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BISC 102 > Lecture 6 > Flashcards

Lecture 6 Flashcards

1
Q

What is phylogeny a study of?

A
  • study of the evolutionary history of related groups of organisms
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2
Q

what is taxonomy

A

naming and classifying

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3
Q

What is a phylogenetic tree

A
  • an illustration of a hypothesis about the relationships among “taxa” (taxonomic categories: species, genera, families, etc.) based on currently available information (open to change)
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4
Q

How are organisms grouped into phylogenetic taxa?

A
  • based on unique shared traits that result from common ancestry (homologies)
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5
Q

what are synapomorphies?

A
  • a trait found in 2 or more taxa that are present in their most recent common ancestor but is missing in more distant ancestors
  • unique to this group
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6
Q
  • What does classic taxonomy lack?
A
  • useful for creating and organizing groups, but provides limited information about evolutionary relationships within and between groups
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7
Q

What is modern tree-building based on?

A
  • modern tree-building is based on CLADISTICS, a series of principles that define a CLADE, a group of organisms that meet the requirements of sharing evolutionary relationships: a common ancestor and all known descendants
  • An evolutionary tree is technically called a CLADOGRAm
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8
Q

What are sister groups on the tree?

A
  • share a recent common ancestor at the node where their branches meet
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9
Q

what is a branch

A
  • a line representing a population through time`
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10
Q

What is the root

A

the most ancestral branch in the tree

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11
Q

What is the tip (terminal node)?

A

endpoint of a branch

  • represents a living or extinct group of genes, species, families, phyla, or other taxa
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12
Q

What is an endpoint?

A

a taxon that diverged prior to the taxa that are the focus of the study

  • helps to root the tree
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13
Q

What is the node (fork)?

A

a point within the tree where a branch splits into 2 or more branches

  • the node represents that most recent common ancestor of the descendant groups
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14
Q

what is polytomy?

A
  • a node that depicts an ancestral branch dividing into 3 or more (rather than 2) descendant branches
  • usually indicates that insufficient data were available to resolve which taxa are more closley related
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15
Q

What is a character or trait

A
  • any genetic, morphological, physiological, development, or behavioural characterisitc to be studied
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16
Q

what is an ancestral trait

A

a character that existed in an ancestor

17
Q

what is a derived trait

A

one that is a modified form of the ancestral triat, found in descendant

18
Q

What is the cladistic approach based on?

A
  • based on the principle that relationships among species can be reconstructed by identifying shared derived traits, called synapomorphies
19
Q

What is a monophyletic group?

A
  • an evolutionary unit that includes an ancestral population and all of its descendants, but no others
20
Q

What is homology?

A
  • similarity in organisms due to common ancestor
  • traits inherited from a common ancestor, even though they may appear different (after descent with modification)
21
Q

What is homoplasy?

A
  • similarity in organisms due to reasons other than common ancestry
  • traits (analogous in function) may appear similar but are not inherited from a common ancestor
  • this is the result of convergent or parallel evolution
  • not helpful for tree-building
22
Q

What is a polyphyletic group?

A
  • an unnatural group that does not include the most recent common ancestor
23
Q

What is a paraphyletic group?

A
  • a group that includes an ancestral population and some of its descendants, but not all
  • loss of trait
24
Q

What is a convergent evolution

A
  • the independent evolution of similar traits in distantly related organisms due to adaptation to similar environments and lifestyles
25
Q

What are the 3 tools for creating a phylogeny and studying history?

A
  • fossils are evidence for history of life on earth, extinction, and evolution
  • comparative anatomy and embryology provide evidence of ancestor/descendant relationships
  • DNA sequences are currently the most widely used evidence in creating phylogenies
26
Q

review flower homology in angiosperms

A

although flowers are very diverse in shape, color, and other traits, they:

  • have structural similarity; petals and sepals are modified leaves
  • Share a genetic similarity for flower development and overall genomics
  • evidence. unites them as true monophyletic clade, derived ultimately from a common ancestor

BISC 102 (23 decks)

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