Chap. 26 - PP/Quiz Flashcards
Phylogeny
The evolutionary history of a species or group of species
What is systematics used for?
Classifying organisms
Determining their evolutionary relationships
What are the 3 schools of Systematics?
Traditional taxonomy
Numerical taxonomy
Cladistics or Phylogenetics
3 Schools of Systematics
a. Traditional taxonomy: based on ______ in ______
b. Numerical taxonomy: classifies organisms by ____ (numeric, ____ degree of similarity)
c. ______ or ______: based on shared, derived characteristics
a. similarities, morphology
b. similarity, quantifiable
c. Cladistics, phylogenetic
Are phylogenetic trees based on phenotypic similarity?
No
T/F Phylogenetic tree branch points mean exact ages
False
Just by looking at a basic phylogenetic tree, can you say which of the two lineages from a branch point evolved earlier?
No
What does a phylogenetic tree use to classify organisms?
“patterns or relatedness” of DNA versus taxa
Phylogenetic Tree:
Which grouping includes a common ancestor along with ALL of its descendants?
Monophyletic
T/F The polyphyletic looks at a common ancestor along with SOME descendants
False
Phylogenetic Tree:
Which grouping looks at only descendants WITHOUT including a common ancestor?
Polyphyletic
With cladograms, the internode represents a what?
Common ancestor
What does a node on a cladogram represent?
speciation event
Describe the difference between homologous and convergent/analogous traits:
Homologous traits are derived from a common ancestor, but convergent/analogous traits are similar but derived from DIFFERENT ancestors
George is looking at two species of turtles. He sees a trait (e.g., eye stripe) that is the same in both species. If he finds that the turtle from which both species came from has this same trait, than that eye stripe trait would be considered a ___ in both of the species he is studying.
homologous
While on trip to the Amazon River, Charlotte notices the wings of a big insect and a bat that came and ate it. Later, it occurs to her how much the insect’s and bat’s wing reminds her of a bird’s wing. Considering the relatedness of those 3 organisms, the similar wing trait in all three would be considered what kind of trait?
analogous
A researcher is looking at a similar trait in two closely related taxa that used to be different, but being in the same environment has led that trait in both species becoming more alike. This is specifically an example of ___.
parallelism
Homoplasy is when two species share a similar or same trait because they both got it from a recent common ancestor. T/F
False
Which methodology used to construct a phylogeny is based on having a common ancestor and evolved characters or traits used to distinguish different lineages from that common ancestor?
Cladistics
When looking at two species (A & B) in a phylogenetic tree that came from the same common ancestor and compared those two to a thrid species (C) that, while it does share some common character states with species A & B, it does not share a common ancestor. Species C would be considered a ___.
outgroup
Sometimes, data from Random Amplification of Polymorphic DNA and RFLP analyses are used to help determin likelihood of shared or similar traits in Cladistic Analysis.
True
If a trait is similar but derived from different, but still closely related, ancestors, it is an example of _____?
Parallelism
What two traits together are referred to as HOMOPLASY?
Convergence and parallelism
Is parallelism an example of homology?
No, homoplasy (similar but derived from closely related ancestors)
Constructing Phylogenies:
When you construct a phylogeny using phonetics, you don’t distinguish between what two traits?
Similar Inherited traits and similar derived traits
What type of phylogeny is based on a common ancestor and evolved characters to distinguish different lineages?
Cladistic Phylogeny
An ancestor species and all its descendants
Clade
PRINCIPLES OF CLADISTIC ANALYSIS
a. ___ ____ _____ from a common ancestor to the various taxa in a group are used to reconstruct a phylogeny
b. There can be an ______ “group of organisms of interest/studied”
c. The outgroup is a ____ closely related to the in-group but not a part of it
d. The ______ is assumed to possess the character states of the ___ ______ to all the in-group taxa
a. character state changes
b. in-group
c. taxon
d. outgroup, common ancestor
What are shared primitive characters? In what analysis are they used?
Character states shared by the out-group and in-group taxa
Character states shared by the out-groups and in-group taxa
Shared primitive characters
Character states among in-group taxa that differ from the character state in the ______ are called ____ ____ ____ and are said to be apomorphic
outgroup, derived character states,
CLADISTIC ANALYSIS
Derived character states are states that differ between what two groups? What are they said to be?
in-group and out-group, apomorphine
What is the primary goal of a phylogeny?
Produce a phylogeny using the fewest number of character state changes
Which length of phylogeny will most reflect the evolutionary history of the in-group?
Parsimonious
CLADISTIC ANALYSIS
What type of characters produce less stable trees?
Morphological
CLADISTIC ANALYSIS
What characters are more reliable than morphology? (hint: excellent for “shallow” cladistic analysis)
DNA data
RFLPs, RAPDs, sequences
If you wanted to show the true evolutionary history/relatedness between related organisms, would you use a phylogeny or cladogram?
Phylogeny/Phylogram
Viral infections, organism fusion, and transposable elements/plasmids are caused by what?
Lateral Gene Transfer
Name 3 instances when homoplasy increases:
a. more taxa are added
b. more characters are added
c. more depth of the phylogeny increases
What is homoplasy?
An analogous structure or molecular sequence that has evolved independently in two species
When morphological characters are used in a phylogram, will observed homoplasy be higher or lower?
Higher
When molecular characters are used to construct a phylogram, will the phylogram be higher or lower than when morphological characters are used?
Lower
As _____ increases, the number of shortest trees increases in a phylogram. This reduces what?
homoplasy, predictability of phylogeny
What is used to describe the relative amount of homoplasy in a phylogram?
Consistency Index (CI)
If CI = 1, what does this mean?
No homoplasy
Only 1 shortest tree (parsimonious)
As C1 gets smaller, what two things increase?
Homoplasy increases
Number of shortest trees increases
Below the species level, CI is close to what?
1
When analyzing taxa above the genus level, Ci values are much more ____. They can dip as low as 0.1 or so.
variable
If you find a phylogeny with an extremely high level of homoplasy, this may be inconsistent with what?
Creation model
Even assuming an evolution model, what should increase as phylogeny goes deeper?
Homoplasy
