How can a keystone species affect an environment?

A keystone species plays a crucial role in maintaining the structure and balance of an ecosystem. Its presence or absence can significantly impact the population dynamics of other species, influencing biodiversity and ecosystem health. For example, predators like sea otters control sea urchin populations, which in turn helps maintain kelp forests. When keystone species are removed, it can lead to dramatic changes, often resulting in ecosystem collapse or reduced biodiversity.