The table shows the distribution of traits (A-E) in six extant species (1-6). A "0" indicates the ancestral condition, and a "1" indicates the derived condition. Which species would you designate as the outgroup?

Question

A.  1

B.  2

C.  3

D.  4

E.  5

F.  6



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?

 

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

F.  6

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 take what you already know and apply it to this unfamiliar situation.
· 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 The outgroup is the species (or group) with the most ancestral characters.
 
Consider Possibilities
· What other information is related to the question? Which information is most useful?
        o The “1”s are derived characters; the ‘”0”s are ancestral characters.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o The outgroup must be the species with the fewest synapomorphies and the most ancestral states (at least relative to the other species).
        o That would be species 6 since it has the most “0” traits.
 
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 species is the outgroup.
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that the outgroup has the most ancestral characters?
        o Did you try drawing the cladogram for this data?