Phanerozoic eon
  • Paleozoic era, mesozoic era, cenozoic era
  • the end permian was in the paleozoic era
  • end cretaceous was in the mesozoic era
166
Q

What are nucleosomes comparable to?

A

Beads on a string

167
Q

Describe (In more detail) the Hershey chase experiment

A

Radioactive bacteria: radioactive phosphorus and sulfur used (sulfur not used in DNA, Phosphate is)

168
Q

When does DNA become transcriptionally inactive?

A

When the DNA wraps around histones (wraps tightly around that prevents access to DNA polymerase, which would normally align the nucleotides)

169
Q

Which is bigger, a sister chromatid or metaphase chromosome?

A

Metaphase chromosomes are larger because they are homologous

170
Q

What are Mendel’s law?

A
  1. Segregation of alleles:
    Two alleles for a heritable character segregate
    (separate from each other) during gamete
    formation and end up in different gametes.
  2. independant assortiment of genes
    During gamete formation,
    a pair of alleles for one gene
    will segregate independently of
    a pair of alleles for another gene.
171
Q

What is the magic ratio for genotypic ratios?

A

1:2:1
- 3:1 ratio for phenotype

172
Q

What are the names of the discovery of DNA components?

A

Miescher- isolation of the nuclein
Griffith - transformation of DNA
Avery - purification of DNA
Hershey-chase - Radioactive DNA (viruses composed of only DNA/RNA and protein)
Rosalin franklin X-ray diffraction
Watson and crick - DNA model
Meselson and stahl - semi conservative model
Arthur kornberg- molecular components of DNA replication

bio (11 decks)

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