Are bat wings and bird wings homologous or homoplastic structures?

Question

_____  As examples of vertebrate forelimbs, they are homologous, but as wings they are homoplastic.
_____  As examples of vertebrate forelimbs, they are homoplastic, but as wings they are homologous.
_____  As vertebrate forelimbs and as wings, they are homologous.
_____  As vertebrate forelimbs and as wings, they are homoplastic.

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 homology?
 
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

__X__  As examples of vertebrate forelimbs, they are homologous, but as wings they are homoplastic.
_____  As examples of vertebrate forelimbs, they are homoplastic, but as wings they are homologous.
_____  As vertebrate forelimbs and as wings, they are homologous.
_____  As vertebrate forelimbs and as wings, they are homoplastic.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses homology.
· 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 Homologous structures arose from a common origin in a recent common ancestor.
        o Homoplastic structures arose by convergent evolution, separately in each lineage.
 
Gather Content
· What do you already know about homology?
        o Homologous structures arose once from a common ancestor.
        o Homoplastic structures, or convergent structures, have the same or similar functions, but arose independently.
        o It is not always as clear whether the same or different genes are responsible for convergent evolution.
 
Consider Possibilities
· What other information is related to the question? Which information is most useful?
        o We have learned that limbs in vertebrates arose once, and become highly modified in different lineages.
        o So the forelimbs of a mouse are homologous with the forelimbs of a lizard... or the (highly modified) forelimbs of a bird or bat. They are all homologous forelimbs.
        o Wings, on the other hand, evolved separately in the bats and birds. So bat wings and bird wings are not homologous wings. They are homoplastic.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o So considering the bat wing and the bird wing, we can say that they are homologous as examples of the vertebrate forelimb.
        o But, as examples of wings, they are not homologous – they are homoplastic. In other words, they are convergent.
        o This example illustrates why it is important to be specific when talking about homology. Some aspects of a feature may be homologous while others are not.
 
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 whether bat wings and bird wings are homologous or homoplastic.
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that as forelimbs, the two examples are homologous? But as wings, they are homoplastic?