Final answer:
Increased keystone species and increased foundation species contribute to the diversity of an ecosystem.
Step-by-step explanation:
The diversity of an ecosystem can be contributed by increased keystone species and increased foundation species. Keystone species are those that have a disproportionate impact on the ecosystem's structure and biodiversity. Their presence affects the prevalence of various species and can lead to changes in species composition and biodiversity if removed from the ecosystem. Foundation species, on the other hand, provide important resources or habitat for other species, supporting and promoting biodiversity within the ecosystem.