Which examples would be considered different species under the biological species concept? Check all that apply.A) Two bear species are able to breed in zoos, but have separate ranges in nature.B) Two skunk species look morphologically similar, but are unable to interbreed.C) Two snake species look different, but often form fertile hybrids.D) Two plant species with no gene flow between them.E) Two tree species have different leaf shapes, but form hybrids in their overlapping ranges.

Question

What will be an ideal response?

Answer 1

A, B, D

Clarify Question
• What is the key concept addressed by the question?
        o This question addresses the biological species concept.
• 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 the biological species concept?
        o In 1942 Ernst Mayr set forth the biological species concept, which defines species as "groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups."
        o In other words, a species is composed of populations whose members mate with each other and produce fertile offspring. Populations whose members do not mate with each other or who cannot produce fertile offspring are members of different species.
        o Some have criticized the biological species concept because in recent years, biologists have detected much greater amounts of interspecies hybridization than was previously thought to occur between populations that seem to coexist as distinct biological entities.
        o Botanists have always been aware that plant species often undergo substantial amounts of hybridization, so many botanists have long felt that the biological species concept is misnamed and only applies to animals.

Choose Answer
• Given what you now know, what information and/or problem-solving approach is most likely to produce the correct answer?
        o Two snake species look different, but often form fertile hybrids. Would they be considered separate species? No, because they are not reproductively isolated.
        o Two tree species have different leaf shapes, but form hybrids in their overlapping ranges. Would they be considered separate species? No, because they are not reproductively isolated.
        o Two skunk species look morphologically similar, but are unable to interbreed. Would they be considered separate species? Yes, because they are reproductively isolated.
        o Two plant species have no gene flow between them. Would they be considered separate species? Yes, because they are reproductively isolated.
        o Two bear species are able to breed in zoos, but have separate ranges in nature. Would they be considered separate species? Yes, because in nature they are reproductively isolated.

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 the biological species concept only distinguishes populations as separate species when they are reproductively isolated in nature?