Final answer:
The principles of linkage and recombination were discovered using the fruit fly, Drosophila melanogaster, which led to the creation of the first genetic maps and advanced our understanding of genetic processes.
Step-by-step explanation:
The principles of linkage and recombination were discovered using the fruit fly, Drosophila melanogaster. This discovery allowed for the establishment of foundational concepts in genetics, such as the idea that genes can be linked on the same chromosome and can recombine through the process of crossing over. It was through studies on Drosophila by scientists like Thomas Hunt Morgan and his students that the first genetic maps were created, directly observing how genes could be physically linked to each other and could exhibit recombination that reshuffles genetic information during gamete formation.