Based on the phylogeny shown, the outgroup would be species

Question

A.  1.
B.  2.
C.  3.
D.  4.
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?

  Gather Content
· What do you already know about phylogenetic trees?

  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

A.  1.


Clarify Question
· What is the key concept addressed by the question?
        o This question addresses phylogenetic trees.
· 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 A phylogeny is an evolutionary tree which represents a hypothesis about patterns of relationship among species.
        o An outgroup is a distantly related species or group of species, relative to the group of species being focused on. The outgroup has ancestral characters, not the derived characters of the group of species in question.

  Gather Content
· What do you already know about phylogenetic trees?
        o A phylogenetic tree is a way of diagramming a hypothesis about evolution.
        o The tips of the twigs represent existing species. As one works down the tree, the joining of twigs and branches reflects the pattern of common ancestry back in time to the single common ancestor of all life.

  Possibilities · What other information is related to the question? Which information is most useful?
        o When a V-style tree is drawn with the Vs upwards, the highest nodes are the most recently-diverged species, and the lower nodes are older divergences between groups.

  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 is most distantly related, compared to the other species.
        o So the outgroup here would be the oldest, lowest node – group 1.
 
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 you to identify the outgroup from a phylogenetic tree.
        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 would be the most distantly related to the other species, with the lowest node?