Variation in pelvic spine among lake populations suggests what?

• A. Local adaptation to the environment.
• B. Random genetic drift with no selection.
• C. There is no evidence of adaptation.
• D. Variation implies global uniform traits.

Answer: (A)

Variation in pelvic spine among lake populations reflects local adaptation to the environment. Different lakes present distinct ecological pressures—such as predator types, prey availability, or water conditions—and natural selection favors the pelvic spine length that best improves fitness in each specific setting. This pattern, seen repeatedly across populations, is evidence of adaptation driven by environmental differences rather than random chance. It also fits with the idea that traits can vary regionally rather than being globally uniform, driven by the local ecology.