What term describes a behavior where one species benefits at a cost to another?

The term that describes a behavior where one species benefits at a cost to another is predation. In this interaction, the predator gains nourishment and other benefits by consuming the prey, which suffers a cost in the form of its life or fitness. This relationship is essential for the balance of ecosystems, as it influences population dynamics and drives natural selection.

In contrast, commensalism refers to a relationship where one species benefits while the other is neither helped nor harmed. Altruism involves one species acting in a way that benefits another at a potential cost to itself, such as when an individual sacrifices its own well-being for the sake of another. Competition occurs when two species vie for the same resources, leading to negative effects for both but does not inherently involve one benefiting directly at the expense of another in the same way predation does.