Which observation would best support the occurrence of character displacement for body size in a salamander species pair in sympatry?

• A. Greater similarity in body size in sympatry
• B. No change in body size
• C. Greater difference in body size in sympatry
• D. Body size is smaller in all cases

Answer: (C)

Character displacement happens when competing species living in the same area evolve to reduce overlap in resource use, often by diverging in a trait like body size. If two salamander species that occur together (sympatry) show a larger difference in body size than when they occur separately (allopatry), that difference helps them partition resources and minimize competition. So, observing a greater body-size difference in sympatry supports the idea that selection is driving divergence to avoid overlap.

Seeing more similarity in body size in sympatry would suggest they’re not shifting to reduce competition; no change in size wouldn’t indicate divergence due to coexistence; and size being smaller in all cases is an absolute statement that doesn’t reflect the scenario of competing species coexisting.