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Biology 1407 - 02M > Chapter 23 > Flashcards

Chapter 23 Flashcards

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1
Q

What is systematics?

A

The study of evolutionary relationships

This helps make an evolutionary tree

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2
Q

What is phylogeny?

A
  • The evolutionary history of an animal
  • Shows which animals are closely related and in what order they evolved
  • Presented in the form of a tree
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3
Q

Who saw that life was similar to a tree and that it came from a single common ancestor?

A

Darwin

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4
Q

Twigs of the phylogenetic trees represent what?

A

The different existing species

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5
Q

The twigs being combined represent what?

A

The recent common ancestor of those existing species

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6
Q

Early phylogenetic trees were constructed with what reasoning?

A

The more time a species spent diverging, the more different those species would be.
- True if species diverged at a constant rate

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7
Q

Similarity is a good predictor of time between evolution. (True/False)

A

False, evolution is not constant; it could be convergent and reversed

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8
Q

What are ancestral similarity?

A

Similarities among species that is inherited from the most recent common ancestor of an entire group

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9
Q

What are derived similarities?

A

Similarities that are not from a recent common ancestor

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10
Q

Cladistics share what?

A

derived characters

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11
Q

What is a character state?

A

In cladistics, one of two or more distinguishable forms of a character, such as the presence or absence of teeth in amniote vertebrates.

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12
Q

What is an outgroup?

A

An animal that is closely related to but not a member of the group under study

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13
Q

What is a cladogram?

A

A figure that depicts the evolutionary relationships among a group of species or other taxa

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14
Q

How do you employ the method of cladistics?

A
  • gather the number of characters (DNA, phenotypic, behavioral) for all species in the analysis
  • organize traits into character states and note which species have them and don’t have them
  • polarize the characters (ancestor/derived)
  • use several outgroups for comparison; if the outgroups has that character state, that state is considered ancestral
  • make a cladogram
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15
Q

What is a synapomorphy?

A

a derived character that is shared by clade members
is informative about phylogenetic relationships

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16
Q

What is a plesiomorphy?

A

another term for an ancestral character state

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17
Q

What is a symplesiomorphy?

A

another term for a shared ancestral character state
are not informative about phylogenetic relationships

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18
Q

What is homoplasy?

A
  • a shared character state that has not been inherited from a common ancestor exhibiting that state
  • may result from convergent evolution or evolutionary reversal
19
Q

What is the principle of parsimony?

A

scientists should favor the hypothesis that requires the fewest assumptions

20
Q

Systematists usually use DNA sequence data to construct phylogenies. (True/False)

A

True, DNA sequence data gives more characters

21
Q

The theory that (using the principle of parsimony) shared derived similarity is indicative of recent common ancestry is wrong in what circumstance?

A
  • When characters evolve rapidly (when stretches of DNA produce mutations that are not eliminated by natural selection)
  • when homoplasy occurs
22
Q

What approaches are used for when evolution happens too quickly and cladistics cannot be used?

A

Statistical approach, such as maximum likelihood

23
Q

How do you use the maximum likelihood method?

A
  • make an assumption about the rate at which characters evolve
  • if characters evolve at different times, group the characters with similar time of evolution, and change the method according to the groups of time
  • fit the data to these assumptions
  • make a phylogenetic tree that is “maximally likely” according to the assumptions

can be used for different characters

24
Q

How can the phylogenetic tree be timed?

A

Either by referencing fossils
or
assuming the rate of evolution

25
Q

What is a molecular clock?

A

method in which the rate of evolution of a molecule is constant through time

26
Q

How do you produce a molecular clock?

A
  • make a confident assumption of the timing of one or more diverging events
  • compare divergence to geological events that occurred that could have led to the divergence
  • divide the amount of DNA divergence by the length of time (DNA divergence per unit of time) (the most common unit of time is per a million year)
27
Q

The molecular clock is usually trustworthy. (True/False)

A

The molecular clock must be treated with caution as the rate of evolution is usually not constant.

28
Q

What is classification?

A

How we place species and higher groups into the taxonomic hierarchy

29
Q

What is taxonomy?

A

The science of classifying living things

30
Q

How is the scientific name constructed?

A

(Genus) (species)
- Genus must be capitalized
- Genus can be abbreviated to first letter
- No two animals can have the same name (unless they are from two different kingdoms)

31
Q

The order of taxonomy is?

A
  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
    (gets more specific as you go down)
32
Q

Do systematics accurately represent traditional classification?

A
  • No, in systematics, animals can be grouped as either monophyletic, paraphyletic, or polyphyletic
  • new understandings of phylogenetic relationships do not always fit well with the traditional taxonomic groups
    (Some animals within a species can be more closely related to other animals rather than animals in their own species)
33
Q

What is a monophyletic group?

A

A group with one recent common ancestor and all its descendants (a clade)

34
Q

What is a paraphyletic group?

A

A group with one recent common ancestor, but does not have all its descendants

35
Q

What is a polyphyletic group?

A

Does not have a recent common ancestor

36
Q

What is the phylogenetic species concept?

A

This defines species based on their phylogenetic relationship and through phylogenetic analysis

Species are groups of populations that have been evolving independently from other populations

37
Q

How is the PSC better than the BSC?

A

It does not look into allopatric species, as it only focuses on the past evolution of an animal rather than its future

The PSC can be applied to sexual and asexual whereas BSC is only for sexual animals

38
Q

What are some criticisms towards the PSC?

A
  • every slightly differentiated population will become a species
  • would make species become paraphyletic
39
Q

How do scientists use both PSC and BSC?

A

They use the historical perspective of the PSC with the process-oriented perspective of the BSC.

40
Q

Larval Dispersal Case Study

A
  • Nondispersing larvae is larvae that stays on the ocean ground while dispersing larvae floats with the current
  • Nondispersing larvae is increasing as more larvae is born due to:
  • nondispersing larvae evolution rarely experience reversal evolution
  • *nondispersing larvae is able to speciate more/become extinct less frequently
41
Q

Larval Stage Elimination Case Study

A
  • Phylogenetic tree shows more instances of evolution with no reversal rather than reversal evolution (less parsimonious explanation)
  • Diversification of evolution of no larval stage
42
Q

Beetle Diversification Case Study

A

phylogenetic position and timing of plant origins shows how beetles are limited in their diet

  • beetles that specialize on conifers have deeper branches that the beetles that specialize on angiosperms

possible explanations based on phylogenetic tree:

  • specializing on angiosperms is a prerequisite for evolution
  • beetles that specialize on angiosperms have a greater species richness, thus, having more chances for mutations
  • angiosperms diversified more than the conifers
43
Q

AIDS Case Study

A
  • AIDS first recognized in 1980s
  • SIV is found in primates
  • HIV descended from SIV (all strains of HIV are more related to different clades from SIV than to other HIV strains)
  • HIV was transferred probably from blood to blood contact
  • AIDS first appears in Africa
  • Earliest sample of HIV was from 1959 while AIDS is thought to have come to humans around 1920s
  • found later due to better technology

Evolution of HIV
- HIV mutates so rapidly we could trace the origins of it from each individual
- Dentist Court Case

44
Q

COVID-19 Case Study

A

COVID origin

  • phylogenetic tree showed how COVID was closely related to viral lineages from a bat
  • first emerged in China, but no bats were there
  • possibly from a bat to some other species to humans

COVID spread

  • phylogenetic was used to see where COVID came from and spread to
  • 7 strains in California and 9 introductions in NYC

Biology 1407 - 02M (8 decks)

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