Keystone species play a critical role in maintaining biodiversity by influencing the structure and function of their ecosystems. These species, often predators, herbivores, or ecological engineers, help to create and maintain habitats, which supports a wide range of other species. Their removal can lead to dramatic shifts in community composition and ecosystem health, resulting in declines in biodiversity. By regulating populations of other species, they ensure that ecosystems remain balanced and resilient, highlighting their importance in conservation efforts aimed at preserving ecological integrity.