The table shows the distribution of traits (A-E) in six extant species (1-6). A "0" indicates the ancestral condition, while a "1" indicates the derived condition. Which trait is represented by the greatest number of plesiomorphies?

Question

A.  A

B.  B

C.  C

D.  D

E.  E



Clarify Question

· What is the key concept addressed by the question?

· What type of thinking is required?

· What key words does the question contain and what do they mean?

 

Gather Content

· What do you already know about cladistics?

 

Consider Possibilities

· What other information is related to the question? Which information is most useful?

 

Choose Answer

· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

  Reflect on Process

· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

E.  E

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses cladistics.
· What type of thinking is required?
        o This question is asking you to analyze the information given, using logic, to dissect the problem and determine the answer.
· What key words does the question contain and what do they mean?
        o Traits are features of an organism, used as data to build a tree.
        o Extant species are still alive – i.e., not extinct.
        o The ancestral condition of a trait is the original condition; the derived condition is the more newly evolved version.
        o Plesiomorphies are ancestral characters.
 
Gather Content
· What do you already know about cladistics?
        o Cladistics is the method used to construct a cladogram — a graphically represented hypothesis of evolutionary relationships.
        o Only shared derived characters (synapomorphies) are useful for inferring phylogenies, and they must be contrasted to an outgroup that has the ancestral characters.
 
Consider Possibilities
· What other information is related to the question? Which information is most useful?
        o A plesiomorphy is an ancestral character, so the question is asking which trait is most often in the ancestral condition in this data chart.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o The ancestral state is marked as “0” in this chart, so the trait represented by the most plesiomorphies is E (with 4/6).
  Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked which of the traits is represented by the most pleiomoprhies.
        o The question required you to analyze the information given, using logic, to dissect the problem and determine the answer.
        o Did you recognize that the trait with the most “0”s was the one with the most pleiomorphies?