Which might NOT be considered a keystone species in its habitat?

Question

Quizplus · Accepted Answer

All of the above can be considered keystone species in their respective habitats. A keystone species is a species that has a disproportionate effect on its environment relative to its abundance. Prey species can act as a keystone species if they are a major food source for many predators, and their decline can cause a ripple effect throughout the food web. Predator species can act as a keystone species if they keep the populations of other species in check, preventing one species from dominating the ecosystem. Plants that feed insects can act as a keystone species if their decline leads to a decline in the insect population, disrupting the food chain. Insects that pollinate plants can act as a keystone species by facilitating the reproduction of many plant species, which in turn serve as important food sources for other species.

Which Might NOT Be Considered a Keystone Species in Its