Step 1: Understanding the Concept:
Population interactions are described by the effect they have on the species involved: positive (+), negative (−), or neutral (0).
Step 2: Detailed Explanation:
1. Amensalism (0, −): One species is inhibited or harmed, while the other is unaffected. An example is a large tree shading out a small plant or the production of antibiotics by fungi (like {Penicillium}) that kill bacteria.
2. Commensalism (+, 0): One benefits, the other is unaffected (e.g., an orchid growing on a mango branch).
3. Parasitism (+, −): One benefits (parasite) and the other is harmed (host).
4. Mutualism (+, +): Both species benefit from the interaction (e.g., lichens).
Step 3: Final Answer
The interaction described is amensalism.