Diversification of mammals after the extinction of the dinosaurs is considered an adaptive radiation because a few mammal species rapidly evolved into most of the current mammalian lineages in a relatively short amount of time. This diversification was partially driven by the evolution of endothermic homeostasis in mammals, which is an example of

Question

A.  allopatric speciation.
B.  reproductive isolation.
C.  a key innovation.
D.  hybridization.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
 
Gather Content
  · What do you already know about adaptive radiation?
 
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

C.  a key innovation.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses adaptive radiation.
· 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.
 
Gather Content
  · What do you already know about adaptive radiation?
        o Adaptive radiations are particularly common in situations in which a species occurs in an environment with few other species and many available resources.
        o One example is the creation of new islands through volcanic activity, such as the Hawaiian and GalaÌpagos Islands. Another example is a catastrophic event leading to the extinction of most other species, a phenomenon termed mass extinction.
        o Adaptive radiation can also result when a new trait, called a key innovation, evolves within a species allowing it to use resources or other aspects of the environment that were previously inaccessible. Classic examples of key innovation leading to adaptive radiation are the evolution of lungs in fish and of wings in birds and insects, both of which allowed descendant species to diversify and adapt to many newly available parts of the environment.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o The evolution of endothermic homeostasis by the early mammals is an example of a key innovation.
 
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 The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that sometimes adaptive radiations are promoted by the evolution of a key innovation – a major evolutionary advance?