What effect would the removal of a keystone species have on an ecological community?

Write a short essay that explains this effect in terms of trophic cascade. Provide a specific example that illustrates this process.

Keystone species have low functional redundancy. This means that if the species were to disappear from the ecosystem, no other species would be able to fill its ecological niche. The ecosystem would be forced to radically change, allowing new and possibly invasive species to populate the habitat.