Based on the phylogeny shown, which characteristic is homoplastic?

Question

A.  tree

B.  needles

C.  flowers

D.  seeds



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

· Consider the different answer options. Which can you rule out?

 

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.  tree

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 Homoplastic means that a character arose by convergent evolution. It is not a synapomorphy because it arose in separate unrelated lineages.
 
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.
        o Each nested clade is defined by a new shared derived character. These new characters are typically labeled on the branch.
 
Consider Possibilities
· Consider the different answer options. Which can you rule out?
        o Are needles, flowers, or seeds homoplastic? No, because they each only appear once on the tree.
 
Choose Answer · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o The character “tree” is homoplastic, because it appears in different clades on the tree.
        o There must have been a preponderance of other characters that made it obvious that trees are the result of convergent evolution in multiple lineages.
 
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 character is homoplastic.
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that the feature “tree” in the phylogeny is homoplastic, since it appears in multiple clades?