Populations of a plant species have been found growing in the mountains at altitudes above 2,500 meters. Populations of a plant that appears similar, with slight differences, have been found in the same mountains at altitudes below 2,300 meters. Describe a plan for collecting two kinds of data that could provide a direct answer to the question: do the populations growing above 2,500 meters and the populations growing below 2,300 meters represent a single species?