Biology

The correct answer is: D.They have a disproportionately large impact on their environment relative to their abundance.

Keystone species play a crucial role in maintaining the structure and balance of an ecosystem. Despite their relatively low abundance or biomass, their presence has a significant impact on the overall ecosystem. For example:

1.Predators (like sea otters) control the populations of prey species, which helps maintain biodiversity.

2.Pollinators (like bees) ensure the reproduction of many plants, supporting entire food webs.

3.Ecosystem engineers (like beavers or coral) physically alter habitats in ways that benefit many other species.