Theme 5A/B: Evolutionary patterns Flashcards

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1
Q

What’s an extant species?

A
  • A living species
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2
Q

What’s a phylogenetic tree?

A
  • A branching diagram that shows the relationships between species, often according to the time since a common ancestor
  • Acts as a hypothesis for evolutionary relationships
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3
Q

What’s the difference between a phylogram and a cladogram?

A
  • Phylogram - a tree where the branch lengths represent the amount of inferred evolutionary change/time
  • Cladogram - a tree where all branches are of equal length
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4
Q

What’s a sister group?

A
  • Two species that share a unique common ancestor not shared by any other species or group
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5
Q

What’s the difference between a character and its character states?

A
  • A character describes a specific trait, while a character state describes the variation within that trait.
  • Ex. A character being a flower, while the character states including blue flowers or yellow flowers
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6
Q

What are homologous characters?

A
  • Characteristics that are shared because of common ancestry
  • Ex. the four limbs of tetrapods
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7
Q

What are analogous characters?

A
  • Similarity in appearance but not in origin
  • Shared because of convergent evolution
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8
Q

What are synapomorphies?

A
  • Homologies shared by some, but not all species. Help build phylogenetic trees
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9
Q

What does the principle of parsimony describe?

A
  • The phylogeny requiring the fewest evolutionary changes is the best estimate of the true phylogeny (most parsimonious)
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10
Q

What are the different kinds of phylogenetic groups?

A
  • Monophyletic - includes a CA and all of its descendants
  • Paraphyletic - includes a CA and some, but not all of its descendants
  • Polyphyletic - Does not include the CA
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11
Q

What’s the difference between anagenesis and cladogenesis?

A
  • Anagenesis - speciation where the ancestor species is wholly replaced by new species
  • Cladogenesis - Parent species splits into two new species
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12
Q

What’s the difference between graduated evolution and punctuated evolution?

A
  • Graduated - Slow and steady gradual evolution
  • Punctuated - Rare and rapid events of branching speciation
    *seems to be a combination of the two
    *fossil record shows the idea of punctuated evolution
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