Question

Give an example of parasitism, commensalism, and mutualism, and show that it is not always easy to distinguish between these relationships.

Answer 1

Examples of interactions:

• Parasitism: A parasite like Cuscuta obtains food from a host plant without killing it.
• Commensalism: Barnacles live on whales and benefit without harming or benefiting the whale.
• Mutualism: Lichens are a mutualistic association between fungi and algae where both benefit.

Distinguishing these interactions is not always easy because interactions can shift. For example, a commensal might harm its host under certain conditions, becoming parasitic. Similarly, mutualism requires both species to benefit, but sometimes benefits may be subtle or indirect, making categorization challenging.