Caribou and reindeer are both herbivores whose diets consist of lichens and grasses. Which interaction is occurring between the caribou and the reindeer?

Commensalism is a type of interaction where one species benefits while the other is neither helped nor harmed. In the case of caribou and reindeer, both species are vying for the same food sources, which does not fit the definition of commensalism as neither species is benefiting without impacting the other.

Mutualism occurs when both species involved in the interaction benefit from one another. While caribou and reindeer may coexist in their environment, they do not have a mutualistic relationship since their competition for resources can lead to negative impacts on one or both populations, rather than benefits.

Parasitism describes a relationship where one organism benefits at the expense of another, typically involving a parasite-host dynamic. Caribou and reindeer do not exhibit this relationship; instead, they are both herbivores competing for the same food sources, which does not involve one benefiting at the other's expense in the traditional parasitic sense.