Digital SAT Reading and Writing Practice Question #431

Biologist Dr. Aris studies a population of *Anolis* lizards that were relocated to a significantly cooler island a decade ago. Over this 10-year period, the lizards have developed markedly shorter limbs, a morphological trait known to conserve body heat. Some researchers argue this shift is a textbook example of phenotypic plasticity—an individual organism’s physical adaptation to its environment during its own lifetime without any alteration to its DNA. Dr. Aris, however, hypothesizes that the limb shortening is driven by rapid genetic adaptation through natural selection across multiple generations. Which finding, if true, would most directly support Dr. Aris's hypothesis over the phenotypic plasticity hypothesis?