NASA Scientists send a small population of dogs to a new planet in order to test if it will be hospitable for human colonization. Through a random lottery, only Great Dane and St. Bernard dog breeds are sent, and the resulting population consists of tall, longhaired dogs. After 100 years these dogs return to Earth and are no longer able to mate with Earth dogs. This scenario is an example of

Question

A.  allopatric speciation through genetic drift.
B.  allopatric speciation through natural selection.
C.  sympatric speciation through genetic drift.
D.  sympatric speciation through natural selection.

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 genetic drift?
 
Choose Answe
· 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.  allopatric speciation through genetic drift.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses genetic drift.
· 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 genetic drift?
        o Random changes may cause reproductive isolation.
        o Given enough time, any two isolated populations will diverge because of genetic drift.
        o In some cases, this random divergence may affect traits responsible for reproductive isolation, and speciation may occur.
 
Choose Answe
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o In this hypothetical example of the dogs on a distant planet, the astronaut-dogs are far away from Earth dogs, thus they are allopatric populations.
        o The incompatibility is likely due to the small size of the population, rather than any natural selection against hybridization – in other words, due to random genetic changes from genetic drift.
 
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 a small distant population is likely to become reproductively isolated by allopatric genetic drift?