What term refers to species that greatly affect the populations and health of an ecosystem?

The term that refers to species that greatly affect the populations and health of an ecosystem is "keystone species." Keystone species play a critical role in maintaining the structure, diversity, and overall balance of their ecosystems. Their presence or absence can lead to significant changes in the ecosystem, influencing various other species and processes within it.

For instance, a keystone species can regulate populations of other organisms, which in turn can impact the availability of resources and habitat for numerous other species. The classic example of a keystone species is the sea otter, which preys on sea urchins. If sea otters are removed from their ecosystem, the sea urchin population can explode, leading to the overgrazing of kelp forests, ultimately damaging the entire marine ecosystem.

Other terms relate to different ecological concepts. Indicator species, for example, are organisms whose presence, absence, or abundance can indicate the overall health of an ecosystem, while generalist species are adaptable to various environments and can thrive in a range of conditions. Specialist species, on the other hand, are adapted to specific ecological niches and can be vulnerable if conditions change. While these concepts are important in ecology, they do not encapsulate the pivotal role that keystone species play in maintaining