What distinguishes keystone species from dominant species in an ecosystem?

Keystone species are characterized by their significant influence on the structure and dynamics of an ecosystem, despite often being relatively low in biomass. Their roles can be crucial in maintaining the ecological balance and diversity within their communities. For instance, a keystone species might control the population of a critical prey or predator, thus affecting multiple other species and the overall health of the ecosystem. This high impact relative to their biomass means that their presence or absence can lead to dramatic changes in the community structure.

In contrast, dominant species tend to have a large biomass and may exert influence due to their abundance, but they do not necessarily play the same pivotal role in maintaining ecological balance. The defining factor for a keystone species is the profound influence they have on their environment, which goes beyond what would be expected based solely on their numbers or biomass.

The other options do not accurately capture the essence of what distinguishes keystone species. While some keystone species might be small in biomass, this is not a defining characteristic in every case. Dominant species can have a significant effect on their environment, contrary to the idea they have no influence. Furthermore, while biomes may be conceptually linked to certain species, they are not named after keystone species specifically, as biomes