What role do keystone species play in ecosystems?

Keystone species are crucial in maintaining the structure and diversity of ecosystems because their presence or activities have a disproportionately large effect on the environment compared to their abundance. This means that a keystone species plays a vital role in regulating the populations of other species in the ecosystem, which contributes to a balanced and functioning community. For instance, predators can help to control the population size of herbivores, preventing overgrazing and allowing vegetation to thrive, which in turn supports a range of other organisms. The loss of a keystone species can lead to significant changes in the ecosystem, often resulting in a decline in biodiversity and the disruption of ecological processes. Overall, the influence of keystone species is critical for sustaining the integrity of the ecosystem, making choice C the correct understanding of their role.