Answer:
It was a follow-up controlled experiment that showed how a species can influence selection in another species.
Step-by-step explanation:
A follow-up (cohort) study is a type of study followed over time in order to determine the development of a particular outcome. Moreover, a controlled experiment is one in which conditions are controlled by the researcher, and thereby it is easier to determine the incidence of the outcome. In the case above described, researchers performed a follow-up controlled experiment in which they measured how a species can influence selective processes undergone by other species.