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?
A. 1
B. 4
C. 2
D. 3
E. 5
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?
E. 5
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 5 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?
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