In that case, the answer is commensalism. This is best described as commensalism, though an argument could be made for mutualism. The future has always been built on the past and present. Of course this would depend on what type of classification was being used. But, in general, molecular data is used to discern relationships between species.
Molecular data form the heart of genetics and subsequently evolution.
Answers will vary. Read the legend by Figure 21.4. 5. Physical limitations of being able to find all species. Answers will vary. The McGraw-Hill Companies.