Chapter 27-28 - Speciation and Phylogenetics (Test 3) Flashcards

1
Q

Define phylogeny of all organisms

A

Genealogical relationships between species

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2
Q

How many domains are they, and what are they?

A

3: Bacteria, Archaea, Eukarya

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3
Q

Characterize the three domains in terms of their nuclei and their # of cells

A

Most bacteria and archaea are prokaryotic; eukaryotes are the others.

Most bacteria and archaea are single-celled; some eukaryotes are multicellular

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4
Q

Who is responsible for the three-domain classification system?

A

Woese – thanks to his experiements tracing ribosomal RNA (rRNA) to construct the tree.

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5
Q

Describe the evolutionary relatoinships of the three domaiB

A

Eukaryotes and Archaea share a common ancestor, which shares a common ancestor with Bacteria.

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6
Q

Are prokaryotic organisms monophyletic?

A

No; prokaryotes can be bacteria or archaea. But archaea have a common ancestor with eukaroytes before they have one with bacteria.

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7
Q

What is taxonomy?

A

The effort to name and classify organisms.

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8
Q

what is anamed group of organisms called re: taxonomy?)

A

a taxon. (plural: taxa)

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9
Q

What is a phylum?

A

a major grouping within each domain

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10
Q

Describe the system for scientific (latin) names and who came up with it.

A

Linnaeus.

Two-part name: Genus (closely related group of species)

Species

Capitalize genus but not species. Italicize or underline separately if handwritten.

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11
Q

What causes speciation?

A

genetic isolation and genetic divergence

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12
Q

What is speciation?

A

A splitting event that creates two or more distinct species from a single acnestral species.

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13
Q

Define species.

A

An evolutionarily independent population or group of populations.

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14
Q

What are three common criteria used to develop species?

A

Biological species concept

Morphospecies concept

phylogenetic species concept

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15
Q

Define the biological species concept

A

The main criterion for identifying species is reproductive isolation.

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16
Q

What are the two types of reproductive isolation

A

prezygotic isolation - prevents individuals of different species from mating.

postzygotic isolation, in which the offspring of different species do not survive or reproduce.

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17
Q

Disadvantages of the biological species concept?

A
  1. Can’t be evaluated in fossils or asexual species
  2. Difficult to apply when populations do not overlap geographically
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18
Q

Define the morphospecies concept

A

Identify evolutionarily independent lineages by size, shape, or other morphological species. Logic: distinguishing features likely to arise if populations are independent and isolated from gene flow.

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19
Q

What are the pros and cons of the morphospecies concept?

A
  1. good: Useful when there is little other data
  2. bad: can lead to the naming of 2+ species when there is only one polymorphic species with differing phenotypes (jaguars with different spots)
  3. bad: Cannot ID cryptic species, which differ in traits other than morphology, like meadowlarks
  4. morphological features used to distinguish species are subjective
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20
Q

What are the five mechanisms of prezygotic isolation?

A
  1. Temporal – lived at different time
  2. habitat – lived in different habitats
  3. behavioral – courtship displays differ
  4. gametic – eggs and sperm are incompatible
  5. mechanical – male and female reproductiv structures are incompatible
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21
Q

What are the three mechanisms of postzygotic reproductive isolation?

A
  1. hybrid viability – hybrid offspring do not develop normally and die as embryos
  2. hybrid sterility – hybrid offspring mature but are sterile as adults
  3. hybrid breakdown
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22
Q

Define the phylogenetic species concept

A

Species are the smallest monophyletic groups on the tree of life

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23
Q

define monophyletic group

A

a clade or lineage. an ancestral population, all of its descendants, and only those descendants.

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24
Q

How do we identify monophyletic groups?

A

synapmorphies

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25
Q

What is a synapmorphy?

A

a trait found in certain groups of organisms and their common ancestors but is missing in more distanct ancestors

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26
Q

What are the advantages and disadvantages of the phylogenetic species concept?

A

Pro:

  1. can be applied to any population.
  2. logical because different species have different synapmorphies only if they are isolated from gene flow and have evolved independently

con:

  1. carefully estimated phylogenies are available only for a small subset of populations.
    2.
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27
Q

What begins speciation?

A

the reduction or elimination of gene flow between species, causing genetic isolation

28
Q

What is allopatry?

A

the state of being geographically separated – (“different homeland”) – species that are separated.

Speciation that begins with geographic isolation is allpatric speciation.

29
Q

How does geographic isolation occur?

A
  • dispersal
  • vicariance, the physical splitting of a habitat
30
Q

Give an example of allopatric speciation by dispersal

A

Finches colonizing a new island. Genetic drift (founder effect) and natural selection led to a new population with larger average beak size

31
Q

Define allopatric speciation by vicariance

A

If a new physical barrier – a mountain range or river splits the geographic range of a species, vicariance has taken place. This interrupts gene flow.

32
Q

Define living in sympatry

A

“together homeland.” populations living close enough to one another to make interbreeding possible live in sympatry.

33
Q

Define sympatric speciation

A

speciation that occurs even though populations live in sympatry

34
Q

What types of events can initiate sympatric speciation?

A
  1. external events like disruptive selection for extreme phenotypes
  2. internal events like chromosomal mutations
35
Q

Give an example of sympatric speciation by disruptive selection

A

apple maggots and hawthorne maggots live in geographical proximity but experience prezygotic reproductive isolation because they evolved specificity for particular fruit environments.

36
Q

Define polyploidy

A

When an error in meiosis or mitosis results in a doubling of the chromosome number

37
Q

what are the two types of polyploids?

A

autopolyploids

allopolyploids

38
Q

define autopolyploid

A

individuals produced when a mutation results in a doubling of chromosome number and the chromosomes all come from the same species

39
Q

define allopolyploidy

A

individuals who are created when parents that belong to different species mate and produce an offspring with two different sets of chromosomes

40
Q

Describe what happens if 2n individual can make 4n offspring through mutation

A

The 4n offspring produce 2n gametes (unlike 2n individuals that make n gametes) and so even if they are able to mate, the resultant 3n (2n + n) offspring are sterile. 4n individuals could mate properly with other 4n individuals. Speciation happened in one generation!

41
Q

Describe the formation of an allopolyploid

A

2n parents with different numbers of chromosomes (say, 2n = 6 and 2n = 4) produce n gametes (3 and 2); they form hybrid offspring that is effectively n = 5 and is sterile. Then an error in mitosis happens before meiosis, doubling the chromosome number and creating offspring 2n = 10. Now meiosis can take place because each chromosome has a homolog.

42
Q

Why are polyploids so successful and why is polyploidy so common among plants?

A

Polploids have more heterozygosity

Polyploids can tolerate higher levels of self-fertilization because they are not as affected by inbreeding depression

genes on duplicated chromosomes can diverge independently, increasing genetic variation

43
Q

What happens when isolated populations come into contact and there is no prezygotic isolation?

A

Populations can fuse and gene flow erases distinctions over time

reinforcement

hybrid zones

speciation by hybridization

extinction of one population

44
Q

What is reinforcement

A

Reinforcement is when formerly isolated populations have difficulty interbreeding because of postzygotic barriers

45
Q

What is adaptive radiation?

A

many species evolving rapidly from a common ancestor due to environmental conditions in isolation

46
Q

What is convergent evolution?

A

similar characteristics evolving in unrelated species via adaptations to similar conditions. (marsupials + flying squirrels)

47
Q

Define homology

A

similarity in organisms due to common ancestry

48
Q

define homoplasy

A

similarity in organisms due to reasons other than common ancestry

49
Q

What are the two mechanisms that trigger adaptive radiations?

A

new resources - ecological opportunity

new ways to exploit resources - morphological innovation

50
Q

What are the five characteristics of life?

A

Composed of cells

reproduce using DNA

acquire energy from environment

grow and develop

maintain homeostasis

51
Q

who first observed cells?

A

Hooke and Leeuwenhoek

52
Q

define Spontaneous generation

A

Life on earth was believed to have developed from nonliving matter that became ordered in molecular aggregates that could self-replicate and metabolize

53
Q

describe All cells from cells

A

All organisms are made of cells (pattern) and all cells come from preexisting cells (process)

54
Q

How might chemical/physical processes on earth have produced very simple cells?

A
  1. abiotic synthesis of small organic molecules
  2. joining of small organic molecules into macromols
  3. packaging molecules into protobionts
  4. origin of self-replicating molecules
55
Q

What was earth’s early atmosphere like?

A

Reducing – not much oxygen. Miller-Urey may have replicated biogenesis conditions

56
Q

what experimental evidence shows how monomers could be joined into macromols?

A

dripping monomers onto hot rock can cause them to form polymers. Waves could have washed monomers onto hot rocks and then back into th esea.

57
Q

What are protobionts?

A

aggregates of abiotically produced molecules surrounded by a membrane that can maintain an internal chemical environment. can repdocue and do simple metabolism.

58
Q

Give an example of a protobiont

A

liposomes

59
Q

What was likely the first genetic material?

A

RNA molecules called ribozymes, not DNA

60
Q

What was Linnaeus’s classification system for life?

A

Two kingdoms: Animalia and Plantae

61
Q

What was Whittaker’s classification of life?

A

Five kingdoms:

Prokaryotes (Monera)

Eukaryotes (protista, plantae, fungi, animalia)

62
Q

What was Wose’s classification system for life?

A

Three domains: bacteria and archaea (prokaryotes)

eukarya (eukaryotes)

63
Q

Descirbe the characteristics of archaea

A
  • Many prokaryotic characteristics:
    • no nuclear envelope or organelles
    • small genome
    • circular chromosome
  • Some similarities with eukaryotes
    • histones with DNA
    • characteristics of DNA synthesis and transcription/translation
    • ribosomal size
64
Q

Describe the characteristcs of the three domains

A

All three have metabolism (ATP), genetic code, and ribosomes

Bacteria are simple

Archaea and Eukarya have histones

65
Q
A