[Campbell Biology P.557] In the example of Mechanical Isolation described in Figure 24.3, wh... | Practice Question

In the example of Mechanical Isolation described in Figure 24.3, what specific morphological characteristic in Bradybaena snails directly causes the reproductive barrier?

  • A: Differences in shell color.
  • B: Incompatible mating calls.
  • C: The direction of their shell spirals, preventing alignment of genital openings.
  • D: Differences in preferred food sources.

Explanation

The passage explicitly states: 'But if a snail attempts to mate with a snail whose shell spirals in the opposite direction g , the two snails' genital openings indicated by arrows will not be aligned, and mating cannot be completed.' This directly points to the direction of shell spiraling as the mechanical barrier.