Which of the following best distinguishes mutualism from commensalism and parasitism in ecological communities?

• A. In mutualism, one species benefits and the other is harmed; in commensalism, both are harmed; in parasitism, both benefit.
• B. In mutualism, both species are harmed; in commensalism, both benefit; in parasitism, one benefits and the other is unaffected.
• C. In mutualism, both species are unaffected; in commensalism, both are harmed; in parasitism, one benefits and the other is unaffected.
• D. In mutualism, both species benefit; in commensalism, one benefits and the other is unaffected; in parasitism, one benefits and the other is harmed.

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by understanding the definitions of mutualism, commensalism, and parasitism. Mutualism is a type of ecological interaction where both species involved benefit from the relationship.
2. Step 2: Define commensalism. In commensalism, one species benefits while the other species is neither harmed nor helped (unaffected). This distinguishes it from mutualism and parasitism.
3. Step 3: Define parasitism. In parasitism, one species (the parasite) benefits at the expense of the other species (the host), which is harmed. This is a key difference from mutualism and commensalism.
4. Step 4: Compare the three interactions. Mutualism involves mutual benefit for both species, commensalism involves benefit for one species with no effect on the other, and parasitism involves benefit for one species while harming the other.
5. Step 5: Use the definitions to evaluate the options provided in the problem. The correct answer is the one that accurately describes mutualism as both species benefiting, commensalism as one species benefiting and the other being unaffected, and parasitism as one species benefiting while the other is harmed.