You observe an interaction between two species. Removal of species A has a negative impact on species B. Removal of species B has a positive impact on species A. Which of the following is the most likely relationship between the two organisms?

• A. They have a mutualistic relationship.
• B. Their interaction is commensalism, as species B no longer benefits when species A is removed.
• C. They are competitors with a similar niche.
• D. Species B is a parasite that relies on species A.

Answer: (D)

Verified step by step guidance

1. Begin by understanding the types of species interactions: mutualism, commensalism, competition, and parasitism.
2. Consider the effect of removing species A: it negatively impacts species B, suggesting that species B depends on species A for some benefit.
3. Consider the effect of removing species B: it positively impacts species A, indicating that species B might be exerting some negative influence on species A.
4. Evaluate the options: mutualism would require both species to benefit, which is not the case here. Commensalism would mean species B benefits without affecting species A, which is also not true. Competition would mean both species are negatively impacted by each other, which doesn't fit the observations.
5. Conclude that the most likely relationship is parasitism, where species B benefits at the expense of species A, aligning with the observed effects of removal.