Under what circumstances does symbiosis occur?

Symbiosis occurs under the circumstances where two species have a close relationship, which can manifest in various forms such as mutualism, commensalism, and parasitism. In mutualistic relationships, both species benefit; in commensalism, one species benefits while the other is neither helped nor harmed; and in parasitism, one species benefits at the expense of the other. The defining characteristic of symbiosis is the close and often long-term interaction between the organisms involved, indicating the complex nature of ecological relationships.

In contrast, competition for resources typically leads to negative interactions between species, where one or both species may suffer due to limited resources. Predation involves a direct interaction where one organism (the predator) hunts and consumes another (the prey), which is not classified as symbiosis since it is a relationship characterized by one organism living off another in a more predatory context, rather than a close, often mutually beneficial relationship. Lastly, while parasitism is a form of symbiosis, it is important to note that not all close relationships involve parasitism; thus, symbiosis is a broader term that encompasses multiple types of interactions beyond just parasitic ones.