Which term describes a close ecological relationship between two species living in proximity, often affecting both?

• A. Succession
• B. Symbiosis
• C. Species-Specific Relationship
• D. Stenothermal

Answer: (B)

Symbiosis describes a close ecological relationship between two species living in close proximity, often affecting both. This umbrella term covers interactions where the two species live together for extended periods, and the outcome can vary: mutualism (both benefit), commensalism (one benefits, the other is largely unaffected), or parasitism (one benefits at the expense of the other). In marine ecosystems, examples include the mutualism between coral and their symbiotic algae, or cleaner fish that remove parasites from larger fish. Succession refers to how communities change over time after a disturbance, stenothermal means tolerance to a narrow temperature range, and “species-specific relationship” isn’t a standard ecological term for this kind of close interaction.