Digital SAT Reading and Writing Practice Question #581

Researchers theorize that the *Ranitomeya imitator* frog evolved its vibrant visual patterns and acoustic calls to mimic the highly toxic *Ranitomeya variabilis* frog, thereby deterring predators through a phenomenon known as Müllerian mimicry. However, a prominent evolutionary biologist challenges this narrative, noting that isolated populations of *R. imitator* in regions completely lacking the toxic *R. variabilis* exhibit the exact same acoustic warning calls. Therefore, the biologist argues, the acoustic call must have evolved independently of any evolutionary pressure to mimic *R. variabilis*. Which finding, if true, would most directly weaken the evolutionary biologist's conclusion?