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Bild 3 > Lecture 6: phylogenetic trees > Flashcards

Lecture 6: phylogenetic trees Flashcards

1
Q

phylogeny

A

evolutionary history of a group of species.

  • branching diagram that show relationships among taxa and patterns of ancestry
  • they are just a hypothesis
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2
Q

Taxonomy (classification)

A

how organisms are classified and named

-defining biological organisms by shared characteristics and then giving names to those groups

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3
Q

Systematics (phylogeny)

A
  • study of the diversification of living organisms and the relationships of these organisms through time
  • can visualize these evolutionary relationships with a phylogenetic tree
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4
Q

Biological Classification

A 
Domain
Kingdom
Phylum
Class
Order 
Family
Genus
Species

“Dang, Katy Perry cooked omelets for Gwen Stefani”

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5
Q

Homology

A
  • similarity due to inheritance of traits from a common ancestor
  • most important character when building phylogeneitc trees
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6
Q

Homoplasy

A
  • similarity due to convergent evolution
  • characters shared between two or more species NOT present in a common ancestor
  • analogous character
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7
Q

Symplesiomorphy

A
  • shared ancestral character
  • character that originated in an ancestor of the taxon
  • Ex: backbone is a shared character for birds
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8
Q

Synapomorphy

A
  • shared DERIVED character
  • character that is UNIQUE to a clade
  • useful for telling us about phylogenetic relationships
  • Ex: feathers are a shared derived character for birds
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9
Q

Clade

A
  • a monophyletic group
  • group of organisms that are more closely related to each other than to any other group, implying a more recent common ancestor
  • an organism and all its descendents
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10
Q

Protobacteria

A
  • thought to be the origin of mitochondria

- Ex: Rhizobium, bacteria that live in close association with plant roots where they fix nitrogen from the atmosphere

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11
Q

Gram- Positive Bacteria

A

-name is in reference to their cell wall; gram positive wall
-Ex: staphylococcus, streptococcus
—> commonly found on our bodies at all times
but certain species can cause illness

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12
Q

Cyanobacteria

A
  • likely the origin of choloplasts
  • they are aquatic
  • live in fresh or salt water
  • they are photosynthetic
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13
Q

Spirochetes

A
  • spiral or cork screwed shaped

- pathogens causing Lyme disease and syphilis

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14
Q

Extremophiles

A

-extreme “loving” organisms that live in extreme environments

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15
Q

Halophile

A
  • Live in salty, highly saline conditions

- Ex: great salt lake

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16
Q

Thermophile

A
  • Live in extremely hot environments

- hot springs, deep sea hypothermal vent

17
Q

Methanogens

A
  • Live in environments with out oxygen present, anoxic environments
  • buried under ice, swamps, guts of organisms
18
Q

Monophyletic group

A
  • contain common ancestor and ALL descendants
  • only valid grouping for systematists
  • can cut off group with just ONE cut
19
Q

Paraphyletic group

A
  • contains common ancestor and SOME but not all descendants

- can cut off with two cuts

20
Q

Polyphyletic group

A

-taxa with DIFFERENT recent common ancestor

21
Q

Ingroup

A

-group of taxa that we are interested in

22
Q

Outgroup

A
  • group we are comparing our group to

- used to help define ingroup

23
Q

Morphological data

A
  • using characters (homologies) to determine if common ancestor existed
  • can build a matrix to see who shares what features; if they share there must have been a recent common ancestor
24
Q

DNA Sequence data

A
  • take a particular portion of genome or DNA and align that portion with the same portion of another species
  • look for differences; fewer differences= more similar
25
Q

Sister taxa

A

-two groups that share an immediate common ancestor and are each other’s closest relatives

26
Q

Topology

A
  • branching pattern
  • always tells you something about the evolutionary relationships of organisms
  • tells us who is related to who and how recently they diverged
27
Q

Branch length

A
  • not always informative
  • the information on patterns of evolutionary descent is the same regardless of the lengths of the branches= topology remains the same
  • can be useful if tree is time scaled
28
Q

Outgroup comparisons

A
  • can distinguish between ancestral and derived character states
  • gives us direction of character change from one species to another
29
Q

Parsimony

A
  • picking best phylogenetic tree based on the assumption that the simplest explanation is most likely to be correct
  • the fewest number of evolutionary changes is the best tree
30
Q

Molecular clocks

A
  • provide a way of estimating the absolute age of evolutionary change
  • lets us put a time scale on how fast evolutionary change is happening
  • assumes that genetic change (DNA sequences) happens at a constant rate–> most mutational change is neutral
  • can calibrate how fast the DNA change happens relative to the fossil record to come up with a clock or scale

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