Which type of symbiotic relationship benefits one species while the other is not significantly affected?

In a symbiotic relationship where one species benefits and the other is not significantly affected, the correct term is commensalism. This type of relationship allows one organism, the commensal, to gain advantages such as food, shelter, or transportation from its partner, the host, without harming or benefiting the host organism in any meaningful way.

For instance, epiphytic plants growing on trees can exemplify commensalism; they receive light and moisture from the atmosphere without taking nutrients or harming the tree they rely on for support. This distinction is key in understanding the nature of commensal relationships, where the interaction is not detrimental or beneficial to the host. Mutualism, in contrast, involves both species benefiting, while parasitism implies one species benefits at the expense of the other. Competition involves struggles between species for the same resources but does not imply a direct symbiotic interaction.